Engine Control System - Tests W/codes - Introduction Cadillac DeVille Concours I final

MODEL IDENTIFICATION

Vehicle model is identified by fourth character (cars), or fifth character (trucks) of Vehicle Identification Number (VIN). VIN is stamped on metal pad on top of left end of instrument panel, near windshield. See MODEL IDENTIFICATION (CARS) table, or MODEL IDENTIFICATION (TRUCKS) table.

CARS

MODEL IDENTIFICATION (CARS)

TRUCKS

MODEL IDENTIFICATION (TRUCKS)

Note. The Service Engine Soon (SES) lamp is also refered to as Malfunction Indicator Lamp (MIL).

Most engine control problems are the result of mechanical breakdowns, poor electrical connections or damaged vacuum hoses. Before considering the computer system as a possible cause of problems, perform basic diagnostic procedures in appropriate BASIC DIAGNOSTIC PROCEDURES article. Failure to do so may result in lost diagnostic time.

If no faults were found while performing basic diagnostic procedures, go to DIAGNOSTIC PROCEDURE under SELF-DIAGNOSTIC SYSTEM. If no fault codes are present and driveability problems exist, go to appropriate TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.). If only intermittent codes are present, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

DESCRIPTION

Note. Powertrain Control Module (PCM) may also be referred to as Vehicle Control Module (VCM) in some diagnostic text and illustrations. Terms may be used interchangeably.

PCM is equipped with a self-diagnostic system which detects system failures or abnormalities. When a malfunction occurs, PCM will store a Diagnostic Trouble Code (DTC) and, in most cases, illuminate the Service Engine Soon (SES) lamp, also called the Malfunction Indicator Light (MIL) located on instrument cluster. Malfunctions are recorded as hard failures or intermittent failures.

There are 4 types of DTC categories

1. Type "A" Emissions related. Illuminates MIL the first time DTC sets.
2. Type "B" Emissions related. Illuminates MIL if fault is active for 2 consecutive driving cycles.
3. Type "C" Non-emissions related. Does not illuminate MIL, but will illuminate SERVICE light.
4. Type "D" Non-emissions related. Does not illuminate MIL or SERVICE light.

Hard Failures

Most hard failures cause MIL to illuminate and remain on until malfunction is repaired. If MIL illuminates and remains on (light may flash) during vehicle operation, cause of malfunction must be determined. See DIAGNOSTIC PROCEDURE .

If a sensor fails, PCM will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but it will most likely display degraded driveability.

Intermittent Failures

Intermittent failures cause MIL to flicker or glow and turn off about 10 seconds after intermittent fault goes away. Corresponding DTC, however, will be retained in PCM memory. If related fault does not reoccur within 50 engine starts, DTC will be erased from PCM memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

SCAN TOOL DISPLAY

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 1 or Tech 2 scan tool. See scan tool operator's manual for additional information.

The following are Tech 1 or Tech 2 scan tool sub-menus in the DTC INFO and SPECIFIC DTC modes

1. DTC INFO MODE Used to search for specific type of stored DTC information. There are 7 choices in this mode. Technician may be instructed to test DTCs in a certain manner. Follow the affected DTC test procedures. To get complete description of any status, hit ENTER key before pressing the desired "F" key.
2. DTC STATUS This selection will display any DTCs that have not run during the current ignition cycle or have reported a test failure during this ignition up to a maximum of 33 DTCs. A DTC test that runs and passes will cause affected DTC to be removed from scan tool screen.
3. FAIL THIS IGN. This selection will display all DTCs that have failed during the present ignition cycle.
4. HISTORY This selection will display only DTCs that are stored in the control module's history memory. It will not display type "D" DTCs. It 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.
5. LAST TEST FAIL This selection will only display DTCs that have 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.
6. MIL REQUEST This selection will only display DTCs that are requesting MIL illumination. Type "C" DTCs cannot be displayed using this option. This selection will report type "B" DTCs only after MIL illumination has been requested.
7. NOT RUN SCC Not Run Since Code Clear option will display up to 33 DTCs that have not run since DTCs were last cleared. Since any displayed DTCs have not run, their condition (passing or failing) is unknown.
8. TEST FAIL SCC Test Fail Since Code Clear selection will display all active and history DTCs that have reported a test failure since the last time DTCs were cleared. DTCs that last failed over 40 warm-up cycles before this option is selected will not be displayed.
9. FAILED SINCE CLEAR This message indicates the DTC has failed at least once within the last 40 warm-up cycles since the last time DTCs were cleared.
10. NOT RUN SINCE CL. Not Run Since Cleared message indicates that the selected diagnostic test has not run since the last time DTCs were cleared. Therefore, the diagnostic test status (passed or failed) is unknown. After DTCs are cleared, this message will continue to be displayed until the diagnostic test runs.
11. NOT RUN THIS IGN. Not Run This Ignition message indicates the selected diagnostic test has not run this ignition cycle.
12. TEST RAN AND PASSED This message indicates the selected diagnostic test has: Passed the last test. Ran and passed during this ignition cycle. Ran and passed since DTCs were last cleared. Test has not failed since DTCs were last cleared. If this message is displayed, repair is complete. If FAILED THIS IGN. message is displayed, repair is incomplete and further diagnosis is required.

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. On-Board Diagnostic (OBD) system check must be performed before using specific DTC testing procedure. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) .
2. If DTCs were displayed, determine whether codes are hard or intermittent. Hard codes will cause MIL to illuminate continuously while engine is running. See «HARD OR INTERMITTENT TROUBLE CODE DETERMINATION»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__hard-or-intermittent-trouble-code-determination) . For diagnosing hard codes, proceed to appropriate DTC test. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. For diagnosing intermittent codes, see appropriate TROUBLE SHOOTING - NO CODES article.
3. If no DTCs are present and a driveability problem exists, refer to SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article. Doing so will help identify proper system or component to check in appropriate SYSTEM & COMPONENT TESTING article.
4. After necessary repairs are made, clear DTCs, verify vehicle will enter "closed loop" operation and ensure DTC does not reset.

RETRIEVING DIAGNOSTIC TROUBLE CODES

DTCs are retrieved using a Tech 1 or Tech 2 scan tool, or other OBD-II compatible scan tool connected to OBD-II 16-pin Data Link Connector (DLC). See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. (Scheme 8) DLC is located below left side of dash.

Scheme 8

ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK

Note. Tech 1 or Tech 2 scan tool is required to perform OBD system check.

The OBD system check determines

1. If Service Engine Soon (SES), also called Malfunction Indicator Light (MIL) operates.
2. If PCM is operating and can recognize a fault.
3. If any DTCs are stored.

After performing procedures in PRELIMINARY INSPECTION & ADJUSTMENTS, BASIC FUEL SYSTEM CHECKS and BASIC IGNITION SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article, this is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in the OBD system check, if no codes are indicated and driveability problems still exist, see appropriate TROUBLE SHOOTING - NO CODES article and SCAN TOOL USAGE .

1.9L (VIN 7 & 8)

1. Turn ignition off. Install scan tool and follow scan tool manufacturer's instructions to proceed with test. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to step 4 .
2. Attempt to start engine. If engine starts, go to next step. If engine does not start, see NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
3. If DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, observe scan tool data to determine if parameters are in correct operating range.
4. Attempt to start engine. If engine starts, go next step. If engine does not start, go to step 12 .
5. If engine exhibits surