Engine Control System - Self-Diagnostics - 4.6l Cadillac Seville V

INTRODUCTION

To properly diagnose and repair this vehicle, follow DIAGNOSTIC PROCEDURE under SELF-DIAGNOSTIC SYSTEM. If no Diagnostic Trouble Codes (DTC) are present and a no-start condition exists, proceed to appropriate BASIC DIAGNOSTIC PROCEDURES article. If no DTCs are present and a driveability condition exists, proceed to the appropriate TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

ON-BOARD DIAGNOSTICS

The Malfunction Indicator Light (MIL) is located on the right side of instrument cluster and is displayed as an engine icon. The MIL is controlled by the Powertrain Control Module (PCM) and is used to indicate that the PCM has detected a problem that affects vehicle emissions and a Diagnostic Trouble Code (DTC) is present. When ignition is first turned on, MIL should come on and remain on until engine is started to verify bulb and circuit operation. If MIL does not illuminate at all, diagnose MIL circuits. See MALFUNCTION INDICATOR LIGHT INOPERATIVE under SYSTEM TESTS. The PCM is programmed with test routines that check the operation of the various systems that the PCM controls. Some tests check the internal functions of the PCM. Some tests are run continuously while other tests run only under specific conditions (referred to as code enable criteria). When the vehicle is operating within the conditions for running a particular test, the PCM checks certain parameters and determines whether or not the values are within an expected range. When the conditions for setting the DTC are met, the PCM will store a DTC and, if code is emission related, illuminate the MIL. The PCM also saves data and input parameters when most DTCs are set. This data is stored in FREEZE FRAME and/or FAILURE RECORDS. See FREEZE FRAME and FAILURE RECORDS .

Freeze Frame

Government regulations require that engine operating conditions be captured whenever the Malfunction Indicator Light (MIL) is illuminated. The data captured is called freeze frame data. The freeze frame data is very similar to a single record of operating conditions. Whenever the MIL is illuminated, the corresponding record of operating conditions is recorded as freeze frame data. A subsequent failure will not update the recorded information. Freeze frame data can only be overwritten with data associated with a misfire or fuel trim malfunction. Data from these faults take precedence over data associated with any other fault. The freeze frame data will not be erased unless the associated history DTC is cleared. The following freeze frame data parameters are stored with a DTC failure.

1. Air/Fuel Ratio
2. Mass Airflow Sensor
3. Fuel Trim (Both Short Term And Long Term For Both Cylinder Banks)
4. Engine Speed
5. Intake Air Temperature
6. Engine Coolant Temperature
7. Vehicle Speed
8. Throttle Position Angle
9. Manifold Absolute Pressure/Barometric Pressure
10. Fuel System Status

Failure Records

When a diagnostic test fails, the Powertrain Control Module (PCM) stores the information as failure records data. Unlike freeze frame data, failure records are stored for multiple Diagnostic Trouble Codes (DTC) or non-emission related DTCs (DTCs that do not illuminate the MIL). The failure records information is updated the first time the test fails during each ignition cycle. Freeze frame/failure records data may be retrieved by using a scan tool. If more than one DTC is set, review the odometer or engine run time data located in the freeze frame/failure records info to determine the most current failure. The stored information will look like normal PCM data. Always capture freeze frame/failure records data information with the scan tool before proceeding with any diagnosis. Loss of this data may prevent accurate diagnosis of an intermittent condition.

DIAGNOSTIC PROCEDURE

Diagnosis of computerized engine control system should be performed in the following order

1. Ensure all engine systems not related to computer system are operating properly. DO NOT proceed with testing unless all other problems have been repaired. Powertrain diagnostic system check must be performed before using specific Diagnostic Trouble Code (DTC) testing procedure. See «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under DIAGNOSTIC SYSTEM CHECKS.
2. If no DTCs are present and a driveability problem exists, diagnose by symptom. See appropriate TROUBLE SHOOTING - NO CODES article. After repairs are made, clear DTCs, verify vehicle will enter "closed loop" operation and ensure DTC does not reset.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Diagnostic Trouble Codes (DTC) are retrieved using a Tech 2 scan tool, or other OBD-II compatible scan tool connected to Data Link Connector (DLC). (Scheme 1) DLC is located below left side of instrument panel. To retrieve DTCs, powertrain diagnostic system check must be performed. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK under DIAGNOSTIC SYSTEM CHECKS.

Scheme 1

CLEARING DIAGNOSTIC TROUBLE CODES

Note. Manufacturer does not recommend disconnecting the battery to clear Powertrain Control Module (PCM) memory. Disconnecting battery may or may not clear PCM memory, but other memory system memories will be cleared. On many OBD-II systems, PCM will retain memory for an extended period of time even with battery disconnected.

Using Scan Tool

Using scan tool manufacturer's instructions, clear DTCs. Freeze frame and failure record data will also be cleared. PCM adaptive learning and system monitors will only be cleared for system which had a stored DTC.

Self-Erasure

After 3 consecutive ignition cycles that the diagnostic runs and does not fail, PCM will turn off the malfunction indicator light. At that time, the PCM will automatically switch to a warm-up cycle counter. A warm-up cycle occurs when engine temperature increases 22°F from start-up and reaches a minimum of 160°F (71°C). The PCM will clear DTCs from memory after 40 consecutive warm-up cycles if the recent malfunction does not reoccur in that time.

SCAN TOOL USAGE

Note. OBD-II vehicles have options available in the scan tool DTC mode to display enhanced information available. However, to fully utilize information and procedures requires the use of a Tech 2 scan tool. See scan tool operator's manual for additional information.

Scan Tool Displays

When scan tool displays a Diagnostic Trouble Code (DTC), status of DTC is also displayed. The following are Tech 2 scan tool sub-menus in the DTC INFO and SPECIFIC DTC modes. DTC statuses will be indicated only when they apply to the DTC that is set.

1. FAIL THIS IGN. This selection indicates that this DTC failed during the present ignition cycle.
2. LAST TEST FAIL This selection indicates that this DTC failed the last time the test ran. If type "A" or "B" DTCs are displayed, the last test may have ran during the previous ignition cycle. For type "C" DTCs, the last failure must have occurred during the current ignition cycle to be displayed as LAST TEST FAIL.
3. MIL REQUEST This selection indicates that this DTC is currently requesting MIL illumination. This selection will report type "B" DTCs only after MIL illumination has been requested (failed twice).
4. TEST FAIL SCC Test Fail Since Code Clear (SCC) indicates that this DTC is active since the last time DTCs were cleared.
5. HISTORY This selection indicates that this DTC is stored in the PCM history memory. Type "B" DTCs will not appear in history until they have been requested by the MIL (failed twice). History will display all type "A" and type "B" DTCs that have the MIL illuminated and have failed within the last 40 warm-up cycles. It will also display type "C" DTCs that have failed within the 40 warm-up cycles.
6. NOT RUN SCC Not Run Since Code Clear (SSC) will display DTCs that have not run since DTCs were last cleared. Since any displayed DTCs have not run, their condition (passing or failing) is unknown.

POWERTRAIN CONTROL MODULE LOCATION

The powertrain control module is located in engine compartment, inside air filter housing.

ENGINE COOLING DIAGNOSTIC SYSTEM CHECK

1. Connect scan tool to Data Link Connector (DLC). (Scheme 1) DLC is located below left side of instrument panel. Turn ignition on. If scan tool powers up, go to next step. If scan tool does not power up, see «SCAN TOOL DOES NOT POWER UP»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) under SYSTEM TESTS.
2. Using scan tool, attempt to communicate with Instrument Panel Cluster (IPC) and Powertrain Control Module (PCM). If scan tool communicates with IPC and PCM, go to next step. If scan tool does not communicate with IPC and PCM, diagnose communication problem. See TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Using scan tool, select PCM display DTCs function. If scan tool displays any DTCs, go to next step. If scan tool does not display DTCs, repair engine cooling system by symptom. See ELECTRIC COOLING FANS - CARS article in ENGINE COOLING.
4. If scan tool displays any DTCs that begin with "U", diagnose communication problem. See TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display any DTCs that begin with "U", repair other DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK

1. Ensure battery is correct battery for vehicle. Ensure battery is fully charged and in good working condition. Replace battery as necessary. If battery is okay, go to next step.
2. Connect scan tool, if not already connected. Turn ignition on. If scan tool powers up, go to next step. If scan tool does not power up, see «SCAN TOOL DOES NOT POWER UP»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) under SYSTEM TESTS.
3. Using scan tool, attempt to communicate with attempt to communicate with each module on class 2 serial data circuit. If scan tool communicates with all modules on class 2 serial data circuit, go to next step. If scan tool does not communicate with all modules on class 2 serial data circuit, diagnose communication problem. See TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
4. Using scan tool, select display DTCs function. If scan tool displays any DTCs, go to next step. If scan tool does not display DTCs, repair charging system by symptom. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.
5. If scan tool displays any DTCs that begin with "U", diagnose communication problem. See TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display any DTCs that begin with "U", go to next step.
6. If scan tool displays DTC B1000, B1007 or B1009, repair as necessary. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display DTC B1000, B1007 or B1009, repair other DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

POWERTRAIN DIAGNOSTIC SYSTEM CHECK

Note. Check for applicable technical service bulletins before proceeding. Do not perform the following procedure if no driveability conditions exists, unless directed here from another procedure. Do not turn ignition off during the following procedure or clear DTCs unless instructed to do so.

1. If a condition exists with starting system, perform engine electrical diagnostic system check. See «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__engine-electrical-diagnostic-system-check) . Ensure battery is fully charged and cables are clean and tight. Ensure Powertrain Control Module (PCM) grounds are clean, tight, and in proper location. See WIRING DIAGRAMS article. PCM is located in engine compartment, inside air filter housing. Install scan tool. If scan tool powers up, go to next step. If scan tool does not power up, see «SCAN TOOL DOES NOT POWER UP»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) under SYSTEM TESTS.
2. Turn ignition on. Attempt to establish communication with PCM, Electronic Brake Control Module (EBCM) and Vehicle Theft Deterrent (VTD) module. If scan tool communicates with all control modules, go to next step. If scan tool does not communicate with all control modules, diagnose communication problem. See TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Attempt to start engine. If engine starts and idles, go to next step. If engine does not start and idle, diagnose engine cranks, but does not start. See NO-START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
4. Using scan tool, select DTC display function for PCM, EBCM and VTD. If any DTCs are present, record DTCs, which module set the DTC and failure record for DTC. Go to next step. If no DTCs are present, go to step 8 .
5. If scan tool displays any DTCs that begin with "U", diagnose communication problem. See TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display any DTCs that begin with "U", go to next step.
6. If scan tool displays DTC P0601, P0602, P0603, P0604, P0606 or P1621, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not display DTC P0601, P0602, P0603, P0604, P0606 or P1621, go to next step.
7. If scan tool displays DTC P0560, P0562, P0563, P0621 or P0622, see appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If scan tool does not display DTC P0562, P0563, P0621 or P0622, diagnose any other DTCs that are present. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .
8. If customer's concern is with the automatic transmission, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS. If customer's concern is not with the automatic transmission, go to next step.
9. If customer's concern is MIL inoperative, diagnose MIL circuits. See «MALFUNCTION INDICATOR LIGHT INOPERATIVE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) under SYSTEM TESTS. If customer's concern is MIL always on, diagnose MIL circuits. See «MALFUNCTION INDICATOR LIGHT ALWAYS ON»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__malfunction-indicator-light-always-on) under SYSTEM TESTS. If customer's concern is a driveability problem, diagnose by symptom. See appropriate TROUBLE SHOOTING - NO CODES article.

POWERTRAIN CONTROL MODULE

After replacing Powertrain Control Module (PCM) or if program needs to be updated, refer to latest Techline information on PCM reprogramming. PCM can only be programmed using Tech 2 and Techline terminal, or by using a personal computer equipped with the current service programming system software installed. After reprogramming, perform INSPECTION/MAINTENANCE PROCEDURES , CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE , OIL LIFE INDEX RESET , IDLE LEARN PROCEDURE and PROGRAMMING THEFT DETERRENT SYSTEM COMPONENTS .

CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE

Battery must be fully charged and in good condition. Scan tool connection at Data Link Connector (DLC) should be clean and tight before starting crankshaft position system variation learn procedure.

1. Close hood. Block drive wheels and set vehicle parking brake. Turn all accessories off. Start engine. Ensure engine is at least 158°F (70°C). Turn ignition off. Using scan tool, select and enable CRANKSHAFT POSITION SYSTEM VARIATION LEARNING PROCEDURE. Start engine.
2. Ensure transaxle is Park. Press and hold brake pedal firmly. Increase engine speed until fuel cutoff is reached at 5150 RPM. Immediately release accelerator pedal after fuel cutoff is reached. The crankshaft position system variation compensating values are learned when the RPM decreases back to idle. Monitor status for DTC P1336.
3. If scan tool indicates DTC P1336 ran and passed, crankshaft position system variation learn procedure is complete. If scan tool indicates DTC P1336 failed or did not run, check for additional DTCs and repair as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If only DTC P1336 is set, repeat crankshaft position system variation learn procedure as necessary.

OIL LIFE INDEX RESET

Note. Oil life index needs to be reset when powertrain control module is replaced.

Turn ignition on. Press the SELECT button on Driver Information Center (DIC) until the OIL LIFE % is displayed. Press and hold the RESET button on DIC until the display reads OIL LIFE 100%. The engine oil life monitor is now reset. Turn ignition off.

IDLE LEARN PROCEDURE

Note. When Powertrain Control Module (PCM) or battery are disconnected, PCM loses power, or PCM is reprogrammed, PCM learned idle position is lost. When learned idle position is lost, engine idle will be unstable.

Start and allow it to idle for 15 seconds. Turn ignition off. Wait 15 seconds. Restart engine and check for proper idle operation.

PROGRAMMING THEFT DETERRENT SYSTEM COMPONENTS

If replacing a Powertrain Control Module (PCM) with a replacement part, after programming, these modules will learn incoming fuel continue password immediately upon receipt of a password message. Once a password message is received and a password is learned, a learn procedure must be performed to change this password again. A PCM which has been previously installed in another vehicle will have learned the other vehicle's fuel continue password and will require a learn procedure after programming to learn current vehicle's password.

1. Turn ignition on. Attempt to start engine, then release key to ON position (vehicle will not start). Observe SECURITY indicator. After about 10 minutes, SECURITY indicator will turn off. Turn ignition off and wait 5 seconds.
2. Repeat step 1 2 more times for a total of 3 cycles in 30 minutes. Vehicle is now ready to relearn key transponder information and/or passwords on next ignition switch transition from OFF to CRANK position.
3. Start engine. Vehicle has now learned the key transponder information and the PCM has now learned the fuel continue password. Using scan tool, clear any DTCs if needed.

DRIVE CYCLES

For drive cycle procedure, see INSPECTION/MAINTENANCE SYSTEM CHECK .

Description

Several states require that a vehicle pass On-Board Diagnostic (OBD) system tests and the Inspection/Maintenance (I/M) emission inspection in order to renew license plates. This is accomplished by viewing the I/M system status display on a scan tool. Using a scan tool, the I/M system status can observed in order to verify that the vehicle meets the criteria that complies with local area requirements.

Conditions For Updating I/M System Status

Each system requires at least one, and sometimes several, diagnostic tests. The results of these tests are reported by a Diagnostic Trouble Code (DTC). A system monitor is complete when either all of the DTCs comprising the monitor have run and passed, or when any one of the DTCs comprising the monitor have illuminated the Malfunction Indicator Light (MIL). Once all of the tests are completed, the I/M system status display will indicate YES in the completed column. For example, when the HO2S heater test indicates YES, all 3 of the oxygen sensor heaters and circuits have been diagnosed. The I/M system status will indicate NO under the completed column when any of the required tests for that system have not run. The following is a list of conditions that will set the I/M system status indicator to NO

1. Vehicle is new from the factory and has not yet been driven through the necessary drive conditions in order to complete the tests.
2. Battery has been disconnected or discharged to less than operating voltage.
3. The PCM power or ground has been interrupted.
4. The PCM has been reprogrammed.
5. PCM DTCs have been cleared as part of a service procedure.

Diagnostic Procedures

1. Perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. If DTC or driveability concern was repaired using powertrain diagnostic system check, go to step 3 . If no DTC or driveability concern was repaired using powertrain diagnostic system check, go to next step.
2. Check for applicable Technical Service Bulletins (TSB) for software updates that may prevent Inspection/Maintenance (I/M) readiness. Perform any reprogramming or repairs indicated by TSBs. If reprogramming or repair service was required, go to «INSPECTION/MAINTENANCE COMPLETE SYSTEM SET PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . If reprogramming or repair service was not required, go to next step.
3. Using scan tool, observe I/M system status display. If more than one test indicates a NO status, go to «INSPECTION/MAINTENANCE COMPLETE SYSTEM SET PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . If only one test indicates a NO status, perform appropriate I/M system set procedure for indicated system. See «INSPECTION/MAINTENANCE SYSTEM SET PROCEDURE INDEX»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) table. INSPECTION/MAINTENANCE SYSTEM SET PROCEDURE INDEX System With NO Status Perform AIR System «INSPECTION/MAINTENANCE AIR SYSTEM SET PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) Catalyst System «INSPECTION/MAINTENANCE CATALYST SYSTEM SET PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) EGR System «INSPECTION/MAINTENANCE EXHAUST GAS RECIRCULATION SYSTEM SET PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) EVAP System «INSPECTION/MAINTENANCE EVAPORATIVE EMISSION SYSTEM SET PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) HO2S/O2S System «INSPECTION/MAINTENANCE HEATED OXYGEN SENSOR/OXYGEN SENSOR SYSTEM SET PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) HO2S Heater System «INSPECTION/MAINTENANCE HEATED OXYGEN SENSOR HEATER SYSTEM SET PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l)

Diagnostic Aids

I/M system status display provides an indication of when control module has completed required tests. This does not necessarily mean that test has passed, only that test has run. If diagnostics fail, a DTC will indicate failure. If a failure indication is present for a DTC associated with one of the I/M regulated systems, it may prevent other required tests from running. I/M system status information may be useful for a technician to determine if diagnostics have run when verifying repairs.

Purpose of this test is to satisfy enable criteria necessary to execute all Inspection/Maintenance (I/M) readiness diagnostics, and to complete the trips (drive cycles) for those particular diagnostics. When all diagnostic tests have been completed, I/M system status indicators are set to YES. Perform this test when more than one or all of the I/M system status indicators are set to NO.

Enable Criteria

Ensure vehicle meets the following conditions before performing procedure

1. Barometric pressure is more than 10.4 psi (72 kPa).
2. Engine coolant temperature is 41-248°F (5-120°C).
3. Intake air temperature is 21-392°F (-6 to 200°C).
4. Battery voltage is 9-18 volts.
5. Fuel level is 1/4-3/4 full.

Note. Before performing this procedure, read diagnostic aid information. See DIAGNOSTIC AIDS .

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . NOTE: Whenever ignition is on, ignition voltage is supplied to Heated Oxygen Sensor (HO2S) heaters. After verifying enable criteria, turn ignition off for approximately 5 minutes to allow sensors to cool before continuing test. Once engine is started, DO NOT turn engine off for remaining portion of procedure.
2. Program scan tool with vehicle information before ignition is turned on. Turn off all accessories, including A/C and blower fan. Set vehicle parking brake. Ensure transmission is in Park. Ensure vehicle meets conditions for running this procedure. See «ENABLE CRITERIA»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__enable-criteria) . Start engine. Allow engine to idle. Allow engine to idle for 2 minutes. Go to next step.
3. Test drive vehicle. Ensure vehicle is accelerated at part throttle to 55 MPH. Drive vehicle at 55 MPH until engine reaches normal operating temperature. This may take 8-10 minutes depending on start-up coolant temperature. Continue test driving vehicle under these conditions for 6 minutes. Go to next step.
4. Reduce vehicle speed to 45 MPH, maintain this speed for one additional minute. Perform 4 decelerations of 25 seconds each from 45 MPH while maintaining the following criteria: Throttle is closed. No brake application. No manual downshift. Vehicle speed remains greater than 25 MPH. After each deceleration period, vehicle speed is returned to 45 MPH under part throttle acceleration and speed is maintained for 15 seconds. Go to next step.
5. Accelerate vehicle at part throttle to 45-55 MPH. Maintain this speed for 2 minutes. Decelerate vehicle to zero MPH. Idle engine for 2 minutes while service brake is depressed and transmission is in Drive. Go to next step.
6. Using scan tool, observe I/M system status display. If all I/M system status indicators updated to YES, go to next step. If any I/M system status indicator did not update to YES, repeat procedure.
7. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate emission related DTCs, system is okay.

Rough road conditions may prevent some tests from running. Extreme high or low ambient temperatures may prevent tests such as HO2S heater and evaporative emission system from initiating. If step is interrupted before completion, perform remaining portion of test procedures. Any portion of test procedure that requires the engine at operating temperature may be repeated. This allows most diagnostics to run and the remaining tests can be performed using individual system set procedures.

If vehicle has recently run, start this procedure at step 3 . This will allow the tests that require engine at operating temperature to run. Using this method allows shorter cool down periods if the tests requiring a cold start do not initiate.

Scan tool can be used to monitor each I/M system status indicator. When all indicators for a test step have updated to YES, testing can move on to next step even if remaining portion of the test is not complete. For example, step 3 is designed to run EVAP, AIR, and HO2S tests. The procedure instructs technician to operate the vehicle in enable conditions for 6 minutes. If all 3 tests have updated to YES within 4 minutes, you do not need to continue with the enable conditions and testing can advance to the next step.

Purpose of this test is to satisfy the enable criteria necessary to execute Inspection/Maintenance (I/M) readiness diagnostics for the Secondary Air Injection (AIR) system. Test may be used to set the I/M system status indicators to YES. Ensure vehicle meets conditions listed in enable criteria before performing procedure. Failure to meet any of the conditions listed may produce inaccurate test results. See ENABLE CRITERIA .

The following conditions are for running a passive test (engine in open loop).

1. Start-up coolant temperature is 41-176°F (5-80°C).
2. Engine coolant temperature is 41-226°F (5-108°C).
3. Intake air temperature is 41-163°F (5-73°C).
4. Mass airflow is less than 35 grams/sec.
5. Air/fuel ratio is more than 12.1:1.
6. Manifold absolute pressure is more than 7.3 psi (50 kPa).
7. Battery voltage is more than 10.2 volts.

The following conditions are for running an active test (engine in closed loop).

1. A failed or inconclusive passive test.
2. Engine load is less than 80 percent.
3. Engine speed is more than 1000 RPM.
4. Engine is operating is closed loop fuel control.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
2. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle for 2 minutes. Accelerate at part throttle to 45 MPH and maintain speed for 3 minutes or until or until I/M system status indicator updates to YES. Using scan tool, monitor I/M system status display. If AIR system status updates to YES, go to step 5 . If AIR system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0410, P1415 and P1416 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If AIR system status updated to YES, go to next step. If AIR system status did not update to YES, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any emission related DTCs, system is okay.

The AIR pump generally operates once per ignition cycle, usually upon initial start-up before the engine goes into closed loop fuel control. Some systems will perform a passive diagnostic test at this time. The active diagnostic test is performed after the engine goes into closed loop fuel control. On vehicles that perform a passive test, the active test will only run if the passive test fails or is intermittent. The active test may not run if the passive test passes.

I/M system status does not indicate whether test has passed or failed, only that test has run. When all diagnostics for a specific system have run and passed, I/M system status will update to YES. If a test for a specific system has failed, I/M system status will update to YES, indicating a determination was made, even if all required tests have not run. When a failure occurs, DTC emission related DTC portion of the I/M system status display will indicate malfunction indicator light is requested. I/M system status also registers number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

Purpose of this test is to satisfy enable criteria necessary to execute Inspection/Maintenance (I/M) readiness diagnostics for the catalyst system. Test may be used to set I/M system status indicators to YES. Ensure vehicle meets conditions listed in enable criteria before performing procedure. Failure to meet any of the conditions listed may produce inaccurate test results. See ENABLE CRITERIA .

1. Barometric pressure is more than 10.5 psi (72 kPa).
2. Engine coolant temperature is 203-212°F (95-100°C), normal operating temperature.
3. Intake air temperature is 21-392°F (-6 to 200°C).
4. Engine is in closed loop.
5. Engine has run for 10 minutes off idle in order to initiate a test.
6. Battery voltage is 10-16 volts.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
2. Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle. Accelerate at part throttle to 55 MPH and maintain speed for 5 minutes. Decelerate to a stop. Allow engine to idle for 2 minutes with service brake applied and transmission in Drive. Using scan tool, monitor I/M system status display. If CATALYST system status updates to YES, go to step 5 . If CATALYST system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, monitor DTC P0420. Operate vehicle within code enable criteria for DTC P0420. See «DTC P0420:CATALYST SYSTEM LOW EFFICIENCY»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) under DIAGNOSTIC TESTS. Operate vehicle within code enable criteria until scan tool indicates diagnostic test has run. Using scan tool, observe I/M system status display. If CATALYST system status updates to YES, go to next step. If CATALYST system status did not update to YES, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any emission related DTCs, system is okay.

The PCM runs a maximum of 12 tests per trip until the catalyst system status updates to YES. If the status does not update, the test outlined in this procedure can be repeated until the I/M system status updates to YES. The I/M system status does not indicate whether the test has passed or failed, only that a decision was made. When all of the diagnostics for a specific system have run and passed, the I/M system status updates to YES. If a test for a specific system has failed, the I/M system status updates to YES, indicating a determination was made, even if all of the required tests have not run. When a failure occurs, the emission related DTC portion of the I/M system status display indicates the malfunction indicator light is requested. The I/M system status also registers the number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

Purpose of this test is to satisfy enable criteria necessary to execute Inspection/Maintenance (I/M) readiness diagnostics for the Exhaust Gas Recirculation (EGR) system. Test may be used to set I/M system status indicators to YES. Ensure vehicle meets conditions listed in enable criteria before performing procedure. Failure to meet any of the conditions listed may produce inaccurate test results. See ENABLE CRITERIA .

1. Barometric pressure is more than 10 psi (70 kPa).
2. Engine coolant temperature is 176-230°F (80-110°C).
3. Intake air temperature is less than 122°F (50°C).
4. Idle speed is steady.
5. Battery voltage is 11-18 volts.
6. Transmission state is steady.
7. Vehicle speed is greater than 23 MPH.
8. A/C state is steady.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
2. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle. Accelerate at part throttle to 45 MPH and maintain speed for one minute. Perform 4 decelerations of 25 seconds each from 45 MPH while maintaining the following criteria: Throttle is closed. No brake application. No manual downshift. Vehicle speed remains greater than 25 MPH. After each deceleration period, vehicle speed is returned to 45 MPH under part throttle acceleration and speed is maintained for 15 seconds. Using scan tool, observe I/M system status display. If EGR system status updates to YES, go to step 5 . If EGR system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0401, P0404, P0405 and P1404 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If EGR system status updated to YES, go to next step. If EGR system status did not update to YES, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any emission related DTCs, system is okay.

Powertrain control module only runs the EGR active tests during a gradual deceleration with a closed throttle and with vehicle speed greater than 23 MPH. Several deceleration cycles may be necessary in order to accumulate a sufficient number of EGR flow samples. This procedure is for a clear, flat road. If procedure is performed on a road with a slight downhill grade, the test may acquire the necessary sample counters in one or 2 decel trips. If the test is interrupted during the procedure, it may take more than 10 deceleration cycles in order to complete the test. If the status does not update, the test outlined in this procedure can be repeated until the I/M system status updates to YES.

I/M system status does not indicate whether test has passed or failed, only that test has run. When all diagnostics for a specific system have run and passed, I/M system status will update to YES. If a test for a specific system has failed, I/M system status will update to YES, indicating a determination was made, even if all required tests have not run. When a failure occurs, DTC emission related DTC portion of the I/M system status display will indicate malfunction indicator light is requested. I/M system status also registers number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

Purpose of this test is to satisfy enable criteria necessary to execute Inspection/Maintenance (I/M) readiness diagnostics for the Evaporative Emission (EVAP) system. Test may be used to set I/M system status indicators to YES. Ensure vehicle meets conditions listed in enable criteria before performing procedure. Failure to meet any of the conditions listed may produce inaccurate test results. See ENABLE CRITERIA .

1. Barometric pressure is more than 10.5 psi (72 kPa).
2. Engine coolant temperature is less than 122°F (50°C).
3. Fuel level is 1/4-3/4 full.
4. Battery voltage is 10-16 volts.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
2. Using a scan tool, select SPECIAL FUNCTIONS. Determine if vehicle is equipped with a SERVICE BAY TEST for EVAP system. If vehicle equipped with EVAP SERVICE BAY TEST, go to next step. If vehicle is not equipped with EVAP SERVICE BAY TEST, go to step 5 .
3. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . Turn off all accessories, including A/C and blower fan. Follow scan tool instructions and perform EVAP SERVICE BAY TEST. If EVAP system passed SERVICE BAY TEST, go to step 8 . If EVAP system did not pass SERVICE BAY TEST, go to next step.
4. Observe scan tool SERVICE BAY TEST for an indication of why test did not pass. Example, a failed DTC or test aborted. If DTC failed, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . After repairs, perform «INSPECTION/MAINTENANCE COMPLETE SYSTEM SET PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
5. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle. Operate vehicle under the following conditions: Acceleration at part throttle to 45 MPH. Maintain this speed until engine reaches normal operating temperature. This may take 8-10 minutes depending on start-up coolant temperature. Continue the operating conditions for an additional 3 minutes after engine reaches normal operating temperature, or until I/M system status indicator updates to YES. If EVAP system status updates to YES, go to step 8 . If EVAP system status does not update to YES, go to next step.
6. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any failed DTCs, go to next step.
7. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0440, P0442, P0446 and P1441 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If EVAP system status updated to YES, go to next step. If EVAP system status did not update to YES, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
8. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any emission related DTCs, system is okay.

Extreme high or low ambient temperatures may prevent EVAP system tests from initiating. Performing a visual inspection prior to running test may prevent having to repeat test. A loose fuel cap may cause test to abort or fail and prevent I/M system from updating. A failed or aborted test will require vehicle to cool down in order to meet enable criteria to run another test.

I/M system status does not indicate whether test has passed or failed, only that test has run. When all diagnostics for a specific system have run and passed, I/M system status will update to YES. If a test for a specific system has failed, I/M system status will update to YES, indicating a determination was made, even if all required tests have not run. When a failure occurs, DTC emission related DTC portion of the I/M system status display will indicate malfunction indicator light is requested. I/M system status also registers number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

Purpose of this test is to satisfy enable criteria necessary to execute Inspection/Maintenance (I/M) readiness diagnostics for Heated Oxygen Sensor/Oxygen Sensor (HO2S/O2S) system. Test may be used to set I/M system status indicators to YES. Ensure vehicle meets conditions listed in enable criteria before performing procedure. Failure to meet any of the conditions listed may produce inaccurate test results. See ENABLE CRITERIA .

1. Engine coolant temperature is more than 176°F (80°C).
2. Engine is in closed loop.
3. Engine has been running more than 4 minutes.
4. Battery voltage is 11.6-16.0 volts.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
2. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle. Accelerate at part throttle to 45-55 MPH and maintain speed for 6 minutes or until I/M system status updates to YES. Using scan tool, observe I/M system status. If HO2S/O2S system status updated to YES, go to step 5 . If HO2S/O2S system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0133, P0140, P0153, P1133, P1134, P1153 and P1154 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If HO2S/O2S system status updated to YES, go to next step. If HO2S/O2S system status did not update to YES, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any emission related DTCs, system is okay.

If status does not update, test outlined in this procedure can be repeated until I/M system status updates to YES.

I/M system status does not indicate whether test has passed or failed, only that test was run. When all diagnostics for a specific system have run and passed, I/M system status will update to YES. If a test for a specific system has failed, I/M system status will update to YES, indicating a determination was made, even if all required tests have not run. When a failure occurs, DTC portion of the I/M system status display will indicate malfunction indicator light is requested. I/M system status also registers number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

Purpose of this test is to satisfy enable criteria necessary to execute Inspection/Maintenance (I/M) readiness diagnostics for Heated Oxygen Sensor (HO2S) heater system. Test may be used to set I/M system status indicators to YES. Ensure vehicle meets conditions listed in enable criteria before performing procedure. Failure to meet any of the conditions listed may produce inaccurate test results. See ENABLE CRITERIA .

The following enable criteria is for HO2S bank 1 sensor 1, and bank 2 sensor 1.

1. Engine speed is 500-3000 RPM.
2. Engine run time is less than 3 minutes.
3. Mass airflow is 4-30 grams/sec.
4. Battery voltage is 9-18 volts.

The following enable criteria is for HO2S bank 1 sensor 2.

1. Engine cold start is determined.
2. Average mass airflow during warm-up is less than 30 grams/sec.
3. Battery voltage is 10-18 volts.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
2. Preprogram scan tool with vehicle information before ignition is turned on. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . Turn off all accessories, including A/C and blower fan. Set vehicle parking brake. Verify transmission is in Park. Start engine and allow it to idle for 2 minutes or until I/M system status indicator updates to YES. If HO2S heater system status updates to YES, go to step 5 . If HO2S heater system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0135, P0141 and P0155 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If HO2S heater system status updated to YES, go to next step. If HO2S heater system status did not update to YES, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If scan tool does not indicate any emission related DTCs, system is okay.

HO2S heater tests will normally run within 2 minutes allotted in procedure. If there is impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not update within allotted period of time, continue operation within enable conditions until test updates to YES. If test does not update to YES, it may have failed or aborted due to loss of enabling conditions. Extremely high ambient temperatures may prevent HO2S heater test from initiating.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

SUMMARY

If no Diagnostic Trouble Codes (DTC) are present and a no-start condition exists, diagnose no-start condition. See appropriate BASIC DIAGNOSTIC PROCEDURES article. If no DTCs are present and a driveability condition exists, diagnose by symptom. See appropriate TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

DIAGNOSTIC TROUBLE CODE DEFINITIONS

Note. Use of Tech 2 scan tool is required to retrieve DTCs. Refer to user reference manual supplied with scan tool.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

Scheme 2

Scheme 3

Scheme 4

1. If powertrain diagnostic system check was performed, go to next step. If powertrain diagnostic system check was not performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition off. On DeVille and Seville, remove and inspect fuse No. 12 (IGN 1 fuse) from rear fuse block. (Scheme 2)or (Scheme 3). On Eldorado, remove and inspect RLY IGN 1 fuse from rear fuse block. (Scheme 4) On all models, rear fuse block is located underneath driver's side rear seat. If fuse is okay, reinstall fuse and go to next step. If fuse is blown, go to step 10.
3. Ensure ignition is off. Disconnect Powertrain Control Module (PCM) connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Connect a 3-amp fused jumper wire between ground and terminal No. 32 (Brown/White wire) at PCM C1 harness connector. (Scheme 5) Observe Malfunction Indicator Light (MIL). If MIL does not illuminate, go to next step. If MIL illuminates, go to step 9.
4. Check condition of fused jumper wire. If fused jumper wire is blown, go to step 11. If fused jumper wire is not blown, go to next step.
5. Turn ignition off. Remove Instrument Panel Cluster (IPC). See REMOVAL & INSTALLATION in appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. On Deville and Seville, check continuity of Brown/White wire between terminal A8 at IPC C2 harness connector and terminal No. 32 at PCM C1 harness connector. (Scheme 5)and (Scheme 6). On Eldorado, check continuity of Brown/White wire between terminal A3 at IPC C2 harness connector and terminal No. 32 at PCM C1 harness connector. (Scheme 5)and (Scheme 7). On all models, if continuity exists, go to next step. If continuity does not exist, repair open in Brown/White wire. After repairs, go to step 14.
6. Using a test light connected to ground, probe terminal A3 (Pink wire) at IPC C2 harness connector (DeVille and Seville) or C1 harness connector (Eldorado). (Scheme 6)or (Scheme 7). Turn ignition on. If test light does not illuminate, go to next step. If test light illuminates, go to step 8.
7. Repair open in Pink wire between IPC and rear fuse block. After repairs, go to step 14.
8. Check for faulty connections at IPC connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 12.
9. Check for faulty connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
10. Repair short to ground in Pink wire between IPC and rear fuse block. Replace fuse. After repairs, go to step 14.
11. Repair short to voltage in Brown/White wire between terminal A8 (DeVille and Seville) or terminal A3 (Eldorado) at IPC C2 harness connector and terminal No. 32 at PCM C1 harness connector. After repairs, go to step 14.
12. Replace IPC. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
14. Recheck operation of MIL. If MIL operates properly, repair is complete. If MIL does not operate properly, go to step 2.

Scheme 5

Scheme 6

Scheme 7

MALFUNCTION INDICATOR LIGHT ALWAYS ON

1. If powertrain diagnostic system check was performed, go to next step. If powertrain diagnostic system check was not performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. If MIL illuminates, go to next step. If MIL does not illuminate, go to step 5.
3. Turn ignition off. Remove Instrument Panel Cluster (IPC). See REMOVAL & INSTALLATION in appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Using a test light connect to positive battery voltage, probe Brown/White wire at terminal A8 (DeVille and Seville) or terminal A3 (Eldorado) at IPC C2 harness connector. (Scheme 6)or (Scheme 7). If test light does not illuminate, go to step 6. If test light illuminates, repair short to ground in Brown/White wire. After repairs, go to step 6.
4. Replace IPC. After repairs, go to step 6.
5. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
6. Recheck operation on MIL. If MIL operates properly, repair is complete. If MIL does not operate properly, go to step 2.

Data Link Connector (DLC) provides operating power for scan tool through terminal No. 16 (Orange wire) and ground through terminal No. 4 (Black wire). DLC provides class 2 serial data signal through terminal No. 2 (Purple wire) and ground through terminal No. 5 (Black/White wire). Scan tool will power up with ignition off.

1. Check for an open or short to ground in Orange wire between ground and terminal No. 16 at Data Link Connector (DLC). (Scheme 1) If an open or short to ground does not exist, go to next step. If an open or short to ground exists, repair wiring harness as necessary. After repair is complete, perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Check for an open in Black wire between ground and terminal No. 4 at DLC. If an open does not exist, go to next step. If an open exists, repair wiring harness as necessary. After repair is complete, perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
3. Inspect terminals No. 4 (Black wire) and No. 16 (Orange wire) at DLC for poor connections. If connections are okay, go to next step. If poor connections are found, repair as necessary. After repair is complete, perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
4. Scan tool may be faulty. See scan tool manufacturer's user guide. Obtain a known-good scan tool. Perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.

If DLC voltage and ground circuits are functioning properly, malfunction must be due to scan tool or scan tool cables.

DIAGNOSTIC TESTS

Note. Before clearing DTCs, perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. Record FREEZE FRAME and FAILURE RECORDS for reference during testing. Data will be erased when DTCs are cleared.

Note. If Powertrain Control Module (PCM) is replaced, NEW PCM must be programmed. See PROGRAMMING .

Heated Oxygen Sensor (HO2S) heater is a device used to reduce the time that it takes for HO2S to go active. The Powertrain Control Module (PCM) uses a high side driver to apply ignition voltage to bank 1 sensor 1 heater, and a low side driver Output Driver Module (ODM) to supply ground path. The PCM monitors high side driver for circuit conditions that are incorrect for commanded state of driver. If PCM detects an improper circuit condition in high side driver for HO2S bank 1 sensor 1, DTC P0030 will set.

Code Enable Criteria

1. System voltage is 9-18 volts.
2. Ignition is on.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Bank 2 sensor 1 is located in left (front) exhaust manifold.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, clear DTCs. Recheck for DTCs. If DTCs P0030, P0036, P1031 and P1032 are all set, go to step 11. If DTCs P0030, P0036, P1031 and P1032 are not all set, go to next step.
3. If DTCs P0030, P1031 and P1032 are all set, go to step 7. If DTCs P0030, P1031 and P1032 are not all set, go to next step.
4. If DTC P0030 is set, go to next step. If DTC P0030 is not set, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Measure voltage between ground and terminal "D" (Dark Green wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 8)and (Scheme 9). If voltage is more than 10 volts, go to step 15. If voltage is 10 volts or less, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for short to ground in Dark Green wire between terminal "D" at HO2S bank 1 sensor 1 harness connector and terminal No. 31 at PCM C1 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). Also check if Dark Green wire at terminal "D" is shorted to Black wire at terminal "C" at HO2S bank 1 sensor 1 harness connector. If Dark Green wire is shorted to ground or shorted to Black wire, repair wiring as necessary. After repairs, go to step 18. If wiring is okay, go to step 17.
7. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Measure voltage between ground and terminal "C" (Black wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 8)and (Scheme 9). If voltage is more than 10 volts, go to step 15. If voltage is 10 volts or less, go to next step.
8. Turn ignition off. Disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. Turn ignition on. Measure voltage between ground and terminal "C" (Black wire) at HO2S bank 1 sensor 1 harness connector. If voltage is 1.2-1.7 volts, go to step 14. If voltage is not 1.2-1.7 volts, go to next step.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal "C" (Black wire) at HO2S bank 1 sensor 1 harness connector. If test light illuminates, repair short to ground in Black wire between PCM and HO2S bank 1 sensor 1. After repairs, go to step 18. If test light does not illuminate, go to next step.
10. Using a test light connected to positive battery voltage, probe terminal "C" (Brown wire) at HO2S bank 2 sensor 1 harness connector. If test light illuminates, repair short to ground in Brown wire between PCM and HO2S bank 2 sensor 1. After repairs, go to step 18. If test light does not illuminate, go to step 17.
11. Turn ignition off. Remove fuse No. 20 (OXY SEN fuse) from underhood fuse block. (Scheme 10) Underhood fuse block is located on right side of engine compartment. Using a test light connected to positive battery voltage, probe fuse No. 20 output terminal (closest terminal to windshield). Observe test light and disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. If test light turns off, go to step 14. If test light does not turn off, go to next step.
12. Observe test light and disconnect HO2S bank 1 sensor 2 connector. HO2S bank 1 sensor 2 is located behind catalytic converter. If test light turns off, go to step 16. If test light does not turn off, go to next step.
13. Repair short to ground in Pink wire between HO2S bank 2 sensor 1 and underhood fuse block or Pink wire between HO2S bank 1 sensor 2 and underhood fuse block. After repairs, go to step 18.
14. Replace HO2S bank 2 sensor 1. After repairs, go to step 18.
15. Replace HO2S bank 1 sensor 1. After repairs, go to step 18.
16. Replace HO2S bank 1 sensor 2. After repairs, go to step 18.
17. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
18. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Scheme 8

Scheme 9

Scheme 10

Heated Oxygen Sensor (HO2S) heater is a device used to reduce the time that it takes for HO2S to go active. The Powertrain Control Module (PCM) uses a high side driver to apply ignition voltage to bank 1 sensor 1 heater, and a low side driver Output Driver Module (ODM) to supply ground path. The PCM monitors high side driver for circuit conditions that are incorrect for commanded state of driver. If PCM detects an improper circuit condition in high side driver for HO2S bank 1 sensor 1, DTC P0030 will set.

1. System voltage is 9-18 volts.
2. Ignition is on.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Bank 2 sensor 1 is located in left (front) exhaust manifold.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, clear DTCs. Recheck for DTCs. If DTCs P0030, P0036, P1031 and P1032 are all set, go to step 11. If DTCs P0030, P0036, P1031 and P1032 are not all set, go to next step.
3. If DTCs P0030, P1031 and P1032 are all set, go to step 7. If DTCs P0030, P1031 and P1032 are not all set, go to next step.
4. If DTC P0030 is set, go to next step. If DTC P0030 is not set, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Measure voltage between ground and terminal "D" (Dark Green wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 9) If voltage is more than 10 volts, go to step 15. If voltage is 10 volts or less, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for short to ground in Dark Green wire between terminal "D" at HO2S bank 1 sensor 1 harness connector and terminal No. 31 at PCM C1 harness connector. (Scheme 5)and (Scheme 9). Also check if Dark Green wire at terminal "D" is shorted to Tan/White wire at terminal "C" at HO2S bank 1 sensor 1 harness connector. If Dark Green wire is shorted to ground or shorted to Tan/White wire, repair wiring as necessary. After repairs, go to step 18. If wiring is okay, go to step 17.
7. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Measure voltage between ground and terminal "C" (Tan/White wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 9) If voltage is more than 10 volts, go to step 15. If voltage is 10 volts or less, go to next step.
8. Turn ignition off. Disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. Turn ignition on. Measure voltage between ground and terminal "C" (Tan/White wire) at HO2S bank 1 sensor 1 harness connector. If voltage is 1.2-1.7 volts, go to step 14. If voltage is not 1.2-1.7 volts, go to next step.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal "C" (Tan/White wire) at HO2S bank 1 sensor 1 harness connector. If test light illuminates, repair short to ground in Tan/White wire between PCM and HO2S bank 1 sensor 1. After repairs, go to step 18. If test light does not illuminate, go to next step.
10. Using a test light connected to positive battery voltage, probe terminal "C" (Tan/White wire) at HO2S bank 2 sensor 1 harness connector. If test light illuminates, repair short to ground in Brown wire between PCM and HO2S bank 2 sensor 1. After repairs, go to step 18. If test light does not illuminate, go to step 17.
11. Turn ignition off. Remove OXY SEN 1 fuse from underhood fuse block. (Scheme 11) Underhood fuse block is located on left side of engine compartment. (Scheme 12) Using a test light connected to positive battery voltage, probe circuit No. 39 at fuse OXY SEN 1 fuse holder output terminal. (Scheme 11) Observe test light and disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. If test light turns off, go to step 14. If test light does not turn off, go to next step.
12. Remove OXY SEN 2 fuse from underhood fuse block. (Scheme 11) Observe test light and disconnect HO2S bank 1 sensor 2 connector. HO2S bank 1 sensor 2 is located behind catalytic converter. If test light turns off, go to step 16. If test light does not turn off, go to next step.
13. Repair short to ground in Pink wire between HO2S bank 2 sensor 1 and underhood fuse block or Pink wire between HO2S bank 1 sensor 2 and underhood fuse block. After repairs, go to step 18.
14. Replace HO2S bank 2 sensor 1. After repairs, go to step 18.
15. Replace HO2S bank 1 sensor 1. After repairs, go to step 18.
16. Replace HO2S bank 1 sensor 2. After repairs, go to step 18.
17. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
18. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Scheme 11

Scheme 12

Heated Oxygen Sensor (HO2S) heater is a device used to reduce the time that it takes for HO2S to go active. HO2S bank 1 sensor 2 heater helps maintain proper sensor temperature for catalyst testing and fuel trim adjustments. HO2S heater receives power through a fused ignition circuit. Powertrain Control Module (PCM) uses a low side driver Output Driver Module (ODM) to turn heater on and off. The PCM monitors the circuit for conditions that are incorrect for commanded state of low side driver. If PCM detects an incorrect circuit condition for commanded state of low side driver, DTC P0036 will set.

1. System voltage is 9-18 volts.
2. Ignition is on.

Note. HO2S bank 1 sensor 2 is located behind catalytic converter.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, clear DTCs. Recheck for DTCs. If DTC P0030, P1031 and/or P1032 is set, go to «DTC P0030: HO2S HEATER CONTROL CIRCUIT VOLTAGE IS GREATER THAN PCM INTERNAL DRIVER CAPACITY - DEVILLE & SEVILLE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If only DTC P0036 is set, go to next step.
3. Start engine and allow it to reach normal operating temperature. Using scan tool, clear DTCs. Recheck for DTCs. If DTC P0036 resets, go to next step. If DTC P0036 does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect HO2S bank 1 sensor 2. HO2S bank 1 sensor 2 is located behind catalytic converter. Turn ignition on. Using a test light connected to ground, probe terminal "D" (Pink wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 8)and (Scheme 9). If test light illuminates, go to next step. If test light does not illuminate, go to step 11.
5. Leave HO2S bank 1 sensor 2 disconnected. Start engine. Using a test light connected to positive battery voltage, probe terminal "C" (Black/White wire) at HO2S bank 1 sensor 2 harness connector. If test light illuminates, leave test light connected and go to next step. If test light does not illuminate, go to step 7.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. If test light illuminates, go to step 13. If test light does not illuminate, go to step 15.
7. Turn ignition off. Ensure test light is still connected between positive battery voltage and terminal "C" (Black/White wire) at HO2S bank 1 sensor 2 harness connector. Turn ignition on. Using scan tool, command HO2S heater driver 4 on and off. If test light turns on and off, go to step 12. If test light does not turn on and off, go to next step.
8. Turn ignition off. Check continuity of Black/White wire between terminal "C" at HO2S bank 1 sensor 2 harness connector and terminal No. 48 at PCM C2 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Black/White wire. After repairs, go to step 16. If continuity exists, go to next step.
9. Measure voltage between ground and terminal "C" (Black/White wire) at HO2S bank 1 sensor 2 harness connector. If any voltage is indicated, repair short to voltage in Black/White wire between HO2S and PCM. After repairs, go to step 16. If no voltage is indicated, go to next step.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to 16. If connectors are okay, go to step 15.
11. Repair open in Pink wire between HO2S bank 1 sensor 2 and underhood fuse block. Underhood fuse block is located on right side of engine compartment. After repairs, go to step 16.
12. Check for poor connections at HO2S bank 1 sensor 2 connector. Repair as necessary. After repairs, go to step 16. If connector is okay, go to next step.
13. Repair short to ground in Black/White wire between HO2S bank 1 sensor 2 and PCM. After repairs, go to step 16.
14. Replace HO2S bank 1 sensor 2. After repairs, go to step 16.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Heated Oxygen Sensor (HO2S) heater is a device used to reduce the time that it takes for HO2S to go active. HO2S bank 1 sensor 2 heater helps maintain proper sensor temperature for catalyst testing and fuel trim adjustments. HO2S heater receives power through a fused ignition circuit. Powertrain Control Module (PCM) uses a low side driver Output Driver Module (ODM) to turn heater on and off. The PCM monitors the circuit for conditions that are incorrect for commanded state of low side driver. If PCM detects an incorrect circuit condition for commanded state of low side driver, DTC P0036 will set.

1. System voltage is 9-18 volts.
2. Ignition is on.

Note. HO2S bank 1 sensor 2 is located behind catalytic converter.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, clear DTCs. Recheck for DTCs. If DTC P0036 resets, go to step 4. If DTC P0036 does not reset, go to next step.
3. Attempt to start engine. If engine does not crank, go to next step. If engine cranks, start engine and allow it to reach normal operating temperature. Using scan tool, monitor DTC information for one minute. If DTC P0036 resets, go to next step. If DTC P0036 does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Remove OXY SEN 2 fuse from underhood fuse block. (Scheme 11) Underhood fuse block is located on left side of engine compartment. (Scheme 12) If fuse is blown, go to next step. If fuse is okay, go to step 6.
5. Turn ignition off. Disconnect HO2S bank 1 sensor 2. HO2S bank 1 sensor 2 is located behind catalytic converter. Using a test light connected to positive battery voltage, probe terminal "D" (Pink wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 9) If test light illuminates, repair short to ground in Pink wire between underhood fuse block and HO2S bank 1 sensor 2. If test light does not illuminate, go to step 14.
6. Turn ignition off. Disconnect HO2S bank 1 sensor 2. HO2S bank 1 sensor 2 is located behind catalytic converter. Turn ignition on. Using a test light connected to ground, probe terminal "D" (Pink wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 9) If test light illuminates, go to next step. If test light does not illuminate, go to step 13.
7. Measure voltage between ground and terminal "C" (Black/White wire) at HO2S bank 1 sensor 2 harness connector. If voltage is about 2 volts, go to step 11. If voltage is not about 2 volts, go to next step.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black/White wire between terminal "C" at HO2S bank 1 sensor 2 harness connector and terminal No. 48 at PCM C2 harness connector. (Scheme 5)and (Scheme 9). If continuity does not exist, repair open in Black/White wire. After repairs, go to step 16. If continuity exists, go to step 12.
9. Turn ignition off. Disconnect HO2S bank 1 sensor 2. HO2S bank 1 sensor 2 is located behind catalytic converter. Turn ignition on. Measure voltage between ground and terminal "C" (Black/White wire) at HO2S bank 1 sensor 2 harness connector. If voltage is about 2 volts, go to step 14. If voltage is not about 2 volts, go to next step.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "C" (Black/White wire) at HO2S bank 1 sensor 2 harness connector. If any voltage is indicated, repair short to voltage in Black/White wire between HO2S bank 1 sensor 2 and PCM. After repairs, go to step 16. If no voltage is indicated, go to next step.
11. Check for poor connections at HO2S bank 1 sensor 2 connector. Repair as necessary. After repairs, go to step 16. If connector is okay, go to next step.
12. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to 16. If connectors are okay, go to step 15.
13. Repair open in Pink wire between HO2S bank 1 sensor 2 and underhood fuse block. After repairs, go to step 16.
14. Replace HO2S bank 1 sensor 2. After repairs, go to step 16.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Mass Airflow (MAF) sensor is an airflow meter that measures the amount of air entering engine. Powertrain Control Module (PCM) uses MAF sensor signal to provide correct fuel delivery for a wide range of engine speeds and loads. A small quantity of air entering the engine indicates deceleration or idle. A large quantity of air entering the engine indicates an acceleration or high load situation. The MAF sensor has an ignition 1 voltage circuit, a ground circuit and a signal circuit. The PCM applies a voltage to MAF sensor on the signal circuit. MAF sensor uses the voltage to produce a frequency based on inlet airflow through the sensor bore. The PCM uses barometric pressure, air density, manifold pressure, throttle position, and engine RPM to calculate a predicted MAF value. The PCM compares actual MAF sensor signal to the predicted MAF value to determine if signal is stuck based on a lack of variation, or is too low, or too high for a given operating condition. DTC P0101 will set if actual MAF sensor signal is not within a predetermined range of calculated MAF value.

Note. Intake Air Temperature (IAT) sensor is integral to MAF sensor. MAF sensor may also be referred to as MAF/IAT sensor.

1. DTC P0102, P0103, P0106, P0107, P0108, P0121, P0122, P0123, P0401, P1122 or P1441 is not set.
2. Engine is running.
3. Ignition 1 signal is 11-18 volts.
4. Throttle Position (TP) sensor angle is less than 47.9 percent.
5. TP sensor is steady within a range of less than 2.9 percent.
6. Manifold Absolute (MAP) sensor signal is steady and less than 8.48 psi (58.5 kPa).
7. Exhaust Gas Recirculation (EGR) position sensor signal is less than 90 percent.
8. Evaporative Emission (EVAP) purge solenoid command is less than 90 percent.
9. Traction control status is inactive.
10. Listed conditions are exist for at least 10 seconds.

Scheme 13

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, go to next step. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Ensure engine is idling. Using scan tool, observe MAP sensor voltage parameter. If voltage is.8-4.0 volts, go to next step. If voltage is not.8-4.0 volts, go to «DTC P0106: MANIFOLD ABSOLUTE PRESSURE SYSTEM PERFORMANCE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition off. Check for objects blocking MAF/IAT sensor air inlet screen. Check for plugged or collapsed intake air duct or dirty air filter element. Check for vacuum leaks in the following components. Air Induction System And Resonator Throttle Body And Gasket Intake Manifold EGR Valve Flange And Pipe MAF/IAT Sensor MAP Sensor EVAP Canister Purge Valve Seal Crankcase Ventilation System Brake Booster If any problems are found, repair as necessary. After repairs, go to step 23. If no problems are found, go to next step.
6. Turn ignition off. Remove MAP sensor vacuum source. (Scheme 13) Leave MAP sensor electrical connector connected. Connect a hand operated vacuum pump to MAP sensor vacuum port. Turn ignition on. Using scan tool, observe MAP sensor parameter while slowly applying vacuum one in. Hg at a time. Apply up to 20 in. Hg. Each one in. Hg of vacuum applied should result in a.4-.6 psi (3-4 kPa) drop in MAP sensor value indicated on scan tool. MAP sensor value should change smoothly with each one in. Hg increase. If MAP sensor value changed smoothly through entire range of test, go to next step. If MAP sensor value did not change smoothly through entire range of test, go to «DTC P0106: MANIFOLD ABSOLUTE PRESSURE SYSTEM PERFORMANCE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
7. Observe scan tool and apply 20 in. Hg vacuum to MAP sensor. If scan tool indicates MAP sensor reading is 4.9 psi (34 kPa) or less, go to next step. If scan tool indicates MAP sensor reading is more than 4.9 psi (34 kPa), go to «DTC P0106: MANIFOLD ABSOLUTE PRESSURE SYSTEM PERFORMANCE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
8. Observe scan tool and disconnect vacuum pump from MAP sensor. If MAP sensor reading returns to original value that was observed in step 6, go to next step. If MAP sensor reading does not return to original value, go to «DTC P0106: MANIFOLD ABSOLUTE PRESSURE SYSTEM PERFORMANCE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
9. Using scan tool, observe TP sensor angle parameter from closed throttle to wide open throttle. If TP sensor value changed from zero to 100 percent smoothly, go to next step. If TP sensor value did not change from zero to 100 percent or did not change smoothly, go to «DTC P0121: THROTTLE POSITION SENSOR CIRCUIT INSUFFICIENT ACTIVITY»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
10. Turn ignition off. Disconnect MAF/IAT sensor connector. Turn ignition on. Measure voltage between ground and terminal "E" (Yellow wire) at MAF/IAT sensor harness connector. (Scheme 14) If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 12.
11. Using a test light connected to ground, probe terminal "D" (Pink wire) at MAF/IAT sensor harness connector. If test light illuminates, go to step 19. If test light does not illuminate, go to step 14.
12. If voltage measured in step 10 is less than 4.5 volts, go to step 15. If voltage measured in step 10 is not less than 4.5 volts, go to next step.
13. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "E" (Yellow wire) at MAF/IAT sensor harness connector. If voltage is zero volts, go to step 22. If voltage is not zero volts, go to step 18.
14. Using a test light connected to ground, probe terminal "D" (Pink wire) at MAF/IAT sensor harness connector. If test light illuminates, go to step 16. If test light does not illuminate, go to step 17.
15. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in Yellow wire between terminal "E" at MAF/IAT sensor harness connector and terminal No. 42 at PCM C1 harness connector. (Scheme 5)and (Scheme 14). Also check if Yellow wire at terminal "E" is shorted to Black wire (DeVille and Seville) or Black/White wire (Eldorado) at terminal "C" at MAF/IAT sensor harness connector. If Yellow wire is open, shorted to ground, or shorted to Black/White wire, repair wiring as necessary. After repairs, go to step 23. If wiring is okay, go to step 20.
16. Repair open or high resistance in Black/White wire between ground and terminal "C" at MAF/IAT sensor. See WIRING DIAGRAMS article. After repairs, go to step 23.
17. Repair short to ground or open in Pink wire between underhood fuse block and terminal "D" at MAF/IAT sensor. Also check appropriate fuse for ignition 1 voltage circuit in underhood fuse block. See WIRING DIAGRAMS article. Replace fuse as necessary. After repairs, go to step 23.
18. Repair short to voltage in Yellow wire between PCM and MAF/IAT sensor. After repairs, go to step 23.
19. Check for poor connections at MAF/IAT sensor connector. Repair connector as necessary. After repairs, go to step 23. If connector is okay, go to step 21.
20. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 23. If connectors are okay, go to step 22.
21. Replace MAF/IAT sensor. After repairs, go to step 23.
22. Replace PCM. Program replacement PCM. See PROGRAMMING. After repairs, go to next step.
23. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
24. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Check for sticking throttle plate. Check for carbon build-up on throttle plate and throttle bore. Unmetered air entering the engine may cause this DTC to set. Ensure oil dipstick is fully seated and oil filler cap is secure. Check for misrouted or damaged MAF/IAT sensor wiring harness. Ensure harness is not close to high-voltage components. Check for non-factory or aftermarket add-on devices.

Scheme 14

Mass Airflow (MAF) sensor is an airflow meter that measures the amount of air entering engine. Powertrain Control Module (PCM) uses MAF sensor signal to provide correct fuel delivery for a wide range of engine speeds and loads. A small quantity of air entering engine indicates deceleration or idle. A large quantity of air entering engine indicates an acceleration or high load situation. The MAF sensor has an ignition 1 voltage circuit, ground circuit and a signal circuit. The PCM applies a voltage to MAF sensor on the signal circuit. MAF sensor uses the voltage to produce a frequency based on inlet airflow through the sensor bore. The frequency will vary within a range of about 2000 Hz at idle to about 10,000 Hz at maximum engine load. DTC P0102 will set if PCM detects a frequency signal lower than the possible range of a normally operating MAF sensor.

Note. Intake Air Temperature (IAT) sensor is integral to MAF sensor. MAF sensor may also be referred to as MAF/IAT sensor.

1. Engine run time is more than 8 seconds.
2. Engine speed is more than 250 RPM.
3. Ignition 1 signal is 10.5 volts or more.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Using scan tool, check MAF sensor frequency parameter. If frequency reading is 1135 Hz or more, go to next step. If frequency reading is less than 1135 Hz, go to step 4.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Check fuse for ignition 1 voltage circuit in underhood fuse block. See WIRING DIAGRAMS article. If fuse is okay, go to next step. If fuse is blown, go to step 14.
5. Disconnect MAF/IAT sensor connector. Turn ignition on. Measure voltage between ground and terminal "E" (Yellow wire) at MAF/IAT sensor harness connector. (Scheme 14) If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 8.
6. Turn ignition off. Connect a 3-amp fused jumper wire between ground and terminal "E" (Yellow wire) at MAF/IAT sensor harness connector. Start engine. Using scan tool, observe 5-volt reference 1 and 5-volt reference 2 parameters. If scan tool indicates OK, go to next step. If scan tool does not indicate OK, go to step 16.
7. Turn ignition off. Connect a test light between terminal "C" (Black wire on DeVille and Seville or Black/White wire on Eldorado) and terminal "D" (Pink wire) at MAF/IAT sensor harness connector. Turn ignition on. If test light illuminates, go to step 18. If test light does not illuminate, go to step 11.
8. If voltage measured in step 5 is less than 4.5 volts, go to step 10. If voltage measured in step 5 is not less than 4.5 volts, go to next step.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "E" (Yellow wire) at MAF/IAT sensor harness connector. If no voltage is indicated, go to step 12. If any voltage is indicated, go to step 15.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in Yellow wire between terminal "E" at MAF/IAT sensor harness connector and terminal No. 42 at PCM C1 harness connector. (Scheme 5)and (Scheme 14). Also check if Yellow wire at terminal "E" is shorted to Black wire (DeVille and Seville) or Black/White wire (Eldorado) at terminal "C" at MAF/IAT sensor harness connector. If Yellow wire is open, shorted to ground, or shorted to Black wire (DeVille and Seville) or Black/White wire (Eldorado), repair wiring as necessary. After repairs, go to step 22. If wiring is okay, go to step 12.
11. Using a test light connected to ground, probe terminal "D" (Pink wire) at MAF/IAT sensor harness connector. If test light illuminates, go to step 13. If test light does not illuminate, go to step 14.
12. Check for continuity between terminal No. 42 (Yellow wire) at PCM C1 harness connector and all other terminals at both PCM C1 and C2 harness connectors. (Scheme 5) If continuity exists between any terminals, go to step 17. If continuity does not exist between any terminals, go to step 19.
13. Repair open or high resistance in Black wire (DeVille and Seville) or Black/White wire (Eldorado) between ground and terminal "C" at MAF/IAT sensor harness connector. See WIRING DIAGRAMS article. After repairs, go to step 22.
14. Repair short to ground or open in Pink wire between underhood fuse block and terminal "D" at MAF/IAT sensor harness connector. Also check fuse for ignition 1 voltage circuit in underhood fuse block. Replace fuse as necessary. After repairs, go to step 22.
15. Repair short to voltage in Yellow wire between PCM and MAF/IAT sensor. After repairs, go to step 22.
16. Repair short between Yellow wire at MAF/IAT sensor harness connector and circuit of 5-volt reference parameter that did not display OK. The 5-volt reference 1 circuit supplies reference voltage to TP sensor, MAP sensor and EGR position sensor. The 5-volt reference 2 circuit supplies reference voltage to A/C pressure sensor and fuel tank pressure sensor. After repairs, go to step 22.
17. Repair circuits that are shorted together. After repairs, go to step 22.
18. Check for poor connections at MAF/IAT sensor connector. Repair connector as necessary. After repairs, go to step 22. If connector is okay, go to step 20.
19. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 22. If connectors are okay, go to step 21.
20. Replace MAF/IAT sensor. After repairs, go to step 22.
21. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
22. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
23. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Low minimum air rate may cause this DTC to set. Check for plugged or misaligned intake air duct. Check for dirty air filter. Check for objects blocking MAF/IAT sensor air inlet screen. Any unmetered air entering engine may also cause this DTC to set. Ensure oil dipstick is fully seated and oil filler cap is secure. Check for misrouted or damaged MAF/IAT sensor wiring harness. Ensure harness is not close to high-voltage components.

Mass Airflow (MAF) sensor is an airflow meter that measures the amount of air entering engine. Powertrain Control Module (PCM) uses the MAF sensor signal to provide correct fuel delivery for a wide range of engine speeds and loads. A small quantity of air entering engine indicates deceleration or idle. A large quantity of air entering engine indicates an acceleration or high load situation. MAF sensor has an ignition 1 voltage circuit, ground circuit and a signal circuit. The PCM applies a voltage to MAF sensor on the signal circuit. MAF sensor uses the voltage to produce a frequency based on inlet airflow through the sensor bore. The frequency will vary within a range of about 2000 Hz at idle to about 10,000 Hz at maximum engine load. DTC P0103 will set if PCM detects a frequency signal higher than the possible range of a normally operating MAF sensor.

Note. Intake Air Temperature (IAT) sensor is integral to MAF sensor. MAF sensor may also be referred to as MAF/IAT sensor.

1. Engine run time is more than 8 seconds.
2. Engine speed is more than 250 RPM.
3. Ignition 1 signal is 10.5 volts or more.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
3. Turn ignition off. Disconnect MAF/IAT sensor connector. Start engine. Using scan tool, check MAF sensor frequency parameter. If frequency reading is zero Hz, go to step 5 . If frequency reading is not zero Hz, go to next step.
4. Check MAF/IAT sensor wiring harness for incorrect routing near ignition control modules, solenoids, relays or motors. If any problems are found, reroute wiring harness as necessary. After repairs, go to step 9 . If no problems are found, go to step 6 .
5. Check for poor connections at MAF/IAT sensor connector. Repair connector as necessary. After repairs, go to step 9 . If connector is okay, go to step 7 . Replace MAF/IAT sensor.
6. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 9 . If connectors are okay, go to step 8 .
7. Replace MAF/IAT sensor. After repairs, go to step 9 .
8. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . After repairs, go to next step.
9. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
10. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Water entering air intake system that reaches MAF/IAT sensor could cause this DTC to set. Water rapidly cools the hot sensing elements in the MAF/IAT sensor causing a false indication of excessive airflow. Check for evidence of water intrusion in the secondary air injection system and the air induction system. Check for faulty connections at MAF/IAT sensor connector.

Manifold Absolute Pressure (MAP) sensor responds to pressure changes in intake manifold. The pressure changes occur based on engine load. Powertrain Control Module (PCM) supplies 5 volts to MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to PCM on the signal circuit which is relative to pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during idle or deceleration. The PCM should detect a high signal voltage at a high MAP, such as with ignition on or at Wide Open Throttle (WOT). MAP sensor value is also used to determine the Barometric Pressure (BARO). This occurs when ignition is on. The BARO reading may also be updated whenever engine is operated at WOT. The PCM monitors MAP sensor signal for voltage outside of the normal range. The PCM calculates a predicted value for the MAP sensor based on throttle position and engine speed. The PCM then compares the predicted value to the actual MAP sensor signal. DTC P0106 will set if actual MAP sensor signal is not within the predicted range for at least one second.

1. DTC P0121, P0122 or P0123 is not set.
2. Engine speed variation is less than 125 RPM.
3. Any change in idle air control position is less than 15 counts.
4. Engine speed is 1000-4000 RPM.
5. Throttle position sensor variation is less than 4 percent.
6. Any change in EGR position is less than 10 grams/sec.
7. Torque converter clutch is unchanged for 3 seconds.
8. Brake switch is off for 3 seconds.
9. A/C clutch state is unchanged for 2 seconds.
10. Traction control is not active.
11. Engine overtemp protection is not active.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, observe TP sensor angle parameter from closed throttle to wide open throttle. If TP sensor value changed from zero to 98 percent smoothly, go to next step. If TP sensor value did not change from zero to 98 percent or did not change smoothly, go to «DTC P0121: THROTTLE POSITION SENSOR CIRCUIT INSUFFICIENT ACTIVITY»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
3. Using scan tool, observe MAP sensor pressure. Compare this value to MAP sensor value observed from a known-good vehicle. If difference between readings is less than.43 psi (3 kPa), go to next step. If difference between readings is.43 psi (3 kPa) or more, go to step 8.
4. Using scan tool, observe MAP sensor pressure. Start engine. If MAP sensor value changes, go to next step. If MAP sensor value does not change, go to step 8.
5. Turn ignition off. Remove MAP sensor vacuum source. (Scheme 13) Leave MAP sensor electrical connector connected. Connect a hand operated vacuum pump to MAP sensor vacuum port. Turn ignition on. Using scan tool, observe MAP sensor parameter while slowly applying vacuum one in. Hg at a time. Apply up to 20 in. Hg. Each one in. Hg of vacuum applied should result in a.4-.6 psi (3-4 kPa) drop in MAP sensor value indicated on scan tool. MAP sensor value should change smoothly with each one in. Hg increase. If MAP sensor value changed smoothly through entire range of test, go to next step. If MAP sensor value did not change smoothly through entire range of test, go to step 16.
6. Observe scan tool and apply 20 in. Hg vacuum to MAP sensor. If scan tool indicates MAP sensor reading is 4.9 psi (34 kPa) or less, go to next step. If scan tool indicates MAP sensor reading is more than 4.9 psi (34 kPa), go to step 8.
7. Disconnect vacuum source from MAP sensor. If MAP sensor reading returns to original value in step 3, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If MAP sensor reading does not return to original value, go to step 16.
8. Turn ignition off. Disconnect MAP sensor connector. Using scan tool, observe MAP sensor voltage. Turn ignition on. If voltage is more than.5 volt, go to step 15. If voltage is.5 volt or less, go to next step.
9. Connect a 3-amp fused jumper wire between Gray and Light Green wires at MAP sensor harness connector. Using scan tool, observe MAP sensor voltage. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 14.
10. Remove jumper wire. Measure voltage between ground and Gray wire at MAP sensor harness connector. If voltage is more than 5.2 volts, go to step 12. If voltage is 5.2 volts or less, go to next step.
11. Using a test light connected to positive battery voltage, probe Orange/Black wire at MAP sensor harness connector. If test light illuminates, go to step 16. If test light does not illuminate, go to step 13.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Gray wire at MAP sensor harness connector. If any voltage is indicated, repair short to voltage in Gray wire between MAP sensor and PCM. After repairs, go to step 20. If no voltage is indicated, go to step 17.
13. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Orange/Black wire between MAP sensor harness connector and terminal No. 6 at PCM C2 harness connector. (Scheme 5) If continuity does not exist, repair open in Orange/Black wire. After repairs, go to step 20. If continuity exists, go to step 17.
14. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Light Green wire between MAP sensor harness connector and terminal No. 23 at PCM C1 harness connector. (Scheme 5) If continuity does not exist, repair open in Light Green wire. After repairs, go to step 20. If continuity exists, go to step 17.
15. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Light Green wire at MAP sensor harness connector. If any voltage is indicated, repair short to voltage in Light Green wire between MAP sensor and PCM. After repairs, go to step 20. If no voltage is indicated, go to step 17.
16. Check for poor connections at MAP sensor connector. Repair connector as necessary. After repairs, go to step 20. If connector is okay, go to step 18.
17. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 20. If connectors are okay, go to step 19.
18. Replace MAP sensor. After repairs, go to step 20.
19. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
20. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
21. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Check for restricted MAP sensor vacuum source. Check for missing or damaged MAP sensor seal. Check for disconnected, damaged, or incorrectly routed vacuum hoses. Check for vacuum leaks at Intake manifold and throttle body. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Manifold Absolute Pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on engine load. Powertrain Control Module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the signal circuit which is relative to pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during idle or deceleration. The PCM should detect a high signal voltage at a high MAP, such as with ignition on or at Wide Open Throttle (WOT). MAP sensor value is also used to determine the Barometric Pressure (BARO). This occurs when ignition is on. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range. DTC P0107 sets when MAP sensor voltage is less than .5 volt for at least 2 seconds.

1. DTC P0121, P0122 or P0123 is not set.
2. Throttle Position (TP) sensor is more than 9 percent when engine speed is more than 1000 RPM.
3. TP sensor is more than zero percent when engine speed is less than 1000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Using scan tool, check for any other DTCs that are set. If DTC P1635 is not set, go to next step. If DTC P1635 is set, go to «DTC P1635: 5-VOLT REFERENCE 1 CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
3. Using scan tool, observe MAP sensor voltage. If voltage is less than.5 volt, go to step 5. If voltage is.5 volt or more, go to next step.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition off. Disconnect MAP sensor connector. (Scheme 13) Turn ignition on. Measure voltage between ground and Gray wire at MAP sensor harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 7.
6. Connect a 3-amp fused jumper wire between Gray and Light Green wires at MAP sensor harness connector. Using scan tool, observe MAP sensor voltage. If voltage is about 5 volts, go to step 9. If voltage is not about 5 volts, go to step 8.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in Gray wire between MAP sensor harness connector and terminal No. 49 at PCM C2 harness connector. (Scheme 5) If an open or short to ground exists, repair wiring as necessary. After repairs, go to step 13. If an open or short to ground does not exist, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in Light Green wire between MAP sensor harness connector and terminal No. 23 at PCM C1 harness connector. (Scheme 5) If an open or short to ground exists, repair wiring as necessary. After repairs, go to step 13. If an open or short to ground does not exist, go to step 10.
9. Check for poor connections at MAP sensor connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to step 11.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 13. If connectors are okay, go to step 12.
11. Replace MAP sensor. After repairs, go to step 13.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Check MAP sensor vacuum source for leaks, restrictions or poor connections. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Manifold Absolute Pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on engine load. Powertrain Control Module (PCM) supplies 5 volts to MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the signal circuit which is relative to pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during idle or deceleration. The PCM should detect a high signal voltage at a high MAP, such as when ignition is on or at a Wide Open Throttle (WOT). MAP sensor value is also used to determine the Barometric Pressure (BARO). This occurs when ignition is on. The BARO reading may also be updated whenever engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range. DTC P0108 will set when PCM detects MAP sensor signal voltage is excessively high.

1. DTC P0121, P0122 or P0123 is not set.
2. Throttle angle is less than 98 percent when engine speed is more than 1000 RPM.
3. Throttle angle is less than 90 percent when engine speed is less than 1000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Using scan tool, check for any other DTCs that are set. If DTC P1635 is not set, go to next step. If DTC P1635 is set, go to «DTC P1635: 5-VOLT REFERENCE 1 CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). NOTE: If engine idle is rough, unstable or incorrect, correct idle condition before continuing with this test. See SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Using scan tool, observe MAP sensor voltage. If voltage is more than 4.5 volts, go to step 5. If voltage is not more than 4.5 volts, go to next step.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition off. Disconnect MAP sensor connector. (Scheme 13) Turn ignition on. Using scan tool, observe MAP sensor voltage. If voltage is less than.5 volt, go to next step. If voltage is.5 volt or more, go to step 8.
6. Measure voltage between Gray and Orange/Black wires at MAP sensor harness connector. If voltage is 4.7-5.2 volts, go to step 11. If voltage is not 4.7-5.2 volts, go to next step.
7. If voltage was more than 5.2 volts in previous step, go to step 10. If voltage was less than 4.7 volts in previous step, go to step 9.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Light Green wire at MAP sensor harness connector. If any voltage is indicated, repair wiring as necessary. After repairs, go to step 15. If no voltage is indicated, go to step 12.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Orange/Black wire between MAP sensor harness connector and terminal No. 6 at PCM C2 harness connector. (Scheme 5) If continuity does not exist, repair open in Orange/Black wire. After repairs, go to step 15. If continuity exists, go to step 12.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Gray wire at MAP sensor harness connector. If any voltage is indicated, repair wiring as necessary. After repairs, go to step 15. If no voltage is indicated, go to step 12.
11. Check for poor connections at MAP sensor connector. Repair connector as necessary. After repairs, go to step 15. If connector is okay, go to step 13.
12. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 15. If connectors are okay, go to step 14.
13. Replace MAP sensor. After repairs, go to step 15.
14. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
15. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
16. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Check MAP sensor vacuum source for leaks, restrictions or poor connections. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Intake Air Temperature (IAT) sensor is a thermistor that measures temperature of air entering the engine. The Powertrain Control Module (PCM) supplies 5 volts to the IAT sensor signal circuit through a pull-up resistor. When intake air is cold, the PCM detects a high voltage on the IAT sensor signal circuit. As the intake air warms, the PCM detects a lower voltage on the IAT sensor signal circuit. The IAT sensor is a thermistor that varies resistance based on temperature. As temperature of sensor increases, resistance decreases. High temperature will result in a low signal voltage. DTC P0112 will set if PCM detects an excessively low IAT sensor signal voltage (high temperature indicated).

Note. IAT sensor is integral to Mass Airflow (MAF) sensor. IAT sensor may also be referred to as MAF/IAT sensor.

1. DTC P0117, P0118, P0125, P0502, P0503, P1114 or P1115 is not set.
2. Engine run time is more than 10 seconds.
3. Engine coolant temperature is less than 212°F (100°C).
4. Vehicle speed is more than 9 MPH.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, observe IAT sensor temperature. If temperature reading is more than 257°F (125°C), go to step 4. If temperature reading is 257°F (125°C) or less, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect MAF/IAT sensor connector. IAT sensor is integral to MAF sensor. Turn ignition on. Using scan tool, observe IAT sensor temperature. If temperature reading is about -40°F (-40°C), go to step 6. If temperature reading is not about -40°F (-40°C), go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for short to ground in Tan wire between terminal "B" at MAF/IAT sensor harness connector and terminal No. 10 at PCM C1 harness connector. (Scheme 5)and (Scheme 14). Also check if Tan wire at terminal "B" is shorted to Black wire at terminal "A", or Black wire (DeVille and Seville) or Black/White wire (Eldorado) at terminal "C" at MAF/IAT sensor harness connector. If Tan wire is shorted to ground, or shorted to Black wire or Black/White wire, repair wiring as necessary. After repairs, go to step 8. If wiring is okay, go to step 7.
6. Replace MAF/IAT sensor. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Intake Air Temperature (IAT) sensor is a thermistor that measures temperature of air entering the engine. The Powertrain Control Module (PCM) supplies 5 volts to the IAT sensor signal circuit through a pull-up resistor. When intake air is cold, the PCM detects a high voltage on the IAT sensor signal circuit. As intake air warms, the PCM detects a lower voltage on the IAT sensor signal circuit. DTC P0113 will set if PCM detects an excessively high IAT sensor signal voltage (low temperature indicated).

Note. IAT sensor is integral to Mass Airflow (MAF) sensor. IAT sensor may also be referred to as MAF/IAT sensor.

1. DTC P0101, P0102, P0103, P0117, P0118, P0125, P0502, P0503, P1114 or P1115 is not set.
2. Engine run time is more than 10 seconds.
3. Engine speed is more than 50 RPM for 5 seconds.
4. Engine coolant temperature is more than 32°F (0°C).
5. Vehicle speed is less than 48 MPH.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, observe IAT sensor temperature parameter. If temperature reading is less than -11°F (-24°C), go to step 4. If temperature reading is -11°F (-24°C) or more go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect MAF/IAT sensor connector. IAT sensor is integral to MAF sensor. Turn ignition on. Measure voltage between ground and terminal "B" (Tan wire) at MAF/IAT sensor harness connector. (Scheme 14) If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 10.
5. Turn ignition off. Connect a jumper wire between terminal "A" (Black wire) and terminal "B" (Tan wire) at MAF/IAT sensor harness connector. Turn ignition on. Using scan tool, observe 5-volt reference 1 and 5-volt reference 2 parameters. If scan tool indicates OK, leave jumper wire connected and go to step 7. If scan tool does not indicate OK, go to next step.
6. Repair short between Tan wire at MAF/IAT sensor harness connector and circuit of 5-volt reference parameter that did not display OK. The 5-volt reference 1 circuit supplies reference voltage to TP sensor, MAP sensor and EGR position sensor. The 5-volt reference 2 circuit supplies reference voltage to A/C pressure sensor and fuel tank pressure sensor. After repairs, go to step 15.
7. Using scan tool, observe IAT sensor temperature parameter. If temperature reading is about 302°F (150°C), go to next step. If temperature reading is not about 302°F (150°C), go to step 9.
8. Check for poor connections at MAF/IAT sensor connector. Repair connector as necessary. After repairs, go to step 15. If connector is okay, go to step 13.
9. Turn ignition off. Disconnect jumper wire. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor connections at PCM and MAF/IAT sensor connectors. Repair connectors as necessary. Check continuity of Black wire between terminal "A" at MAF/IAT sensor harness connector and terminal No. 4 at PCM C2 harness connector. (Scheme 5)and (Scheme 14). If continuity exists, go to step 14. If continuity does not exist, repair open in Black wire. After repairs, go to step 15.
10. If voltage measured in step 4 is 5 volts or less, go to step 12. If voltage measured in step 4 is more than 5 volts, go to next step.
11. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "B" (Tan wire) at MAF/IAT sensor harness connector. If any voltage is indicated, repair short to voltage in Tan wire between MAF/IAT sensor and PCM. After repairs, go to step 15. If no voltage is indicated, go to step 14.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor connections at PCM and MAF/IAT sensor connectors. Repair connectors as necessary. Check continuity of Tan wire between terminal "B" at MAF/IAT sensor harness connector and terminal No. 10 at PCM C1 harness connector. (Scheme 5)and (Scheme 14). If continuity exists, go to step 14. If continuity does not exist, repair open in Tan wire. After repairs, go to step 15.
13. Replace MAF/IAT sensor. After repairs, go to step 15.
14. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
15. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
16. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Engine Coolant Temperature (ECT) sensor is a thermistor that measures temperature of engine coolant. The Powertrain Control Module (PCM) supplies 5 volts to the ECT sensor signal circuit through a pull-up resistor. When engine coolant temperature is cold, ECT sensor resistance is high. When engine coolant temperature increases, ECT sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the ECT sensor signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT sensor signal circuit. DTC P0117 will set if PCM detects an excessively low ECT sensor signal voltage, indicating a high temperature.

1. DTC P0112, P0113, P1111 or P1112 is not set.
2. Engine run time is more than 10 seconds.
3. Intake air temperature is less than 158°F (70°C).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, observe ECT sensor temperature. If temperature reading is more than 257°F (125°C), go to step 4. If temperature reading is 257°F (125°C) or less, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect ECT sensor harness connector. (Scheme 13) Turn ignition on. If ECT sensor temperature reading is about -40°F (-40°C), go to step 6. If ECT sensor temperature reading is not about -40°F (-40°C), go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check ECT sensor signal circuit (Yellow wire as follows: Using a test light connected to positive battery voltage, probe terminal No. 31 (Yellow wire) at PCM C2 harness connector. (Scheme 5) If test light illuminates, Yellow wire is shorted to ground between ECT sensor and PCM. Check for continuity between Yellow wire and Black wire (DeVille and Seville) or Brown wire (Eldorado) at ECT sensor harness connector. Continuity should not exist. If continuity exists, Yellow and Black wires (DeVille and Seville) or Yellow and Brown wires (Eldorado) are shorted together between ECT sensor and PCM. If any problems are found, repair wiring as necessary. After repairs, go to step 8. If no problems are found, go to next step.
6. Replace ECT sensor. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Engine Coolant Temperature (ECT) sensor is a thermistor that measures temperature of the engine coolant. The Powertrain Control Module (PCM) supplies 5 volts to the ECT sensor signal circuit through a pull-up resistor. When engine coolant temperature is cold, ECT sensor resistance is high. When engine coolant temperature increases, ECT sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the ECT sensor signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT sensor signal circuit. DTC P0118 will set if PCM detects an excessively high ECT sensor signal voltage, indicating a low temperature.

1. DTC P0112, P0113, P1111 or P1112 is not set.
2. Engine run time has been more than 60 seconds.
3. Intake air temperature is more than 19°F (-7°C).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, observe ECT sensor temperature. If temperature reading is less than -11°F (-24°C), go to step 4. If temperature reading is -11°F (-24°C) or more, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect ECT sensor connector. (Scheme 14) Turn ignition on. Measure voltage between ground and Yellow wire at ECT sensor harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 10.
5. Connect a 3-amp jumper wire between Yellow wire and Black wire (DeVille and Seville) or Brown wire (Eldorado) at ECT sensor harness connector. Using scan tool, observe 5-volt reference 1 and 5-volt reference 2 parameters. If scan tool indicates OK, leave jumper wire connected and go to step 7. If scan tool does not indicate OK, go to next step.
6. Repair short between Yellow wire at ECT sensor harness connector and circuit of 5-volt reference parameter that did not display OK. The 5-volt reference 1 circuit supplies reference voltage to TP sensor, MAP sensor and EGR position sensor. The 5-volt reference 2 circuit supplies reference voltage to A/C pressure sensor and fuel tank pressure sensor. After repairs, go to step 15.
7. Using scan tool, observe ECT sensor temperature. If temperature reading is about 302°F (150°C), go to next step. If temperature reading is not about 302°F (150°C), go to step 9.
8. Check for poor connections at ECT sensor connector. Repair connector as necessary. After repairs, go to step 15. If connector is okay, go to step 13.
9. Turn ignition off. Disconnect jumper wire. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black wire (DeVille and Seville) or Brown wire (Eldorado) between ECT sensor harness connector and terminal No. 68 at PCM C2 harness connector. (Scheme 5) If continuity exists, go to step 14. If continuity does not exist, repair open in Black wire (DeVille and Seville) or Brown wire (Eldorado). After repairs, go to step 15.
10. If voltage measured in step 4 is more than 5 volts, go to next step. If voltage measured in step 4 is not more than 5 volts, go to step 12.
11. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 31 (Yellow wire) at PCM C2 harness connector. (Scheme 5) If no voltage is indicated, go to step 14. If any voltage is indicated, repair short to voltage in Yellow wire between PCM and ECT sensor. After repairs, go to step 15.
12. Turn ignition off. Disconnect jumper wire. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Yellow wire between ECT sensor harness connector and terminal No. 31 at PCM C2 harness connector. (Scheme 5) If continuity exists, go to step 14. If continuity does not exist, repair open in Yellow wire. After repairs, go to step 15.
13. Replace ECT sensor. After repairs, go to step 15.
14. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
15. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
16. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Throttle Position (TP) sensor is used by the Powertrain Control Module (PCM) to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with 3 circuits, a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM provides TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from closed throttle position to Wide Open Throttle (WOT) position provides PCM with a signal voltage from less than one volt to more than 4 volts through the TP sensor signal circuit. When conditions for running this DTC are met, the PCM will use the Manifold Absolute Pressure (MAP) sensor to determine if the predicted operating range of the TP sensor is correct. A skewed MAP sensor may cause this DTC to set and should be tested for proper operation if the TP sensor is determined to be operating properly and DTC P0121 continues to set.

1. DTC P0106, P0107, P0108, P0122, P0123, P0506, P0507, P1106, P1107, P1121 or P1122 is not set.
2. Engine run time is more than 30 seconds.
3. Engine coolant temperature is more than 32°F (0°C).
4. MAP reading is less than 8 psi (55 kPa) for a TP sensor skewed high test.
5. MAP reading is more than 9.28 psi (64 kPa) for a TP sensor skewed low test.
6. MAP is steady for 5 seconds or more.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, observe TP sensor angle parameter while slowly opening throttle to WOT. If TP sensor angle increased steadily from zero percent to 98 percent, go to next step. If TP sensor angle did not increase steadily from zero percent to 98 percent, go to step 4.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect TP sensor connector. (Scheme 14) Turn ignition on. Using scan tool, observe TP sensor voltage. If voltage is zero volts, go to next step. If voltage is not zero volts, to step 6.
5. Turn ignition off. Connect a 3-amp fused jumper wire between Gray and Dark Blue wires at TP sensor harness connector. Using scan tool, observe TP sensor voltage. If voltage is 5 volts, go to step 9. If voltage is not 5 volts, go to step 7.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 62 (Dark Blue wire) at PCM C1 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Dark Blue wire. After repairs, go to 14. If no voltage is indicated, go to step 12.
7. Turn ignition off. Check continuity of Gray wire between TP sensor harness connector and terminal No. 51 at PCM C2 harness connector. If continuity exists, go to next step. If continuity does not exist, repair open in Gray wire. After repairs, go to step 14.
8. Check continuity of Dark Blue wire between TP sensor harness connector and terminal No. 62 at PCM C1 harness connector. If continuity exists, go to step 11. If continuity does not exist, repair open in Dark Blue wire. After repairs, go to step 14.
9. Check continuity of Black wire between TP sensor harness connector and terminal No. 69 at PCM C2 harness connector. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire. After repairs, go to step 14.
10. Check for poor connections at TP sensor connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
11. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
12. Replace TP sensor. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

A skewed MAP sensor signal may cause PCM to incorrectly determine that the TP sensor is out of range. Check for an unusually low or high MAP sensor reading. If DTC is determined to be intermittent or TP sensor system is still suspect, go to DTC P1121: THROTTLE POSITION SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE and/or INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Throttle Position (TP) sensor is used by the Powertrain Control Module (PCM) to determine throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with 3 circuits, a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM provides TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from closed throttle position to Wide Open Throttle (WOT) position provides PCM with a signal voltage from less than one volt to more than 4 volts through the TP sensor signal circuit. DTC P0122 will set if PCM detects an excessively low signal voltage.

Only condition for running this DTC is ignition must be on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, observe TP sensor voltage parameter. If voltage is less than.16 volt, go to step 4. If voltage is.16 or more, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, go to «DTC P1122: THROTTLE POSITION SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect TP sensor connector. (Scheme 14) Connect a 3-amp fused jumper wire between Gray and Dark Blue wires at TP sensor harness connector. Turn ignition on. Using scan tool, observe TP sensor voltage. If voltage is 5 volts, go to step 11. If voltage is not 5 volts, go to next step.
5. Remove jumper wire. Measure voltage between Gray and Black wires at TP sensor harness connector. If voltage is about 5 volts, go to step 9. If voltage is not about 5 volts, go to next step.
6. Turn ignition off. Check continuity of Gray wire between TP sensor harness connector and terminal No. 51 at PCM C2 harness connector. If continuity exists, go to next step. If continuity does not exist, repair open in Gray wire. After repairs, go to step 14.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe Gray wire at TP sensor harness connector. If test light does not illuminate, go to next step. If test light illuminates, repair short to ground in Gray wire between TP sensor and PCM. After repairs, go to step 14.
8. Reconnect PCM connectors. Connect DVOM between Gray and Black wires at TP sensor harness connector. Turn ignition on. Observe voltage reading while disconnecting all sensors, one at a time, that use a 5-volt reference signal. If voltage reading changes, replace sensor that caused voltage to change. After repairs, go to step 14. If voltage does not change, reconnect connectors and go to step 10.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Dark Blue wire between TP sensor harness connector and terminal No. 62 at PCM C1 harness connector. If continuity exists, go to next step. If continuity does not exist, repair open in Dark Blue wire. After repairs, go to step 14.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
11. Check for poor connections at TP sensor connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to next step.
12. Replace TP sensor. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Throttle Position (TP) sensor is used by the Powertrain Control Module (PCM) to determine throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with 3 circuits, a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM provides TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from closed throttle position to Wide Open Throttle (WOT) position provides the PCM with a signal voltage from less than one volt to more than 4 volts through TP sensor signal circuit. DTC P0123 will set if PCM detects an excessively high signal voltage.

Only condition for running this DTC is ignition must be on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, observe TP sensor voltage parameter with throttle closed. If voltage is more than 4.8 volts, go to step 4. If voltage is 4.8 volts or less, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, go to «DTC P1121: THROTTLE POSITION SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect TP sensor. (Scheme 14) Turn ignition on. Using scan tool, observe TP sensor voltage parameter. If voltage is zero volts, go to next step. If voltage is not zero volts, go to step 8.
5. Measure voltage between ground and Gray wire at TP sensor harness connector. If voltage is 5 volts, go to next step. If voltage is not 5 volts, go to step 9.
6. Using a test light connected to positive battery voltage, probe Black wire at TP sensor harness connector. If test light illuminates, go to step 10. If test light does not illuminate, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black wire between TP sensor harness connector and terminal No. 69 at PCM C2 harness connector. (Scheme 5) If continuity exists, go to step 15. If continuity does not exist, repair open in Black wire. After repairs, go to step 18.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 62 (Dark Blue wire) at PCM C1 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Dark Blue wire between PCM and TP sensor. After repairs, go to step 18. If no voltage is indicated, go to step 15.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 51 (Gray wire) at PCM C2 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Gray wire between PCM and TP sensor. After repairs, go to step 18. If no voltage is indicated, go to next step.
10. Turn ignition off. Reconnect PCM connectors. Turn ignition on. Connect a DVOM between Gray and Black wires at TP sensor harness connector. Note voltage reading. Using scan tool, command EGR valve to 100 percent while observing DVOM. If voltage changed, go to next step. If voltage did not change, go to step 14.
11. Disconnect EGR valve connector. (Scheme 15) With DVOM still connected, command EGR valve to 100 percent. If voltage changed, go to step 13. If voltage did not change, go to next step.
12. Replace EGR valve. After repairs, go to step 18.
13. Gray wire between EGR valve and PCM is shorted to 5-volt reference circuit. Repair wiring as necessary. See WIRING DIAGRAMS article. After repairs, go to step 18.
14. Check for poor connections at TP sensor connector. Repair connector as necessary. After repairs, go to step 18. If connector is okay, go to step 16.
15. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 18. If connectors are okay, go to step 17.
16. Replace TP sensor. After repairs, go to step 18.
17. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
18. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Scheme 15

Engine Coolant Temperature (ECT) sensor monitors temperature of coolant. This input is used by the Powertrain Control Module (PCM) for engine control and as an enabling criteria for some diagnostics. If engine coolant temperature does not increase normally or does not reach regulating temperature of thermostat, diagnostics that use the ECT as an enabling criteria may not run when expected. DTC P0125 will set if an excessive amount of time passes before engine coolant temperature reaches closed loop operation temperature of 154°F (68°C).

1. DTC P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0502, P0503, P1111, P1112, P1114 or P1115 is not set.
2. Engine is running.
3. Engine coolant temperature at start-up is 104°F (40°C).
4. Engine coolant temperature is more than -40°F (-40°C).
5. Intake air temperature is -40 to 104°F (-40 to 40°C).
6. Vehicle speed is more than one MPH.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Check coolant level. If coolant level is okay, go to next step. If coolant level is low, check cooling system for leaks. Repair as necessary and top off coolant level.
3. Turn ignition off. Disconnect ECT sensor connector. (Scheme 14) Connect a 3-amp fused jumper wire between Yellow wire and Black wire (DeVille and Seville) or Brown wire (Eldorado) at ECT sensor harness connector. Turn ignition on. Using scan tool, observe ECT sensor temperature. If temperature reading is more than 280°F (138°C), go to step 7. If temperature reading is 280°F (138°C) or less, go to next step.
4. Turn ignition off. Disconnect jumper wire. Reconnect jumper wire between ground and Yellow wire at ECT sensor harness connector. Turn ignition on. Using scan tool, observe ECT sensor temperature. If temperature reading is more than 280°F (138°C), go to next step. If temperature reading is 280°F (138°C) or less, go to step 6.
5. Repair open or high resistance in Black wire (DeVille and Seville) or Brown wire (Eldorado) between ECT sensor and PCM. After repairs, go to step 10.
6. Repair open or high resistance in Yellow wire between ECT sensor and PCM. After repairs, go to step 10.
7. Remove ECT sensor. Suspend ECT sensor and a thermometer in a pan of water. Place pan on a burner or hot plate. Measure resistance between ECT sensor terminals with sensor at specified temperature. See «ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) table. If resistance is as specified, go to next step. If resistance is not as specified, go to step 9.
8. Reinstall ECT sensor. Diagnose cooling system thermostat.
9. Replace ECT sensor. After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

DTC P0125 is designed to detect a skewed ECT sensor or a faulty thermostat. A skewed IAT sensor may also cause this DTC to set. IAT sensor should read near ambient temperature while driving.

ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0130 will set if HO2S bank 1 sensor 1 signal voltage remains at 350-500 millivolts for about 16 seconds during 120 second monitoring period.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0151, P0152, P0153, P0154, P0201-P0208, P1133, P1134, P1153 or P1154 is not set.
2. Engine is running.
3. System voltage is 9-18 volts.
4. Predicted HO2S heater temperature is more than 1112°F (600°C).
5. Engine coolant temperature is more than 167°F (75°C).
6. Traction control is not active.
7. Catalyst test is not active.
8. Engine speed is 500-5000 RPM.
9. Mass airflow is 3-30 grams/sec.
10. Closed loop fuel control is enables.
11. Listed conditions exist for 5 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Ensure engine is at normal operating temperature. Increase engine speed to 1200 RPM for 2 minutes. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is 350-500 millivolts, go to step 4. If voltage is not 350-500 millivolts, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Connect a jumper wire between terminal "A" (Tan wire) and terminal "B" (Purple/White wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 8)and (Scheme 9). Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is less than 150 millivolts, go to step 7. If voltage is 150 millivolts or more, go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Tan wire between terminal No. 52 at PCM C1 harness connector and terminal "A" at HO2S bank 1 sensor 1 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Tan wire. After repairs, go to step 11. If continuity exists, go to next step.
6. Check continuity of Purple/White wire between terminal No. 53 at PCM C1 harness connector and terminal "B" at HO2S bank 1 sensor 1 harness connector. If continuity does not exist, repair open in Purple/White wire. After repairs, go to step 11. If continuity exists, go to step 9.
7. Check for poor connections at HO2S bank 1 sensor 1 connector. Repair connector as necessary. After repairs, go to step 11. If connector is okay, go to next step.
8. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 1. After repairs, go to step 11.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 11. If connectors are okay, go to next step.
10. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
11. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
12. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0131 will set if HO2S bank 1 sensor 1 signal voltage remains less than 75 millivolts for about 50 seconds during normal closed loop fuel control. DTC P0131 will also set if HO2S bank 1 sensor 1 signal voltage remains at less than 575 millivolts during power enrichment fuel control.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. Throttle position angle is 3-25 percent.
3. System voltage is 9-18 volts.
4. Closed loop fuel control enabled.
5. Air/fuel ratio is 14.5-14.8:1.
6. EGR flow diagnostic test is not active.
7. Fuel injectors are not disabled.
8. Secondary air injection diagnostic test is not active.
9. Catalyst diagnostic test is not active.
10. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed code enable criteria. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is less than 75 millivolts, go to step 4. If voltage is 75 millivolts or more, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is about 450 millivolts, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If voltage is not about 450 millivolts, go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check if Purple/White wire at terminal "B" at HO2S bank 1 sensor 1 harness connector is shorted to ground. (Scheme 8)and (Scheme 9). Also check if Purple/White wire at terminal "B" is shorted to Tan wire at terminal "A" at HO2S bank 1 sensor 1 harness connector. If Purple/White wire is shorted to ground or shorted to Tan wire, repair wiring as necessary. After repairs, go to step 7. If wiring is okay, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too low will cause a lean condition. The PCM will compensate for some decrease in fuel pressure, but if fuel pressure is too low, DTC P0131 may set. Check fuel injectors. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If fuel injectors deliver improper fuel volume, DTC P0131 may set. Check for exhaust leaks. Exhaust leaks may cause outside air to be drawn into the exhaust gas stream, and pass the HO2S. This causes HO2S signal to indicate a false lean condition. Check for Secondary Air Injection (AIR) system leaks. Check AIR system hoses, check valves, and piping for leaks. Check for poor connections or for signs of any damage. Check for disconnected or damaged vacuum hoses. Check for vacuum leaks at throttle body, EGR valve, EVAP purge solenoid, and intake manifold. Check for fuel contamination. Water, even in small amounts, can be delivered to fuel injectors. Water can cause a lean exhaust. Also, excessive alcohol in the fuel can cause a lean condition. Check with customer in order to verify conditions under which the DTC set. Check if vehicle ran out of fuel. If none of the previous conditions are set, replace HO2S. Using scan tool, review front and rear long term fuel trim values fail records data. If both banks were lean, check for a condition that would cause a lean engine operation. If only the rear bank was lean, the lean condition is isolated to that bank. Check for an intermittent short to ground on HO2S signal circuit. If condition is not set, check with customer about type of fuel used. Recommend using fuels of 10 percent or less ethanol.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0132 will set if HO2S bank 1 sensor 1 signal voltage remains more than 900 millivolts for about 50 seconds during normal closed loop fuel control. DTC will also set if HO2S bank 1 sensor 1 signal voltage remains at more than 200 millivolts during deceleration fuel control.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. Throttle position angle is 3-25 percent.
3. System voltage is 9-18 volts.
4. Closed loop fuel control enabled.
5. Air/fuel ratio is 14.4-14.9:1.
6. Fuel injectors are not disabled.
7. EGR flow diagnostic test is not active.
8. Secondary air injection diagnostic test is not active.
9. Catalyst diagnostic test is not active.
10. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed code enable criteria. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is more than 900 millivolts, go to step 4. If voltage is 900 millivolts or less, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is about 450 millivolts, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If voltage is not about 450 millivolts, go to next step.
5. Turn ignition off and wait 30 seconds. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Measure voltage between ground and terminal No. 53 (Purple/White wire) at PCM C1 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Purple/White wire between PCM and HO2S bank 1 sensor 1. After repairs, go to step 7. If no voltage is indicated, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too high will cause a rich condition. The PCM will compensate for some increase in fuel pressure, but if fuel pressure is high enough, DTC P0132 may set. Check fuel injectors. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If fuel injectors deliver improper fuel volume, DTC P0132 may set. Check EVAP canister and hoses for fuel saturation. Check for silicone contamination. Silicone contamination of HO2S can also cause a high HO2S voltage signal. This condition is indicated by a powdery White deposit on tip of HO2S that is exposed to exhaust stream. If none of the previous conditions are present, replace HO2S. Using scan tool, review front and rear long term fuel trim values fail records data. If both banks were rich, check for a condition that would cause a rich engine operation. If only the rear bank was rich, the rich condition is isolated to that bank. Check for an intermittent short to voltage on HO2S signal circuit.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0133 will set if HO2S bank 1 sensor 1 lean-to-rich or rich-to-lean average transition response time during the sample period is more than 219 milliseconds.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0135, P0151, P0152, P0201-P0208, P0300, P0410, P0440, P0442, P0443, P0446, P0449, P1133, P1415, P1416 or P1441 is not set.
2. Engine speed is 1200-2800 RPM.
3. Throttle position angle is more than 3 percent.
4. Mass airflow is 15-35 grams/sec.
5. System voltage is 9-18 volts.
6. Closed loop fuel control enabled.
7. Engine coolant temperature is more than 167°F (75°C).
8. Transmission is not in Park, Reverse or Neutral.
9. Engine run time is 3 minutes.
10. EGR flow diagnostic test is not active.
11. Secondary air injection diagnostic test is not active.
12. Catalyst diagnostic test is not active.
13. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If any other DTCs are set except HO2S DTCs, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
2. Start engine. Ensure engine is at normal operating temperature. Increase engine speed to 1200 RPM for 2 minutes. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If scan tool does not indicate HO2S voltage varying outside 400-500 millivolts (DeVille and Seville) or 327-625 millivolts (Eldorado), go to step 4. If scan tool indicates HO2S voltage varying outside 400-500 millivolts (DeVille and Seville) or 327-625 millivolts (Eldorado), go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Check for exhaust leaks. Ensure HO2S bank 1 sensor 1 is installed correctly. Check for damaged HO2S bank 1 sensor 1 wiring harness. If any problems are found, repair as necessary. After repairs, go to step 13. If no problems are found, go to next step.
5. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Measure voltage between ground and terminal "B" (Purple/White wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 8)and (Scheme 9). If voltage is about 450 millivolts, go to next step. If voltage is not about 450 millivolts, go to step 8.
6. Turn ignition off. Connect a jumper wire between terminal "A" (Tan wire) and terminal "B" (Purple/White wire) at HO2S bank 1 sensor 1 harness connector. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is about zero volts, go to step 9. If voltage is not about zero volts, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Tan wire between terminal No. 52 at PCM C1 harness connector and terminal "A" at HO2S bank 1 sensor 1 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Tan wire. After repairs, go to step 13. If continuity exists, go to step 11.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Purple/White wire between terminal No. 53 at PCM C1 harness connector and terminal "B" at HO2S bank 1 sensor 1 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Purple/White wire. After repairs, go to step 13. If continuity exists, go to step 11.
9. Check for poor connections at HO2S bank 1 sensor 1 connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to next step.
10. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 1. After repairs, go to step 13.
11. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 13. If connectors are okay, go to next step.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and for poor terminal-to-wire connections. Inspect wiring harness for damage. If harness appears to be okay, observe scan tool while moving connectors and wiring harnesses related to HO2S bank 1 sensor 1. A change in scan tool display will indicate malfunction location. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since diagnostic test last failed may help to diagnose the condition. The information may help determine how often condition that set the DTC occurs.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0134 will set if HO2S bank 1 sensor 1 signal voltage remains 400-500 millivolts for about one minute.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. System voltage is 9-18 volts.
3. Engine run time is 3 minutes.
4. EGR flow diagnostic test is not active.
5. Catalyst diagnostic test is not active.
6. Secondary air injection diagnostic test is not active.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) If no other DTCs are set, go to next step.
3. Start engine. Ensure engine is at normal operating temperature. Increase engine speed to 1200 RPM for 2 minutes. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If scan tool indicates HO2S voltage varying outside 400-500 millivolts, go to next step. If scan tool does not indicate HO2S voltage varying outside 400-500 millivolts, go to step 5.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition off. Connect a jumper wire between terminal "A" (Tan wire) and terminal "B" (Purple/White wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 8)and (Scheme 9). Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is about 75 millivolts, go to step 7. If voltage is not about 75 millivolts, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Tan wire between terminal No. 52 at PCM C1 harness connector and terminal "A" at HO2S bank 1 sensor 1 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). Also check continuity of Purple/White wire between terminal No. 53 at PCM C1 harness connector and terminal "B" at HO2S bank 1 sensor 1 harness connector. If continuity does not exist in Tan wire or Purple/White wire, repair open in wiring as necessary. After repairs, go to step 11. If continuity exists in both wires, go to step 9.
7. Check for poor connections at HO2S bank 1 sensor 1 connector. Repair connector as necessary. After repairs, go to step 11. If connector is okay, go to next step.
8. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 1. After repairs, go to step 11.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 11. If connectors are okay, go to next step.
10. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
11. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
12. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and for poor terminal-to-wire connections. Inspect wiring harness for damage. If harness appears to be okay, observe scan tool while moving connectors and wiring harnesses related to HO2S bank 1 sensor 1. A change in scan tool display will indicate malfunction location. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since the diagnostic test last failed may help to diagnose condition. The information may help determine how often condition that set the DTC occurs.

Heated Oxygen Sensor (HO2S) heater is used to reduce the time that it takes for HO2S to go active. The Powertrain Control Module (PCM) controls HO2S heaters using a high side driver, 2 low side drivers, and a current monitoring driver. The current monitoring driver tests condition of the heaters. The high side driver provides HO2S bank 1 sensor 1 heater with ignition voltage. A fused ignition feed provides HO2S bank 1 sensor 2, and bank 2 sensor 1 with ignition voltage. HO2S receives ground through one of the low side drivers. With engine running, PCM turns on the high side, and the low side drivers to warm-up the oxygen sensors. When proper conditions are present, the PCM keeps high side driver on, turns on the current monitor driver, and then turns off the warm-up driver. This allows the PCM to record a total current value for both of the fuel control heaters. If test conditions remain stable, the PCM enters second stage of the test. During this stage, the PCM keeps the current monitor on, and turns off the high side driver. This allows the PCM to record a current value for bank 2 sensor 1 heater circuit. The PCM subtracts the bank 2 sensor 1 current value from the total current value to determine the current value for bank 1 sensor 1. DTC P0135 will set if PCM detects HO2S bank 1 sensor 1 current value is outside of calibrated range.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold.

1. DTC P0030, P1031 or P1032 is not set.
2. System voltage during current measurement is steady within one volt of actual system voltage.
3. Engine speed is 500-3000 RPM.
4. Engine run time is more than 5 minutes.
5. HO2S overtemp control is not active.
6. Mass airflow is 4-30 grams/sec.
7. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, clear DTCs. Observe DTC information for 30 seconds. If DTCs P0030, P1031 and P1032 are set, go to «DTC P0030: HO2S HEATER CONTROL CIRCUIT VOLTAGE IS GREATER THAN PCM INTERNAL DRIVER CAPACITY - DEVILLE & SEVILLE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) or «DTC P0030: HEATED OXYGEN SENSOR HEATER CONTROL CIRCUIT - BANK 1 SENSOR 1 - ELDORADO»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTCs P0030, P1031 and P1032 are not set, go to next step.
3. Start engine. Using scan tool, observe DTC information for 5 minutes. If P0135 and P0155 are set, go to step 5. If P0135 and P0155 are not set, go to next step.
4. If P0135 is set, go to step 7. If P0135 is not set, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Using a test light connected to ground, probe terminal "D" (Dark Green wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 8)and (Scheme 9). Using scan tool, command HO2S heater driver 1 on and off. If test light turns on and off, go to step 11. If test light does not turn on and off, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 31 (Dark Green wire) at PCM C1 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Dark Green wire between HO2S bank 1 sensor 1 and PCM. After repairs, go to step 13. If no voltage is indicated, go to step 12.
7. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Measure voltage between ground and terminal "D" (Dark Green wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 8)and (Scheme 9). If voltage is more than 10 volts, go to step 9. If voltage is 10 volts or less, go to next step.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Dark Green wire between terminal "D" at HO2S bank 1 sensor 1 harness connector and terminal No. 31 at PCM C1 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Dark Green wire. After repairs, go to step 13. If continuity exists, go to step 10.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black/White wire (DeVille and Seville) or Tan/White wire (Eldorado) between terminal "C" at HO2S bank 1 sensor 1 harness connector and terminal No. 68 at PCM C2 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Black wire (DeVille and Seville) or Tan/White wire (Eldorado). After repairs, go to step 13. If continuity exists, go to next step.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 13. If connectors are okay, go to step 12.
11. Replace HO2S bank 1 sensor 1. After repairs, go to step 13.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

An intermittent open in HO2S ignition signal circuit or ground circuit may cause DTC to set. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0137 will set if HO2S bank 1 sensor 2 signal voltage remains less than 9 millivolts for about 50 seconds during normal closed loop fuel control.

Note. HO2S bank 1 sensor 2 is located behind catalytic converter.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. Throttle position angle is 3-25 percent.
3. System voltage is 9-18 volts.
4. Closed loop fuel control enabled.
5. Air/fuel ratio is 14.4-14.9:1.
6. EGR flow diagnostic test is not active.
7. Fuel injectors are not disabled.
8. Secondary air injection diagnostic test is not active.
9. Catalyst diagnostic test is not active.
10. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed code enable criteria. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is less than 9 millivolts, go to step 4. If voltage is 9 millivolts or more, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Raise and support vehicle. Remove HO2S bank 1 sensor 2 heat shield. HO2S bank 1 sensor 2 is located behind catalytic converter. Disconnect HO2S bank 1 sensor 2 connector. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is about 450 millivolts, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If voltage is not about 450 millivolts, go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check if Dark Green/White wire at terminal "B" at HO2S bank 1 sensor 2 harness connector is shorted to ground. (Scheme 8)and (Scheme 9). Also check if Dark Green/White wire at terminal "B" is shorted to Dark Blue/White wire at terminal "A" at HO2S bank 1 sensor 2 harness connector. If Dark Green/White wire is shorted to ground or shorted to Dark Blue/White wire, repair wiring as necessary. After repairs, go to step 7. If wiring is okay, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check exhaust system for leaks. Exhaust leaks may cause outside air to be drawn into the exhaust gas stream, and pass the HO2S. This causes the HO2S signal to indicate a false lean condition. For intermittent conditions, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since diagnostic test last failed may assist in diagnosing condition. Information may help determine how often condition that set DTC occurs.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0138 will set if HO2S bank 1 sensor 2 signal voltage remains more than 950 millivolts for about 50 seconds during normal closed loop fuel control.

Note. HO2S bank 1 sensor 2 is behind catalytic converter.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. Throttle position angle is between 3-25 percent.
3. System voltage is 9-18 volts.
4. Closed loop fuel control enabled.
5. Air/fuel ratio is 14.4-14.9:1.
6. EGR flow diagnostic test is not active.
7. Secondary air injection diagnostic test is not active.
8. Catalyst diagnostic test is not active.
9. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed code enable criteria. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is more than 600 millivolts (DeVille and Seville) or more than 950 (Eldorado), go to step 4. If voltage is 600 millivolts or less (DeVille and Seville) or 950 millivolts or less (Eldorado), go to next step.
3. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Raise and support vehicle. Remove HO2S bank 1 sensor 2 heat shield. HO2S bank 1 sensor 2 is located behind catalytic converter. Disconnect HO2S bank 1 sensor 2 connector. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is about 450 millivolts, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If voltage is not about 450 millivolts, go to next step.
5. Turn ignition off and wait 30 seconds. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Measure voltage between ground and terminal No. 51 (Dark Green/White wire) at PCM C1 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Dark Green/White wire between PCM and HO2S bank 1 sensor 2. After repairs, go to step 7. If no voltage is indicated, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check for silicone contamination. Silicone contamination of HO2S can also cause a high HO2S voltage signal. This condition is indicated by a powdery White deposit on tip of HO2S that is exposed to exhaust stream. Reviewing failure records vehicle mileage since diagnostic test last failed may help to diagnose condition. Information may help to determine how often condition that set DTC occurs.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0140 will set if HO2S bank 1 sensor 2 signal voltage remains 400-500 millivolts for about 80 seconds.

Note. Post catalytic HO2S is also referred to as HO2S bank 1 sensor 2. HO2S bank 1 sensor 2 is behind catalytic converter.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0141, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. System voltage is 9-18 volts.
3. Engine run time is 3 minutes.
4. EGR flow diagnostic test is not active.
5. Secondary air injection diagnostic test is not active.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions). If no other DTCs are set, go to next step.
3. Start engine. Ensure engine is at normal operating temperature. Increase engine speed to 1200 RPM for 2 minutes. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If scan tool indicates HO2S voltage varying outside 300-500 millivolts, go to next step. If scan tool does not indicate HO2S voltage varying outside 300-500 millivolts, go to step 5.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition off. Raise and support vehicle. Remove HO2S bank 1 sensor 2 heat shield. HO2S bank 1 sensor 2 is located behind catalytic converter. Disconnect HO2S bank 1 sensor 2 connector. Turn ignition on. Connect a jumper wire between terminal "A" (Dark Blue/White wire) and terminal "B" (Dark Green/White wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 8)and (Scheme 9). Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is less than 150 millivolts, go to step 7. If voltage is 150 millivolts or more, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Dark Blue/White wire between terminal No. 50 at PCM C1 harness connector and terminal "A" at HO2S bank 1 sensor 2 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). Also check continuity of Dark Green/White wire between terminal No. 51 at PCM C1 harness connector and terminal "B" at HO2S bank 1 sensor 2 harness connector. If continuity does not exist in Dark Blue/White wire or Dark Green/White wire, repair open in wiring as necessary. After repairs, go to step 11. If continuity exists in both wires, go to step 9.
7. Check for poor connections at HO2S bank 1 sensor 2 connector. Repair connector as necessary. After repairs, go to step 11. If connector is okay, go to next step.
8. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 2. After repairs, go to step 11.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 11. If connectors are okay, go to next step.
10. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
11. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
12. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and for poor terminal-to-wire connections. Inspect wiring harness for damage. If harness appears to be okay, observe scan tool while moving connectors and wiring harnesses related to HO2S bank 1 sensor 2. A change in scan tool display will indicate malfunction location. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since diagnostic test last failed may help to diagnose condition. The information may help determine how often condition that set DTC occurs.

Heated Oxygen Sensor (HO2S) heater is used to reduce time that it takes for HO2S to go active. HO2S bank 1 sensor 2 heater helps to maintain sensor at proper temperature for catalyst testing, and additional adjustments to fuel trim. The HO2S heater receives power through a fused ignition circuit. The Powertrain Control Module (PCM) turns sensor heater on and off using a low side driver output driver module located within PCM. The PCM only tests the heater after a cold start. PCM determines a cold start based on difference between Engine Coolant Temperature (ECT) at last key off, and ECT at current key on. When HO2S voltage indicates a sufficiently active sensor, PCM looks at how much time has elapsed since start-up. DTC P0141 will set if PCM determines that too much time was required for sensor to become active.

Note. HO2S bank 1 sensor 2 is located behind catalytic converter.

1. DTC P0137, P0138 or P0140 is not set.
2. Difference between engine coolant temperature at last key off and current key on indicates a cold start.
3. System voltage is 10-18 volts.
4. Average mass airflow is less than 30 grams/sec.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, clear DTCs. Observe DTC information for 30 seconds. If DTC P0036 sets, go to «DTC P0036: HO2S HEATER CONTROL CIRCUIT VOLTAGE IS GREATER THAN PCM INTERNAL DRIVER CAPACITY - DEVILLE & SEVILLE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) or «DTC P0036: HEATED OXYGEN SENSOR HEATER CONTROL CIRCUIT - BANK 1 SENSOR 2 - ELDORADO»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTC P0036 is not set, go to next step.
3. Using scan tool, command HO2S heater driver 4 on. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If scan tool indicates HO2S voltage varying outside 400-500 millivolts, to next step. If scan tool does not indicate HO2S voltage varying outside 400-500 millivolts, go to step 5.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Raise and support vehicle. Remove HO2S bank 1 sensor 2 heat shield. HO2S bank 1 sensor 2 is located behind catalytic converter. Disconnect HO2S bank 1 sensor 2 connector. Turn ignition on. Connect a jumper wire between terminal "A" (Dark Blue/White wire) and terminal "B" (Dark Green/White wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 8)and (Scheme 9). Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is less than 150 millivolts, go to step 9. If voltage is 150 millivolts or more, go to next step.
6. Turn ignition off. Disconnect jumper wire. Reconnect jumper wire between ground and terminal "B" (Dark Green/White wire) at HO2S bank 1 sensor 2 harness connector. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is less than 150 millivolts, go to step 8. If voltage is 150 millivolts or more, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Dark Green/White wire between terminal No. 51 at PCM C1 harness connector and terminal "B" at HO2S bank 1 sensor 2 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Dark Green/White wire. After repairs, go to step 13. If continuity exists, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Dark Blue/White wire between terminal No. 50 at PCM C1 harness connector and terminal "A" at HO2S bank 1 sensor 2 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Dark Blue/White wire. After repairs, go to step 13. If continuity exists, go to step 10.
9. Check for poor connections at HO2S bank 1 sensor 2 connector. Repair connector as necessary. After repairs, go to step 13. If connectors are okay, go to step 11.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 13. If connectors are okay, go to step 12.
11. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 2. After repairs, go to step 13.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

For intermittent conditions, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0150 will set if HO2S bank 2 sensor 1 signal voltage remains at 350-500 millivolts for about 16 seconds during 120 second monitoring period.

Note. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0151, P0152, P0153, P0154, P0201-P0208, P1133, P1134, P1153 or P1154 is not set.
2. Engine is running.
3. System voltage is 9-18 volts.
4. Predicted HO2S heater temperature is more than 1112°F (600°C).
5. Engine coolant temperature is more than 167°F (75°C).
6. Traction control is not active.
7. Catalyst test is not active.
8. Engine speed is 500-5000 RPM.
9. Mass airflow is 3-30 grams/sec.
10. Closed loop fuel control is enables.
11. Listed conditions exist for 5 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Ensure engine is at normal operating temperature. Increase engine speed to 1200 RPM for 2 minutes. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If voltage is 350-500 millivolts, go to step 4. If voltage is not 350-500 millivolts, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. Connect a jumper wire between terminal "A" (Tan/White wire) and terminal "B" (Purple/White wire) at HO2S bank 2 sensor 1 harness connector. (Scheme 8)and (Scheme 9). Turn ignition on. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If voltage is less than 150 millivolts, go to step 7. If voltage is 150 millivolts or more, go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Tan/White wire between terminal No. 54 at PCM C1 harness connector and terminal "A" at HO2S bank 2 sensor 1 harness connector. If continuity does not exist, repair open in Tan/White wire. After repairs, go to step 11. If continuity exists, go to next step.
6. Check continuity of Purple/White wire between terminal No. 55 at PCM C1 harness connector and terminal "B" at HO2S bank 2 sensor 1 harness connector. If continuity does not exist, repair open in Purple/White wire. After repairs, go to step 11. If continuity exists, go to step 9.
7. Check for poor connections at HO2S bank 2 sensor 1 connector. Repair connector as necessary. After repairs, go to step 11. If connector is okay, go to next step.
8. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 2 sensor 1. After repairs, go to step 11.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 11. If connectors are okay, go to next step.
10. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
11. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
12. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0151 will set if HO2S bank 2 sensor 1 signal voltage remains less than 75 millivolts for about 50 seconds during normal closed loop fuel control. DTC P0151 will also set if HO2S bank 1 sensor 1 signal voltage remains at less than 575 millivolts during power enrichment fuel control.

Note. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. Throttle position angle is 3-25 percent.
3. System voltage is 9-18 volts.
4. Closed loop fuel control enabled.
5. Air/fuel ratio is 14.5-14.8:1.
6. EGR flow diagnostic test is not active.
7. Fuel injectors are not disabled.
8. Secondary air injection diagnostic test is not active.
9. Catalyst diagnostic test is not active.
10. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed code enable criteria. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If voltage is less than 75 millivolts, go to step 4. If voltage is 75 millivolts or more, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. Turn ignition on. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If voltage is about 450 millivolts, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If voltage is not about 450 millivolts, go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check if Purple/White wire at terminal "B" at HO2S bank 2 sensor 1 harness connector is shorted to ground. (Scheme 8)and (Scheme 9). Also check if Purple/White wire at terminal "B" is shorted to Tan/White wire at terminal "A" at HO2S bank 2 sensor 1 harness connector. If Purple/White wire is shorted to ground or shorted to Tan/White wire, repair wiring as necessary. After repairs, go to step 7. If wiring is okay, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too low will cause a lean condition. The PCM will compensate for some decrease in fuel pressure, but if fuel pressure is too low, DTC P0151 may set. Check fuel injectors. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If fuel injectors deliver improper fuel volume, DTC P0151 may set. Check for exhaust leaks. Exhaust leaks may cause outside air to be drawn into the exhaust gas stream, and pass the HO2S. This causes the HO2S signal to indicate a false lean condition. Check for Secondary Air Injection (AIR) system leaks. Check AIR system hoses, check valves, and piping for leaks. Check for poor connections or for signs of any damage. Check for disconnected or damaged vacuum hoses. Check for vacuum leaks at throttle body, EGR valve, EVAP purge solenoid, and intake manifold. Check for fuel contamination. Water, even in small amounts, can be delivered to fuel injectors. Water can cause a lean exhaust. Also, excessive alcohol in the fuel can cause a lean condition. Check with customer in order to verify conditions under which DTC set. Check if vehicle ran out of fuel. If none of the previous conditions are present, replace HO2S. Using scan tool, review front and rear long term fuel trim values fail records data. If both banks were lean, check for a condition that would cause a lean engine operation. If only rear bank was lean, the lean condition is isolated to that bank. Check for an intermittent short to ground on HO2S signal circuit. If condition is not present, check with customer about type of fuel used. Recommend using fuels of 10 percent or less ethanol.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0152 will set if HO2S bank 2 sensor 1 signal voltage remains more than 900 millivolts for about 50 seconds during normal closed loop fuel control. DTC P0152 will also set if HO2S bank 2 sensor 1 signal voltage remains at more than 200 millivolts during deceleration fuel control.

Note. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. Throttle position angle is between 3-25 percent.
3. System voltage is 9-18 volts.
4. Closed loop fuel control enabled.
5. Air/fuel ratio is 14.4-14.9:1.
6. Fuel injectors are not disabled.
7. EGR flow diagnostic test is not active.
8. Secondary air injection diagnostic test is not active.
9. Catalyst diagnostic test is not active.
10. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed code enable criteria. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If voltage is more than 900 millivolts, go to step 4. If voltage is 900 millivolts or less, go to next step.
3. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect HO2S bank 2 sensor 1 connector. HO2S bank 1 sensor 1 is located in left (front) exhaust manifold. Turn ignition on. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If voltage is about 450 millivolts, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If voltage is not about 450 millivolts, go to next step.
5. Turn ignition off and wait 30 seconds. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Measure voltage between ground and terminal No. 55 (Purple/White wire) at PCM C1 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Purple/White wire between PCM and HO2S bank 2 sensor 1. After repairs, go to step 7. If no voltage is indicated, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too high will cause a rich condition. PCM will compensate for some increase in fuel pressure, but if fuel pressure is high enough, DTC P0152 may set. Check fuel injectors. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Check EVAP canister and hoses for fuel saturation. If fuel injectors deliver improper fuel volume, DTC P0152 may set. Check for silicone contamination. Silicone contamination of HO2S can also cause a high HO2S voltage signal. This condition is indicated by a powdery White deposit on tip of HO2S that is exposed to exhaust stream. Using scan tool, review front and rear long term fuel trim values fail records data. If both banks were rich, check for a condition that would cause a rich engine operation. If only front bank was rich, the rich condition is isolated to that bank. Check for an intermittent short to voltage on HO2S signal circuit.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0153 will set if HO2S bank 2 sensor 1 lean-to-rich or rich-to-lean average transition response time during the sample period is more than 219 milliseconds.

Note. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0135, P0151, P0152, P0201-P0208, P0300, P0410, P0440, P0442, P0443, P0446, P0449, P1133, P1415, P1416 or P1441 is not set.
2. Engine speed is 1200-2800 RPM.
3. Throttle position angle is more than 3 percent.
4. Mass airflow is 15-35 grams/sec.
5. System voltage is 9-18 volts.
6. Closed loop fuel control enabled.
7. Engine coolant temperature is more than 167°F (75°C).
8. Transmission is not in Park, Reverse or Neutral.
9. Engine run time is 3 minutes.
10. EGR flow diagnostic test is not active.
11. Secondary air injection diagnostic test is not active.
12. Catalyst diagnostic test is not active.
13. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If any other DTCs are set except HO2S DTCs, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
2. Start engine. Ensure engine is at normal operating temperature. Increase engine speed to 1200 RPM for 2 minutes. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If scan tool indicates HO2S voltage varying outside 325-625 millivolts, go to next step. If scan tool does not indicate HO2S voltage varying outside 325-625 millivolts, go to step 4.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Check for exhaust leaks. Ensure HO2S bank 2 sensor 1 is installed correctly. Check for damaged HO2S bank 2 sensor 1 wiring harness. If any problems are found, repair as necessary. After repairs, go to step 13. If no problems are found, go to next step.
5. Turn ignition off. Disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. Turn ignition on. Measure voltage between ground and terminal "B" (Purple/White wire) at HO2S bank 2 sensor 1 harness connector. (Scheme 8)and (Scheme 9). If voltage is about 450 millivolts, go to next step. If voltage is not about 450 millivolts, go to step 8.
6. Turn ignition off. Connect a jumper wire between terminal "A" (Tan/White wire) and terminal "B" (Purple/White wire) at HO2S bank 2 sensor 1 harness connector. Turn ignition on. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If voltage is about zero volts, go to step 9. If voltage is not about zero volts, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Tan/White wire between terminal No. 54 at PCM C1 harness connector and terminal "A" at HO2S bank 2 sensor 1 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Tan/White wire. After repairs, go to step 13. If continuity exists, go to step 11.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Purple/White wire between terminal No. 55 at PCM C1 harness connector and terminal "B" at HO2S bank 2 sensor 1 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Purple/White wire. After repairs, go to step 13. If continuity exists, go to step 11.
9. Check for poor connections at HO2S bank 2 sensor 1 connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to next step.
10. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 2 sensor 1. After repairs, go to step 13.
11. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 13. If connectors are okay, go to next step.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and for poor terminal-to-wire connections. Inspect wiring harness for damage. If harness appears to be okay, observe scan tool while moving connectors and wiring harnesses related to HO2S bank 2 sensor 1. A change in scan tool display will indicate malfunction location. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since diagnostic test last failed may help to diagnose condition. The information may help determine how often condition that set DTC occurs.

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width. DTC P0154 will set if HO2S bank 2 sensor 1 signal voltage remains 400-500 millivolts for about 80 seconds.

Note. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. System voltage is 9-18 volts.
3. Engine run time is 3 minutes.
4. EGR flow diagnostic test is not active.
5. Catalyst diagnostic test is not active.
6. Secondary air injection diagnostic test is not active.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions). If no other DTCs are set, go to next step.
3. Start engine. Ensure engine is at normal operating temperature. Increase engine speed to 1200 RPM for 2 minutes. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If scan tool indicates HO2S voltage varying outside 400-500 millivolts, go to next step. If scan tool does not indicate HO2S voltage varying outside 400-500 millivolts, go to step 5.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition off. Connect a jumper wire between terminal "A" (Tan/White wire) and terminal "B" (Purple/White wire) at HO2S bank 2 sensor 1 harness connector. (Scheme 8)and (Scheme 9). Turn ignition on. Using scan tool, observe HO2S bank 2 sensor 1 voltage. If voltage is less than 75 millivolts, go to step 7. If voltage is 75 millivolts or more, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Tan/White wire between terminal No. 54 at PCM C1 harness connector and terminal "A" at HO2S bank 2 sensor 1 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). Also check continuity of Purple/White wire between terminal No. 55 at PCM C1 harness connector and terminal "B" at HO2S bank 2 sensor 1 harness connector. If continuity does not exist at Tan/White wire or Purple/White wire, repair open in wiring as necessary. After repairs, go to step 11. If continuity exists in both wires, go to step 9.
7. Check for poor connections at HO2S bank 2 sensor 1 connector. Repair connector as necessary. After repairs, go to step 11. If connector is okay, go to next step.
8. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 2 sensor 1. After repairs, go to step 11.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 11. If connectors are okay, go to next step.
10. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
11. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 3.
12. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and for poor terminal-to-wire connections. Inspect wiring harness for damage. If harness appears to be okay, observe scan tool while moving connectors and wiring harnesses related to HO2S bank 2 sensor 1. A change in scan tool display will indicate malfunction location. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since diagnostic test last failed may help to diagnose condition. The information may help determine how often condition that set DTC occurs.

Heated Oxygen Sensor (HO2S) heater is used to reduce time that it takes for HO2S to go active. The Powertrain Control Module (PCM) controls HO2S heaters using a high side driver, 2 low side drivers, and a current monitoring driver. The current monitoring driver tests the condition of the heaters. The high side driver provides HO2S bank 1 sensor 1 heater with ignition voltage. A fused ignition feed provides HO2S bank 1 sensor 2, and bank 2 sensor 1 with ignition voltage. HO2S receives ground through one of the low side drivers. With engine running, PCM turns on the high side, and the low side drivers to warm-up oxygen sensors. When proper conditions are present, the PCM keeps the high side driver on, turns on the current monitor driver, and then turns off the warm-up driver. This allows the PCM to record a total current value for both of the fuel control heaters. If test conditions remain stable, the PCM enters the second stage of the test. During this stage, the PCM keeps the current monitor on, and turns off the high side driver. This allows PCM to record a current value for bank 2 sensor 1 heater circuit. PCM subtracts bank 2 sensor 1 current value from total current value to determine current value for bank 1 sensor 1. DTC P0155 will set if PCM detects HO2S bank 2 sensor 1 current value is outside of calibrated range.

Note. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold.

1. DTC P0030, P1031 or P1032 is not set.
2. System voltage during current measurement is steady within one volt of actual system voltage.
3. Engine speed is 500-3000 RPM.
4. Engine run time is more than 3 minutes.
5. Mass airflow is 4-30 grams/sec.
6. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, clear DTCs. Observe DTC information for 30 seconds. If DTCs P0030, P1031 and P1032 are set, go to «DTC P0030: HO2S HEATER CONTROL CIRCUIT VOLTAGE IS GREATER THAN PCM INTERNAL DRIVER CAPACITY - DEVILLE & SEVILLE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) or «DTC P0030: HEATED OXYGEN SENSOR HEATER CONTROL CIRCUIT - BANK 1 SENSOR 1 - ELDORADO»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTCs P0030, P1031 and P1032 are not set, go to next step.
3. Start engine. Using scan tool, observe DTC information for 5 minutes. If P0135 and P0155 are set, go to «DTC P0135: HEATED OXYGEN SENSOR HEATER CIRCUIT - BANK 1 SENSOR 1»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If P0135 and P0155 are not set, go to next step.
4. If P0155 is set, go to next step. If P0155 is not set, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. On DeVille and Seville, remove fuse No. 20 (OXY SEN fuse) from underhood fuse block. (Scheme 10) Underhood fuse block is located on right side of engine compartment. Check continuity of Pink wire between fuse holder output terminal for fuse No. 20 and terminal "D" at HO2S bank 2 sensor 1 harness connector. (Scheme 8) On Eldorado, remove OXY SEN 1 (10-amp) fuse from underhood fuse block. (Scheme 11) Underhood fuse block is located on left side of engine compartment. (Scheme 12) Check continuity of Pink wire between fuse holder output terminal for OXY SEN 1 fuse and terminal "D" at HO2S bank 2 sensor 1 harness connector. (Scheme 9) On all models, if continuity does not exist, repair open in Pink wire. After repairs, go to step 12. If continuity exists, reinstall fuse and go to next step.
6. Turn ignition on. Measure voltage between ground and terminal "C" (Brown wire) at HO2S bank 2 sensor 1 harness connector. If voltage is about 5 volts, go to step 8. If voltage is not about 5 volts, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Brown wire between terminal "C" at HO2S bank 2 sensor 1 harness connector and terminal No. 33 at PCM C2 harness connector. (Scheme 5), (Scheme 8) and (Scheme 9). If continuity does not exist, repair open in Brown wire. After repairs, go to step 12. If continuity exists, go to step 9.
8. Check for poor connections at HO2S bank 2 sensor 1 connector. Repair connector as necessary. After repairs, go to step 12. If connector is okay, go to step 10.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 12. If connectors are okay, go to step 11.
10. Replace HO2S bank 2 sensor 1. After repairs, go to step 12.
11. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
12. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
13. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

An intermittent open in HO2S ignition signal circuit or ground circuit may cause DTC to set. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Powertrain Control Module (PCM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy and emission control. Fuel delivery is controlled differently during open loop and closed loop. During open loop the PCM determines fuel delivery based on sensor signals, without oxygen sensor input. During closed loop the PCM adds oxygen sensor inputs to calculate short term and long term fuel trim (fuel delivery adjustments). If oxygen sensors indicate a lean condition, fuel trim values will be more than zero percent. If oxygen sensors indicate a rich condition, fuel trim values will be less than zero percent. Short term fuel trim values change rapidly in response to Heated Oxygen Sensor (HO2S) voltage signals. Long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1. DTC P0171 will set if PCM detects an excessively lean condition.

1. DTC P0101, P0102, P0103, P0107, P0108, P0121, P0122, P0123, P0130, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0300, P0401, P0403, P0404, P0405, P0410, P0440, P0442, P0446, P0506, P0507, P1404 or P1441 is not set.
2. Coolant temperature is 68-239°F (20-115°C).
3. Intake air temperature is 68-212°F (20-100°C).
4. Manifold absolute pressure is 2.1-12.3 psi (15-85 kPa).
5. Vehicle speed is less than 82 MPH.
6. Engine speed is 500-4000 RPM.
7. Barometric pressure is more than 10.1 psi (75 kPa).
8. Mass airflow is 3-60 grams/sec.
9. Fuel level is more than 10 percent.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If any other DTCs are set, repair DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
2. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, record LONG TERM FUEL TRIM data. Turn ignition off. Turn ignition on. Using scan tool, review FREEZE FRAME RECORDS and/or FAILURE RECORDS and record data. If long term fuel trim is more than 23 percent, go to next step. If long term fuel trim is 23 percent or less, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
3. Start engine and allow it to idle. Using scan tool, observe HO2S voltage. If voltage is 200-800 millivolts and fluctuating, go to next step. If voltage is not 200-800 millivolts or is not fluctuating, go to step 5.
4. Turn ignition off. Check vacuum hoses for splits, kinks and proper routing. Check for contaminated fuel. Ensure fuel tank has enough fuel. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too low will cause a lean condition. If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to step 6.
5. Turn ignition off. Ensure HO2S is installed correctly and wiring harness is not touching exhaust. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for continuity between terminal "A" (Tan wire) and terminal "B" (Purple/White wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 8)and (Scheme 9). If continuity exists, Purple/White and Tan wires are shorted together. Repair wiring as necessary. After repairs, go to step 7. If continuity does not exist, diagnose fuel system. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
6. Operate engine at idle. Check for missing, loose, or leaking exhaust components. Check for vacuum leaks at intake manifold, throttle body and injector "O" rings. Check air induction system and air intake ducts for leaks. Check crankcase ventilation system for leaks. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, check engine mechanical condition and repair as necessary.
7. After repairs, using scan tool fuel trim reset function, reset long term fuel trim. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

System will go lean if an injector is not suppling enough fuel. A lean condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel. An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Do not attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

Powertrain Control Module (PCM) controls air/fuel metering system in order to provide best possible combination of driveability, fuel economy and emission control. Fuel delivery is controlled differently during open loop and closed loop. During open loop the PCM determines fuel delivery based on sensor signals, without oxygen sensor input. During closed loop the PCM adds oxygen sensor inputs to calculate short term and long term fuel trim (fuel delivery adjustments). If oxygen sensors indicate a lean condition, fuel trim values will be more than zero percent. If oxygen sensors indicate a rich condition, fuel trim values will be less than zero percent. Short term fuel trim values change rapidly in response to Heated Oxygen Sensor (HO2S) voltage signals. Long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1. Fuel trim diagnostic will conduct a test to determine if a rich condition actually exists or if excessive vapor from EVAP canister is causing a rich condition. DTC P0172 will set if PCM detects an excessively rich condition.

1. DTC P0101, P0102, P0103, P0107, P0108, P0121, P0122, P0123, P0130, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0300, P0401, P0403, P0404, P0405, P0410, P0440, P0442, P0446, P0506, P0507, P1404 or P1441 is not set.
2. Coolant temperature is 68-239°F (20-115°C).
3. Intake air temperature is 68-212°F (20-100°C).
4. Manifold absolute pressure is 2.1-12.3 psi (15-85 kPa).
5. Vehicle speed is less than 82 MPH.
6. Engine speed is 500-4000 RPM.
7. Barometric pressure is more than 10.1 psi (75 kPa).
8. Mass airflow is 3-60 grams/sec.
9. Fuel level is more than 10 percent.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If any other DTCs are set, repair DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .
2. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, record long term fuel trim data. Turn ignition off. Turn ignition on. Using scan tool, record LONG TERM FUEL TRIM data. Turn ignition off. Turn ignition on. Using scan tool, review FREEZE FRAME RECORDS and/or FAILURE RECORDS and record data. If long term fuel trim is less than -13 percent, go to next step. If long term fuel trim is -13 percent or more, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
3. Start engine and allow it to idle. Using scan tool, observe HO2S voltage. If voltage is 200-800 millivolts and fluctuating, go to next step. If voltage is not 200-800 millivolts or is not fluctuating, go to step 5 .
4. Turn ignition off. Check Mass Airflow (MAF) sensor inlet screen for blockage. Check vacuum hoses for splits, kinks and proper routing. Check for collapsed or restricted air intake duct. Check for restricted or dirty air filter. Check for throttle body blockage. If any problems are found, repair as necessary. After repairs, go to step 7 . If no problems are found, go to step 6 .
5. Turn ignition off. Ensure HO2S is installed correctly and wiring harness is not touching exhaust. If any problems are found, repair as necessary. After repairs, go to step 7 . If no problems are found, diagnose fuel system. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
6. Check for excessive fuel in crankcase. Check evaporative emissions control system. See FUEL EVAPORATION under EMISSION SYSTEMS & SUBSYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Check fuel pressure regulator for proper operation. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTICS article. Ensure all fuel injectors are functioning properly. Perform fuel injector balance test. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, check engine mechanical condition and repair as necessary.
7. After repairs, using scan tool fuel trim reset function, reset long term fuel trim. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Fuel contamination, such as water or alcohol will affect fuel trim. A bad MAF sensor can cause a rich condition. Using scan tool, review failure records. If an intermittent condition is suspect, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Powertrain Control Module (PCM) controls air/fuel metering system in order to provide best possible combination of driveability, fuel economy and emission control. Fuel delivery is controlled differently during open loop and closed loop. During open loop the PCM determines fuel delivery based on sensor signals, without oxygen sensor input. During closed loop the PCM adds oxygen sensor inputs to calculate short term and long term fuel trim (fuel delivery adjustments). If oxygen sensors indicate a lean condition, fuel trim values will be more than zero percent. If oxygen sensors indicate a rich condition, fuel trim values will be less than zero percent. Short term fuel trim values change rapidly in response to Heated Oxygen Sensor (HO2S) voltage signals. Long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1.

1. DTC P0101, P0102, P0103, P0107, P0108, P0121, P0122, P0123, P0130, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0300, P0401, P0403, P0404, P0405, P0410, P0440, P0442, P0446, P0506, P0507, P1404 or P1441 is not set.
2. Coolant temperature is 68-239°F (20-115°C).
3. Intake air temperature is 68-212°F (20-100°C).
4. Manifold absolute pressure is 2.1-12.3 psi (15-85 kPa).
5. Vehicle speed is less than 82 MPH.
6. Engine speed is 500-4000 RPM.
7. Barometric pressure is more than 10.1 psi (75 kPa).
8. Mass airflow is 3-60 grams/sec.
9. Fuel level is more than 10 percent.

DTC will set if PCM detects an excessively lean condition.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If any other DTCs are set, repair DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
2. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, record long term fuel trim data. Turn ignition off. Turn ignition on. Using scan tool, record LONG TERM FUEL TRIM data. Turn ignition off. Turn ignition on. Using scan tool, review FREEZE FRAME RECORDS and/or FAILURE RECORDS and record data. If long term fuel trim is more than 23 percent, go to next step. If long term fuel trim is 23 percent or less, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
3. Start engine and allow it to idle. Using scan tool, observe HO2S voltage. If voltage is 200-800 millivolts and fluctuating, go to next step. If voltage is not 200-800 millivolts or is not fluctuating, go to step 5.
4. Turn ignition off. Check vacuum hoses for splits, kinks and proper routing. Check for contaminated fuel. Ensure fuel tank has enough fuel. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too low will cause a lean condition. If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to step 6.
5. Turn ignition off. Ensure HO2S is installed correctly and wiring harness is not touching exhaust. Disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for continuity between terminal "A" (Tan/White wire) and terminal "B" (Purple/White wire) at HO2S bank 2 sensor 1 harness connector. (Scheme 8) If continuity exists, Purple/White and Tan/White wires are shorted together. Repair wiring as necessary. After repairs, go to step 7. If continuity does not exist, diagnose fuel system. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
6. Operate engine at idle. Check for missing, loose, or leaking exhaust components. Check for vacuum leaks at intake manifold, throttle body and injector "O" rings. Check air induction system and air intake ducts for leaks. Check crankcase ventilation system for leaks. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, check engine mechanical condition and repair as necessary.
7. After repairs, using scan tool fuel trim reset function to reset long term fuel trim. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

System will go lean if an injector is not suppling enough fuel. A lean condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel. An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Do not attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

Powertrain Control Module (PCM) controls air/fuel metering system in order to provide best possible combination of driveability, fuel economy and emission control. Fuel delivery is controlled differently during open loop and closed loop. During open loop the PCM determines fuel delivery based on sensor signals, without oxygen sensor input. During closed loop the PCM adds oxygen sensor inputs to calculate short term and long term fuel trim (fuel delivery adjustments). If oxygen sensors indicate a lean condition, fuel trim values will be more than zero percent. If oxygen sensors indicate a rich condition, fuel trim values will be less than zero percent. Short term fuel trim values change rapidly in response to Heated Oxygen Sensor (HO2S) voltage signals. Long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1. Fuel trim diagnostic will conduct a test to determine if a rich condition actually exists or if excessive vapor from EVAP canister is causing a rich condition. DTC P0175 will set if PCM detects an excessively rich condition.

1. DTC P0101, P0102, P0103, P0107, P0108, P0121, P0122, P0123, P0130, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0300, P0401, P0403, P0404, P0405, P0410, P0440, P0442, P0446, P0506, P0507, P1404 or P1441 is not set.
2. Coolant temperature is 68-239°F (20-115°C).
3. Intake air temperature is 68-212°F (20-100°C).
4. Manifold absolute pressure is 2.1-12.3 psi (15-85 kPa).
5. Vehicle speed is less than 82 MPH.
6. Engine speed is 500-4000 RPM.
7. Barometric pressure is more than 10.1 psi (75 kPa).
8. Mass airflow is 3-60 grams/sec.
9. Fuel level is more than 10 percent.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If any other DTCs are set, repair DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .
2. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, record long term fuel trim data. Turn ignition off. Turn ignition on. Using scan tool, record LONG TERM FUEL TRIM data. Turn ignition off. Turn ignition on. Using scan tool, review FREEZE FRAME RECORDS and/or FAILURE RECORDS and record data. If long term fuel trim is less than -13 percent, go to next step. If long term fuel trim is -13 percent or more, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
3. Start engine and allow it to idle. Using scan tool, observe HO2S voltage. If voltage is 200-800 millivolts and fluctuating, go to next step. If voltage is not 200-800 millivolts or is not fluctuating, go to step 5 .
4. Turn ignition off. Check vacuum hoses for splits, kinks and proper routing. Check for contaminated fuel. Ensure fuel tank has enough fuel. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too low will cause a lean condition. If any problems are found, repair as necessary. After repairs, go to step 7 . If no problems are found, go to step 6 .
5. Turn ignition off. Ensure HO2S is installed correctly and wiring harness is not touching exhaust. If any problems are found, repair as necessary. After repairs, go to step 7 . If no problems are found, diagnose fuel system. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
6. Check for excessive fuel in crankcase. Check evaporative emissions control system. See FUEL EVAPORATION under EMISSION SYSTEMS & SUBSYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Check fuel pressure regulator for proper operation. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTICS article. Ensure all fuel injectors are functioning properly. Perform fuel injector balance test. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, check engine mechanical condition and repair as necessary.
7. After repairs, using scan tool fuel trim reset function, reset long term fuel trim. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Fuel contamination, such as water or alcohol will affect fuel trim. A bad MAF sensor can cause a rich condition. Using scan tool, review failure records. If an intermittent condition is suspect, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Powertrain Control Module (PCM) enables appropriate fuel injector on intake stroke for each cylinder. Ignition voltage is supplied to fuel injectors. The PCM controls each fuel injector by grounding the control circuit via a solid state device called a driver. The PCM monitors driver state. DTC P0201-P0208 will set if PCM detects an incorrect voltage on fuel injector control circuit.

1. Engine is running.
2. Ignition voltage is 11-16 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, record FREEZE FRAME and/or FAILURE RECORDS data for this DTC, then clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, observe misfire current counters. If any misfire current counters are incrementing, go to step 4 . If no misfire current counters are incrementing, go to next step.
3. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .
4. Turn ignition off. Disconnect fuel injector connector for DTC that is set. See «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) table. Turn ignition on. Using a test light connected to ground, probe Pink wire at suspect fuel injector harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 . DIAGNOSTIC TROUBLE CODE IDENTIFICATION DTC Injector No. P0201 (1) 1 P0202 2 P0203 3 P0204 4 P0205 5 P0206 6 P0207 7 P0208 8 (1) Injector No. 1 is the first injector on right (rear) cylinder head.
5. Connect Fuel Injector Test Light (J 34730-405) between suspect fuel injector harness connector. Start engine. If test light blinks, go to step 9 . If test light does not blink, go to next step.
6. If test light remains on at all times, go to step 8 . If test light does not remain on at all times, go to next step.
7. Check suspect fuel injector control circuit for an open or short to voltage. See «INJECTOR CONTROL CIRCUIT IDENTIFICATION»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) table. If any problems are found, repair wiring as necessary. After repairs, go to step 14 . If no problems are found, go to step 10 . INJECTOR CONTROL CIRCUIT IDENTIFICATION Injector No. Wire Color 1 Black 2 Light Green 3 Pink/Black 4 Light Blue/Black 5 Black/White 6 Yellow/Black 7 Red/Black 8 Dark Blue/White
8. Using a test light connected to positive battery voltage, probe control circuit at suspect fuel injector harness connector. See «INJECTOR CONTROL CIRCUIT IDENTIFICATION»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) table. If test light illuminates, repair short to ground in fuel injector control circuit. After repairs, go to step 14 . If test light does not illuminate, go to step 13 .
9. Check suspect fuel injector connector for poor connections. Repair connector as necessary. After repairs, go to step 14 . If no problem was found, go to step 12 .
10. Check PCM connectors for poor connections. PCM is located in engine compartment, inside air filter housing. Repair connectors as necessary. After repairs, go to step 14 . If connectors are okay, go to step 13 .
11. Repair open or short to ground in ignition voltage circuit between fuel injector and underhood fuse block. After repairs, go to step 14 .
12. Replace fuel injector. See FUEL SYSTEMS in appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 14 .
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Performing fuel injector coil test may help isolate an intermittent condition. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If an intermittent condition is suspect, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Powertrain Control Module (PCM) provides ignition voltage to coil side of fuel pump relay. When ignition is first turned on, PCM energizes fuel pump relay, which applies power to fuel pump. The PCM enables fuel pump relay as long as engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, PCM de-energizes fuel pump relay after 2 seconds. The PCM monitors voltage on fuel pump relay control circuit. DTC P0230 will set if PCM detects an incorrect voltage on fuel injector control circuit.

1. Engine is running.
2. Ignition voltage is 8-16 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, command fuel pump relay on and off. Listen for fuel pump relay operating noise. On DeVille and Seville, fuel pump relay (F/PMP relay) is located in rear fuse block. (Scheme 2)or (Scheme 3). Rear fuse block is located underneath driver's side rear seat. On Eldorado, fuel pump relay is located in underhood fuse block. (Scheme 11) Underhood fuse block is located on left side of engine compartment. (Scheme 12) On all models, if fuel pump relay turns on and off as commanded, go to next step. If fuel pump relay does not turn on and off as commanded, go to step 4.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Remove fuel pump relay. Turn ignition on. Using a test light connected to ground, probe fuel pump relay control circuit No. 465 (Dark Green/White wire) at fuel pump relay connector in rear fuse block (DeVille and Seville) or in underhood fuse block (Eldorado). (Scheme 11)or (Scheme 16). Using scan tool, command fuel pump relay on and off. If test light turns on and off as commanded, disconnect test light and go to next step. If test light does not turn on and off as commanded, go to step 6.
5. Turn ignition off. On DeVille and Seville, connect a test light between fuel pump relay control circuit No. 465 (Dark Green/White wire) and fuel pump relay ground circuit No. 750 (Black wire) at fuel pump relay connector in rear fuse block. On Eldorado, connect a test light between fuel pump relay control circuit No. 465 (Dark Green/White wire) and fuel pump relay ground circuit No. 451 (Black wire) at fuel pump relay connector in underhood fuse block. On all models, turn ignition on. Using scan tool, command fuel pump relay on and off. If test light turns on and off as commanded, go to step 9. If test light does not turn on and off as commanded, go to step 11.
6. If test light is always on, go to step 8. If test light is always off, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in fuel pump relay control circuit No. 465 (Dark Green/White wire) between fuel pump relay connector in rear fuse block (DeVille and Seville) or underhood fuse block (Eldorado) and terminal No. 70 at PCM C1 harness connector. (Scheme 5), (Scheme 11) and (Scheme 16). If Dark Green/White wire is open or shorted to ground, repair wiring as necessary. After repairs, go to step 14. If Dark Green/White wire is not open or shorted to ground, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 70 (Dark Green/White wire) at PCM C1 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Dark Green/White wire between PCM and fuel pump relay connector. After repairs, go to step 14. If no voltage is indicated, go to step 10.
9. Check fuel pump relay connector for poor connections. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
10. Check PCM connectors for poor connections. PCM is located in engine compartment, inside air filter housing. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
11. Repair open in fuel pump relay ground circuit (Black wire). See WIRING DIAGRAMS article. After repairs, go to step 14.
12. Replace fuel pump relay. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Scheme 16

Powertrain Control Module (PCM) uses information from Crankshaft Position (CKP) sensors and Camshaft Position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring variations in crankshaft rotation speed for each cylinder, the PCM is able to detect individual misfire events. A misfire rate that is high enough can cause catalytic converter damage. Malfunction indicator light will flash on and off when conditions for catalytic converter damage are present. DTC P0300 will sets if PCM detects a crankshaft rotation speed variation indicating a misfire rate sufficient to cause emission levels to exceed mandated standard.

1. DTC P0101, P0102, P0103, P0106, P0107, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0335, P0336, P0340, P0341, P0385, P0386, P0502, P0503, P0705, P0713, P1114, P1115, P1121, P1122, P1336 or P1372 is not set.
2. Engine speed is 500-5850 RPM.
3. Battery voltage is 9-18 volts.
4. Engine coolant temperature is 19-248°F (-7 to 120°C). If engine coolant temperature at start-up is less than 19°F (-70°C), test will be delayed until temperature is more than 70°F (21°C).
5. Throttle angle is steady.
6. A/C compressor clutch is steady.
7. EGR flow test is inactive.
8. Fuel level is more than 10 percent.
9. Torque management is not active.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Incorrect CKP system variation data in PCM may cause DTC to set with no apparent misfire. Any of the following conditions can cause incorrect CKP system variation data: Replace engine. Replacing PCM. Reprogramming PCM. Replacing CKP sensor. Performing internal engine repairs that affect CKP sensor-to-crankshaft reluctor wheel relationship. If none of the listed conditions apply to vehicle, go to next step. If any of the listed conditions apply to vehicle, CKP system variation learn procedure must be performed before continuing with misfire diagnosis. See «CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__crankshaft-position-sensor-system-variation-learn) under PROGRAMMING. NOTE: If any other DTCs are set, repair DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .
3. Start engine. Using scan tool, select MISFIRE BAR GRAPH or MISFIRE COUNTERS. If any cylinders indicate excessive misfire, go to next step. If no cylinders indicate excessive misfire, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. If misfire seems to be affecting specific cylinders, go to step 8 . If misfire is random to all cylinders, go to next step.
5. Turn ignition off. Check PCM and ignition control module grounds. See WIRING DIAGRAMS article. Ensure engine grounds are clean, tight and in their proper locations. If any problems are found, repair as necessary. After repairs, go to step 13 . If no problems are found, go to next step.
6. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not as specified, repair fuel system as necessary. After repairs, go to step 13 . If fuel pressure is as specified, go to next step.
7. Check for fuel contamination. Water, even in small amounts, can be delivered to fuel injectors. Water can cause a lean exhaust. Also, excessive alcohol in the fuel can cause a lean condition. If any problems are found, repair as necessary. After repairs, go to step 13 . If no problems are found, go next step.
8. Operate engine at idle. Check for vacuum leaks at intake manifold, throttle body and injector "O" rings. If any problems are found, repair as necessary. After repairs, go to step 13 . If no problems are found, go to next step.
9. Perform fuel injector balance test and fuel injector coil test. See FUEL INJECTOR BALANCE TEST and FUEL INJECTOR COIL TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If any problems are found, repair as necessary. After repairs, go to step 13 . If no problems are found, go to next step.
10. Check ignition system operation. See ELECTRONIC IGNITION SYSTEM DIAGNOSIS in appropriate SYSTEM & COMPONENT TESTING article. If any problems are found, repair as necessary. After repairs, go to step 13 . If no problems are found, go to next step.
11. Check for the following mechanical conditions: Damaged accessory drive belt or pulley. Damaged driven accessory (generator, water pump, drive belt tensioner, etc.). Loose or broke motor mount. Engine mechanical problems. If any problems are found, repair as necessary. After repairs, go to step 13 . If no problems are found, go to next step.
12. Ensure transaxle torque converter clutch is functioning properly. See appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Using scan tool, perform CKP system variation learn procedure. See CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE under PROGRAMMING. Ensure all connections are clean and properly tightened. A damaged serpentine belt or belt driven accessory can cause engine load variations sufficient to set a misfire DTC. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. A malfunctioning fuel pump, a plugged filter, or a malfunctioning fuel system pressure regulator will contribute to a lean condition. Performing fuel injector coil test. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Check for contaminated fuel. Excessive open loop operation caused by extended idling or short trip driving may leave deposits on heated oxygen sensors. Deposits cause oxygen sensors to respond slowly to exhaust oxygen content, affecting fuel control and causing a misfire to be indicated at idle. This condition is not permanent. In order to determine if this condition is causing DTC P0300 to be set, review FREEZE FRAME/FAILURE RECORDS for DTC P0300. If DTC P0300 occurs at high engine speeds, the condition described above did not cause DTC P0300 to set. If DTC P0300 occurs at idle or very low engine speeds and at engine coolant temperatures less than 176°F (80°C), the condition described is very likely the cause of the DTC P0300 being set. The deposits on the heated oxygen sensors can be eliminated by operating vehicle fully warm at mass airflows more than 15 grams/sec. DTC may set if vehicle misfires while running out of fuel. If no misfire is currently present, but history counters indicate random misfire was once present, ask customer if vehicle has run out of fuel. If this is the case, no further repair may be necessary.

Powertrain Control Module (PCM) uses a knock sensor to detect engine detonation, or spark knock. Knock sensor produces an AC signal at all engine speeds and loads. The PCM makes adjustments to spark timing based on the amplitude and frequency of knock sensor signal. The PCM uses the knock sensor to calculate amount of normal engine noise (a noise channel) for a wide range of engine speeds and loads. The PCM compares actual knock sensor signal to learned noise channel. DTC P0325 will set if PCM detects a malfunction in the integrated knock sensor diagnostic circuity that will not allow proper diagnosis of knock sensor system.

1. Engine speed is more than 3000 RPM.
2. System voltage is more than 11 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . After repairs, go to next step.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to step 2 . If DTC runs and passes, go to next step.
5. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Powertrain Control Module (PCM) uses a knock sensor to detect engine detonation, or spark knock. Knock sensor produces an AC signal at all engine speeds and loads. The PCM makes adjustments to spark timing based on the amplitude and frequency of knock sensor signal. The PCM uses knock sensor to calculate amount of normal engine noise (a noise channel) for a wide range of engine speeds and loads. The PCM compares actual knock sensor signal to learned noise channel. DTC P0326 will set when knock sensor voltage and variation is not within normally expected ranges for more than 4 seconds.

1. Engine speed is more than 600 RPM.
2. Knock detection is enabled.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Check for loose engine accessory or accessory bracket. If any problems are found, repair as necessary. After repairs, go to step 4 . If no problems are found, go to next step.
3. Start engine. Check for excessive mechanical noise. If any problems are found, repair as necessary. After repairs, go to step 4 . If no problems are found, fault may be intermittent. See TROUBLE SHOOTING - NO CODES article.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to step 2 . If DTC runs and passes, go to next step.
5. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Powertrain Control Module (PCM) uses a knock sensor to detect engine detonation, or spark knock. Knock sensor produces an AC signal at all engine speeds and loads. The PCM makes adjustments to spark timing based on the amplitude and frequency of knock sensor signal. The PCM uses knock sensor to calculate amount of normal engine noise (a noise channel) for a wide range of engine speeds and loads. The PCM compares actual knock sensor signal to learned noise channel. DTC P0327 will set if PCM detects a knock sensor signal of less than .4 volt.

1. Engine speed is more than 3000 RPM.
2. System voltage is more than 11 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Operate vehicle within conditions for running DTC in code enable criteria. Using scan tool, monitor specific DTC information for DTC P0327 until test runs. If scan tool indicates DTC P0327 failed last test, go to step 4. If scan tool does not indicate DTC P0327 failed last test, go to next step.
3. Using scan tool, observe and record the FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Disconnect knock sensor/starter solenoid 3-pin connector. Connector is located on right side of engine compartment, near rear corner of intake manifold. Set DVOM to 400 mV AC scale. Check frequency at Dark Blue and Gray wires at knock sensor/starter solenoid harness connector (component side). Tap on engine block with a non-metallic object. If frequency fluctuates while tapping block, go to next step. If frequency does not fluctuate, go to step 6.
5. Turn ignition on. Using scan tool, save FREEZE FRAME & FAILURE RECORDS data stored when DTC was set. Turn ignition off. Reconnect knock sensor/starter solenoid connector. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Check frequency between terminals No. 19 (Dark Blue wire) and No. 35 (Gray wire) at PCM C2 harness connector. (Scheme 5) If frequency fluctuates while tapping on block, go to step 8. If frequency does not fluctuate while tapping on block, go to next step 7.
6. Ensure ignition is off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Remove intake manifold to access knock sensor. See REMOVAL & INSTALLATION in appropriate article in ENGINES. Disconnect knock sensor connector. Check knock sensor signal circuit (Dark Blue wire) and knock sensor ground circuit (Gray wire) as follows: Check for open or short to ground in Dark Blue wire between knock sensor harness connector and knock sensor/starter solenoid connector. Check for continuity between Dark Blue and Gray wires at knock sensor harness connector. Continuity should not exist. If continuity exists, Dark Blue and Gray wires are shorted together. Check continuity of Gray wire between knock sensor harness connector and knock sensor/starter solenoid connector. Continuity should exist. If continuity does not exist, Gray wire is open. Turn ignition on. Connect a test light between ground and Dark Blue wire at knock sensor harness connector. Test light should not illuminate. If test light illuminates, Dark Blue wire is shorted to voltage. Check knock sensor connector for poor connections. If any problems are found, repair as necessary. After repairs, go to step 11. If no problems are found, go to step 9.
7. Disconnect knock sensor/starter solenoid connector. Ensure PCM is disconnected. Check knock sensor signal circuit (Dark Blue wire) and knock sensor ground circuit (Gray wire) as follows: Check for open or short to ground in Dark Blue wire between knock sensor/starter solenoid connector and terminal No. 19 at PCM C2 harness connector. (Scheme 5) Check for continuity between terminals No. 19 (Dark Blue wire) and No. 35 (Gray wire) at PCM C2 harness connector. Continuity should not exist. If continuity exists, Dark Blue and Gray wires are shorted together. Check continuity of Gray wire between knock sensor/starter solenoid connector and terminal No. 35 at PCM C2 harness connector. Continuity should exist. If continuity does not exist, Gray wire is open. Turn ignition on. Using a test light connected to ground, probe terminal No. 35 (Gray wire) at PCM C2 harness connector. Test light should not illuminate. If test light illuminates, Gray wire is shorted to voltage. Check knock sensor/starter solenoid connector for poor connections. Repair as necessary. After repairs, go to step 11.
8. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 11. If connectors are okay, go to step 10.
9. Replace knock sensor. After repairs, go to step 11.
10. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
11. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 4.
12. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) uses dual Crankshaft Position (CKP "A" and CKP "B") sensors to determine crankshaft position. The PCM supplies an ignition voltage and a ground for each sensor. During engine rotation, a slotted ring, machined into the crankshaft, causes CKP sensors to return a series of on and off pulses to the PCM. The PCM uses these pulses to decode position of crankshaft. The PCM uses 2 basic methods of decoding engine position: angle based and time based (using either CKP "A" or CKP "B" sensor input). During normal operation, the PCM uses the angle based method. In order to operate in this mode, PCM must receive signal pulses from both CKP sensors. The PCM uses the signal pulses to determine an initial crankshaft position, and to generate 24X reference and 4X reference signals. Once initial crankshaft position is determined, the PCM continuously monitors both sensors for valid signal inputs. As long as both signal inputs remain, the PCM will continue to use the angle based mode. When either CKP signal is lost, the PCM will compare the 24X reference signal to the Camshaft Position (CMP) sensor signal. If PCM detects a valid CMP signal, and the 24X reference to CMP signal correlation is correct, the PCM determines that CKP sensor "A" is at fault. However, if the 24X reference to CMP correlation is incorrect, the PCM determines that CKP sensor "B" is at fault. If PCM determines that CKP sensor "A" is at fault, DTC P0335 will set. The PCM will switch from angle based mode to time based mode "B" using CKP sensor "B" signal input.

Only condition for running this DTC is engine must be cranking or running.

Scheme 17

Scheme 18

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Attempt to start engine. Using scan tool, monitor DTC information. If DTC P0335, P0340 and P0385 are all set, go to step 11. If DTC P0335, P0340 and P0385 are all not set, go to next step. NOTE: If DTC P0386 is also set, continue with this test before diagnosing DTC P0386.
3. Start engine. Using scan tool, monitor CKP sensor status parameter. If scan tool indicates CKP sensor status as ANGLE, go to next step. If scan tool does not indicate CKP sensor status as ANGLE, turn ignition off and go to step 5.
4. Ensure engine is running. Observe scan tool and wiggle CKP sensor "A" wiring harness. (Scheme 17) If CKP sensor status changes or engine stalls, a fault exists in CKP sensor "A" wiring harness or connector. Repair as necessary. After repairs, go to step 21. If CKP sensor status does not change and engine does not stall, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition on. Raise and support vehicle. Disconnect CKP sensor "A" connector. (Scheme 17) Using a test light connected to ground, probe terminal "A" (Light Green wire) at CKP sensor "A" harness connector. (Scheme 18) If test light illuminates, go to next step. If test light does not illuminate, go to step 8.
6. Connect test light between terminal "A" (Light Green wire) and terminal "B" (Yellow/Black wire) at CKP sensor "A" harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 9.
7. Using scan tool, clear DTCs. Using scan tool, command PCM to operate in TIME A mode. Using a test light connected to positive battery voltage, repeatedly touch terminal "C" (Light Blue/White wire) at CKP sensor "A" harness connector. Observe 24X crank sensor data on scan tool. If scan tool indicates an RPM when touching Light Blue/White wire, go to step 15. If scan tool does not indicate an RPM when touching Light Blue/White wire, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Light Green wire (DeVille and Seville) or Light Green/Black wire (Eldorado) between terminal "A" at CKP sensor "A" harness connector and terminal No. 65 at PCM C2 harness connector. (Scheme 5)and (Scheme 18). If continuity exists, go to step 16. If continuity does not exist, repair open in Light Green wire (DeVille and Seville) or Light Green/Black wire (Eldorado). After repairs, go to step 21.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Yellow/Black wire between terminal "B" at CKP sensor "A" harness connector and terminal No. 66 at PCM C2 harness connector. (Scheme 5)and (Scheme 18). If continuity exists, go to step 16. If continuity does not exist, repair open in Yellow/Black wire. After repairs, go to step 21.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Check CKP sensor "A" signal circuit (Light Blue/White wire) as follows: Check for open or short to ground in Light Blue/White wire between terminal "C" at CKP sensor "A" harness connector and terminal No. 2 at PCM C1 harness connector. (Scheme 5)and (Scheme 18). Check for continuity between terminal "B" (Yellow/Black wire) and terminal "C" (Light Blue/White wire) and at CKP sensor "A" harness connector. Continuity should not exist. If continuity exists, Light Blue/White and Yellow/Black wires are shorted together. Check for continuity between terminals No. 2 (Light Blue/White wire) and No. 14 (Yellow wire) at PCM C1 harness connector. Continuity should not exist. If continuity exists, Light Blue/White and Yellow wires are shorted together. Turn ignition on. Connect a test light between ground and terminal No. 2 (Light Blue/White wire) at PCM C1 harness connector. Test light should not illuminate. If test light illuminates, Light Blue/White wire is shorted to voltage. If any problems are found, repair as necessary. After repairs, go to step 21. If no problems are found, go to step 16.
11. Disconnect CMP sensor connector. CMP sensor is located in front of right (rear) cylinder head. Using scan tool, monitor 12-volt reference parameter. If scan tool displays OK, go to step 17. If scan tool does not display OK, go to next step.
12. Raise and support vehicle. Disconnect CKP sensor "A" connector. (Scheme 17) Using scan tool, monitor 12-volt reference parameter. If scan tool displays OK, go to step 18. If scan tool does not display OK, go to next step.
13. Raise and support vehicle. Disconnect CKP sensor "B" connector. (Scheme 17) Using scan tool, monitor 12-volt reference parameter. If scan tool displays OK, go to step 19. If scan tool does not display OK, go to next step.
14. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Ensure CKP sensor "A", CKP sensor "B" and CMP sensor are disconnected. Check 12-volt reference circuits for a short to ground as follows: Using a test light connected to battery voltage, probe terminal No. 65 (Light Green wire on DeVille and Seville or Light Green/Black wire on Eldorado) at PCM C2 harness connector. (Scheme 5) Test light should not illuminate. If test light illuminates, Light Green wire (DeVille and Seville) or Light Green/Black wire (Eldorado) is shorted to ground between PCM and CKP sensor "A". Using a test light connected to battery voltage, probe terminal No. 25 (Light Green wire) at PCM C2 harness connector. Test light should not illuminate. If test light illuminates, Light Green wire is shorted to ground between PCM and CKP sensor "B". Using a test light connected to battery voltage, probe terminal No. 58 (Red wire) at PCM C1 harness connector. Test light should not illuminate. If test light illuminates, Red wire is shorted to ground between PCM and CMP sensor. If any problems are found, repair as necessary. After repairs, go to step 21. If no problems are found, go to step 20.
15. Check for poor connections at CKP sensor "A" connector. Repair connector as necessary. After repairs, go to step 21. If connector is okay, go to step 18.
16. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 21. If connectors are okay, go to step 20.
17. Replace CMP sensor. After repairs, go to step 11.
18. Replace CKP sensor "A". After repairs, go to step 21.
19. Replace CKP sensor "B". After repairs, go to step 21.
20. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
21. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
22. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

If condition is intermittent, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Ignition system DTCs set with ignition switch in START position if starter relay or starter is inoperative. When PCM enables starter operation, the PCM also initiates diagnostic test routines for DTCs P0335, P0340, and P0385. The PCM will not receive signal input from CKP and CMP sensors if a condition exists which prevents engine from cranking. When this occurs, DTCs will set. If DTC P0615 is set, diagnose DTC P0615 first. See appropriate STARTERS article in STARTING & CHARGING SYSTEMS. If DTC P0335, P0340, and/or P0385 are set and no problem is found, check if there is a no-crank condition or an intermittent no-crank condition. Check if an attempt was made to crank engine with shift lever not in Park or Neutral.

When diagnosing CKP sensors, it may be necessary to enable a specific decode mode (ANGLE, TIME A or TIME B). In order to enable a specific crank decode, use scan tool and perform the following

1. Turn ignition on.
2. Select ENGINE OUTPUT CONTROLS.
3. Select CRANK POSITION SENSING DECODE mode.
4. Select desired mode (ANGLE, TIME A or TIME B) by pressing SELECT STATE.
5. Command decode mode by pressing COMMAND STATE.

The commanded state remains valid for current ignition cycle. A specific decode mode cannot be commanded with engine running, or after commanding a desired decode mode. In order to command a different decode mode, ignition must be cycled off and on.

Powertrain Control Module (PCM) uses dual Crankshaft Position (CKP "A" and CKP "B") sensors to determine crankshaft position. The PCM supplies an ignition voltage and a ground for each sensor. During engine rotation, a slotted ring, machined into the crankshaft, causes CKP sensors to return a series of on and off pulses to the PCM. The PCM uses these pulses to decode position of crankshaft. The PCM uses 2 basic methods of decoding engine position: angle based and time based (using either CKP "A" or CKP "B" sensor input). During normal operation, the PCM uses the angle based method. In order to operate in this mode, PCM must receive signal pulses from both CKP sensors. The PCM uses the signal pulses to determine an initial crankshaft position, and to generate 24X reference and 4X reference signals. Once initial crankshaft position is determined, the PCM continuously monitors both sensors for valid signal inputs. As long as both signal inputs remain, the PCM will continue to use the angle based mode. When either CKP signal is lost, the PCM will compare the 24X reference signal to the Camshaft Position (CMP) sensor signal. If PCM detects a valid CMP signal, and the 24X reference to CMP signal correlation is correct, the PCM determines that CKP sensor "A" is at fault. However, if the 24X reference to CMP correlation is incorrect, the PCM determines that CKP sensor "B" is at fault. If PCM determines that CKP sensor "B" is at fault, DTC P0385 will set. The PCM will switch from angle based mode to time based "A" mode using CKP sensor "A" signal input. If after switching to time based "A" mode PCM detects an intermittent loss of CKP sensor "A" signal, DTC P0336 will set.

1. Engine cranking or running.
2. DTC P0385 is set.
3. No cam faults are present.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If DTC P0385 is also set, repair DTC before continuing with this test. See «DTC P0385: CRANKSHAFT POSITION SENSOR "B" CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l)
2. Ensure ignition is on. Raise and support vehicle. Disconnect CKP sensor "A" connector. (Scheme 17) Check for an intermittent open or short to ground in 12-volt reference circuit (Light Green wire on DeVille and Seville or Light Green/Black wire on Eldorado) between terminal "A" at CKP sensor "A" harness connector and terminal No. 65 at PCM C2 harness connector. (Scheme 5)and (Scheme 18). Also check for poor connections at CKP sensor "A"connector. If any problems are found, repair as necessary. After repairs, go to step 6. If no problems are found, go to next step.
3. Check for an intermittent open in low reference circuit (Yellow/Black wire) between terminal "B" at CKP sensor "A" harness connector and terminal No. 66 at PCM C2 harness connector. Also check for poor terminal contact at CKP sensor "A". If any problems are found, repair as necessary. After repairs, go to step 6. If no problems are found, go to next step.
4. Check CKP "A" signal circuit (Light Blue/White wire) for intermittent open, intermittent short to 12-volt reference circuit (Light Green wire on DeVille and Seville or Light Green/Black wire on Eldorado), intermittent short to battery voltage, intermittent short to ground or intermittent short to low reference circuit (Yellow/Black wire) at CKP sensor "A" harness connector. If any problems are found, repair as necessary. After repairs, go to step 6. If no problems are found, go to next step.
5. Check for poor terminal contact at terminal No. 2 (Light Blue wire) at PCM C1 harness connector. (Scheme 5) Also check for poor terminal contact at terminals No. 65 (Light Green wire on DeVille and Seville or Light Green/Black wire on Eldorado) and No. 66 (Yellow/Black wire) at PCM C2 harness connector. If any problems are found, repair as necessary. After repairs, go to step 6. If no problems are found, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
6. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, observe and record the FREEZE FRAME/FAILURE RECORDS data for this DTC. Clear DTCs. Using scan tool, command system to operate in TIME A mode. See «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) for assistance on selecting crank position sensing decode mode. Monitor SPECIFIC DTC INFO for this DTC. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

When diagnosing CKP sensors, it may be necessary to enable a specific decode mode (ANGLE, TIME A or TIME B). In order to enable a specific crank decode, use scan tool and perform the following

1. Turn ignition on.
2. Select ENGINE OUTPUT CONTROLS.
3. Select CRANK POSITION SENSING DECODE mode.
4. Select desired mode (ANGLE, TIME A or TIME B) by pressing SELECT STATE.
5. Command decode mode by pressing COMMAND STATE.

The commanded state remains valid for current ignition cycle. A specific decode mode cannot be commanded with engine running, or after commanding a desired decode mode. In order to command a different decode mode, ignition must be cycled off and on.

Powertrain Control Module (PCM) uses Camshaft Position (CMP) sensor high resolution signal to determine position of valve train in relation to engine cylinders. The PCM uses CMP high resolution signal to sequence the ignition system and fuel injectors. The PCM supplies a 12-volt reference and a low reference to the CMP sensor. The CMP sensor returns a signal pulse in response to the reluctor track, located on camshaft sprocket. If during operation, the PCM detects a loss of CMP sensor high resolution signal, DTC P0340 will set.

Only condition for running this DTC is no CKP sensor DTCs set with engine speed more than 400 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Attempt to start engine. Using scan tool, monitor DTC information. If DTC P0335, P0340 and P0385 are all set, go to step 9. If DTC P0335, P0340 and P0385 are all not set, go to next step.
3. Ensure engine is running. Using scan tool, monitor DTC information. If DTC P0340 runs and passes, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If DTC P0340 resets, go to next step.
4. Disconnect CMP sensor connector. CMP sensor is located in front of right (rear) cylinder head. Turn ignition on. Connect a test light between Red and Pink/Black wires at CMP sensor harness connector. If test light does not illuminate, go to next step. If test light illuminates, go to step 6.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor connections at PCM connectors. Repair connectors as necessary. If connectors are okay, check continuity of Red wire between CMP sensor harness connector and terminal No. 58 at PCM C1 harness connector. (Scheme 5) Also, check continuity of Pink/Black wire between CMP sensor harness connector and terminal No. 67 at PCM C2 harness connector. If both readings indicate continuity exists, go to step 16. If either reading indicates continuity does not exist, repair open in Red or Pink/Black wire wire. After repairs, go to step 17.
6. Ensure ignition is on. Using a test light connected to positive battery voltage, repeatedly touch Orange wire at CMP sensor harness connector. Using scan tool, observe CMP sensor display. If scan tool indicates an RPM when touching Orange wire, go to step 8. If scan tool does not indicate an RPM when touching Orange wire, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor connections at PCM connectors. Repair connectors as necessary. If connectors are okay, turn ignition on. Check CMP sensor high resolution sensor circuit (Orange wire) as follows: Check for open or short to ground in Orange wire between CMP sensor harness connector and terminal No. 1 at PCM C1 harness connector. (Scheme 5) Check for continuity between Orange and Red wires at CMP sensor harness connector. Continuity should not exist. If continuity exists, Orange and Red wires are shorted together. Check for continuity between Orange and Pink/Black wires at CMP sensor harness connector. Continuity should not exist. If continuity exists, Orange and Pink/Black wires are shorted together. Turn ignition on. Using a test light connected to ground, probe terminal No. 1 (Orange wire) at PCM C1 harness connector. Test light should not illuminate. If test light illuminates, Orange wire is shorted to voltage. If any problems are found, repair as necessary. After repairs, go to step 17. If no problems are found, go to step 16.
8. Check for poor connections at CMP sensor connector. Repair connector as necessary. After repairs, go to step 17. If connector is okay, go to step 13.
9. Disconnect CMP sensor connector. CMP sensor is located in front of right (rear) cylinder head. Turn ignition on. Using scan tool, monitor 12-volt reference parameter. If scan tool displays OK, go to step 13. If scan tool does not display OK, go to next step.
10. Raise and support vehicle. Disconnect CKP sensor "A" connector. (Scheme 17) Using scan tool, monitor 12-volt reference parameter. If scan tool displays OK, go to step 14. If scan tool does not display OK, go to next step.
11. Disconnect CKP sensor "B" connector. Using scan tool, monitor 12-volt reference parameter. If scan tool displays OK, go to step 15. If scan tool does not display OK, go to next step.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Ensure CKP sensor "A", CKP sensor "B" and CMP sensor are disconnected. Check 12-volt reference circuits for a short to ground as follows: Using a test light connected to battery voltage, probe terminal No. 65 (Light Green wire on DeVille and Seville or Light Green/Black wire on Eldorado) at PCM C2 harness connector. (Scheme 5) Test light should not illuminate. If test light illuminates, Light Green wire (DeVille and Seville) or Light Green/Black wire (Eldorado) is shorted to ground between PCM and CKP sensor "A". Using a test light connected to battery voltage, probe terminal No. 25 (Light Green wire) at PCM C2 harness connector. Test light should not illuminate. If test light illuminates, Light Green wire is shorted to ground between PCM and CKP sensor "B". Using a test light connected to battery voltage, probe terminal No. 58 (Red wire) at PCM C1 harness connector. Test light should not illuminate. If test light illuminates, Red wire is shorted to ground between PCM and CMP sensor. Repair wiring as necessary. After repairs, go to step 17.
13. Replace CMP sensor. After repairs, go to step 17.
14. Replace CKP sensor "A". After repairs, go to step 17.
15. Replace CKP sensor "B". After repairs, go to step 17.
16. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
17. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
18. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) uses the Camshaft Position (CMP) sensor high resolution signal to determine position of valve train in relation to engine cylinders. The PCM uses CMP high resolution signal to sequence the ignition system and fuel injectors. The PCM supplies a 12-volt reference and a low reference to the CMP sensor. The CMP sensor returns a signal pulse in response to the reluctor track, located on the camshaft sprocket. If during operation, the PCM detects an incorrect correlation between CMP signal and CKP signal, DTC P0341 will set.

Only condition for running this DTC is engine running at less than 2000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, check if DTC P0340 is also set. If DTC P0340 is set, go to next step. If DTC P0340 is not set, go to step 7.
3. Check for an intermittent open in 12-volt reference circuit (Red wire) between terminal "C" at CMP sensor harness connector and terminal No. 58 at PCM C1 harness connector. (Scheme 5)and (Scheme 18). CMP sensor is located in front of right (rear) cylinder head. PCM is located in engine compartment, inside air filter housing. Also check for poor connections at PCM and CMP sensor connectors. Repair connectors as necessary. After repairs, go to step 8. If connectors are okay, go to next step.
4. Check for an intermittent open or short to ground in high resolution signal circuit (Orange wire) between terminal "A" at CMP sensor harness connector and terminal No. 1 at PCM C1 harness connector. Check for an intermittent short between terminal "A" (Orange wire) and terminal "C" (Red wire) at CMP sensor harness connector. Also check for poor connections at PCM and CMP sensor connectors. If any problems are found, repair as necessary. After repairs, go to step 8. If no problems are found, go to next step.
5. Check for an intermittent open in low reference circuit (Pink/Black wire) between terminal "B" at CMP sensor harness connector and terminal No. 67 at PCM C2 harness connector. If any problems are found, repair as necessary. After repairs, go to step 8. If no problems are found, go to next step.
6. Check CMP harness wiring for improper routing near high frequency devices. Repair as necessary. After repairs, go to step 8. If routing is okay, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
7. Check valve train for damage or misaligned camshaft timing components. Check for proper camshaft timing. See appropriate article in ENGINES. Repair as necessary. After repairs, go to next step. If no problem is found, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

An individual ignition coil is used for each cylinder. There are 2 separate Ignition Control Module (ICM) assemblies located on valve cover for each cylinder bank. Each ICM assembly contains an ignition module and 4 coils, which connects directly to spark plug using a boot. The ICM receives power from a fused ignition feed circuit. PCM uses the individual IC circuits to control coil sequencing and spark timing for each cylinder. DTC P0351 will set if PCM detects a short to ground in IC circuit.

Only condition for running this DTC is engine running at more than 2000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to idle. Using scan tool, select MISFIRE COUNTERS. If misfire counters increment for cylinder No. 1, go to next step. If misfire counters do not increment for cylinder No. 1, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Disconnect rear ICM connector. Rear ICM is located on right (rear) valve cover. Using a test light connected to positive battery voltage, probe terminal "F" (Purple wire) at rear ICM harness connector. (Scheme 19) If test light illuminates, go to next step. If test light does not illuminate, go to step 6.
4. Observe test light and disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. If test light is still illuminated, go to next step. If test light is not illuminated, go to step 7.
5. Repair short to ground in Purple wire between terminal "F" at rear ICM harness connector and terminal No. 61 at PCM C1 harness connector. (Scheme 5)and (Scheme 19). After repairs, go to step 8.
6. Replace rear ICM. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Scheme 19

An individual ignition coil is used for each cylinder. There are 2 separate Ignition Control Module (ICM) assemblies located on valve cover for each cylinder bank. Each ICM assembly contains an ignition module and 4 coils, which connects directly to spark plug using a boot. The ICM receives power from a fused ignition feed circuit. PCM uses the individual IC circuits to control coil sequencing and spark timing for each cylinder. DTC P0352 will set if PCM detects a short to ground in IC circuit.

Only condition for running this DTC is engine running at more than 2000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to idle. Using scan tool, select MISFIRE COUNTERS. If misfire counters increment for cylinder No. 2, go to next step. If misfire counters do not increment for cylinder No. 2, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Disconnect front ICM connector. Front ICM is located on left (front) valve cover. Using a test light connected to positive battery voltage, probe terminal "G" (Red/White wire) at front ICM harness connector. (Scheme 19) If test light illuminates, go to next step. If test light does not illuminate, go to step 6.
4. Observe test light and disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. If test light is still illuminated, go to next step. If test light is not illuminated, go to step 7.
5. Repair short to ground in Red/White wire between terminal "G" at front ICM harness connector and terminal No. 22 at PCM C2 harness connector. (Scheme 5)and (Scheme 19). After repairs, go to step 8.
6. Replace rear ICM. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

An individual ignition coil is used for each cylinder. There are 2 separate Ignition Control Module (ICM) assemblies located on valve cover for each cylinder bank. Each ICM assembly contains an ignition module and 4 coils, which connects directly to spark plug using a boot. The ICM receives power from a fused ignition feed circuit. PCM uses the individual IC circuits to control coil sequencing and spark timing for each cylinder. DTC P0353 will set if PCM detects a short to ground in IC circuit.

Only condition for running this DTC is engine running at more than 2000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to idle. Using scan tool, select MISFIRE COUNTERS. If misfire counters increment for cylinder No. 3, go to next step. If misfire counters do not increment for cylinder No. 3, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Disconnect rear ICM connector. Rear ICM is located on right (rear) valve cover. Using a test light connected to positive battery voltage, probe terminal "E" (Light Blue wire) at rear ICM harness connector. (Scheme 19) If test light illuminates, go to next step. If test light does not illuminate, go to step 6.
4. Observe test light and disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. If test light is still illuminated, go to next step. If test light is not illuminated, go to step 7.
5. Repair short to ground in Light Blue wire between terminal "E" at rear ICM harness connector and terminal No. 21 at PCM C2 harness connector. (Scheme 5)and (Scheme 19). After repairs, go to step 8.
6. Replace rear ICM. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

An individual ignition coil is used for each cylinder. There are 2 separate Ignition Control Module (ICM) assemblies located on valve cover for each cylinder bank. Each ICM assembly contains an ignition module and 4 coils, which connects directly to spark plug using a boot. The ICM receives power from a fused ignition feed circuit. PCM uses the individual IC circuits to control coil sequencing and spark timing for each cylinder. DTC P0354 will set if PCM detects a short to ground in IC circuit.

Only condition for running this DTC is engine running at more than 2000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to idle. Using scan tool, select MISFIRE COUNTERS. If misfire counters increment for cylinder No. 4, go to next step. If misfire counters do not increment for cylinder No. 4, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Disconnect front ICM connector. Front ICM is located on left (front) valve cover. Using a test light connected to positive battery voltage, probe terminal "D" (Dark Green/White wire) at front ICM harness connector. (Scheme 19) If test light illuminates, go to next step. If test light does not illuminate, go to step 6.
4. Observe test light and disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. If test light is still illuminated, go to next step. If test light is not illuminated, go to step 7.
5. Repair short to ground in Dark Green/White wire between terminal "D" at front ICM harness connector and terminal No. 59 at PCM C2 harness connector. (Scheme 5)and (Scheme 19). After repairs, go to step 8.
6. Replace rear ICM. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

An individual ignition coil is used for each cylinder. There are 2 separate Ignition Control Module (ICM) assemblies located on valve cover for each cylinder bank. Each ICM assembly contains an ignition module and 4 coils, which connects directly to spark plug using a boot. The ICM receives power from a fused ignition feed circuit. PCM uses the individual IC circuits to control coil sequencing and spark timing for each cylinder. DTC P0355 will set if PCM detects a short to ground in IC circuit.

Only condition for running this DTC is engine running at more than 2000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to idle. Using scan tool, select MISFIRE COUNTERS. If misfire counters increment for cylinder No. 5, go to next step. If misfire counters do not increment for cylinder No. 5, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Disconnect rear ICM connector. Rear ICM is located on right (rear) valve cover. Using a test light connected to positive battery voltage, probe terminal "D" (Dark Green wire) at rear ICM harness connector. (Scheme 19) If test light illuminates, go to next step. If test light does not illuminate, go to step 6.
4. Observe test light and disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. If test light is still illuminated, go to next step. If test light is not illuminated, go to step 7.
5. Repair short to ground in Dark Green wire between terminal "D" at rear ICM harness connector and terminal No. 62 at PCM C2 harness connector. (Scheme 5)and (Scheme 19). After repairs, go to step 8.
6. Replace rear ICM. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

An individual ignition coil is used for each cylinder. There are 2 separate Ignition Control Module (ICM) assemblies located on valve cover for each cylinder bank. Each ICM assembly contains an ignition module and 4 coils, which connects directly to spark plug using a boot. The ICM receives power from a fused ignition feed circuit. PCM uses the individual IC circuits to control coil sequencing and spark timing for each cylinder. DTC P0356 will set if PCM detects a short to ground in IC circuit.

Only condition for running this DTC is engine running at more than 2000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to idle. Using scan tool, select MISFIRE COUNTERS. If misfire counters increment for cylinder No. 6, go to next step. If misfire counters do not increment for cylinder No. 6, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Disconnect front ICM connector. Front ICM is located on left (front) valve cover. Using a test light connected to positive battery voltage, probe terminal "E" (Light Blue/White wire) at front ICM harness connector. (Scheme 19) If test light illuminates, go to next step. If test light does not illuminate, go to step 6.
4. Observe test light and disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. If test light is still illuminated, go to next step. If test light is not illuminated, go to step 7.
5. Repair short to ground in Light Blue/White wire between terminal "E" at front ICM harness connector and terminal No. 60 at PCM C2 harness connector. (Scheme 5)and (Scheme 19). After repairs, go to step 8.
6. Replace rear ICM. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

An individual ignition coil is used for each cylinder. There are 2 separate Ignition Control Module (ICM) assemblies located on valve cover for each cylinder bank. Each ICM assembly contains an ignition module and 4 coils, which connects directly to spark plug using a boot. The ICM receives power from a fused ignition feed circuit. PCM uses the individual IC circuits to control coil sequencing and spark timing for each cylinder. DTC P0357 will set if PCM detects a short to ground in IC circuit.

Only condition for running this DTC is engine running at more than 2000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to idle. Using scan tool, select MISFIRE COUNTERS. If misfire counters increment for cylinder No. 7, go to next step. If misfire counters do not increment for cylinder No. 7, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Disconnect rear ICM connector. Rear ICM is located on right (rear) valve cover. Using a test light connected to positive battery voltage, probe terminal "G" (Red wire) at rear ICM harness connector. (Scheme 19) If test light illuminates, go to next step. If test light does not illuminate, go to step 6.
4. Observe test light and disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. If test light is still illuminated, go to next step. If test light is not illuminated, go to step 7.
5. Repair short to ground in Red wire between terminal "G" at rear ICM harness connector and terminal No. 22 at PCM C1 harness connector. (Scheme 5)and (Scheme 19). After repairs, go to step 8.
6. Replace rear ICM. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

An individual ignition coil is used for each cylinder. There are 2 separate Ignition Control Module (ICM) assemblies located on valve cover for each cylinder bank. Each ICM assembly contains an ignition module and 4 coils, which connects directly to spark plug using a boot. The ICM receives power from a fused ignition feed circuit. PCM uses the individual IC circuits to control coil sequencing and spark timing for each cylinder. DTC P0358 will set if PCM detects a short to ground in IC circuit.

Only condition for running this DTC is engine running at more than 2000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to idle. Using scan tool, select MISFIRE COUNTERS. If misfire counters increment for cylinder No. 8, go to next step. If misfire counters do not increment for cylinder No. 8, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Disconnect front ICM connector. Front ICM is located on left (front) valve cover. Using a test light connected to positive battery voltage, probe terminal "F" (Purple/White wire) at front ICM harness connector. (Scheme 19) If test light illuminates, go to next step. If test light does not illuminate, go to step 6.
4. Observe test light and disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. If test light is still illuminated, go to next step. If test light is not illuminated, go to step 7.
5. Repair short to ground in Purple/White wire between terminal "F" at front ICM harness connector and terminal No. 61 at PCM C2 harness connector. (Scheme 5)and (Scheme 19). After repairs, go to step 8.
6. Replace rear ICM. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) uses dual Crankshaft Position (CKP "A" and CKP "B") sensors to determine crankshaft position. The PCM supplies an ignition voltage and a ground for each sensor. During engine rotation, a slotted ring, machined into the crankshaft, causes CKP sensors to return a series of on and off pulses to the PCM. The PCM uses these pulses to decode position of crankshaft. The PCM uses 2 basic methods of decoding engine position: angle based and time based (using either CKP "A" or CKP "B" sensor input). During normal operation, the PCM uses the angle based method. In order to operate in this mode, PCM must receive signal pulses from both CKP sensors. The PCM uses the signal pulses to determine an initial crankshaft position, and to generate 24X reference and 4X reference signals. Once initial crankshaft position is determined, the PCM continuously monitors both sensors for valid signal inputs. As long as both signal inputs remain, the PCM will continue to use the angle based mode. When either CKP signal is lost, the PCM will compare the 24X reference signal to the Camshaft Position (CMP) sensor signal. If PCM detects a valid CMP signal, and the 24X reference to CMP signal correlation is correct, the PCM determines that CKP sensor "A" is at fault. However, if the 24X reference to CMP correlation is incorrect, the PCM determines that CKP sensor "B" is at fault. If PCM determines that CKP sensor "B" is at fault, DTC P0385 will set. The PCM will switch from angle based mode to time based "A" mode using CKP sensor "A" signal input.

Only condition for running this DTC is engine must be cranking or running.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Attempt to start engine. Using scan tool, monitor DTC information. If DTC P0335, P0340 and P0385 are all set, go to step 11. If DTC P0335, P0340 and P0385 are all not set, go to next step. NOTE: If DTC P0336 is also set, continue with this test before diagnosing DTC P0336.
3. Start engine. Using scan tool, monitor CKP sensor status parameter. If scan tool indicates CKP sensor status as ANGLE, go to next step. If scan tool does not indicate CKP sensor status as ANGLE, turn ignition off and go to step 5.
4. Ensure engine is running. Observe scan tool and wiggle CKP sensor "B" wiring harness. (Scheme 17) If CKP sensor status changes or engine stalls, a fault exists in CKP sensor "B" wiring harness or connector. Repair as necessary. After repairs, go to step 21. If CKP sensor status does not change and engine does not stall, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition on. Raise and support vehicle. Disconnect CKP sensor "B" connector. (Scheme 17) Using a test light connected to ground, probe terminal "A" (Light Green wire) at CKP sensor "B" harness connector. (Scheme 18) If test light illuminates, go to next step. If test light does not illuminate, go to step 8.
6. Connect test light between terminal "A" (Light Green wire) and terminal "B" (Yellow wire) at CKP sensor "B" harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 9.
7. Using scan tool, clear DTCs. Using scan tool, command PCM to operate in TIME B mode. Using a test light connected to positive battery voltage, repeatedly touch terminal "C" (Yellow/Black wire) at CKP sensor "B" harness connector. Observe 24X crank sensor data on scan tool. If scan tool indicates an RPM when touching Yellow wire, go to step 15. If scan tool does not indicate an RPM when touching Yellow/Black wire, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Light Green wire between terminal "A" at CKP sensor "B" harness connector and terminal No. 25 at PCM C2 harness connector. (Scheme 5)and (Scheme 18). If continuity exists, go to step 16. If continuity does not exist, repair open in Light Green wire. After repairs, go to step 21.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Yellow wire between terminal "B" at CKP sensor "B" harness connector and terminal No. 28 at PCM C2 harness connector. (Scheme 5)and (Scheme 18). If continuity exists, go to step 16. If continuity does not exist, repair open in Yellow wire. After repairs, go to step 21.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Check CKP sensor "B" signal circuit (Yellow/Black wire) as follows: Check for open or short to ground in Yellow/Black wire between terminal "C" at CKP sensor "B" harness connector and terminal No. 14 at PCM C1 harness connector. See 21. Check for continuity between terminal "B" (Yellow wire) and terminal "C" (Yellow/Black wire) at CKP sensor "B" harness connector. Continuity should not exist. If continuity exists, Yellow and Yellow/Black wires are shorted together. Check for continuity between terminals No. 2 (Light Blue/White wire) and No. 14 (Yellow/Black wire) at PCM C1 harness connector. Continuity should not exist. If continuity exists, Light Blue/White and Yellow wires are shorted together. Turn ignition on. Connect a test light between ground and terminal No. 14 (Yellow/Black wire) at PCM C1 harness connector. Test light should not illuminate. If test light illuminates, Yellow wire is shorted to voltage. If any problems are found, repair as necessary. After repairs, go to step 21. If no problems are found, go to step 16.
11. Disconnect CMP sensor connector. CMP sensor is located in front of right (rear) cylinder head. Using scan tool, monitor 12-volt reference parameter. If scan tool displays OK, go to step 17. If scan tool does not display OK, go to next step.
12. Raise and support vehicle. Disconnect CKP sensor "A" connector. (Scheme 17) Using scan tool, monitor 12-volt reference parameter. If scan tool displays OK, go to step 18. If scan tool does not display OK, go to next step.
13. Raise and support vehicle. Disconnect CKP sensor "B" connector. (Scheme 17) Using scan tool, monitor 12-volt reference parameter. If scan tool displays OK, go to step 19. If scan tool does not display OK, go to next step.
14. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Ensure CKP sensor "A", CKP sensor "B" and CMP sensor are disconnected. Check 12-volt reference circuits for a short to ground as follows: Using a test light connected to battery voltage, probe terminal No. 65 (Light Green wire on DeVille and Seville or Light Green/Black wire on Eldorado) at PCM C2 harness connector. (Scheme 5) Test light should not illuminate. If test light illuminates, Light Green wire (DeVille and Seville) or Light Green/Black wire (Eldorado) is shorted to ground between PCM and CKP sensor "A". Using a test light connected to battery voltage, probe terminal No. 25 (Light Green wire) at PCM C2 harness connector. Test light should not illuminate. If test light illuminates, Light Green wire is shorted to ground between PCM and CKP sensor "B". Using a test light connected to battery voltage, probe terminal No. 58 (Red wire) at PCM C1 harness connector. Test light should not illuminate. If test light illuminates, Red wire is shorted to ground between PCM and CMP sensor. If any problems are found, repair as necessary. After repairs, go to step 21. If no problems are found, go to step 20.
15. Check for poor connections at CKP sensor "B"connector. Repair connector as necessary. After repairs, go to step 21. If connector is okay, go to step 19.
16. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 21. If connectors are okay, go to step 20.
17. Replace CMP sensor. After repairs, go to step 21.
18. Replace CKP sensor "A". After repairs, go to step 21.
19. Replace CKP sensor "B". After repairs, go to step 21.
20. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
21. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
22. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

If starter relay is inoperative or if starter is inoperative, ignition systems DTCs set with ignition switch in START position. When PCM enables starter operation, PCM also initiates diagnostic test routines for DTCs P0335, P0340 and P0385. If a condition exists which prevents engine from cranking, PCM will not receive the signal input from CKP sensors and CMP sensor, and DTCs will set. If DTC P0615 is set, diagnose DTC P0615 first. See appropriate STARTERS article in STARTING & CHARGING SYSTEMS. If DTC P0335, P0340 and/or P0385 is set and no problem is found, check for no-crank or intermittent no-crank condition. Also check if an attempt to crank engine with shift lever not in Park or Neutral.

When diagnosing CKP sensors, it may be necessary to enable a specific decode mode (ANGLE, TIME A or TIME B). In order to enable a specific crank decode, use scan tool and perform the following

1. Turn ignition on.
2. Select ENGINE OUTPUT CONTROLS.
3. Select CRANK POSITION SENSING DECODE mode.
4. Select desired mode (ANGLE, TIME A or TIME B) by pressing SELECT STATE.
5. Command decode mode by pressing COMMAND STATE.

The commanded state remains valid for the current ignition cycle. A specific decode mode cannot be commanded with engine running, or after commanding a desired decode more. In order to command a different decode mode, ignition must be cycled off and on.

Powertrain Control Module (PCM) uses dual Crankshaft Position (CKP "A" and CKP "B") sensors to determine crankshaft position. The PCM supplies an ignition voltage and a ground for each sensor. During engine rotation, a slotted ring, machined into the crankshaft, causes CKP sensors to return a series of on and off pulses to the PCM. The PCM uses these pulses to decode position of crankshaft. The PCM uses 2 basic methods of decoding engine position: angle based and time based (using either CKP "A" or CKP "B" sensor input). During normal operation, the PCM uses the angle based method. In order to operate in this mode, PCM must receive signal pulses from both CKP sensors. The PCM uses the signal pulses to determine an initial crankshaft position, and to generate 24X reference and 4X reference signals. Once initial crankshaft position is determined, the PCM continuously monitors both sensors for valid signal inputs. As long as both signal inputs remain, the PCM will continue to use the angle based mode. When either CKP signal is lost, the PCM will compare the 24X reference signal to the Camshaft Position (CMP) sensor signal. If PCM detects a valid CMP signal, and the 24X reference to CMP signal correlation is correct, the PCM determines that CKP sensor "A" is at fault. However, if the 24X reference to CMP correlation is incorrect, the PCM determines that CKP sensor "B" is at fault. If PCM determines that CKP sensor "A" is at fault, DTC P0335 will set. The PCM will switch from angle based mode to time based "B" mode using CKP sensor "B" signal input. If after switching to time based "B" mode, PCM detects an intermittent loss of CKP sensor "B" signal, DTC P0386 will set.

1. Engine is cranking or running.
2. DTC P0335 is set.
3. No cam faults are present.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If DTC P0335 is also set, repair DTC before continuing with this test. See «DTC P0335: CRANKSHAFT POSITION SENSOR "A" CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
2. Ensure ignition is on. Raise and support vehicle. Disconnect CKP sensor "B" connector. (Scheme 17) Check for an intermittent open or short to ground in 12-volt reference circuit (Light Green wire) between terminal "A" at CKP sensor "B" harness connector and terminal No. 25 at PCM C2 harness connector. (Scheme 5)and (Scheme 18). Also check for poor connections at CKP sensor "B"connector. If any problems are found, repair as necessary. After repairs, go to step 6. If no problems are found, go to next step.
3. Check for an intermittent open in low reference circuit (Yellow wire) between terminal "B" at CKP sensor "B" harness connector and terminal No. 28 at PCM C2 harness connector. Also check for poor terminal contact at CKP sensor "B". If any problems are found, repair as necessary. After repairs, go to step 6. If no problems are found, go to next step.
4. Check CKP "B" signal circuit (Yellow/Black wire) for intermittent open, intermittent short to 12-volt reference circuit (Light Green wire), intermittent short to battery voltage, intermittent short to ground or intermittent short to low reference circuit (Yellow wire) at CKP sensor "B" harness connector. If any problems are found, repair as necessary. After repairs, go to step 6. If no problems are found, go to next step.
5. Check for poor terminal contact at terminal No. 14 (Yellow/Black wire) at PCM C1 harness connector. (Scheme 5) Also check for poor terminal contact at terminals No. 25 (Light Green wire) and No. 28 (Yellow wire) at PCM C2 harness connector. If any problems are found, repair as necessary. After repairs, go to step 6. If no problems are found, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
6. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

When diagnosing CKP sensors, it may be necessary to enable a specific decode mode (ANGLE, TIME A or TIME B). In order to enable a specific crank decode, use scan tool and perform the following

1. Turn ignition on.
2. Select ENGINE OUTPUT CONTROLS.
3. Select CRANK POSITION SENSING DECODE mode.
4. Select desired mode (ANGLE, TIME A or TIME B) by pressing SELECT STATE.
5. Command decode mode by pressing COMMAND STATE.

The commanded state remains valid for the current ignition cycle. A specific decode mode cannot be commanded with engine running, or after commanding a desired decode more. In order to command a different decode mode, ignition must be cycled off and on.

Powertrain Control Module (PCM) tests Exhaust Gas Recirculation (EGR) system during deceleration by momentarily commanding EGR valve open while monitoring Manifold Absolute Pressure (MAP) sensor signal. When EGR valve is opened, the PCM should see a proportional increase in MAP. If expected increase in MAP is not seen, PCM notes amount of error that was detected and adjusts an internal failure counter toward a failure threshold level. When failure counter exceeds failure threshold level, PCM will set DTC P0401.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0201-P0208, P0300, P0335, P0336, P0385, P0386, P0405, P0449, P0502, P0503, P0506 or P0507 is not set.
2. System voltage is 11-18 volts.
3. A/C status does not change.
4. Transaxle range does not change.
5. Throttle position angle is less than 1.19 percent, deceleration.
6. Deceleration fuel cut-off is steady for .3 second.
7. Engine coolant temperature is 176-230°F (80-110°C).
8. Engine speed is 700-1200 RPM.
9. Idle air control valve position is consistently more than 8 counts.
10. Manifold Absolute Pressure (MAP) is steady at 2-10 psi (15-70 kPa).
11. Vehicle speed is more than 37 MPH.
12. Barometric Pressure is more than 10 psi (70 kPa).
13. Vehicle needs to be driven at more than 50 MPH, then allowed to decelerate. When vehicle is decelerating while meeting all of the criteria listed, PCM will enable test to run. During the test, desired EGR parameter and EGR position sensor on scan tool will change from zero to a calibrated value more than zero.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If any MAP DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions). If no MAP DTCs are set, go to next step.
3. Check exhaust system for leaks and modification of original parts. If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to next step.
4. Check EGR valve gasket and pipes for leaks. (Scheme 15) If any problems are found, repair EGR system as necessary. After repairs, go to step 7. If no problems are found, go to next step.
5. Remove EGR valve. Check EGR valve pintle and passages for leaks and/or restrictions. If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to next step.
6. Remove EGR inlet and outlet pipes from intake and exhaust manifolds. Inspect manifold EGR ports, inlet pipes and outlet pipes for blockage/damage. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

If EGR valve shows signs of excessive heat, check exhaust system for blockage or for a plugged catalytic converter. A vacuum restriction to the MAP sensor can cause EGR flow test to fail due to insufficient MAP changes being monitored during the test. An engine that is running poorly may cause this DTC to set. Check for poor connection or damaged wiring harness. If wiring harness appears to be okay, observe EGR position sensor display on scan tool while moving connectors and wiring harnesses that are related to EGR valve. A change in the display indicates location of malfunction.

In order to verify a repair, select CLEAR INFO on scan tool, and run EGR flow test, keeping the following conditions in mind

1. PCM will only run EGR flow test during a gradual deceleration.
2. PCM will only run EGR test during a closed throttle condition.
3. PCM will only run EGR test with vehicle speeds at more than 37 MPH.
4. Several deceleration cycles will be necessary in order to run a sufficient number of EGR flow test samples. A sufficient number of samples is usually 5-15 samples.
5. If within enabling RPM (700-1200 RPM) engine speed decreases more than 500 RPM, PCM will reset test.
6. If within enabling RPM (700-1200 RPM) engine speed increases more than 75 RPM, PCM will reset test.
7. When PCM commands EGR valve open, engine speed will decrease. If engine speed decreases to less than 500 RPM, test will not run.

Powertrain Control Module (PCM) monitors Exhaust Gas Recirculation (EGR) valve pintle position input to ensure valve responds properly to PCM commands. The linear EGR valve is controlled by using an ignition positive driver and ground circuit within the PCM. The driver has the ability to detect an electrical malfunction in the EGR solenoid high control circuit or EGR low control circuit. If an electrical malfunction occurs, the driver signals the PCM to set DTC P0403.

1. Engine is cranking or running.
2. System voltage is 8-18 volts.

Scheme 20

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Ensure ignition is on. Using scan tool, command EGR from zero to 100 percent. If EGR position sensor remains close to desired EGR position at all commanded positions, go to next step. If EGR position sensor does not remain close to desired EGR position at all commanded positions, go to step 4.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect EGR valve connector. (Scheme 15) Turn ignition on. Using a test light connected to ground, probe terminal "E" (Red wire) at EGR valve harness connector. (Scheme 20) Using scan tool, command EGR 0-10 percent. If test light turns on and off with each command, go to next step. If test light does not turn on and off with each command, go to step 6.
5. Connect test light between terminal "A" (Gray wire) and terminal "E" (Red wire) at EGR valve harness connector. Using scan tool, command EGR 0-10 percent. If test light turns on and off with each command, go to step 10. If test light does not turn on and off with each command, go to step 9.
6. If test light remains on with each command, go to step 8. If test light does not remain on with each command, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in Red wire between terminal "E" at EGR valve harness connector and terminal No. 71 at PCM C1 harness connector. (Scheme 5)and (Scheme 20). If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to step 11.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "E" (Red wire) at EGR valve harness connector. If any voltage is indicated, repair short to voltage in Red wire between EGR valve and PCM. After repairs, go to step 14. If no voltage is indicated, go to step 11.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Gray wire between terminal "A" at EGR valve harness connector and terminal No. 70 at PCM C2 harness connector. (Scheme 5)and (Scheme 20). If continuity does not exist, repair open in Gray wire. After repairs, go to step 14. If continuity exists, go to step 11.
10. Check for poor connections at EGR valve connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
11. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
12. Replace EGR valve. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) monitors Exhaust Gas Recirculation (EGR) valve pintle position input to ensure valve responds properly to PCM commands. The PCM compares EGR position sensor with desired EGR position when valve is commanded open. If difference between EGR position sensor and desired EGR position is more than 8 percent, DTC P0404 will set.

1. Ignition voltage is more than 11 volts.
2. EGR is enabled.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If DTC P0403 or P0405 is set, diagnose affected DTC(s) first. See «DTC P0403: EXHAUST GAS RECIRCULATION SOLENOID CONTROL CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) or «DTC P0405: EXHAUST GAS RECIRCULATION POSITION SENSOR CIRCUIT LOW VOLTAGE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
2. Ensure ignition is on. Using scan tool, command EGR valve from zero to 100 percent. If EGR position sensor remains within 8 percent of desired EGR position at all commanded positions, go to next step. If EGR position sensor does not remain within 8 percent of desired EGR position at all commanded positions, go to step 4.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect EGR valve connector. (Scheme 15) Turn ignition on. Using a test light connected to ground, probe terminal "E" (Red wire) at EGR valve harness connector. (Scheme 20) Using scan tool, command EGR 0-10 percent. If test light turns on and off with each command, go to next step. If test light does not turn on and off with each command, go to step 13.
5. Turn ignition off, then back on. Using scan tool, observe EGR position sensor parameter. If EGR position sensor is zero percent, go to next step. If EGR position is not zero percent, go to step 9.
6. Measure voltage between terminal "B" (Black wire) and terminal "D" (Gray wire) at EGR valve harness connector. (Scheme 20) If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 8.
7. Connect a 3-amp fused jumper wire between terminal "C" (Brown wire) and terminal "D" (Gray wire) at EGR valve harness connector. Using scan tool, observe EGR position sensor parameter. If EGR position sensor is about 100 percent, go to step 14. If EGR position is not about 100 percent, go to step 11.
8. Measure voltage between ground and terminal "D" (Gray wire) at EGR valve harness connector. (Scheme 20) If voltage is about 5 volts, go to step 10. If voltage is not about 5 volts, go to step 12.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "C" (Brown wire) at EGR valve harness connector. If any voltage is indicated, repair short to voltage in Brown wire between EGR valve and PCM. After repairs, go to step 18. If no voltage is indicated, go to step 15.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black wire between terminal "B" at EGR valve harness connector and terminal No. 12 at PCM C2 harness connector. (Scheme 5)and (Scheme 20). If continuity does not exist, repair open in Black wire. After repairs, go to step 18. If continuity exists, go to step 15.
11. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal "C" (Brown wire) at EGR valve harness connector. (Scheme 20) If test light illuminates, repair short to ground in Brown wire between EGR valve and PCM. After repairs, go to step 18. If test light does not illuminate, go to step 16.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check 5-volt reference circuit (Gray wire wire) as follows: Check for open or short to ground in Gray wire between terminal "D" at EGR valve harness connector and terminal No. 50 at PCM C2 harness connector. (Scheme 5)and (Scheme 20). Turn ignition on. Using a test light connected to ground, probe terminal No. 50 (Gray wire) at PCM C2 harness connector. Test light should not illuminate. If test light illuminates, Gray wire is shorted to voltage. If any problems are found, repair as necessary. After repairs, go to step 18. If no problems are found, go to step 16.
13. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal "E" (Red wire) at EGR valve harness connector. (Scheme 20) If test light illuminates, repair short to ground in Red wire between EGR valve and PCM. After repairs, go to step 18. If test light does not illuminate, go to step 15.
14. Check for poor connections at EGR valve connector. Repair connector as necessary. After repairs, go to step 18. If connector is okay, go to step 16.
15. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 18. If connectors are okay, go to step 17.
16. Replace EGR valve. After repairs, go to step 18.
17. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
18. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Remove EGR valve and inspect for deposits that may interfere with EGR valve pintle extending completely or cause pintle to stick. If problem is intermittent, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Powertrain Control Module (PCM) monitors Exhaust Gas Recirculation (EGR) valve pintle position input to ensure valve responds properly to commands from PCM, and to detect a fault if EGR valve position signal circuit is open or shorted. If PCM detects an excessively low EGR valve position signal voltage, DTC P0405 will set.

Only condition for running this DTC is system voltage must be more than 11.6 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: If DTC P1635 is set, diagnose DTC before continuing with this test. See «DTC P1635: 5-VOLT REFERENCE 1 CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
2. Ensure ignition is on. Using scan tool, observe EGR valve position sensor voltage. If voltage is less than.11 volt, go to step 4. If voltage is.11 volt or more, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault my be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect EGR valve connector. (Scheme 15) Connect a 3-amp fused jumper wire between terminal "C" (Brown wire) and terminal "D" (Gray wire) at EGR valve harness connector. Turn ignition on. Using scan tool, observe EGR position sensor parameter. If EGR position sensor is about 100 percent, remove jumper wire and go to step 10. If EGR position is not about 100 percent, remove jumper wire and go to next step.
5. Measure voltage between ground and terminal "D" (Gray wire) at EGR valve harness connector. (Scheme 20) If voltage is about 5 volts, go to step 9. If voltage is not about 5 volts, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Gray wire between terminal "D" at EGR valve harness connector and terminal No. 50 at PCM C2 harness connector. (Scheme 5)and (Scheme 20). If continuity does not exist, repair open in Gray/Black wire. After repairs, go to step 15. If continuity exists, go to next step.
7. Using a test light connected to positive battery voltage, probe terminal No. 50 (Gray wire) at PCM C2 harness connector. (Scheme 5) If test light illuminates, repair short to ground in Gray wire between PCM and EGR valve. After repairs, go to step 15. If test light does not illuminate, go to next step.
8. Ensure ignition is off. Reconnect PCM connectors. Connect DVOM between terminal "B" (Black wire) and terminal "D" (Gray wire) at EGR valve harness connector. Observe DVOM and disconnect Throttle Position (TP) sensor, and then Manifold Absolute Pressure (MAP) sensor. A voltage change indicates a faulty sensor. If any problems are found, replace TP sensor or MAP sensor as necessary. After repairs, go to step 15. If no problems are found, go to step 11.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in EGR valve position signal circuit (Brown wire) between terminal "C"at EGR valve harness connector and terminal No. 52 at PCM C2 harness connector. (Scheme 5)and (Scheme 20). If any problems are found, repair as necessary. After repairs, go to step 15. If no problems are found, go to step 11.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for continuity between terminal "C" (Brown wire) and terminal "E" (Red wire) at EGR valve harness connector. If continuity exists, Brown wire is shorted to Red wire. Repair wiring as necessary. After repairs, go to step 15. If continuity does not exist, go to step 12.
11. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 15. If connectors are okay, go to step 14.
12. Check for poor connections at EGR valve connector. Repair connector as necessary. After repairs, go to step 15. If connector is okay, go to step 13.
13. Replace EGR valve. After repairs, go to step 15.
14. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
15. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
16. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

The Secondary Air Injection (AIR) pump lowers tailpipe emissions during start-up. The AIR system consists of AIR pump, shutoff valves, AIR solenoid, system hoses and pipes, AIR pump relay, fuses, and related wiring. The Powertrain Control Module (PCM) uses the AIR pump relay to control the AIR pump. The PCM also controls the AIR solenoid valve that supplies vacuum to the AIR shutoff valves. With AIR system inactive, the AIR shutoff valves prevent airflow in either direction. With AIR system active, the PCM applies ground to the AIR pump relay and to the AIR solenoid. Fresh air flows from the pump, through the system hoses, past the shutoff valves, and into the exhaust stream. The air helps the catalyst to quickly get to a working temperature, lowering tailpipe emissions during a start-up. The PCM runs a passive test and an active test in order to diagnose the AIR system. Both tests involve a response from the fuel control Heated Oxygen Sensor (HO2S) bank 1 sensor 1, and HO2S bank 2 sensor 1. If both passive tests pass, the PCM takes no further action. If either part of the passive test fails or is inconclusive, the PCM initiates the active tests. If PCM determines that HO2S voltages did not respond as expected during the tests, DTC P0410 will set.

The following conditions are for running a passive test (engine in open loop).

1. Engine is running.
2. Engine speed is more than 600 RPM.
3. Throttle is steady.
4. Engine load is less than 80 percent.
5. System voltage is more than 10.5 volts.
6. Mass airflow is less than 35 grams/sec.
7. Air/fuel ratio is more than 12.5:1.
8. Engine coolant temperature is 41-230°F (5-110°C).
9. Intake air temperature is 41-140°F (5-60°C).
10. Power enrichment or deceleration fuel cutoff is not active.

The following conditions are for running an active test (engine in closed loop).

1. Engine is running.
2. Engine speed is more than 600 RPM.
3. Throttle is steady.
4. Engine load is less than 80 percent.
5. System voltage is more than 10.5 volts.
6. Mass airflow is less than 35 grams/sec.
7. Fuel system is in closed loop.
8. Evaporative emissions purge is active.
9. Engine coolant temperature is more than 154°F (68°C).

Scheme 21

Scheme 22

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. On DeVille and Seville, remove and inspect fuse No. 45 (AIR PUMP fuse) from underhood fuse block. (Scheme 10) Underhood fuse block is located on right side of engine compartment. On Eldorado, remove and inspect AIR fuse from underhood right fuse block. (Scheme 12)and (Scheme 21). On all models, if fuse is okay, reinstall fuse and go to next step. If fuse is blown, go to step 14.
3. If DTC P0412 or P0418 is also set, repair DTC before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions). If DTC P0412 or P0418 is not set, go to next step.
4. Ensure ignition is on. Using scan tool, select OUTPUT CONTROLS and enable AIR system. If AIR pump turns on, go to step 9. If AIR pump does not turn on, go to next step.
5. Turn ignition off. Disconnect AIR pump relay. AIR pump relay is located near shock tower on right side of engine compartment (DeVille and Seville) or left side of engine compartment (Eldorado). Turn ignition on. Using a test light connected to ground, probe terminal No. 30 (Red wire) at AIR pump relay harness connector. (Scheme 22) If test light illuminates, go to next step. If test light does not illuminate, go to step 16.
6. Connect a fused 3-amp jumper wire between terminals No. 30 (Red wire) and No. 87 (Red wire) at AIR pump relay harness connector. (Scheme 22) If AIR pump turns on, go to step 22. If AIR pump does not turn on, go to next step.
7. Ensure jumper wire is still connected. Disconnect AIR pump connector. Using a test light connected to ground, probe terminal "B" (Red wire) at AIR pump harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 17.
8. Ensure jumper wire is still connected. Connect a test light between terminal "A" (Black wire) and terminal "B" (Red wire) at AIR pump harness connector. If test light illuminates, go to step 24. If test light does not illuminate, go to step 18.
9. Disconnect vacuum source from AIR solenoid. AIR solenoid is located near right (rear) valve cover and has a 2-pin connector with Pink and Pink/Black wires. Connect a vacuum gauge to vacuum source. Start engine and allow it to idle. If any engine vacuum is displayed on vacuum gauge, go to next step. If no engine vacuum is displayed on vacuum gauge, go to step 21. NOTE: AIR solenoid may also be referred to as AIR by-pass valve solenoid or AIR vacuum control solenoid valve.
10. Turn ignition off. Reconnect vacuum source to AIR solenoid. Disconnect AIR solenoid-to-AIR shutoff valves vacuum hose at AIR solenoid. Connect a vacuum gauge to AIR solenoid port. Start engine and allow it to idle. Using scan tool, select OUTPUT CONTROLS and enable AIR system. If vacuum is indicated on vacuum gauge when AIR system is enabled, go to next step. If no vacuum is indicated on vacuum gauge when AIR system is enabled, go to step 23.
11. Inspect vacuum lines to each AIR shutoff valve. Check for blockage, poor connections and damage. If any problems are found, repair as necessary. After repairs, go to step 21. If no problems are found, go to next step.
12. Disconnect both AIR intermediate hoses and/or pipes from AIR shutoff valves. Start engine and allow it to idle. Using scan tool, enable AIR system. If air is present at both hoses, no problem is indicated at this time. Fault may be intermittent. If air is not present at both hoses, go to next step.
13. Check for restrictions, poor connections, and damage at following components: AIR inlet and outlet hoses from AIR pump. AIR intermediate hoses and/or pipes. AIR crossover hose and/or pipe. If any problems are found, repair as necessary. After repairs, go to step 26. If no problems are found, no problem is indicated at this time. Fault may be intermittent.
14. Turn ignition off. Disconnect AIR pump relay connector. AIR pump relay is located near shock tower on right side of engine compartment (DeVille and Seville) or left side of engine compartment (Eldorado). Using a test light connected to positive battery voltage, probe terminal No. 30 (Red wire) at AIR pump relay harness connector. (Scheme 22) If test light illuminates, go to step 19. If test light does not illuminate, go to next step.
15. Disconnect AIR pump connector. Using a test light connected to positive battery voltage, probe terminal "B" (Red wire) at AIR pump harness connector. If test light illuminates, go to step 20. If test light does not illuminate, go to step 25.
16. Repair open in Red wire between fuse and AIR pump relay. After repairs, go to step 26.
17. Repair open in Red wire between AIR pump and AIR pump relay. After repairs, go to step 26.
18. Repair faulty ground connection or open in Black wire between AIR pump relay and ground. After repairs, go to step 26.
19. On DeVille and Seville, repair short to ground in Red wire between fuse No. 45 and underhood fuse block. On Eldorado, repair short to ground in Red wire between AIR fuse and right underhood fuse block. On all models, after repairs, go to step 26.
20. Repair short to ground in Red wire between AIR pump relay and AIR pump. After repairs, go to step 26.
21. Repair vacuum hose as necessary. After repairs, go to step 26.
22. Replace AIR pump relay. After repairs, go to step 26.
23. Replace AIR solenoid. After repairs, go to step 26.
24. Check for poor connections at AIR pump connector. Repair connector as necessary. After repairs, go to step 26. If connector is okay, go to next step.
25. Replace AIR pump. After repairs, go to next step.
26. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
27. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) uses the Output Driver Modules (ODM) to control many functions of the engine and transaxle. The ODMs supply the ground path for the PCM-controlled device when the PCM commands the device on. Each ODM can control several outputs. Unlike quad driver modules used in earlier model years, the ODMs are able to diagnose each output circuit. The PCM monitors ODMs for circuit conditions that are incorrect for the commanded state of the ODM. If PCM detects an improper circuit condition in the ODM that controls the AIR vacuum control solenoid valve, DTC P0412 will set.

1. Engine is running.
2. System voltage is 8-16 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P0102, P0410, P0418 and P0443 are set, go to next step. If DTC P0102, P0410, P0418 and P0443 are not set, go to step 4.
3. Check for short to ground in ignition feed circuit (Pink wire) to Secondary Air Injection (AIR) pump relay. See WIRING DIAGRAMS article. AIR pump relay is located near shock tower on right side of engine compartment (DeVille and Seville) or left side of engine compartment (Eldorado). Repair as necessary and replace fuse. If wiring is okay, check for a shorted component that shares ignition feed fuse. See POWER DISTRIBUTION article in WIRING DIAGRAMS. Repair as necessary. After repairs, go to step 16.
4. Turn ignition on. Using scan tool, command AIR solenoid on and off. If AIR solenoid turns on and off with each command, go to next step. AIR solenoid is located near right (rear) valve cover and has a 2-pin connector with Pink and Pink/Black wires. If AIR solenoid does not turn on and off with each command, go to step 6. NOTE: AIR solenoid may also be referred to as AIR by-pass valve solenoid or AIR vacuum control solenoid valve.
5. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
6. Turn ignition off. Disconnect AIR solenoid connector. AIR solenoid is located near right (rear) valve cover and has a 2-pin connector with Pink and Pink/Black wires. Turn ignition on. Using a test light connected to ground, probe Pink wire at AIR solenoid harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13.
7. Connect a test light between Pink and Pink/Black wires at AIR solenoid harness connector. Using scan tool, command AIR solenoid on and off. If test light turns on and off with each command, go to step 11. If test light does not turn on and off with each command, go to next step.
8. If test light remains illuminated with each command, go to step 10. If test light does not remain illuminated with each command, go to next step.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to voltage in Pink/Black wire between AIR solenoid harness connector and terminal No. 66 at PCM C1 harness connector. (Scheme 5) If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 12.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal No. 66 (Pink/Black wire) at PCM C1 harness connector. (Scheme 5) If test light illuminates, repair short to ground in Pink/Black wire between PCM and AIR solenoid. After repairs, go to step 16. If test light does not illuminate, go to step 15.
11. Check for poor connections at AIR solenoid connector. Repair connector as necessary. After repairs, go to step 16. If connector is okay, go to step 14.
12. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 16. If connectors are okay. go to step 15.
13. On DeVille and Seville, repair Pink wire between AIR solenoid and fuse No. 11 (IGN 1 fuse) in underhood fuse block. On Eldorado, repair Pink wire between AIR solenoid and ECS fuse in underhood fuse block. On all models, after repairs, go to step 16.
14. Replace AIR solenoid. After repairs, go to step 16.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) uses the Output Driver Modules (ODM) to control many functions of the engine and transaxle. The ODMs supply the ground path for the PCM-controlled device when the PCM commands the device on. Each ODM can control several outputs. Unlike quad driver modules used in earlier model years, the ODMs are able to diagnose each output circuit. The PCM monitors ODMs for circuit conditions that are incorrect for the commanded state of the ODM. If PCM detects an improper circuit condition in the ODM that controls the AIR pump relay, DTC P0418 will set.

1. Engine is running.
2. System voltage is 8-16 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P0102, P0410, P0412 and P0443 are set, go to next step. If DTC P0102, P0410, P0412 and P0443 are not set, go to step 4.
3. Check for short to ground in ignition feed circuit (Pink wire) to Secondary Air Injection (AIR) pump relay. See WIRING DIAGRAMS article. AIR pump relay is located near shock tower on right side of engine compartment (DeVille and Seville) or left side of engine compartment (Eldorado). Repair as necessary and replace fuse. If wiring is okay, check for a shorted component that shares ignition feed fuse. See POWER DISTRIBUTION article in WIRING DIAGRAMS. Repair as necessary. After repairs, go to step 16.
4. Turn ignition on. Using scan tool, command AIR pump relay on and off. If AIR pump relay turns on and off with each command, go to next step. AIR pump relay is located near shock tower on right side of engine compartment (DeVille and Seville) or left side of engine compartment (Eldorado). If AIR pump relay does not turn on and off with each command, go to step 6.
5. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
6. Turn ignition off. Disconnect AIR pump relay. Turn ignition on. Using a test light connected to ground, probe terminal No. 85 (Pink wire) at AIR pump relay harness connector. (Scheme 22) If test light illuminates, go to next step. If test light does not illuminate, go to step 13.
7. Connect a test light between terminals No. 85 (Pink wire) and No. 86 (Brown wire) at AIR pump relay harness connector. Using scan tool, command AIR pump relay on and off. If test light turns on and off with each command, go to step 11. If test light does not turn on and off with each command, go to next step.
8. If test light remains illuminated with each command, go to step 10. If test light does not remain illuminated with each command, go to next step.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to voltage in Brown wire between terminal No. 86 at AIR pump relay harness connector and terminal No. 75 at PCM C1 harness connector. (Scheme 5)and (Scheme 22). If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 12.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal No. 75 (Brown wire) at PCM C1 harness connector. (Scheme 5) If test light illuminates, repair short to ground in Brown wire between PCM and AIR pump relay. After repairs, go to step 16. If test light does not illuminate, go to step 15.
11. Check for poor connections at AIR pump relay connector. Repair connector as necessary. After repairs, go to step 16. If connector is okay, go to step 14.
12. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 16. If connectors are okay. go to step 15.
13. On DeVille and Seville, repair Pink wire between AIR pump relay and fuse No. 11 (IGN 1 fuse) in underhood fuse block. On Eldorado, repair Pink wire between AIR pump relay and ECS fuse in underhood fuse block. On all models, after repairs, go to step 16.
14. Replace AIR pump relay. After repairs, go to step 16.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) tests the ability of catalytic converter to lower exhaust emissions. The PCM determines catalytic converter performance by calculating oxygen storage capacity. The PCM calculates this data by comparing oxygen content of exhaust entering catalytic converter, read from front and rear Heated Oxygen Sensors (HO2S), to exhaust leaving catalytic converter read from the post HO2S.

Catalytic converter efficiency test is performed in 2 stages. The first stage calculates post-converter oxygen sensor deviations (difference from the average value), compares these deviations to the maximum allowable deviation (based on airflow), and records a failure if those deviations are excessive. The second stage is only run if the first stage fails or DTC P0420 is currently set. The second stage averages the difference between the deviations calculated in the first stage and the maximum allowable deviations. If the second stage average is too high, DTC P0420 will set.

1. DTC P0030, P0036, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0130, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0150, P0151, P0152, P0153, P0154, P0155, P0171, P0172, P0174, P0175, P0201-P0208, P0300, P0335, P0336, P0340, P0341, P0351-P0358, P0385, P0386, P0404, P0405, P0410, P0412, P0418, P0440, P0442, P0443, P0446, P0449, P0452, P0453, P0502, P0503, P0506, P0507, P1031, P1032, P1133, P1134, P1153, P1154, P1336, P1359, P1360, P1372, P1415, P1416 or P1441 is not set.
2. Engine speed since end of last idle period is more than 800 RPM for 46 seconds.
3. Idle period is less than 60 seconds.
4. Actual engine speed is within 100 RPM of desired engine speed, for non-California vehicles.
5. Actual engine speed is within 125 RPM of desired engine speed, for California vehicles.
6. Engine run time is more than 7.5 minutes.
7. Predicted catalyst temperature is 788-1202°F (420-650°C).
8. Barometric pressure is more than 10.1 psi (75 kPa).
9. Engine coolant temperature is 160-248°F (71-120°C).
10. Intake air temperature is 21-392°F (6-200°C).
11. Engine is in closed loop fuel control.
12. Less than 6 tests have been attempted during this ignition cycle.
13. One test has been attempted during idle period.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If any other DTCs are set, diagnose DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If no other DTCs are set, go to next step.
3. Check exhaust system for leaks, damage, and loose or missing hardware. Repair exhaust system as necessary. After repairs, go to step 6 . If exhaust system is okay, go to next step.
4. Ensure original 3-way catalytic converter is installed correctly. Check catalytic converter for damage, severe discoloration or tampering. Ensure oxygen sensors are properly installed and wiring and connections are okay. If any problems are found, repair as necessary. After repairs, go to step 6 . If no problems are found, go to next step.
5. Replace catalytic converter. After repairs, go to next step.
6. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Fuel with high sulfur content can cause a marginal converter to look bad. Check fuel quality.

Evaporative Emission (EVAP) large leak test applies vacuum to EVAP system and monitors vacuum decay. The Powertrain Control Module (PCM) monitors Fuel Tank Pressure (FTP) sensor signal to determine vacuum decay rate. At an appropriate time, the PCM turns EVAP canister purge valve on (open) and EVAP canister vent valve on (closed). This allows engine to draw a vacuum on EVAP system. At a calibrated time, or vacuum level, the PCM turns purge valve off (closed), sealing the system, and monitors FTP sensor input to determine EVAP system vacuum. If system is unable to achieve calibrated vacuum level, or if vacuum level decreases too rapidly, DTC P0440 will set.

1. DTC P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1106, P1107, P1112, P1114, P1115, P1121 or P1122 is not set.
2. System voltage is 10-18 volts.
3. Barometric pressure is more than 10.1 psi (75 kPa).
4. Fuel level is 15-85 percent.
5. Engine coolant temperature is 39-86°F (4-30°C).
6. Intake air temperature is 39-86°F (4-30°C).
7. Start-up engine coolant temperature and intake air temperature are within 48°F (9°C) of each other.
8. Vehicle speed sensor is less than 75 MPH.

Note. EVAP Pressure/Purge Diagnostic Station (J 41413) is required to pressurize EVAP system in the following test.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P0443 or DTC P0449 is also set, see «DTC P0443: EVAPORATIVE EMISSION PURGE VALVE 1 CONTROL CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) or «DTC P0449: EVAPORATIVE EMISSION VENT VALVE CONTROL CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTC P0443 or DTC P0449 is not set, go to next step.
3. Inspect EVAP system for the following conditions. Check for loose, missing or damaged service port Schrader valve. Check for loose, incorrect, missing or damaged fuel filler cap. Check for damaged EVAP canister purge valve. (Scheme 23) Raise and support vehicle. Check for disconnected, improperly routed, kinked or damaged EVAP pipes and hoses. Check for damaged EVAP canister vent valve. EVAP canister vent valve is located near fuel tank. (Scheme 24) Check for damaged EVAP canister. EVAP canister is located near fuel tank. (Scheme 25) If any problems are found, repair as necessary. After repairs, go to 17. If no problems are found, go to next step.
4. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure/Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Monitor pressure gauge for one minute. If pressure stays at 5 in. H2O, go to next step. If pressure does not stay at 5 in. H2O, go to step 7.
5. Using scan tool, observe Fuel Tank Pressure (FTP) sensor value. Compare EVAP pressure/purge diagnostic station value to scan tool FTP sensor value. If EVAP pressure/purge diagnostic station value is near scan tool value, go to next step. If EVAP pressure/purge diagnostic station value is not near scan tool value, go to step 11.
6. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Disconnect EVAP purge pipe from EVAP canister purge valve. (Scheme 23) If EVAP system pressure decreases, go to step 8. If EVAP system pressure does not decrease, go to step 9.
7. Using EVAP pressure/purge diagnostic station, continuously pressurize EVAP system. Using Ultrasonic Leak Detector (J 41416) check EVAP system for leaks. Carefully leak test all EVAP system hoses, tubes and connections. It may be necessary to partially lower fuel tank to inspect components located in upper portion of fuel tank. If any leaks are found, repair as necessary. After repairs, go to step 17. If no leaks are found, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
8. Connect a vacuum gauge to EVAP purge valve purge pipe port. Start engine and allow it to idle. Using scan tool, command EVAP canister purge valve to 50 percent. If vacuum gauge indicates an increase in vacuum, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If vacuum gauge does not indicate an increase in vacuum, go to step 14.
9. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Disconnect purge pipe from EVAP canister. (Scheme 25) If EVAP system pressure decreases, go to step 15. If EVAP system pressure does not decrease, go to next step.
10. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Disconnect vapor pipe from EVAP canister. If EVAP system pressure decreases, go to 16. If EVAP system pressure does not decrease, go to step 13.
11. Using scan tool, monitor FTP sensor voltage. If voltage is more than 4.3 volts, go to «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT HIGH VOLTAGE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If voltage is 4.3 volts or less, go to next step.
12. Replace FTP sensor. FTP sensor is located on top of fuel tank. On DeVille and Seville, FTP sensor can be accessed through an inspection panel in trunk. On Eldorado, check trunk floor area to see if an inspection panel exists. If no inspection panel exists, fuel tank must be removed to access FTP sensor. On all models, after repairs, go to step 17.
13. Repair pinched or obstructed EVAP vapor pipe. After repairs, go to step 17.
14. Replace EVAP canister purge valve. After repairs, go to step 17.
15. Repair restriction in EVAP purge pipe. After repairs, go to step 17.
16. Replace EVAP canister. After repairs, go to next step.
17. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Monitor pressure gauge for 5 minutes. If pressure stays at 5 in. H2O, go to next step. If pressure does not stay at 5 in. H2O, go to step 7.
18. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Using scan tool, command EVAP purge valve to 50 percent. If EVAP system pressure decreases, go to next step. If EVAP system pressure does not decrease, go to step 9.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Use EVAP Pressure/Purge Diagnostic Station (J 41413) to pressurize EVAP system to aid in locating intermittent leaks. Move all EVAP components while testing with Ultrasonic Leak Detector (J 41416). A temporary blockage in EVAP canister purge valve, purge pipe or EVAP canister could cause an intermittent condition. Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to set occurs. This may assist in diagnosing condition.

Scheme 23

Scheme 24

Scheme 25

This DTC tests Evaporative Emission (EVAP) system for a small leak. Powertrain Control Module (PCM) monitors Fuel Tank Pressure (FTP) sensor signal to determine vacuum decay rate. At an appropriate time, PCM turns EVAP canister purge valve and EVAP canister vent valve on. This allows engine to draw a vacuum on EVAP system. At a calibrated time, or vacuum level, PCM turns EVAP canister purge valve off, sealing the system, and monitors FTP sensor input to determine EVAP system vacuum decay. If PCM detects a leak larger than calibrated amount, DTC P0442 will set.

1. DTC P0107. P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1106. P1107, P1112, P1114, P1115, P1121 or P1122 is not set.
2. System voltage is 10-18 volts.
3. Barometric pressure is more than 10.1 psi (75 kPa).
4. Fuel level is 15-85 percent.
5. Engine coolant temperature is 39-86°F (4-30°C).
6. Intake air temperature is more than 39-86°F (4-30°C).
7. Start-up engine coolant temperature and intake air temperature are within 48°F (9°C) of each other.
8. Vehicle speed sensor is less than 75 MPH.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P0443 or DTC P0449 is also set, see «DTC P0443: EVAPORATIVE EMISSION PURGE VALVE 1 CONTROL CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) or «DTC P0449: EVAPORATIVE EMISSION VENT VALVE CONTROL CIRCUIT»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTC P0443 or DTC P0449 is not set, go to next step.
3. Inspect EVAP system for the following conditions. Check for loose, missing or damaged service port Schrader valve. Check for loose, incorrect, missing or damaged fuel filler cap. Check for damaged EVAP canister purge valve. (Scheme 23) Raise and support vehicle. Check for disconnected, improperly routed, kinked or damaged EVAP pipes and hoses. Check for damaged EVAP canister vent valve. EVAP canister vent valve is located near fuel tank. (Scheme 24) Check for damaged EVAP canister. EVAP canister is located near fuel tank. (Scheme 25) If any problems are found, repair as necessary. After repairs, go to 6. If no problems are found, go to next step.
4. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure/ Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Monitor pressure gauge for one minute. If pressure stays at 5 in. H2O, go to «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) If pressure does not stay at 5 in. H2O, go to next step.
5. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure/ Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, continuously pressurize system to 15 in. H2O. Using Ultrasonic Leak Detector (J 41416) check EVAP system for leaks. Carefully leak test all EVAP system hoses, tubes and connections. It may be necessary to partially lower fuel tank to inspect components located in upper portion of fuel tank. If any leaks are found, repair as necessary. After repairs, go to next step. If no problems are found, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
6. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure/ Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Monitor pressure gauge for one minute. If pressure stays at 5 in. H2O, go to next step. If pressure does not stay at 5 in. H2O, go to step 2.
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

EVAP system tests run when engine is first started and meets code enable criteria for this DTC. Use EVAP Pressure/Purge Diagnostic Station (J 41413) to pressurize EVAP system to aid in locating intermittent leaks. Move all EVAP components while testing with Ultrasonic Leak Detector (J 41416).

An ignition voltage is supplied directly to Evaporative Emission (EVAP) canister purge valve. EVAP canister purge valve is pulse width modulated. Powertrain Control Module (PCM) controls EVAP canister purge valve "ON" time by grounding the control circuit via an internal switch called a driver. Scan tool displays amount of "ON" time as a percentage. The PCM monitors driver status. If PCM detects an incorrect voltage for the commanded state of the driver, DTC P0443 will set.

1. Engine speed is more than 400 RPM.
2. System voltage is 6-18 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, command EVAP canister purge valve to 50 percent, and then to zero percent. If a clicking noise is felt or heard from EVAP canister purge valve when commanded to 50 percent, go to next step. (Scheme 23) If a clicking noise is not felt or heard from EVAP canister purge valve when commanded to 50 percent, go to step 4.
3. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect EVAP purge valve connector. Turn ignition on. Using a test light connected to ground, probe Pink wire at EVAP purge valve harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11.
5. Connect a test light between Pink and Dark Green/White wires at EVAP purge valve harness connector. Using scan tool, command EVAP canister purge valve to zero percent. If test light illuminates, go to step 9. If test light does not illuminate, go to next step.
6. Using scan tool, command EVAP canister purge valve to 50 percent. If test light illuminates, go to step 8. If test light does not illuminate, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to voltage in Dark Green/White wire between EVAP canister purge valve harness connector and terminal No. 42 at PCM C2 harness connector. (Scheme 5) If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Using a test light connected to positive battery voltage, probe Dark Green/White wire at EVAP canister purge valve harness connector. If test light illuminates, repair short to ground in Dark Green/White wire between EVAP canister purge valve and PCM. After repairs, go to step 14. If test light does not illuminate, go to step 13.
9. Check for poor connections at EVAP purge valve connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
11. Repair open or short to ground in power circuit (Pink wire) to EVAP canister purge valve. On DeVille and Seville, also check fuse No. 11 (IGN 1 fuse) in underhood fuse block. On Eldorado, also check ECS fuse in underhood fuse block. On all models, after repairs go to step 14.
12. Replace EVAP canister purge valve. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

This DTC tests Evaporative Emission (EVAP) system for a restricted or blocked EVAP vent path. Powertrain Control Module (PCM) commands EVAP canister purge valve and EVAP canister vent valve on. This allows a vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the PCM commands EVAP canister purge valve and EVAP canister vent valve off. The PCM monitors Fuel Tank Pressure (FTP) sensor for a decrease in vacuum. If vacuum does not decrease to near zero in. H2O in a calibrated time, DTC P0446 will set.

1. DTC P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0440, P0442, P0443, P0449, P0452, P0453, P1106. P1107, P1111, P1112, P1114, P1115, P1121 or P1122 is not set.
2. System voltage is 10-18 volts.
3. Barometric pressure is more than 10.1 psi (75 kPa).
4. Fuel level is 15-85 percent.
5. Engine coolant temperature is 39-86°F (4-30°C).
6. Intake air temperature is 39-86°F (4-30°C).
7. Vehicle speed sensor is less than 75 MPH.

Note. EVAP Pressure/Purge Diagnostic Station (J 41413) is required to pressurize EVAP system in the following test.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P0443, P0449, P0452 or P0543 is also set, repair DTC(s) before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions). If DTC P0443, P0449, P0452 or P0543 is not set, go to next step.
3. Check for damaged EVAP canister vent valve or pinched EVAP canister vent valve hose. EVAP canister vent valve is located near fuel tank. (Scheme 24) If any problems are found, repair as necessary. After repairs, go to 14. If no problems are found, go to next step.
4. Disconnect purge line from EVAP canister purge valve. (Scheme 23) Ensure ignition is on. Using scan tool, observe fuel tank pressure parameter. If scan tool indicates fuel tank pressure is about zero in. H2O, go to next step. If scan tool does not indicate fuel tank pressure is about zero in. H2O, go to step 8.
5. Turn ignition off. Reconnect all connectors and components. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure/Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, command EVAP vent valve ON. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Using scan tool, command EVAP vent valve OFF. If fuel tank pressure changes to zero in. H2O, no problem is indicated. Fault may be intermittent. See «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If fuel tank pressure does not change to zero in. H2O, go to step 7.
6. While observing scan tool, disconnect vent hose from EVAP canister vent valve. (Scheme 24) If fuel tank pressure changes to zero in. H2O, go to step 10. If fuel tank pressure does not change to zero in. H2O, go to next step.
7. Disconnect vent hose/pipe from EVAP canister. (Scheme 25) If fuel tank pressure changes to zero in. H2O, go to step 13. If fuel tank pressure does not change to zero in. H2O, go to step 11.
8. Using scan tool, monitor FTP sensor voltage. If voltage is more than 4.3 volts, go to «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT HIGH VOLTAGE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If voltage is 4.3 volts or less, go to next step.
9. Check for poor connections at FTP sensor connector. FTP sensor is located on top of fuel tank. On DeVille and Seville, FTP sensor can be accessed through an inspection panel in trunk. On Eldorado, check trunk floor area to see if an inspection panel exists. If no inspection panel exists, fuel tank must be removed to access FTP sensor. On all models, repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
10. Replace EVAP canister vent valve. After repairs, go to step 14.
11. Replace EVAP canister. After repairs, go to step 14.
12. Replace FTP sensor. FTP sensor is located on top of fuel tank and can be accessed through an inspection panel in trunk. After repairs, go to step 14.
13. Repair pinched or obstructed EVAP vent hose/pipe. After repairs, go to next step.
14. Turn ignition off. Reconnect all connectors and components. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure/ Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, command EVAP vent valve ON. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Using scan tool, command EVAP vent valve OFF. If fuel tank pressure changes to zero in. H2O, go to next step. If fuel tank pressure does not change to zero in. H2O, go to step 3.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent valve inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.

An ignition voltage is supplied directly to Evaporative Emission (EVAP) canister vent valve. Powertrain Control Module (PCM) controls EVAP vent valve by grounding control circuit via an internal switch called a driver. Primary function of the driver is to supply ground for the controlled component. The PCM monitors driver status. If PCM detects an incorrect voltage for commanded state of the driver, DTC P0449 will set.

1. Engine is running.
2. System voltage is 6-18 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine and allow it to idle. Using scan tool, command EVAP vent valve on and off. If a clicking noise is felt or heard from EVAP vent valve, go to next step. EVAP canister vent valve is located near fuel tank. (Scheme 24) If a clicking noise is not felt or heard from EVAP vent valve, go to step 4.
3. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect EVAP vent valve connector. Turn ignition on. Using a test light connected to ground, probe Pink wire at EVAP vent valve harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11.
5. Connect a test light between Pink and White wires at EVAP purge valve harness connector. Using scan tool, command EVAP vent valve on and off. If test light turns on and off with each command, go to step 9. If test light does not turn on and off with each command, go to next step.
6. If test light remains on with each command, go to step 8. If test light does not remain on with each command, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to voltage in White wire between EVAP canister vent valve harness connector and terminal No. 73 at PCM C1 harness connector. (Scheme 5) If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Using a test light connected to positive battery voltage, probe White wire at EVAP canister vent valve harness connector. If test light illuminates, repair short to ground in White wire between EVAP canister vent valve and PCM. After repairs, go to step 14. If test light does not illuminate, go to step 10.
9. Check for poor connections at EVAP vent valve connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
11. Repair open or short to ground in power circuit (Pink wire) to EVAP canister vent valve. Also check fuse No. 11 (VENT SOL fuse) in rear fuse block. Rear fuse block is located underneath driver's side rear seat. After repairs, go to step 14.
12. Replace EVAP canister vent valve. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Fuel Tank Pressure (FTP) sensor measures the difference between air pressure or vacuum in the Evaporative Emission (EVAP) system, and outside air pressure. The Powertrain Control Module (PCM) supplies a 5-volt reference and a low reference circuit to FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If PCM detects FTP sensor signal voltage less than calibrated value, DTC P0452 will set.

Only condition for running this DTC is engine must be running.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P1639 is also set, go «DTC P1639: 5-VOLT REFERENCE 2 CIRCUIT - DEVILLE & SEVILLE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) or «DTC P1639: 5-VOLT REFERENCE 2 CIRCUIT - ELDORADO»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTC P1639 is not set, go to next step.
3. Ensure ignition is on. Using scan tool, observe FTP sensor voltage. If voltage is less than.1 volt, go to step 5. If voltage is.1 volt or more, go to next step.
4. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Disconnect FTP sensor. FTP sensor is located on top of fuel tank. On DeVille and Seville, FTP sensor can be accessed through an inspection panel in trunk. On Eldorado, check trunk floor area to see if an inspection panel exists. If no inspection panel exists, fuel tank must be removed to access FTP sensor. On all models, turn ignition on. Connect a jumper wire between terminal "B" (Dark Green wire) and terminal "C" (Gray wire) at FTP sensor harness connector. (Scheme 26) Using scan tool, observe FTP sensor voltage. If voltage is about 5 volts, go to step 8. If voltage is not about 5 volts, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Gray wire between terminal "C" at FTP sensor harness connector and terminal No. 17 at PCM C2 harness connector. (Scheme 5)and (Scheme 26). If continuity does not exist, repair open in Gray wire. After repairs, go to step 12. If continuity exists, go to next step.
7. Check FTP sensor signal circuit (Dark Green wire) as follows: Check continuity of Dark Green wire between terminal "B" at FTP sensor harness connector and terminal No. 5 at PCM C1 harness connector. Continuity should exist. If continuity does not exist, Dark Green wire is open. Check for continuity between terminal "A" (Black wire) and terminal "B" (Dark Green wire) at FTP sensor harness connector. Continuity should not exist. If continuity exists, Black and Dark Green wires are shorted together. Using a test light connected to positive battery voltage, probe terminal "B" (Dark Green wire) at FTP sensor harness connector. Test light should not illuminate. If test light illuminates, Dark Green wire is shorted to ground. If any problems are found, repair as necessary. After repairs, go to step 12. If no problems are found, go to step 9.
8. Check for poor connections at FTP sensor connector. Repair connector as necessary. After repairs, go to step 12. If connector is okay, go to step 10.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 12. If connectors are okay, go to step 11.
10. Replace FTP sensor. After repairs, go to step 12.
11. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
12. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
13. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Scheme 26

Fuel Tank Pressure (FTP) sensor measures the difference between air pressure or vacuum in the Evaporative Emission (EVAP) system, and outside air pressure. The Powertrain Control Module (PCM) supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If PCM detects FTP sensor signal voltage more than calibrated value, DTC P0453 will set.

Only condition for running this DTC is engine must be running.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Idle engine for one minute. Using scan tool, monitor DTC information. If DTC P1639 sets, go to «DTC P1639: 5-VOLT REFERENCE 2 CIRCUIT - DEVILLE & SEVILLE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) or «DTC P1639: 5-VOLT REFERENCE 2 CIRCUIT - ELDORADO»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTC P1639 is not set, go to next step.
3. Turn ignition on. Using scan tool, observe FTP sensor voltage. If voltage is more than 4.3 volts, go to step 5. If voltage is 4.3 volts or less, go to next step.
4. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Disconnect FTP sensor. FTP sensor is located on top of fuel tank. On DeVille and Seville, FTP sensor can be accessed through an inspection panel in trunk. On Eldorado, check trunk floor area to see if an inspection panel exists. If no inspection panel exists, fuel tank must be removed to access FTP sensor. On all models, turn ignition on. Using scan tool, observe FTP sensor voltage. If voltage is more than 4.3 volts, go to next step. If voltage is 4.3 volts or less, go to step 7.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor connections at PCM connectors. Repair connectors as necessary. If connectors are okay, check FTP sensor signal circuit (Dark Green wire) as follows: Check for continuity between terminal "B" (Dark Green wire) and terminal "C" (Gray wire) at FTP sensor harness connector. (Scheme 26) Continuity should not exist. If continuity exists, Dark Green and Gray wires are shorted together. Using a test light connected to ground, probe terminal "B" (Dark Green wire) at FTP sensor harness connector. Test light should not illuminate. If test light illuminates, Dark Green wire is shorted to voltage. If any problems are found, repair as necessary. After repairs, go to step 13. If no problems are found, go to step 12.
7. Using a test light connected to positive battery voltage, probe terminal "A" (Black wire) at FTP sensor harness connector. If test light illuminates, go to step 9. If test light does not illuminate, go to next step.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black wire between terminal "A" at FTP sensor harness connector and terminal No. 13 at PCM C2 harness connector. (Scheme 5)and (Scheme 26). If continuity does not exist, repair open in Black wire. After repairs, go to step 13. If continuity exists, go to step 10.
9. Check for poor connections at FTP sensor connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to step 11.
10. Check for poor connections at PCM connectors. Repair connector as necessary. After repairs, go to step 13. If connectors are okay, go to step 12.
11. Replace FTP sensor. After repairs, go to step 13.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

DTC P0480: COOLING FAN RELAY NO. 1 CONTROL CIRCUIT

Battery voltage is supplied to cooling fan 1 relay from fuse No. 47 (DeVille and Seville) or COOL FANS fuse (Eldorado). The Powertrain Control Module (PCM) controls cooling fan 1 relay by grounding the low speed cooling fan relay control circuit via an internal solid state device called a driver. Primary function of the driver is to supply ground for the component being controlled. Each driver has a fault line which is monitored by PCM. When PCM is commanding a component on, voltage potential of control circuit should be low (about zero volts). When PCM is commanding that the control circuit to a component be turned off, voltage potential of circuit should be high (about battery voltage). If fault detection circuit senses a voltage other than what is expected, DTC P0480 will set.

PCM will monitor the control circuit for short to ground, short to voltage, open circuit, open relay coil, internally shorted or excessively low resistance relay coil. When PCM detects any of these conditions, DTC will set and the affected driver will be disabled.

1. Engine speed is more than 425 RPM.
2. System voltage is 8-18 volts.

Scheme 27

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «ENGINE COOLING DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__engine-cooling-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: On DeVille and Seville, cooling fan 1 relay may also be referred to as cooling fan primary relay.
2. Ensure ignition is on. Using scan tool, command low speed fans on and off. If cooling fan 1 relay turns on and off with each command, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). On DeVille and Seville, cooling fan 1 relay is located in underhood fuse block. (Scheme 10) On Eldorado, cooling fan 1 relay is located below cooling fans. (Scheme 27) On all models, if cooling fan 1 relay does not turn on and off with each command, go to next step.
3. Turn ignition off. Remove cooling fan 1 relay. Turn ignition on. On DeVille and Seville, using a test light connected to ground, probe battery voltage circuit at cooling fan 1 relay connector in underhood fuse block. See WIRING DIAGRAMS article. On Eldorado, using a test light connected to ground, probe Red wire at cooling fan 1 relay harness connector. On all models, if test light illuminates, go to next step. If test light does not illuminate, go to step 8.
4. On DeVille and Seville, connect a test light between cooling fan 1 relay control circuit (Dark Green wire) and battery voltage circuit at cooling fan 1 relay connector in underhood fuse block. On Eldorado, connect a test light between cooling fan 1 relay control circuit (Dark Green wire) and Red wire at cooling fan 1 relay harness connector. On all models, using scan tool, command low speed fans on and off. If test light turns on and off with each command, go to step 10. If test light does not turn on and off with each command, go to next step.
5. If test light remains illuminated with each command, go to step 7. If test light does not remain illuminated with each command, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check control circuit (Dark Green wire) for cooling fan 1 relay as follows: On DeVille and Seville, check continuity of Dark Green wire between cooling fan 1 relay connector in underhood fuse block and terminal No. 25 at PCM C1 harness connector. (Scheme 5) On Eldorado, check continuity of Dark Green wire between cooling fan 1 relay harness connector and terminal No. 25 at PCM C1 harness connector. (Scheme 5) On all models, continuity should exist. If continuity does not exist, Dark Green wire is open. Turn ignition on. Measure voltage between ground and terminal No. 25 (Dark Green wire) at PCM C1 harness connector. If any voltage is indicated, Dark Green wire is shorted to voltage between PCM and cooling fan 1 relay connector. If any problems are found, repair wiring as necessary. After repairs, go to step 14. If no problems are found, go to step 9.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal No. 25 (Dark Green wire) at PCM C1 harness connector. (Scheme 5) If test light illuminates, repair short to ground in Dark Green wire between PCM and cooling fan 1 relay connector. After repairs, go to step 14. If test light does not illuminate, go to step 9.
8. Turn ignition off. On DeVille and Seville, check for an open or short to ground in cooling fan relay 1 battery voltage circuit between cooling fan relay 1 connector and output side of fuse No. 47 at underhood fuse block. On Eldorado, check for an open or short to ground in Red wire between cooling fan relay 1 harness connector and output side of COOLING FANS fuse holder. On all models, if any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to step 11.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
10. Turn ignition off. Check for poor connections at cooling fan 1 relay connector. Repair connector as necessary. After repairs, go to step 14. If connectors are okay, go to step 12.
11. Repair short to ground in cooling fan motor supply voltage circuit (Gray wire). After repairs, go to step 14.
12. Replace cooling fan 1 relay. After replacing relay, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection. Review FREEZE/FAILURE RECORDS vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

DTC P0481: COOLING FAN RELAY NO. 2 CONTROL CIRCUIT

Battery voltage is supplied to the cooling fan S/P relay and cooling fan 2 relay from fuse No. 46 (DeVille and Seville) or COOL FANS fuse (Eldorado). The Powertrain Control Module (PCM) controls the relays by grounding the high speed cooling fan relay control circuit via an internal solid state device called a driver. Primary function of the driver is to supply ground for the component being controlled. Each driver has a fault line which is monitored by PCM. When PCM is commanding a component on, voltage potential of control circuit should be low (about zero volts). When PCM is commanding that the control circuit to a component be turned off, voltage potential of circuit should be high (about battery voltage). If fault detection circuit senses a voltage other than what is expected, DTC P0481 will set.

PCM will monitor the control circuit for short to ground, short to voltage, open circuit, open relay coil, internally shorted or excessively low resistance relay coil. When PCM detects any of these conditions, DTC P0481 will set and the affected driver will be disabled.

1. Engine speed is more than 425 RPM.
2. System voltage is 8-18 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «ENGINE COOLING DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__engine-cooling-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Ensure ignition is on. Using scan tool, command high speed fans on and off. If cooling fan S/P relay and cooling fan 2 relay turn on and off with each command, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). On DeVille and Seville, cooling fan S/P relay and cooling fan 2 relay are located in underhood fuse block. On Eldorado, S/P relay and cooling fan 2 relay are located below cooling fan motors. (Scheme 27) On all models, if cooling fan S/P relay and cooling fan 2 relay do not turn on and off with each command, go to next step. NOTE: Cooling fan S/P relay may also be referred to as cooling fan series/parallel relay.
3. Turn ignition off. Remove cooling fan 2 relay. Turn ignition on. On DeVille and Seville, using a test light connected to ground, probe battery voltage circuit at cooling fan 2 relay connector in underhood fuse block. See WIRING DIAGRAMS article. On Eldorado, using a test light connected to ground, probe Red wire at cooling fan 2 relay harness connector. On all models, if test light illuminates, go to next step. If test light does not illuminate, go to step 8.
4. On DeVille and Seville, connect a test light between cooling fan 2 relay control circuit (Dark Blue wire) and battery voltage circuit at cooling fan 2 relay connector in underhood fuse block. On Eldorado, connect a test light between Dark Blue and Red wires at cooling fan 2 relay harness connector. On all models, using scan tool, command high speed fans on and off. If test light turns on and off with each command, go to step 9. If test light does not turn on and off with each command, go to next step.
5. If test light remains illuminated with each command, go to step 7. If test light does not remain illuminated with each command, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check control circuit (Dark Blue wire) for cooling fan 2 relay as follows: On DeVille and Seville, check continuity of Dark Blue wire between cooling fan 2 relay connector in underhood fuse block and terminal No. 55 at PCM C2 harness connector. (Scheme 5) Also check continuity of Dark Blue wire between cooling fan S/P relay connector in underhood fuse block and terminal No. 55 at PCM C2 harness connector. On Eldorado, check continuity of Dark Blue wire between cooling fan 2 relay harness connector and terminal No. 55 at PCM C2 harness connector. (Scheme 5) Also check continuity of Dark Blue wire between cooling fan S/P relay harness connector and terminal No. 55 at PCM C2 harness connector. On all models, both readings should indicate continuity exists. If continuity does not exist, Dark Blue wire is open. Turn ignition on. Measure voltage between ground and terminal No. 55 (Dark Blue wire) at PCM C2 harness connector. If any voltage is indicated, Dark Blue wire is shorted to voltage between PCM and cooling fan 2 relay or cooling fan S/P relay connector in underhood fuse block. If any problems are found, repair wiring as necessary. After repairs, go to step 12. If no problems are found, go to step 9.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal No. 55 (Dark Blue wire) at PCM C2 harness connector. (Scheme 5) If test light illuminates, repair short to ground in Dark Blue wire between PCM and cooling fan 2 relay connector or cooling fan S/P relay connector. After repairs, go to step 12. If test light does not illuminate, go to step 9.
8. Turn ignition off. Check for an open or short to ground in battery voltage circuit for cooling fan S/P relay and cooling fan 2 relay. If any problems are found, repair as necessary. After repairs, go to step 12. If no problems are found, go to step 10.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 12. If connectors are okay, go to step 11.
10. Repair short to ground in cooling fan motor supply voltage circuit (Light Blue wire). After repairs, go to step 12.
11. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
12. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
13. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection. Review FREEZE/FAILURE RECORDS vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

Idle Air Control (IAC) valve is located on throttle body. It consists of a movable pintle, driven by a gear attached to an electric motor called a stepper motor. The IAC valve motor is a 2 phase bi-polar permanent magnet stepper motor that is capable of highly accurate rotation, or movement, every time polarity of a winding is changed. Polarity can be seen when observing a test light connected between ground or B+ and an IAC valve circuit while the Powertrain Control Module (PCM) is attempting to change engine RPM (test light will flash on or off each time polarity is changed). The PCM does not use a physical sensor to determine IAC pintle position, but uses a predicted number of counts, one count represents one change in polarity which equals one step of the stepper motor. The PCM counts the steps it has commanded to determine IAC pintle position. The PCM uses IAC valve to control engine idle speed. It does this by changing pintle position in the idle air passage of the throttle body. This varies airflow around throttle plate when throttle is closed. To determine desired position of IAC pintle at idle or during deceleration, the PCM refers to the following inputs: engine RPM, battery voltage, air temperature, engine coolant temperature, throttle position sensor angle, engine load, and vehicle speed. When ignition is turned off after an ignition cycle, the PCM will first seat the IAC pintle in the air by-pass bore, and then retract it a predetermined amount of counts to allow proper amount of air to by-pass throttle plate for engine start-up. This procedure is known as an IAC reset.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0335, P0336, P0340, P0341, P0385, P0386, P0401, P0403, P0404, P0405, P0440, P0442, P0443, P0446, P0449, P1106, P1107, P1111, P1112, P1114, P1115, P1121, P1122, P1336, P1372, P1404 or P1441 is not set.
2. Engine coolant temperature is more than -40°F (-40°C).
3. Intake air temperature is more than -1°F (-18°C).
4. Ignition voltage is 10.5-16 volts.
5. Barometric pressure is more than 9.43 psi (65 kPa).
6. Engine run time is more than 40 seconds.
7. Transmission gear state has not changed for 3 seconds.
8. Torque converter clutch state has not changed in 3 seconds.
9. Throttle position sensor is less than 1.5 percent.
10. Spark advance is less than 12.39 degrees.
11. Spark retard is more than -13.79 degrees.
12. Vehicle speed sensor is less than 2 MPH.
13. Listed conditions exist present for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Set parking brake and block drive wheels. Start engine. Turn all accessories off. Using scan tool RPM control function, slowly increment engine speed to 1700 RPM, then to 600 RPM, then back to 1700 RPM. Exit RPM control function. If engine speed stabilizes within 100 RPM of commanded RPM, go to next step. If engine speed does not stabilize within 100 RPM of commanded RPM, go step 4.
3. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition off. Disconnect IAC valve connector. Connect IAC Motor Driver (J 37027-A) to IAC valve. Start engine. Using IAC motor driver, command IAC valve in until about 600 RPM is reached, then command IAC valve out until about 1700 RPM is reached. Return engine speed to desired idle as indicated on scan tool data list. If engine speed steadily decreased to about 600 RPM, and then steadily increased to about 1700 RPM when IAC valve was commanded, go to next step. If engine speed did not steadily decrease to about 600 RPM, and then steadily increase to about 1700 RPM when IAC valve was commanded, go to step 11.
5. Using a test light connected to ground, probe any IAC valve circuit at IAC valve harness connector using Connector Test Adapter Kit (J 36616). Start engine. Using IAC motor driver, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM while observing a scan tool until IAC counts start to increment. Observe test light while IAC counts are incrementing. Return engine idle speed to desired idle as indicated on scan tool data list. Repeat procedure for remaining 3 IAC valve circuits. If test light remained on, (never flashed) while IAC counts were incrementing at any IAC valve circuit, go to step 10. If test light did not remain on, (never flashing) while IAC counts were incrementing at any IAC valve circuit, go to next step.
6. If test light remained off (never flashed), go to step 9. If test light did not remain off, go to next step.
7. Using connector test kit adapter, connect a test light between terminal "C" (Light Blue/Black wire) and terminal "D" (Light Blue/White wire) at IAC valve harness connector. (Scheme 28) Using IAC motor driver, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM while observing scan tool until IAC counts start to increment. Observe test light while IAC counts are incrementing. Return engine idle speed to desired idle as indicated on scan tool data list. Repeat procedure with test light connected between terminal "A" (Light Green/Black wire) and terminal "B" (Light Green/White wire) at IAC valve harness connector. Return engine speed to desired idle as indicated on scan tool data list. If test light remained on (never flashing) while IAC counts were incrementing during test, go to next step. If test light did not remain on (never flashing) while IAC counts were incrementing during test, go to step 15.
8. Check for poor connections at IAC valve connector. Repair connector as necessary. After repairs, go to step 16. If connectors are okay, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a DVOM, check for an open or short ground on IAC valve circuit where test light remained off. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 12.
10. Turn ignition on. Using a DVOM, check for short to voltage on IAC valve circuit where test light remained illuminated. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 12.
11. Visually and physically inspect for the following: Throttle body damage and tampering. Throttle lever screw tampering, if equipped. Restricted air intake system. Inspect for a possible collapsed or clogged air intake duct before and after air filter element, restricted air filter element, or restriction at throttle body intake screen, if equipped. Remove IAC valve. Inspect for the following: A clogged IAC passage. Excessive deposits on throttle plate. Excessive deposits in throttle bore. Excessive deposits on IAC valve pintle. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 13.
12. Check for poor connections at PCM connectors. Repair connector as necessary. After repairs, go to step 16. If connectors are okay, go to step 15.
13. Check for poor connections at IAC valve connector. Repair connector as necessary. After repairs, go to step 16. If connector is okay, go to next step.
14. Replace IAC valve. After repairs, go to step 16.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Inspect for the following conditions

1. Check for restricted air intake system.
2. Check for collapsed, clogged, or loose air intake ducts, clogged air filter, and proper operation of mass airflow sensor.
3. Check for a tampered or damaged throttle stop screw.
4. Check for a tampered or damaged throttle plate, throttle shaft, or throttle linkage.
5. Check for objects blocking IAC passage or throttle bore.
6. Check for excessive deposits in IAC passage or on IAC pintle. Check for excessive deposits in throttle bore or on throttle plate.
7. Check for vacuum leaks.
8. A low or unstable idle condition could be caused by a non-IAC system problem that cannot be overcome by IAC valve. See SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article.

Scheme 28

Powertrain Control Module (PCM) monitors system voltage to make sure that voltage stays within the proper range. Damage to components and incorrect data input can occur when voltage is out of range. PCM monitors system voltage over an extended length of time. If PCM detects a system voltage out of an expected range for the calibrated length of time, DTC P0560 will set.

1. System voltage is less than 9 volts.
2. Engine speed is more than 1000 RPM.
3. Vehicle speed is less than 25 MPH.

1. If engine electrical diagnostic system check has already been performed, go to next step. If engine electrical diagnostic system check has not been performed, go to «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__engine-electrical-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Ensure ignition is on. Using scan tool, observe IGNITION 1 signal voltage parameter in PCM data list. If voltage is more than 9 volts, go to step 6. If voltage is 9 volts or less, go to next step.
3. Check battery voltage and compare voltage reading with ignition 1 signal voltage parameter in PCM data list. If voltages differ by more than.8 volt, go to next step. If voltages does not differ by more than.8 volt, diagnose charging system and repair as necessary.
4. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for high resistance in battery voltage supply circuit (Orange wire) to terminals No. 20 and 21 at PCM harness connector. (Scheme 5) See WIRING DIAGRAMS article. If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to next step.
5. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 7. If connectors are okay, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) monitors system voltage to make sure that voltage stays within the proper range. Damage to components and incorrect data input can occur when voltage is out of range. PCM monitors system voltage over an extended length of time. If PCM detects an excessively low system voltage, DTC P0562 will set.

1. Engine speed is more than 1500 RPM.
2. System voltage is 9.5-18.0 volts.

1. If engine electrical diagnostic system check has already been performed, go to next step. If engine electrical diagnostic system check has not been performed, go to «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__engine-electrical-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Ensure ignition is on. Using scan tool, observe IGNITION 1 signal voltage parameter in PCM data list. If voltage is more than 10.5 volts, go to step 6. If voltage is 10.5 volts or less, go to next step.
3. Check battery voltage and compare voltage reading with ignition 1 signal voltage parameter in PCM data list. If voltages differ by more than.8 volt, go to next step. If voltages do not differ by more than.8 volt, diagnose charging system and repair as necessary.
4. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for high resistance in battery voltage supply circuit (Orange wire) to terminals No. 20 and 21 at PCM harness connector. (Scheme 5) See WIRING DIAGRAMS article. If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to next step.
5. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 7. If connectors are okay, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) monitors system voltage to make sure that voltage stays within the proper range. Damage to components and incorrect data input can occur when voltage is out of range. PCM monitors system voltage over an extended length of time. If PCM detects an excessively high system voltage, DTC P0563 will set.

1. Engine speed is more than 1500 RPM.
2. System voltage is 9.5-18.0 volts.

1. If engine electrical diagnostic system check has already been performed, go to next step. If engine electrical diagnostic system check has not been performed, go to «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__engine-electrical-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Ensure ignition is on. Using scan tool, observe IGNITION 1 signal voltage parameter in PCM data list. If voltage is 16 volts or more, go to next step. If voltage is less than 16 volts, go to step 4 .
3. Check battery voltage and compare voltage reading with ignition 1 signal voltage parameter in PCM data list. If voltages differ by more than .8 volt, go to next step. If voltages does not differ by more than .8 volt, diagnose charging system and repair as necessary.
4. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . After repairs, go to next step.
5. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
6. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Powertrain Control Module (PCM) uses an Electrically Erasable Programmable Read Only Memory (EEPROM) to store software and calibration information. PCM uses a checksum to verify integrity of the information. At time of programming, PCM calculates a checksum and stores the value in the EEPROM. With ignition on, PCM retrieves the information and performs a checsum. PCM compares the ignition on value to the value stored in the EEPROM. If checksum at ignition on does not match stored checksum, DTC P0601 will set.

Only condition for running this DTC is ignition must be on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .

DTC P0601 indicates that contents of EEPROM have changed since PCM was programmed. PCM must be replaced and reprogrammed.

Powertrain Control Module (PCM) uses an Electrically Erasable Programmable Read Only Memory (EEPROM) to store software and calibration information. EEPROM is not replaceable, PCM must be replaced. Replacement PCM does not contain final program information. Replacement PCM must be programed. If replacement PCM is not programmed, DTC P0602 will set. When DTC sets, PCM disables fuel pump relay and fuel injectors.

1. DTC P0601 is not set.
2. Ignition is on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Reprogram PCM using correct software. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . If DTC P0602 resets, go to next step.
3. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .

Powertrain Control Module (PCM) copies program information that is stored in the Electrically Erasable Programmable Read Only Memory (EEPROM) to the Random Access Memory (RAM). This allows PCM to work with, and update the information. PCM tests all areas of the RAM. If PCM detects an error in any area of the RAM, DTC P0603 will set.

Only condition for running this DTC is ignition must be on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P1621 is also set, go to step 4 . If DTC P1621 is not also set, go to next step.
3. Ensure ignition is on. Using scan tool, clear DTCs. Monitor SPECIFIC DTC INFO for this DTC. If DTC runs and passes, no problem is indicated at this time. Fault may be intermittent. If DTC resets, go to next step.
4. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .

Powertrain Control Module (PCM) copies program information that is stored in the Electrically Erasable Programmable Read Only Memory (EEPROM) to the Random Access Memory (RAM). This allows PCM to work with, and update the information. PCM tests all areas of the RAM. If PCM detects an error in any area of the RAM, DTC P0604 will set.

Only condition for running this DTC is ignition must be on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .

Powertrain Control Module (PCM) is capable of diagnosing a malfunction within the controller. If PCM detects a malfunction within the controller, DTC P0606 will set.

1. DTC P0601 or P0604 is not set.
2. Ignition is on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) .

Powertrain Control Module (PCM) uses Output Driver Modules (ODM) to control many functions of the engine and transaxle. The ODMs supply the ground path for the PCM-controlled device when the PCM commands the device on. Each ODM can control several outputs. Unlike quad driver modules used in earlier model years, the ODMs are able to diagnose each output circuit. The PCM monitors ODMs for circuit conditions that are incorrect for the commanded state of the ODM. If PCM detects an improper circuit condition in the ODM that controls the Malfunction Indicator Light (MIL), DTC P0650 will set.

1. Engine is running.
2. System voltage is 8-16 volts.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. NOTE: MIL may also be referred to as SERVICE ENGINE SOON light.
2. Turn ignition on. Observe MIL on right side of instrument cluster. If MIL is on, go to next step. If MIL if off, go to step 5.
3. Using scan tool, command MIL OFF. If MIL is off, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If MIL is on, go to next step.
4. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Remove Instrument Panel Cluster (IPC). See REMOVAL & INSTALLATION in appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Using a test light connected to positive battery voltage, probe terminal No. 32 (Brown/White wire) at PCM C1 harness connector. (Scheme 5) If test light illuminates, repair short to ground in Brown/White wire between PCM and instrument cluster. After repairs, go to step 13. If test light does not illuminate, go to step 11.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Using a test light connected to ground, probe terminal No. 32 (Brown/White wire) at PCM C1 harness connector. (Scheme 5) If test light illuminates, go to next step. If test light does not illuminate, go to step 7.
6. Turn ignition off. Remove Instrument Panel Cluster (IPC). See REMOVAL & INSTALLATION in appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Turn ignition on. Using a test light connected to ground, probe terminal No. 32 (Brown/White wire) at PCM C1 harness connector. (Scheme 5) If test light illuminates, repair short to voltage in Brown/White wire between PCM and instrument cluster. After repairs, go to step 13. If test light does not illuminate, go to step 10.
7. Turn ignition off. Reconnect PCM connectors. Remove Instrument Panel Cluster (IPC). See REMOVAL & INSTALLATION in appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Turn ignition on. Using a test light connected to positive battery voltage, probe terminal No. 32 (Brown/White wire) at PCM C1 harness connector. Using scan tool, command MIL on and off. If test light turns on and off, go to next step. If test light does not turn on and off, go to step 9.
8. Check for poor connections at IPC connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to step 12.
9. Turn ignition off. Disconnect PCM connectors. On Deville and Seville, check continuity of Brown/White wire between terminal A8 at IPC C2 harness connector and terminal No. 32 at PCM C1 harness connector. (Scheme 5)and (Scheme 6). On Eldorado, check continuity of Brown/White wire between terminal A3 at IPC C2 harness connector and terminal No. 32 at PCM C1 harness connector. (Scheme 5)and (Scheme 7). On all models, if continuity exists, go to next step. If continuity does not exist, repair open in Brown/White wire. After repairs, go to step 13.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 13. If connectors are okay, go to next step.
11. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to step 13.
12. Replace IPC. After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Heated Oxygen Sensor (HO2S) heater is used to reduce the time that it takes for HO2S to go active. The Powertrain Control Module (PCM) controls HO2S heaters using a high side driver, 2 low side drivers, and a current monitoring driver. The current monitoring driver tests condition of the heaters. The high side driver provides HO2S bank 1 sensor 1 heater with ignition voltage. A fused ignition feed provides HO2S bank 2 sensor 1 with ignition voltage. HO2S receives ground through one of the low side drivers. With engine running, PCM turns on high side and low side drivers to warm-up oxygen sensors. DTC will set if PCM detects an incorrect circuit condition for commanded state of current monitoring driver (DTC P1031) or low side driver (DTC P1032).

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Bank 2 sensor 1 is located in left (front) exhaust manifold.

1. System voltage is 9-18 volts.
2. Ignition is on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Using scan tool, clear DTCs. Observe DTC information for 30 seconds. If DTCs P0030, P1031 and P1032 are set, go to «DTC P0030: HO2S HEATER CONTROL CIRCUIT VOLTAGE IS GREATER THAN PCM INTERNAL DRIVER CAPACITY - DEVILLE & SEVILLE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) or «DTC P0030: HEATED OXYGEN SENSOR HEATER CONTROL CIRCUIT - BANK 1 SENSOR 1 - ELDORADO»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTCs P0030, P1031 and P1032 are not set, go to next step.
3. Start engine. Using scan tool, observe DTC information for 5 minutes. If P1031 and P1032 are set, go to next step. If P1031 and P1032 are not set, no problems is indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. Turn ignition on. Using a test light connected to ground, probe terminal "A" (Tan wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 8) Using scan tool, command HO2S heater driver 3 on and off. If test light turns on and off, go to step 9. If test light does not turn on and off, go to next step.
5. Turn ignition off. Disconnect HO2S bank 2 sensor 1 connector. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold. Turn ignition on. Using a test light connected to ground, probe terminal "A" (Tan/White wire) at HO2S bank 2 sensor 1 harness connector. (Scheme 8) Using scan tool, command HO2S heater driver 3 on and off. If test light turns on and off, go to step 8. If test light does not turn on and off, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 52 (Tan wire) at PCM C1 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Tan wire between HO2S bank 1 sensor 1 and PCM. After repairs, go to step 11. If no voltage is indicated, go to next step.
7. Measure voltage between ground and terminal No. 54 (Tan/White wire) at PCM C1 harness connector. If any voltage is indicated, repair short to voltage in Tan/White wire between HO2S bank 2 sensor 1 and PCM. After repairs, go to step 11. If no voltage is indicated, go to step 10.
8. Replace HO2S bank 2 sensor 1. After repairs, go to step 11.
9. Replace HO2S bank 1 sensor 1. After repairs, go to step 11.
10. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
11. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
12. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Manifold Absolute Pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on engine load. Powertrain Control Module (PCM) supplies 5 volts to MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the signal circuit which is relative to pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during idle or deceleration. The PCM should detect a high signal voltage at a high MAP, such as when ignition is on or at a Wide Open Throttle (WOT). MAP sensor value is also used to determine the Barometric Pressure (BARO). This occurs when ignition is on. The BARO reading may also be updated whenever engine is operated at WOT. The PCM monitors MAP sensor signal for voltage outside of the normal range. DTC P1106 will set when PCM detects MAP sensor signal voltage is intermittently high.

1. DTC P0121, P0122 or P0123 is not set.
2. Throttle angle is less than 98 percent when engine speed is more than 1000 RPM.
3. Throttle angle is less than 90 percent when engine speed is less than 1000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Using scan tool, check for any other DTCs that are set. If DTC P0108 or P1635 is not set, go to next step. If DTC P0108 or P1635 is set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
3. Using scan tool, observe MAP sensor voltage. If voltage is more than 4.5 volts, go to step 5. If voltage is 4.5 volts or less, go next step.
4. Using scan tool, observe MAP sensor voltage while wiggling MAP sensor connector, PCM connectors and relate wiring harnesses. (Scheme 13) PCM is located in engine compartment, inside air filter housing. If voltage is more than 4.5 volts, go to next step. If voltage is 4.5 volts or less, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition off. Disconnect MAP sensor connector. Turn ignition on. Using scan tool, observe MAP sensor voltage. If voltage is less than.5 volt, go to next step. If voltage is.5 volt or more, go to step 8.
6. Measure voltage between Gray and Orange/Black wires at MAP sensor harness connector. If voltage is 4.7-5.2 volts, go to step 11. If voltage is not 4.7-5.2 volts, go to next step.
7. If voltage was more than 5.2 volts in previous step, go to step 10. If voltage was less than 4.7 volts in previous step, go to step 9.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Light Green wire at MAP sensor harness connector. If any voltage is indicated, repair short to voltage in Light Green wire between MAP sensor and PCM. After repairs, go to step 13. If no voltage is indicated, go to step 12.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Orange/Black wire between MAP sensor harness connector and terminal No. 6 at PCM C2 harness connector. (Scheme 5) If continuity does not exist, repair open in Orange/Black wire. After repairs, go to step 13. If continuity exists, go to step 12.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Gray wire at MAP sensor harness connector. If any voltage is indicated, repair short to voltage in Gray wire between MAP sensor and PCM. After repairs, go to step 13. If no voltage is indicated, go to step 12.
11. Check for poor connections at MAP sensor connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
12. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to next step. If connectors are okay, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Check MAP sensor vacuum source for leaks, restrictions and poor connections. If condition is still intermittent, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Manifold Absolute Pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on engine load. Powertrain Control Module (PCM) supplies 5 volts to MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the signal circuit which is relative to pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during idle or deceleration. The PCM should detect a high signal voltage at a high MAP, such as when ignition is on or at a Wide Open Throttle (WOT). MAP sensor value is also used to determine the Barometric Pressure (BARO). This occurs when ignition is on. The BARO reading may also be updated whenever engine is operated at WOT. The PCM monitors MAP sensor signal for voltage outside of the normal range. DTC P1107 will set when PCM detects MAP sensor signal voltage is intermittently low.

1. DTC P0121, P0122 or P0123 is not set.
2. Throttle angle is more than 9 percent when engine speed is more than 1000 RPM.
3. Throttle angle is more than zero percent when engine speed is less than 1000 RPM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Using scan tool, check for any other DTCs that are set. If DTC P0107 or P1635 is not set, go to next step. If DTC P0107 or P1635 is set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
3. Using scan tool, observe MAP sensor voltage. If voltage is less than.5 volt, go to step 5. If voltage is.5 volt or more, go next step.
4. Using scan tool, observe MAP sensor voltage while wiggling MAP sensor connector, PCM connectors and relate wiring harnesses. (Scheme 13) PCM is located in engine compartment, inside air filter housing. If voltage is less than.5 volt, go to next step. If voltage is.5 volt or more, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Turn ignition off. Disconnect MAP sensor connector. Turn ignition on. Using scan tool, observe MAP sensor voltage. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 7.
6. Connect a 3-amp fused jumper wire between Gray and Light Green wires at MAP sensor harness connector. Using scan tool, observe MAP sensor voltage. If voltage is about 5 volts, go to step 9. If voltage is not about 5 volts, disconnect jumper wire and go to step 8.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in 5-volt reference circuit (Gray wire) between MAP sensor harness connector and terminal No. 49 at PCM C2 harness connector. (Scheme 5) If any problems are found, repair as necessary. After repairs, go to step 11. If no problems are found, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in signal circuit (Light Green wire) between MAP sensor harness connector and terminal No. 23 at PCM C1 harness connector. (Scheme 5) If any problems are found, repair as necessary. After repairs, go to step 11. If no problems are found, go to step 10.
9. Check for poor connections at MAP sensor connector. Repair connector as necessary. After repairs, go to step 11. If connector is okay, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to next step. If connectors are okay, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
11. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
12. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Check MAP sensor vacuum source for leaks, restrictions and poor connections. If condition is still intermittent, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Intake Air Temperature (IAT) sensor is a thermistor that measures temperature of air entering the engine. The Powertrain Control Module (PCM) supplies 5 volts to the IAT sensor signal circuit through a pull-up resistor. When intake air is cold, the PCM detects a high voltage on IAT sensor signal circuit. As intake air warms, the PCM detects a lower voltage on IAT sensor signal circuit. DTC P1111 will set if PCM detects an intermittently high IAT sensor signal voltage (low temperature indicated).

Note. IAT sensor is integral to Mass Airflow (MAF) sensor. IAT sensor may also be referred to as MAF/IAT sensor.

1. DTC P0101, P0102, P0103, P0117, P0118, P0125, P0502, P0503, P1114 or P1115 is not set.
2. Engine run time is more than 5 seconds.
3. Engine speed is more than 50 RPM for 5 seconds.
4. Engine coolant temperature is more than 140°F (60°C).
5. Vehicle speed is less than 48 MPH.
6. Mass airflow is less than 12 grams/sec.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Check for any other DTCs that are set. If no other DTCs are set, go to next step. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
3. Ensure ignition is off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Disconnect MAF/IAT sensor connector. IAT sensor is integral to MAF sensor. Check IAT sensor signal circuit (Tan wire) as follows: While wiggling wiring harness, check continuity of Tan wire between terminal "B" at MAF/IAT sensor harness connector and terminal No. 10 at PCM C1 harness connector. (Scheme 5)and (Scheme 14). Continuity should exist. If continuity does not exist, Tan wire is open. Turn ignition on. While wiggling wiring harness, measure voltage between ground and terminal No. 10 at PCM C1 harness connector. If any voltage is indicated, Tan wire is shorted to voltage. Check PCM and MAF/IAT sensor connectors for poor connections. If any problems are found, repair as necessary. After repairs, go to step 5. If no problems are found, go to next step.
4. Turn ignition off. While wiggling wiring harness, check continuity of Black wire between terminal "A" at MAF/IAT sensor harness connector and terminal No. 4 at PCM C2 harness connector. If continuity does not exist, repair open in Black wire. After repairs, go to next step. If continuity exists, no problem is indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
6. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Intake Air Temperature (IAT) sensor is a thermistor that measures temperature of air entering the engine. The Powertrain Control Module (PCM) supplies 5 volts to the IAT sensor signal circuit through a pull-up resistor. When intake air is cold, the PCM detects a high voltage on IAT sensor signal circuit. As intake air warms, the PCM detects a lower voltage on IAT sensor signal circuit. DTC P1112 will set if PCM detects an intermittently low IAT sensor signal voltage (high temperature indicated).

Note. IAT sensor is integral to Mass Airflow (MAF) sensor. IAT sensor may also be referred to as MAF/IAT sensor.

1. DTC P0101, P0102, P0103, P0117, P0118, P0125, P0502, P0503, P1114 or P1115 is not set.
2. Engine coolant temperature is less than 212°F (100°C).
3. Vehicle speed is more than 9 MPH.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Check for any other DTCs that are set. If no other DTCs are set, go to next step. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
3. Ensure ignition is off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Disconnect MAF/IAT sensor connector. IAT sensor is integral to MAF sensor. Check IAT sensor signal circuit (Tan wire) as follows: Using a test light connected to positive battery voltage, probe terminal "B" (Tan wire) at MAF/IAT sensor harness connector while wiggling wiring harness. (Scheme 14) Test light should not illuminate. If test light illuminates, Tan wire is shorted to ground. While wiggling wiring harness, check for continuity between terminal "A" (Black wire) and terminal "B" (Tan wire) at MAF/IAT sensor harness connector. Continuity should not exist. If continuity exists, Tan and Black wires are shorted together between MAF/IAT sensor and PCM. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, no problems are indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
5. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Engine Coolant Temperature (ECT) sensor is a thermistor that measures temperature of engine coolant. Powertrain Control Module (PCM) supplies 5 volts to ECT sensor signal circuit through a pull-up resistor. When ECT is cold, sensor resistance is high. When ECT increases, sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the ECT sensor signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT sensor signal circuit. DTC P1114 will set if PCM detects an intermittently low ECT sensor signal voltage (high temperature indicated).

1. DTC P0112, P0113, P1111 or P1112 is not set.
2. Engine run time is more than 10 seconds.
3. Intake air temperature is less than 158°F (70°C).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Check for any other DTCs that are set. If no other DTCs are set, go to next step. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
3. Ensure ignition is off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Disconnect ECT sensor connector. (Scheme 13) Check ECT sensor signal circuit (Yellow wire) as follows: Using a test light connected to positive battery voltage, probe terminal Yellow wire at ECT sensor harness connector while wiggling wiring harness. Test light should not illuminate. If test light illuminates, Yellow wire is shorted to ground. While wiggling wiring harness, check for continuity between Yellow and Black wire (DeVille and Seville) or Brown wire (Eldorado) at ECT sensor harness connector. Continuity should not exist. If continuity exists, Yellow wire and Black wire (DeVille and Seville) or Brown wire (Eldorado) are shorted together between ECT sensor and PCM. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, no problems are indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
5. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Engine Coolant Temperature (ECT) sensor is a thermistor that measures temperature of engine coolant. Powertrain Control Module (PCM) supplies 5 volts to ECT sensor signal circuit through a pull-up resistor. When ECT is cold, sensor resistance is high. When ECT increases, sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the ECT sensor signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT sensor signal circuit. DTC P1115 will set if PCM detects an intermittently high ECT sensor signal voltage (low temperature indicated).

1. DTC P0112, P0113, P1111 or P1112 is not set.
2. Engine run time is more than 60 seconds.
3. Intake air temperature is more than 19°F (-7°C).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Check for any other DTCs that are set. If no other DTCs are set, go to next step. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).
3. Ensure ignition is off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Disconnect ECT sensor connector. (Scheme 13) Check ECT sensor signal circuit (Yellow wire) as follows: While wiggling wiring harness, check continuity of Yellow wire between ECT sensor harness connector and terminal No. 31 at PCM C2 harness connector. (Scheme 5) Continuity should exist. If continuity does not exist, Yellow wire is open. Turn ignition on. While wiggling wiring harness, measure voltage between ground and terminal No. 31 at PCM C2 harness connector. If any voltage is indicated, Yellow wire is shorted to voltage. Check PCM and ECT sensor connectors for poor connections. If any problems are found, repair as necessary. After repairs, go to step 5. If no problems are found, go to next step.
4. Turn ignition off. While wiggling wiring harness, check continuity of Black wire (DeVille and Seville) or Brown wire (Eldorado) between ECT harness connector and terminal No. 68 at PCM C2 harness connector. If continuity does not exist, repair open in Black wire (DeVille and Seville) or Brown wire (Eldorado). After repairs, go to next step. If continuity exists, no problem is indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
6. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Throttle Position (TP) sensor is used by the Powertrain Control Module (PCM) to determine throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with 3 circuits, a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM provides TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from closed throttle position to wide open throttle (WOT) position provides the PCM with a signal voltage from less than one volt to more than 4 volts through TP sensor signal circuit. DTC P1121 will set if PCM detects an intermittent excessively high signal voltage.

Only condition for running this DTC is ignition must be on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition off. Disconnect TP sensor connector. (Scheme 13) Connect a DVOM between ground and 5-volt reference circuit (Gray wire) at TP sensor harness connector. Turn ignition on. Lightly wiggle related engine wiring harnesses and connectors for all 5-volt reference circuits while observing voltage reading. See WIRING DIAGRAMS article. Any change in voltage indicates area where a short to voltage may exist. If voltage changes, repair wiring or connectors as necessary. After repairs, go to step 9. If voltage does not change, go to next step.
3. Connect a DVOM between ground and signal circuit (Dark Blue wire) at TP sensor harness connector. Turn ignition on. Lightly wiggle related engine wiring harnesses and connectors while observing voltage reading. Any change in voltage indicates area where a short to voltage may exist. If voltage changes, repair wiring or connectors as necessary. After repairs, go to step 9. If voltage does not change, go to next step.
4. Turn ignition off. Measure resistance between ground and low reference circuit (Black/White wire) at TP sensor harness connector. Lightly wiggle related engine wiring harnesses and connectors while observing resistance reading. Any change in resistance indicates area where an open or high resistance may exist. If resistance changes, repair wiring or connectors as necessary. After repairs, go to step 9. If resistance does not change, go to next step.
5. Check for poor connections at TP sensor connector. Repair connector as necessary. After repairs, go to step 9. If connector is okay, go to next step.
6. Check for poor connections at PCM connectors. PCM is located in engine compartment, inside air filter housing. Repair connectors as necessary. After repairs, go to step 9. If connectors are okay, go to next step.
7. Connect one end of a jumper wire to Dark Blue wire at TP sensor harness connector and other end to DVOM. Using a second jumper wire, connect one end to Gray wire at TP sensor harness connector and other end to DVOM. Set DVOM to 40K (Omega) scale. Ensure jumper wires have a good connection at TP sensor and DVOM test leads. Press MIN MAX button on DVOM. Slowly depress accelerator pedal to Wide Open Throttle (WOT) and then back to closed throttle position several times. Press MIN MAX button, and record MAX reading. Press MIN MAX button again, and record MIN reading. Disconnect jumper wire from Gray wire, and reconnect jumper wire to Black/White wire at TP sensor harness connector. Press MIN MAX button on DVOM. Slowly depress accelerator pedal to WOT and back to closed throttle position several times. Press MIN MAX button, and record MAX reading. Press MIN MAX button again, and record MIN reading. If a MAX value of OL, or a MIN value of zero ohms is recorded in either test, go to next step. If a MAX value of OL, or a MIN value of zero ohms is not recorded in either test, no problem is indicated. Diagnose by symptom. See SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article.
8. Replace TP sensor. After repairs, go to next step.
9. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
10. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Throttle Position (TP) sensor is used by the Powertrain Control Module (PCM) to determine throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with 3 circuits, a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM provides TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from closed throttle position to Wide Open Throttle (WOT) position provides the PCM with a signal voltage from less than one volt to more than 4 volts through TP sensor signal circuit. DTC P1122 will set if PCM detects an intermittent excessively low signal voltage.

Only condition for running this DTC is ignition must be on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition off. Disconnect TP sensor connector. (Scheme 13) Connect a DVOM between ground and 5-volt reference circuit (Gray wire) at TP sensor harness connector. Turn ignition on. Lightly wiggle related engine wiring harnesses and connectors for all 5-volt reference circuits while observing voltage reading. See WIRING DIAGRAMS article. Any change in voltage indicates area where an intermittent open, high resistance or short to ground may exist. If voltage changes, repair wiring or connectors as necessary. After repairs, go to step 8. If voltage does not change, go to next step.
3. Connect a DVOM between ground and signal circuit (Dark Blue wire) at TP sensor harness connector. Turn ignition on. Lightly wiggle related engine wiring harnesses and connectors while observing voltage reading. Any change in voltage indicates area where an intermittent open, high resistance or short to ground may exist. If voltage changes, repair wiring or connectors as necessary. After repairs, go to step 8. If voltage does not change, go to next step.
4. Check for poor connections at TP sensor connector. Repair connector as necessary. After repairs, go to step 8. If connector is okay, go to next step.
5. Check for poor connections at PCM connectors. PCM is located in engine compartment, inside air filter housing. Repair connectors as necessary. After repairs, go to step 8. If connectors are okay, go to next step.
6. Connect one end of a jumper wire to Dark Blue wire at TP sensor harness connector and other end to DVOM. Using a second jumper wire, connect one end to Gray wire at TP sensor harness connector and other end to DVOM. Set DVOM to 40K (Omega) scale. Ensure jumper wires have a good connection at TP sensor and DVOM test leads. Press MIN MAX button on DVOM. Slowly depress accelerator pedal to Wide Open Throttle (WOT) and then back to closed throttle position several times. Press MIN MAX button, and record MAX reading. Press MIN MAX button again, and record MIN reading. Disconnect jumper wire from Gray wire, and reconnect jumper wire to Black/White wire at TP sensor harness connector. Press MIN MAX button on DMM. Slowly depress accelerator pedal to WOT and back to closed throttle position several times. Press MIN MAX button, and record MAX reading. Press MIN MAX button again, and record MIN reading. If a MAX value of OL, or a MIN value of zero ohms is recorded in either test, go to next step. If a MAX value of OL, or a MIN value of zero ohms is not recorded in either test, no problem is indicated. Diagnose by symptom. See SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article.
7. Replace TP sensor. After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, PCM adjusts injector pulse width.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. System voltage is 9-18 volts.
3. Engine run time is more than 3 minutes.
4. Engine speed is 1200-2800 RPM.
5. Mass airflow is 5-35 gram/sec.
6. Throttle position angle is more than 3 percent.
7. Engine coolant temperature is more than 167°F (75°C).
8. Closed loop fuel control is enabled.
9. Air/fuel ratio is between 14.5-14.8:1.
10. Transmission not in Park, Reverse or Neutral.
11. Listed conditions exist met for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If sent here from another DTC diagnostic test, go to step 4 . If not sent here from another DTC diagnostic test, go to next step.
3. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If no other DTCs are set, go to next step.
4. Start engine. Using scan tool, observe ECT sensor parameters. View both engine speed and HO2S bank 1 sensor 1 until engine is at normal operating temperature. Increase engine speed to 2000 RPM for 2 minutes. If HO2S bank 1 sensor 1 voltage rapidly switches from less than 325 millivolts to more than 625 millivolts, go to next step. If HO2S bank 1 sensor 1 voltage does not rapidly switch from less than 325 millivolts to more than 625 millivolts, go to step 6 .
5. Increase engine speed to 2000 RPM. Using scan tool, observe LOOP STATUS. If scan tool indicates CLOSED, no problem is indicated at this time. If scan tool does not indicate CLOSED, go to step 9 .
6. If voltage in step 4 stays within 325-625 millivolts the majority of the time, go to step 9 . If voltage does not stay within 325-625 millivolts the majority of the time, go to next step.
7. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to 10 . If connectors are okay, go to next step.
8. Check for poor connections at HO2S bank 1 sensor 1 connector. Repair connector as necessary. After repairs, go to step 10 . If connector is okay, go to next step.
9. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 1. After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors HO2S activity to determine a time ratio for lean-to-rich switches, and for rich-to-lean switches. The PCM counts number of lean-to-rich and rich-to-lean switches for 100 seconds. The PCM records time required to complete all transitions. With this information, PCM determines an average transition time for lean-to-rich switches and for rich-to-lean switches.

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0135, P0151, P0152, P0201-P0208, P0300, P0410, P0440, P0442, P0443, P0446, P0449, P1133, P1415, P1416 or P1441 is not set.
2. Engine speed is 1200-2800 RPM.
3. Throttle position angle is more than 3 percent.
4. Exhaust gas recirculation is not active.
5. Secondary air injection system tests are not active.
6. Catalyst test is not active.
7. Mass airflow is 15-35 grams/sec.
8. System voltage is 9-18 volts.
9. Closed loop fuel control enabled.
10. Engine coolant temperature is more than 167°F (75°C).
11. Transmission is not in Park, Reverse or Neutral.
12. Engine run time is 3 minutes.
13. Listed conditions exist met for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If sent here from another DTC diagnostic test, go to step 4 . If not sent here from another DTC diagnostic test, go to next step.
3. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If no other DTCs are set, go to next step.
4. Start engine. Using scan tool, observe ECT sensor parameters. View both engine speed and HO2S bank 1 sensor 1 until engine is at normal operating temperature. Increase engine speed to 2000 RPM for 2 minutes. If HO2S bank 1 sensor 1 voltage rapidly switches from less than 325 millivolts to more than 625 millivolts, go to next step. If HO2S bank 1 sensor 1 voltage does not rapidly switch from less than 325 millivolts to more than 625 millivolts, go to step 6 .
5. Increase engine speed to 2000 RPM. Using scan tool, observe LOOP STATUS. If scan tool indicates CLOSED, no problem is indicated at this time. If scan tool does not indicate CLOSED, go to step 9 .
6. If voltage in step 4 stays within 325-625 millivolts the majority of the time, go to step 9 . If voltage does not stay within 325-625 millivolts the majority of the time, go to next step.
7. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to 10 . If connectors are okay, go to next step.
8. Check for poor connections at HO2S bank 1 sensor 1 connector. Repair connector as necessary. After repairs, go to step 10 . If connector is okay, go to next step.
9. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 1. After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors HO2S activity to determine a time ratio for lean-to-rich switches, and for rich-to-lean switches. The PCM counts number of lean-to-rich and rich-to-lean switches.

Note. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416 or P1441 is not set.
2. System voltage is 9-18 volts.
3. Engine run time is more than 3 minutes.
4. Engine speed is 1200-2800 RPM.
5. Mass airflow is 5-35 gram/sec.
6. Throttle position angle is more than 3 percent.
7. Engine coolant temperature is more than 167°F (75°C).
8. Closed loop fuel control is enabled.
9. Air/fuel ratio is 14.5-14.8:1.
10. Transmission not in Park, Reverse or Neutral.
11. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If sent here from another DTC diagnostic test, go to step 4 . If not sent here from another DTC diagnostic test, go to next step.
3. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If no other DTCs are set, go to next step.
4. Start engine. Using scan tool, observe ECT sensor parameters. View both engine speed and HO2S bank 2 sensor 1 until engine is at normal operating temperature. Increase engine speed to 2000 RPM for 2 minutes. If HO2S bank 2 sensor 1 voltage rapidly switches from less than 325 millivolts to more than 625 millivolts, go to next step. If HO2S bank 2 sensor 1 voltage does not rapidly switch from less than 325 millivolts to more than 625 millivolts, go to step 6 .
5. Increase engine speed to 2000 RPM. Using scan tool, observe LOOP STATUS. If scan tool indicates CLOSED, no problem is indicated at this time. If scan tool does not indicate CLOSED, go to step 9 .
6. If voltage in step 4 stays within 325-625 millivolts the majority of the time, go to step 9 . If voltage does not stay within 325-625 millivolts the majority of the time, go to next step.
7. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to 10 . If connectors are okay, go to next step.
8. Check for poor connections at HO2S bank 2 sensor 1 connector. Repair connector as necessary. After repairs, go to step 10 . If connector is okay, go to next step.
9. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 2 sensor 1. After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Heated Oxygen Sensor (HO2S) is used to detect oxygen content in the exhaust. The Powertrain Control Module (PCM) supplies HO2S with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The HO2S varies voltage based on oxygen content in the exhaust. When exhaust stream is lean (more oxygen), HO2S produces a low voltage signal. When exhaust stream is rich (less oxygen), HO2S produces a high voltage signal. The PCM monitors HO2S activity to determine a time ratio for lean-to-rich switches, and for rich-to-lean switches. The PCM counts number of lean-to-rich and rich-to-lean switches for 100 seconds. The PCM records time required to complete all transitions. With this information, PCM determines an average transition time for lean-to-rich switches and for rich-to-lean switches.

Note. HO2S bank 2 sensor 1 is located in left (front) exhaust manifold.

1. DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0135, P0151, P0152, P0201-P0208, P0300, P0410, P0440, P0442, P0443, P0446, P0449, P1133, P1415, P1416 or P1441 is not set.
2. Engine speed is 1200-2800 RPM.
3. Throttle position angle is more than 3 percent.
4. Exhaust gas recirculation is not active.
5. Secondary air injection system tests are not active.
6. Catalyst test is not active.
7. Mass airflow is 15-35 grams/sec.
8. System voltage is 9-18 volts.
9. Closed loop fuel control enabled.
10. Engine coolant temperature is more than 167°F (75°C).
11. Transmission is not in Park, Reverse or Neutral.
12. Engine run time is 3 minutes.
13. Listed conditions exist for 3 seconds.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If sent here from another DTC diagnostic test, go to step 4 . If not sent here from another DTC diagnostic test, go to next step.
3. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) . If no other DTCs are set, go to next step.
4. Start engine. Using scan tool, observe ECT sensor parameters. View both engine speed and HO2S bank 2 sensor 1 until engine is at normal operating temperature. Increase engine speed to 2000 RPM for 2 minutes. If HO2S bank 2 sensor 1 voltage rapidly switches from less than 325 millivolts to more than 625 millivolts, go to next step. If HO2S bank 2 sensor 1 voltage does not rapidly switch from less than 325 millivolts to more than 625 millivolts, go to step 6 .
5. Increase engine speed to 2000 RPM. Using scan tool, observe LOOP STATUS. If scan tool indicates CLOSED, no problem is indicated at this time. If scan tool does not indicate CLOSED, go to step 9 .
6. If voltage in step 4 stays within 325-625 millivolts the majority of the time, go to step 9 . If voltage does not stay within 325-625 millivolts the majority of the time, go to next step.
7. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to 10 . If connectors are okay, go to next step.
8. Check for poor connections at HO2S bank 2 sensor 1 connector. Repair connector as necessary. After repairs, go to step 10 . If connector is okay, go to next step.
9. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 2 sensor 1. After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Powertrain Control Module (PCM) has the ability to disable 4 injectors during an engine over temperature (overheating) condition. Engine is considered over temperature whenever ECT reaches 268°F (131°C). This protection mode allows PCM to alternate between groups of cylinders, thereby reducing coolant temperature. This is accomplished by disabling the fuel injectors. DTC P1258 is set to show that an overheating condition was or is observed by the PCM and that the protection mode has been engaged.

1. If engine cooling diagnostic system check has already been performed, go to next step. If engine cooling diagnostic system check has not been perform, go to «ENGINE COOLING DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__engine-cooling-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Check cooling fan operation. If cooling fans are not functioning properly, diagnose cooling fans as necessary. See ELECTRIC COOLING FANS - CARS article in ENGINE COOLING. If cooling fans are functioning properly, diagnose cooling system and repair as necessary.

Crankshaft Position (CKP) system variation learning feature is used to calculate the reference period errors that are caused by slight tolerance variations in crankshaft, and in CKP sensors. Calculated error allows the Powertrain Control Module (PCM) to accurately compensate for reference period variations. This procedure enhances the ability of the PCM to detect misfire events over a wider range of engine speed and load conditions. PCM stores CKP system variation values after a learn procedure has been performed. DTC P1336 indicates CKP system variation values have not been stored in the PCM, and CKP system variation learn procedure must be performed. CKP system variation learn procedure must be performed any time the following service procedures are performed, regardless if DTC P1336 is set or not

1. PCM replacement.
2. PCM reprogrammed.
3. Engine replacement.
4. Crankshaft replacement.
5. CKP sensor replacement.
6. Any engine repairs which disturbs crankshaft to crankshaft position sensor relationship.

1. DTC P0335, P0336, P0340, P0341, P0385, P0386 or P1372 is not set.
2. Engine coolant temperature is more than 158°F (70°C).

DTC sets when PCM has not successfully learned crankshaft position system variation.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Perform CKP system variation learn procedure. See «CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__crankshaft-position-sensor-system-variation-learn) under PROGRAMMING. After procedure is complete, go to next step.
3. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

CKP system variation compensating values are stored in PCM memory after a learn procedure has been performed. If actual crankshaft position system variation is not within CKP system variation compensating values stored in PCM, DTC P0300 may set. See DIAGNOSTIC AIDS in DTC P0300: ENGINE MISFIRE DETECTED.

Vehicle is equipped with 2 separate ignition module assemblies. One assembly for each bank of cylinders. Each assembly contains an Ignition Control Module (ICM) and 4 ignition coils. Each ICM consists of an ignition 1 voltage circuit, ground circuit, IC timing low reference circuit and IC control circuits for cylinders No. 1-8.

Only condition for running this DTC is ignition must be on.

DTC will set if during PCM power-up, PCM detects an open or short to voltage in IC circuit group for cylinders No. 1, 4, 6 and 7.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P1360 is also set, go to next step. If DTC P1360 is not also set, go to step 5.
3. With engine idling, observe MISFIRE CURRENT CYL # display on scan tool. If misfire current cyl # is incrementing for any even cylinders, go to step 6. If misfire current cyl # is not incrementing for any even cylinders, go to next step.
4. With engine idling, observe MISFIRE CURRENT CYL # display on scan tool. If misfire current cyl # is incrementing for any odd cylinders, go to step 7. If misfire current cyl # is not incrementing for any odd cylinders, go to step 15.
5. With engine idling, observe MISFIRE CURRENT CYL # display on scan tool. If current cyl # is incrementing for any 2 cylinders, go to step 8. If current cyl # is not incrementing for any 2 cylinders, go to step 11.
6. Locate front ICM assembly on left (front) valve cover. Inspect front ICM assembly for the following conditions: Check ICM assembly for disconnected or damaged harness connector. Check ICM assembly for a loss of power or ground. See WIRING DIAGRAMS article. Check for poor connections at ICM assembly connector. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 14.
7. Locate rear ICM assembly on right (rear) valve cover. Inspect rear ICM assembly for the following conditions: Check ICM assembly for disconnected or damaged harness connector. Check ICM assembly for a loss of power or ground. See WIRING DIAGRAMS article. Check for poor connections at ICM assembly connector. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 14.
8. If incrementing cylinders are even (cylinder No. 4 and 6), go to next step. If incrementing cylinders are not even, go to step 10.
9. Turn ignition off. Disconnect front ICM assembly connector. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 59 (Dark Green/White wire) at PCM C2 harness connector. (Scheme 5) Also measure voltage between ground and terminal No. 60 (Light Blue/White wire) at PCM C2 harness connector. If any voltage is indicated at any terminal, repair short to voltage in appropriate wire between PCM and front ICM assembly. After repairs, go to step 16. If no voltage is indicated at both terminals, go to step 15.
10. Turn ignition off. Disconnect rear ICM assembly connector. Disconnect PCM connectors PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 61 (Purple wire) at PCM C1 harness connector. (Scheme 5) Also measure voltage between ground and terminal No. 22 (Red wire) at PCM C1 harness connector. If any voltage is indicated at any terminal, repair short to voltage in appropriate wire between PCM and rear ICM assembly. After repairs, go to step 16. If no voltage is indicated at both terminals, go to step 15.
11. Turn ignition off. Disconnect ICM assembly connector associated with incrementing misfire current cyl #. Connect a DVOM between ground and affected IC circuit terminal at ICM harness connector. See WIRING DIAGRAMS article. On DeVille and Seville, remove fuses No. 21 (INJR 1 fuse) and No. 16 (INJR 2 fuse) from underhood fuse block. (Scheme 10) On Eldorado, remove both INJ fuses from underhood fuse block. (Scheme 11) On all models, measure frequency of affected IC circuit while cranking engine. If frequency is 1-2 Hz, go to step 13. If frequency is not 1-2 Hz, go to next step.
12. Turn ignition off. Check continuity of affected IC circuit between appropriate ICM harness connector and PCM. See WIRING DIAGRAMS article. If continuity does not exist, repair open in IC circuit. After repairs, go to step 16. If continuity exists, go to step 15.
13. Check for poor connections at ICM assembly. Repair connector as necessary. After repairs, go to step 16. If connector is okay, go to next step.
14. Replace appropriate ICM assembly. After repairs, go to step 16.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

MISFIRE CURRENT CYL #/ MISFIRE HISTORY CYL # displays on scan tool provides information that may be useful in diagnosing DTC P1359. Misfire current cyl # counter may normally display a small amount of activity, typically 0-10 counts. However, display should not increment steadily. If misfire current cyl # increments steadily for a single cylinder within IC circuit group, condition is isolated to IC circuit for specific cylinder. If misfire current cyl # increments randomly within IC circuit group, condition may be due to poor connections at PCM or a faulty PCM. If misfire current cyl # increments steadily for a cylinder bank, DTC P1360 may set. DTC P1360 may result from a loss of power or ground to ICM assembly, faulty ICM assembly connector or faulty ICM assembly.

Vehicle is equipped with 2 separate ignition module assemblies. One assembly for each bank of cylinders. Each assembly contains an Ignition Control Module (ICM) and 4 ignition coils. Each ICM consists of an ignition 1 voltage circuit, ground circuit, IC timing low reference circuit and IC control circuits for cylinders No. 1-8. DTC P1360 will set if during PCM power-up, PCM detects an open or short to voltage in IC circuit group for cylinders No. 2, 3, 5 and 8 cylinders.

Only condition for running this DTC is ignition must be on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P1359 is also set, go to next step. If DTC P1359 is not also set, go to step 5.
3. With engine idling, observe MISFIRE CURRENT CYL # display on scan tool. If misfire current cyl # is incrementing for any even cylinders, go to step 6. If misfire current cyl # is not incrementing for any even cylinders, go to next step.
4. With engine idling, observe MISFIRE CURRENT CYL # display on scan tool. If misfire current cyl # is incrementing for any odd cylinders, go to step 7. If misfire current cyl # is not incrementing for any odd cylinders, go to step 15.
5. With engine idling, observe MISFIRE CURRENT CYL # display on scan tool. If current cyl # is incrementing for any 2 cylinders, go to step 8. If current cyl # is not incrementing for any 2 cylinders, go to step 11.
6. Locate front ICM assembly on left (front) valve cover. Inspect front ICM assembly for the following conditions: Check ICM assembly for disconnected or damaged harness connector. Check ICM assembly for a loss of power or ground. See WIRING DIAGRAMS article. Check for poor connections at ICM assembly connector. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 14.
7. Locate rear ICM assembly on right (rear) valve cover. Inspect rear ICM assembly for the following conditions: Check ICM assembly for disconnected or damaged harness connector. Check ICM assembly for a loss of power or ground. See WIRING DIAGRAMS article. Check for poor connections at ICM assembly connector. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 14.
8. If incrementing cylinders are even (cylinder No. 2 and 8), go to next step. If incrementing cylinders are not even, go to step 10.
9. Turn ignition off. Disconnect front ICM assembly connector. Disconnect PCM connectors PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 22 (Red/White wire) at PCM C2 harness connector. (Scheme 5) Also measure voltage between ground and terminal No. 61 (Purple/White wire) at PCM C2 harness connector. If any voltage is indicated at any terminal, repair short to voltage in appropriate wire between PCM and front ICM assembly. After repairs, go to step 16. If no voltage is indicated at both terminals, go to step 15.
10. Turn ignition off. Disconnect rear ICM assembly connector. Disconnect PCM connectors PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 21 (Light Blue wire) at PCM C2 harness connector. (Scheme 5) Also measure voltage between ground and terminal No. 62 (Dark Green wire) at PCM C2 harness connector. If any voltage is indicated at any terminal, repair short to voltage in appropriate wire between PCM and rear ICM assembly. After repairs, go to step 16. If no voltage is indicated at both terminals, go to step 15.
11. Turn ignition off. Disconnect ICM assembly connector associated with incrementing misfire current cyl #. Connect a DVOM between ground and affected IC circuit terminal at ICM harness connector. See WIRING DIAGRAMS article. On DeVille and Seville, remove fuses No. 21 (INJR 1 fuse) and No. 16 (INJR 2 fuse) from underhood fuse block. (Scheme 10) On Eldorado, remove both INJ fuses from underhood fuse block. (Scheme 11) On all models, measure frequency of affected IC circuit while cranking engine. If frequency is 1-2 Hz, go to step 13. If frequency is not 1-2 Hz, go to next step.
12. Turn ignition off. Check continuity of affected IC circuit between appropriate ICM harness connector and PCM. See WIRING DIAGRAMS article. If continuity does not exist, repair open in IC circuit. After repairs, go to step 16. If continuity exists, go to step 15.
13. Check for poor connections at ICM assembly. Repair connector as necessary. After repairs, go to step 16. If connector is okay, go to next step.
14. Replace appropriate ICM assembly. After repairs, go to step 16.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

MISFIRE CURRENT CYL #/ MISFIRE HISTORY CYL # displays on scan tool provides information that may be useful in diagnosing DTC P1360. Misfire current cyl # counter may normally display a small amount of activity, typically 0-10 counts. However, display should not increment steadily. Misfire history cyl # will display a very large number for circuits with largest failure occurrence.

Powertrain Control Module (PCM) uses dual Crankshaft Position (CKP "A" and CKP "B") sensors to determine crankshaft position. PCM supplies an ignition voltage and a ground for each sensor. During engine rotation, a slotted ring, machined into the crankshaft, causes CKP sensors to return a series of on and off pulses to the PCM. The PCM uses these pulses to decode position of crankshaft. The PCM uses 2 basic methods of decoding engine position: angle based and time based (using either CKP "A" or CKP "B" sensor input). During normal operation, the PCM uses the angle based method. In order to operate in this mode, PCM must receive signal pulses from both CKP sensors. The PCM uses the signal pulses to determine an initial crankshaft position, and to generate 24X reference and 4X reference signals. Once initial crankshaft position is determined, the PCM continuously monitors both sensors for valid signal inputs. As long as both signal inputs remain, the PCM will continue to use the angle based mode. When either CKP signal is lost, the PCM will compare the 24X reference signal to the Camshaft Position (CMP) sensor signal. If PCM detects a valid CMP signal, and the 24X reference to CMP signal correlation is correct, the PCM determines that CKP sensor "A" is at fault. However, if the 24X reference to CMP correlation is incorrect, the PCM determines that CKP sensor "B" is at fault. If while in angle-based mode PCM detects an intermittent loss of either CKP signal, DTC P1372.

1. Engine cranking or running.
2. PCM is operating in angle-based mode of decoding engine position.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Allow engine to reach normal operation temperature. Using scan tool, monitor specific DTC information for DTC P1372. If DTC P1372 sets, turn ignition off and go to step 4. If DTC P1372 does not set, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Turn ignition on. Using scan tool, command TIME MODE B. Start engine. Raise and support vehicle. Wiggle CKP sensor "B" wiring harness and connector. (Scheme 17) Using scan tool, monitor specific DTC information for DTC P0386. If DTC P0386 sets, go to «DTC P0386: CRANKSHAFT POSITION SENSOR "B" PERFORMANCE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTC P0386 does not set, turn ignition off and go to next step.
5. Turn ignition on. Using scan tool, command TIME MODE A. Start engine. Raise and sport vehicle. Wiggle CKP sensor "A" wiring harness and connector. (Scheme 17) Using scan tool, monitor specific DTC information for DTC P0336. If DTC P0336 sets, go to «DTC P0336: CRANKSHAFT POSITION SENSOR "A" PERFORMANCE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). If DTC P0336 does not set, go to next step.
6. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

If DTC P1372 and both intermittent DTCs P0336 and P0386 are set, check what time mode you are in to determine which sensor is good. When diagnosing CKP sensors, it may be necessary to enable a specific decode mode (ANGLE, TIME A or TIME B). In order to enable a specific crank decode, use scan tool and perform the following

1. Turn ignition on.
2. Select ENGINE OUTPUT CONTROLS.
3. Select CRANK POSITION SENSING DECODE mode.
4. Select desired mode (ANGLE, TIME A or TIME B) by pressing SELECT STATE.
5. Command decode mode by pressing COMMAND STATE.

The commanded state remains valid for current ignition cycle. A specific decode mode cannot be commanded with engine running, or after commanding a desired decode mode. In order to command a different decode mode, ignition must be cycled off and on. For intermittent faults, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

Rough roads cause torque on the tires that is transmitted to the powertrain. This condition slows done the crankshaft, giving the appearance of a misfire. Electronic Brake and Traction Control Module (EBTCM) determines rough road surfaces using input from wheel speed sensors. EBTCM then sends rough road data to the Powertrain Control Module (PCM) via class 2 serial data. PCM uses rough road data to enhance misfire diagnostics. This data allows PCM to distinguish crankshaft speed variations causes by rough road surfaces from variations caused by true misfires. If EBTCM is unable to identify rough road conditions when PCM detects a misfire condition, DTC P1380 will set.

1. Engine load is less than 100 percent.
2. Engine speed is less than 6500 RPM.
3. Vehicle speed is more than .6 MPH.
4. A misfire DTC is occurring and requesting malfunction indicator light on.

If powertrain diagnostic system check has already been performed, perform anti-lock brake diagnostic system check. See DIAGNOSTIC SYSTEM CHECK in appropriate ANTI-LOCK article in BRAKES. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM.

If DTC P1380 is set, it indicates that ABS/TCS system has detected a malfunction which will not allow EBTCM to transmit correct rough road data to the PCM.

Rough roads cause torque on the tires that is transmitted to the powertrain. This condition slows done the crankshaft, giving the appearance of a misfire. Electronic Brake and Traction Control Module (EBTCM) determines rough road surfaces using input from wheel speed sensors. EBTCM then sends rough road data to the Powertrain Control Module (PCM) via class 2 serial data. PCM uses rough road data to enhance misfire diagnostics. This data allows PCM to distinguish crankshaft speed variations causes by rough road surfaces from variations caused by true misfires. If a loss of communication occurs that causes PCM not to receive rough road information when a misfire condition is requesting Malfunction Indicator Light (MIL) on, DTC P1381 will set.

1. Engine load is less than 87 percent.
2. Engine speed is less than 5000 RPM.
3. Vehicle speed is more than 10 MPH.
4. A misfire DTC is occurring and requesting MIL on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Ensure ignition is on. Using scan tool, select CHASSIS APPLICATION and attempt to display ABS data. If ABS data can be displayed, no problem is indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If ABS data cannot be displayed, perform anti-lock brake diagnostic system check. See DIAGNOSTIC SYSTEM CHECK in appropriate ANTI-LOCK article in BRAKES.

The Powertrain Control Module (PCM) monitors Exhaust Gas Recirculation (EGR) valve pintle position input to ensure valve responds properly to PCM commands. When ignition is turned on, the PCM learns the EGR learned minimum position. PCM compares this position to EGR position sensor when EGR valve is commanded closed. If EGR position sensor indicates EGR valve is still open when PCM is commanding EGR valve closed, DTC P1404 will set.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Ensure ignition is on. Using scan tool, check EGR position sensor parameter. If scan tool indicates zero percent, go to next step. If scan tool does not indicate zero percent, go to step 5.
3. Using scan tool, command EGR valve from zero percent to 100 percent. If desired EGR position remains close to EGR position sensor at all commanded positions, go to next step. If desired EGR position does not remain close to EGR position sensor at all commanded positions, go to step 6.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Disconnect EGR valve connector. (Scheme 23) Turn ignition on. Using scan tool, observe EGR position sensor parameter. If scan tool indicates zero percent, go to next step. If scan tool does not indicate zero percent, go to step 9.
6. Measure voltage between terminal "B" (Black wire) and terminal "D" (Gray wire) at EGR valve harness connector. (Scheme 20) If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 8.
7. Connect a 3-amp fused jumper wire between terminal "C" (Brown wire) and terminal "D" (Gray wire) at EGR valve harness connector. Using scan tool, observe EGR position sensor parameter. If EGR position sensor is about 100 percent, go to step 13. If EGR position is not about 100 percent, go to step 11.
8. Measure voltage between ground and terminal "D" (Gray wire) at EGR valve harness connector. (Scheme 20) If voltage is about 5 volts, go to step 10. If voltage is not about 5 volts, go to step 12.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "C" (Brown wire) at EGR valve harness connector. If any voltage is indicated, repair short to voltage in Brown wire between EGR valve and PCM. After repairs, go to step 17. If no voltage is indicated, go to step 14.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black wire between terminal "B" at EGR valve harness connector and terminal No. 12 at PCM C2 harness connector. (Scheme 5)and (Scheme 20). If continuity does not exist, repair open in Black wire. After repairs, go to step 17. If continuity exists, go to step 14.
11. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal "C" (Brown wire) at EGR valve harness connector. (Scheme 20) If test light illuminates, repair short to ground in Brown wire between EGR valve and PCM. After repairs, go to step 17. If test light does not illuminate, go to step 15.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check 5-volt reference circuit (Gray wire) as follows: Check for open or short to ground in Gray wire between terminal "D" at EGR valve harness connector and terminal No. 50 at PCM C2 harness connector. (Scheme 5)and (Scheme 20). Turn ignition on. Using a test light connected to ground, probe terminal No. 50 (Gray wire) at PCM C2 harness connector. Test light should not illuminate. If test light illuminates, Gray wire is shorted to voltage. If any problems are found, repair as necessary. After repairs, go to step 17. If no problems are found, go to step 15.
13. Check for poor connections at EGR valve connector. Repair connector as necessary. After repairs, go to step 17. If connector is okay, go to step 16.
14. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 17. If connectors are okay, go to step 16.
15. Replace EGR valve. After repairs, go to step 17.
16. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
17. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
18. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Check for excessive deposits on EGR valve pintle and seat. Remove EGR valve and check for deposits that may interfere with EGR valve pintle extending completely or cause pintle to stick.

The Secondary Air Injection (AIR) pump lowers tail pipe emissions during start-up. The AIR system consists of AIR pump, shutoff valves, AIR solenoid, system hoses and pipes, AIR pump relay, fuses, and related wiring. The Powertrain Control Module (PCM) uses the AIR pump relay to control the AIR pump. The PCM also controls the AIR solenoid that supplies vacuum to the AIR shutoff valves. With AIR system inactive, the AIR shutoff valves prevent airflow in either direction. With AIR system active, the PCM applies ground to the AIR pump relay and to the AIR solenoid. Fresh air flows from the pump, through the system hoses, past the shutoff valves, and into the exhaust stream. The air helps the catalyst to quickly get to a working temperature, lowering tail pipe emissions during a start-up. The PCM runs a passive test and an active test in order to diagnose the AIR system. Both tests involve a response from the fuel control Heated Oxygen Sensor (HO2S) bank 1 sensor 1, and HO2S bank 2 sensor 1. If both passive tests pass, the PCM takes no further action. If either part of the passive test fails or is inconclusive, the PCM initiates the active tests. If PCM determines that HO2S voltages did not respond as expected during the tests, DTC P1415 will set.

The following conditions are for running a passive test (engine in open loop).

1. Engine is running.
2. Engine speed is more than 600 RPM.
3. Throttle is steady.
4. Engine load is less than 80 percent.
5. System voltage is more than 10.5 volts.
6. Mass airflow is less than 35 grams/sec.
7. Air/fuel ratio is more than 12.5:1:1.
8. Engine coolant temperature is 41-230°F (5-110°C).
9. Intake air temperature is 41-140°F (5-60°C).
10. Power enrichment or deceleration fuel cutoff is not active.

The following conditions are for running an active test (engine in closed loop).

1. Engine is running.
2. Engine speed is more than 600 RPM
3. Throttle is steady.
4. Engine load is less than 80 percent.
5. System voltage is more than 10.5 volts.
6. Mass airflow is less than 35 grams/sec.
7. Fuel system is in closed loop.
8. Evaporative emissions purge is active.
9. Engine coolant temperature is more than 154°F (68°C).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Ensure engine is at normal operating temperature. Turn all accessories off. Using scan tool, monitor HO2S bank 1 sensor 1 voltage. Using scan tool, enable AIR system. Observe and record HO2S voltage while AIR system is enabled. If voltage drops to less than 350 millivolts, no problem is indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If voltage does not drop to less than 350 millivolts, go to next step.
3. Turn ignition off. Disconnect vacuum hose from bank 1 (rear cylinder head) shutoff valve. Connect a vacuum gauge to disconnected vacuum hose. Start engine and allow it to idle. Using scan tool, select OUTPUT CONTROLS and enable AIR system. If vacuum is indicated on vacuum gauge, go to next step. If no vacuum is indicated on vacuum gauge, go to step 5 .
4. Inspect all AIR pipes and hoses. Check for blockage, poor connections and damage. Check components for evidence of heat damage. If any problems are found, repair as necessary. After repairs, go to step 7 . If no problems are found, go to step 6 .
5. Replace vacuum hose between AIR solenoid and bank 1 AIR shutoff valve. After repairs, go to step 7 .
6. Replace bank 1 AIR shutoff valve. After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

The Secondary Air Injection (AIR) pump lowers tail pipe emissions during start-up. The AIR system consists of AIR pump, shutoff valves, AIR solenoid, system hoses and pipes, AIR pump relay, fuses, and related wiring. The Powertrain Control Module (PCM) uses the AIR pump relay to control the AIR pump. The PCM also controls the AIR solenoid that supplies vacuum to the AIR shutoff valves. With AIR system inactive, the AIR shutoff valves prevent airflow in either direction. With AIR system active, the PCM applies ground to the AIR pump relay and to the AIR solenoid. Fresh air flows from the pump, through the system hoses, past the shutoff valves, and into the exhaust stream. The air helps the catalyst to quickly get to a working temperature, lowering tail pipe emissions during a start-up. The PCM runs a passive test and an active test in order to diagnose the AIR system. Both tests involve a response from the fuel control Heated Oxygen Sensor (HO2S) bank 1 sensor 1, and HO2S bank 2 sensor 1. If both passive tests pass, the PCM takes no further action. If either part of the passive test fails or is inconclusive, the PCM initiates the active tests. If PCM determines that HO2S voltages did not respond as expected during the tests, DTC P1416 will set.

The following conditions are for running a passive test (engine in open loop).

1. Engine is running.
2. Engine speed is more than 600 RPM.
3. Throttle is steady.
4. Engine load is less than 80 percent.
5. System voltage is more than 10.5 volts.
6. Mass airflow is less than 35 grams/sec.
7. Air/fuel ratio is more than 12.5:1.
8. Engine coolant temperature is 41-230°F (5-110°C).
9. Intake air temperature is 41-140°F (5-60°C).
10. Power enrichment or deceleration fuel cutoff is not active.

The following conditions are for running an active test (engine in closed loop).

1. Engine is running.
2. Engine speed is more than 600 RPM.
3. Throttle is steady.
4. Engine load is less than 80 percent.
5. System voltage is more than 10.5 volts.
6. Mass airflow is less than 35 grams/sec.
7. Fuel system is in closed loop.
8. Evaporative emissions purge is active.
9. Engine coolant temperature is more than 154°F (68°C).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start engine. Ensure engine is at normal operating temperature. Turn all accessories off. Using scan tool, monitor HO2S bank 2 sensor 1 voltage. Using scan tool, enable AIR system. Observe and record HO2S voltage while AIR system is enabled. If voltage drops to less than 350 millivolts, no problem is indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If voltage does not drop to less than 350 millivolts, go to next step.
3. Turn ignition off. Disconnect vacuum hose from bank 2 (rear cylinder head) shutoff valve. Connect a vacuum gauge to disconnected vacuum hose. Start engine and allow it to idle. Using scan tool, select OUTPUT CONTROLS and enable AIR system. If vacuum is indicated on vacuum gauge, go to next step. If no vacuum is indicated on vacuum gauge, go to step 5 .
4. Inspect all AIR pipes and hoses. Check for blockage, poor connections and damage. Check components for evidence of heat damage. If any problems are found, repair as necessary. After repairs, go to step 7 . If no problems are found, go to step 6 .
5. Replace vacuum hose between AIR solenoid and bank 2 AIR shutoff valve. After repairs, go to step 7 .
6. Replace bank 2 AIR shutoff valve. After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

This DTC tests for undesired intake manifold vacuum flow to Evaporative Emission (EVAP) system. The Powertrain Control Module (PCM) seals the EVAP system by commanding EVAP canister purge valve off and EVAP canister vent valve on. The PCM monitors Fuel Tank Pressure (FTP) sensor to determine if a vacuum is being drawn on the EVAP system. If vacuum in the EVAP system is more than a predetermined value within a predetermined time, DTC P1441 will set.

1. DTC P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0440, P0442, P0446, P0443, P0449, P0452, P0453, P1106. P1107, P1111, P1112, P1114, P1115, P1121 or P1122 is not set.
2. System voltage is 10-18 volts.
3. Barometric pressure is more than 10.1 psi (75 kPa).
4. Fuel level is 15-85 percent.
5. Engine coolant temperature at start-up is 39-86°F (4-30°C).
6. Intake air temperature at start-up is 39-86°F (4-30°C).
7. Vehicle speed sensor is less than 75 MPH.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. If DTC P0443, P0449, P0452 or P0453 is also set, diagnose DTC(s) before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions). If DTC P0443, P0449, P0452 or P0453 is not also set, go to next step.
3. Remove the fuel fill cap. Ensure ignition is on. Using scan tool, monitor fuel tank pressure. If fuel tank pressure is -.5 to +.5 in. H2O, go to next step. If fuel tank pressure is not -.5 to +.5 in. H2O, go to «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT HIGH VOLTAGE»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
4. Disconnect EVAP purge pipe from EVAP canister purge valve. (Scheme 23) Install a vacuum gauge to EVAP canister purge valve purge port. Disconnect EVAP canister purge valve connector. Monitor vacuum on vacuum gauge. Start engine and allow it to idle. Increase engine speed 1200-1500 RPM. If vacuum gauge indicates an increase in vacuum, go to next step. If vacuum gauge does not indicate an increase in vacuum, see «DIAGNOSTIC AIDS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l).
5. Replace EVAP canister purge valve. After repairs, go to next step.
6. Using scan tool, monitor fuel tank pressure. Start engine and allow it to idle for 30 seconds. If fuel tank pressure is -.5 to +.5 in. H2O, go to next step. If fuel tank pressure is not -.5 to +.5 in. H2O, go to step 3.
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

An intermittent condition could be caused by an improperly installed or damaged EVAP canister purge valve or by a temporary blockage in EVAP canister purge valve.

This test functions on the assumption that a sudden decrease in non-drive wheel speed must be caused by a brake application. Non-drive wheel speed and brakelight switch status are supplied to the PCM through the serial data from the Electronic Brake and Traction Control Module (EBTCM). If there is a 6 MPH or greater decrease of non-drive wheel speed in .4 second and a transition of the Torque Converter Clutch (TCC) or extended travel contacts of the TCC brake switch occurs without a transition of the stoplight switch, DTC P1575 will set.

1. DTC P1574 is not set.
2. Traction control and anti-lock brake systems have not failed.
3. Traction control and anti-lock brake systems are not active.
4. Non-drive wheel speed goes to more than 20 MPH and then does not go to less than 4 MPH.

Scheme 29

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Release brake pedal. Using scan tool, observe extended travel brake parameter. If scan tool displays RELEASED, go to next step. If scan tool does not display RELEASED, go to step 6.
3. Depress brake pedal more than half-way down. If scan tool displays APPLIED, no problem is indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If scan tool does not display APPLIED, go to next step. NOTE: Brake switch consists of extended travel brake switch and TCC brake switch.
4. Disconnect brake switch 4-pin connector. If scan tool displays APPLIED, go to step 14. If scan tool does not display APPLIED, go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 44 (Gray wire) at PCM C1 harness connector. (Scheme 5) If any voltage is indicated, repair short to voltage in Gray wire between PCM and brake switch. After repairs, go to step 17. If no voltage is indicated, go to step 16.
6. Using scan tool, observe TCC brake switch display. If scan tool displays RELEASED, go to next step. If scan tool does not display RELEASED, go to step 11.
7. Turn ignition off. Disconnect brake switch connector. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. On DeVille and Seville, check continuity of Pink wire between output side of fuse No. 12 (IGN 1 fuse) in rear fuse block and terminal "C" at brake switch harness connector. (Scheme 2), (Scheme 3) and (Scheme 29). Rear fuse block is located underneath driver's side rear seat. On Eldorado, check continuity of Pink wire between output side of RLY IGN fuse (circuit No. 1039) in rear fuse block and terminal "C" at brake switch harness connector. (Scheme 4)and (Scheme 29). Rear fuse block is located underneath driver's side rear seat. On all models, if continuity does not exist, repair open in Pink wire. After repairs, go to step 17. If continuity exists, go to next step.
8. Connect a 3-amp fused jumper wire between terminal "C" (Pink wire) and terminal "D" (Gray wire) at brake switch harness connector. Using scan tool, observe extended travel brake switch parameter. If scan tool displays RELEASED, go to next step. If scan tool does not display RELEASED, go to step 10.
9. Check for poor connections at brake switch connector. Repair connector as necessary. After repairs, go to step 17. If connector is okay, go to step 14.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Gray wire between terminal "D" at brake switch harness connector and terminal No. 44 at PCM C1 harness connector. (Scheme 5)and (Scheme 29). If continuity does not exist, repair open Gray wire. After repairs, go to step 17. If continuity exists, go to step 15.
11. On DeVille and Seville, check fuse No. 12 (IGN 1 fuse) in rear fuse block. (Scheme 2)or (Scheme 3). On Eldorado, check RLY IGN fuse in rear fuse block. (Scheme 4) On all models, if fuse is okay, go to step 13. If fuse is blown, go to next step.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for a short to ground as follows: Using a test light connected to positive battery voltage, probe terminal "A" (Pink wire) and terminal "C" (Pink wire) at brake switch harness connector. Test light should not illuminate at either terminal. If test light illuminates, Pink wire(s) is shorted to ground between fuse block and PCM. Using a test light connected to positive battery voltage, probe terminal "D" (Gray wire) at brake switch harness connector. Test light should not illuminate. If test light illuminates, Gray wire is shorted to ground between brake switch and PCM. Using a test light connected to positive battery voltage, probe terminal "B" (Purple wire) at brake switch harness connector. Test light should not illuminate. If test light illuminates, Purple wire is shorted to ground between brake switch and PCM. If any problems are found, repair short to ground as necessary. After repairs, go to step 17. If no problems are found, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
13. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Purple wire between terminal "B" at brake switch harness connector and terminal No. 80 at PCM C2 harness connector. (Scheme 5)and (Scheme 29). If continuity does not exist, repair open in Purple wire. After repairs, go to step 17. If continuity exists, go to next step.
14. Replace brake switch. After repairs, go to step 17.
15. Check for poor connections at PCM connectors. Repair connector as necessary. After repairs, go to step 17. If connectors are okay, go to next step.
16. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to step 17.
17. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
18. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) checks the integrity of the non-volatile memory area of the Electrically Erasable Programmable Read-Only Memory (EEPROM). The PCM uses the EEPROM to store the information at key off. There are several locations where the information is stored within the non-volatile memory. If PCM detects a problem in one location of the EEPROM, the PCM will attempt to store the data in another location. If PCM runs out of valid places to store the information, DTC P1621 will set.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . After repairs, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.

The customer-snapshot feature lets customer store the Powertrain Control Module (PCM) data when a driveability problem occurs. This feature permits several snapshots during each ignition cycle. When customer requests the snapshot, PCM stores the data, and sets DTC P1624. The PCM also illuminates the malfunction indicator light for a specific length of time to tell the customer that the data has been stored.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, see DIAGNOSTIC AIDS. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

This DTC informs the technician that the customer has initiated the customer snapshot function. PCM will store up to 6 snapshots in the failure records before over-writing the first recorded snapshot. The customer snapshot function may help to diagnose conditions which could not be duplicated during previous diagnosis. If no other DTCs are set, fault is most likely intermittent.

Powertrain Control Module (PCM) uses the 5-volt reference 1 circuit as a sensor feed to the Throttle Position (TP) sensor, Manifold Absolute Pressure (MAP) sensor and Exhaust Gas Recirculation (EGR) position sensor. The PCM monitors voltage on the 5-volt reference 1 circuit. If the voltage is out of tolerance, DTC P1635 will set.

Only condition for running this DTC is engine must be running.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Check PCM and engine grounds. Ensure grounds are clean and tight. See WIRING DIAGRAMS article. If any problems are found, repair as necessary. After repairs, go to step 13. If no problems are found, go to next step.
4. Turn ignition off. Disconnect EGR valve connector. (Scheme 23) Turn ignition on. Measure voltage between ground and terminal "D" (Gray wire) at EGR valve harness connector. (Scheme 20) If voltage is about 5 volts, go to step 6. If voltage is not about 5 volts, go to next step.
5. If voltage is more than 5 volts, go to step 9. If voltage is less than 5 volts, go to step 7.
6. Reconnect EGR valve connector. Disconnect TP sensor connector. Measure voltage between ground and Gray wire at TP sensor harness connector. If voltage is about 5 volts, no problem is indicated at this time. Fault may be intermittent. If voltage is not about 5 volts, go to step 10.
7. Monitor DVOM while disconnecting all other devices (TP and MAP sensors) connected to 5-volt reference 1 circuit one at a time. If voltage changes when one of the components is disconnected, replace affected component. After repairs, go to step 13. If voltage does not change when one of the components is disconnected, go to next step.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check TP sensor, MAP sensor and EGR valve 5-volt reference 1 circuit for a short to ground or a short to any sensor low reference circuit. See WIRING DIAGRAMS article. If any problems are found, repair wiring as necessary. After repairs, go to step 13. If no problems are found, go to step 12.
9. Turn ignition off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Check TP sensor, MAP sensor and EGR valve 5-volt reference 1 circuit for short to voltage. See WIRING DIAGRAMS article. Also check for short to voltage in MAP sensor signal circuit (Light Green wire) between MAP sensor harness connector and terminal No. 23 at PCM C1 harness connector. (Scheme 5) If any problems are found, repair as necessary. After repairs, go to step 13. If no problems are found, go to step 12.
10. Turn ignition off. Check for continuity between terminal "D" (Gray wire) and terminal "E" (Red wire) at EGR valve harness connector. (Scheme 20) If continuity exists, Gray and Red wires are shorted together. Repair wiring as necessary. After repairs, go to step 13. If continuity does not exist, go to next step.
11. Replace EGR valve. After replacing EGR valve, go to step 13.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions).

Powertrain Control Module (PCM) uses the 5-volt reference 2 circuit as a sensor feed to the A/C pressure sensor and Fuel Tank Pressure (FTP) sensor. The PCM monitors voltage on the 5-volt reference 2 circuit. If the voltage is out of tolerance, DTC P1639 will set.

Only condition for running this DTC is engine must be running.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Check PCM and engine grounds. Ensure grounds are clean and tight. See WIRING DIAGRAMS article. If any problems are found, repair as necessary. After repairs, go to step 17 . If no problems are found, go to next step.
4. Turn ignition off. Disconnect A/C pressure sensor connector. Sensor is located in discharge hose of A/C compressor. Turn ignition on. Measure voltage between ground and Gray wire at A/C pressure sensor harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 6 .
5. Turn ignition off. Reconnect A/C pressure sensor connector. Disconnect FTP sensor connector. FTP sensor is located on top of fuel tank and can be accessed through an inspection panel in trunk. Measure voltage between ground and Gray wire at FTP sensor harness connector. If voltage is about 5 volts, no problem is indicated at this time. Fault may be intermittent. If voltage is not about 5 volts, go to step 13 .
6. If voltage is more than 5 volts, go to next step. If voltage is less than 5 volts, go to step 8 .
7. Turn ignition off. Disconnect A/C pressure sensor connector. Turn ignition on. Connect DVOM between ground and Gray wire at A/C pressure sensor harness connector. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. If no voltage is indicated, go to step 15 . If any voltage is indicated, go to step 12 .
8. Ensure DVOM is still connected as in step 4 . Disconnect FTP sensor connector. FTP sensor is located on top of fuel tank and can be accessed through an inspection panel in trunk. Turn ignition on. If voltage is about 5 volts, go to step 14 . If voltage is not about 5 volts, go to next step.
9. Turn ignition off. Check for continuity between Gray and Black wires at FTP sensor harness connector. Also check for continuity between Gray and Black wires at A/C pressure sensor harness connector. If either reading indicates continuity, go to step 11 . If both readings indicate no continuity exists, go to next step.
10. Check for continuity between ground and Gray wire at FTP sensor harness connector. Also check for continuity between ground and Gray wire at A/C pressure sensor harness connector. If either reading indicates continuity exists, go to next step. If both readings indicate continuity does not exist, go to step 15 .
11. Repair shorted wiring as necessary. After repairs, go to step 17 .
12. Repair short to voltage as necessary. After repairs, go to step 17 .
13. Replace A/C pressure sensor. After repairs, go to step 17 .
14. Replace FTP sensor. After repairs, go to step 17 .
15. Turn ignition off. Ensure PCM is disconnected. Check FTP sensor and A/C pressure sensor 5-volt reference circuit (Gray wire) for an open, short to ground or poor connection at PCM connector. See WIRING DIAGRAMS article. If any problems are found, repair as necessary. After repairs, go to step 17 . If no problems are found, go to next step.
16. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . After repairs, go to next step.
17. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
18. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

Powertrain Control Module (PCM) uses the 5-volt reference 2 circuit as a sensor feed to the Fuel Tank Pressure (FTP) sensor. The PCM monitors voltage on the 5-volt reference 2 circuit. If the voltage is out of tolerance, DTC P1639 will set.

Only condition for running this DTC is engine must be running.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__powertrain-diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Check PCM and engine grounds. Ensure grounds are clean and tight. See WIRING DIAGRAMS article. If any problems are found, repair as necessary. After repairs, go to step 12 . If no problems are found, go to next step.
4. Turn ignition off. Disconnect FTP sensor connector. FTP sensor is located on top of fuel tank. Check trunk floor area to see if an inspection panel exists. If no inspection panel exists, fuel tank must be removed to access FTP sensor. Measure voltage between ground and Gray wire at FTP sensor harness connector. If voltage is about 5 volts, go to step 10 . If voltage is not about 5 volts, go to next step.
5. If voltage is more than 5 volts, go to next step. If voltage is less than 5 volts, go to step 7 .
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Gray wire at FTP sensor harness connector. Also measure voltage between and Dark Green wire at FTP sensor harness connector. If no voltage is indicated, go to step 11 . If any voltage is indicated, repair short to voltage in Gray or Dark Green wire as necessary. After repairs, go to step 12 .
7. Turn ignition off. Check for continuity between Gray and Black wires at FTP sensor harness connector. If continuity does not exist, go to step 9 . If continuity exists, go to next step.
8. Check for continuity between ground and Gray wire at FTP sensor harness connector. If continuity exists, go to next step. If continuity does not exist, go to step 11 .
9. Repair shorted wiring as necessary. After repairs, go to step 12 .
10. Replace FTP sensor. After repairs, go to step 12 .
11. Replace PCM. Program replacement PCM. See «PROGRAMMING»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l) . After repairs, go to next step.
12. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
13. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-trouble-code-definitions) .

See also:
• DIAGNOSTIC PROCEDURE
• MALFUNCTION INDICATOR LIGHT INOPERATIVE
• FREEZE FRAME
• FAILURE RECORDS
• POWERTRAIN DIAGNOSTIC SYSTEM CHECK
• DIAGNOSTIC TROUBLE CODE DEFINITIONS
• ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK
• MALFUNCTION INDICATOR LIGHT ALWAYS ON
• CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE
• OIL LIFE INDEX RESET
• IDLE LEARN PROCEDURE
• PROGRAMMING THEFT DETERRENT SYSTEM COMPONENTS
• ENABLE CRITERIA
• P0480
• P0481
• ENGINE COOLING DIAGNOSTIC SYSTEM CHECK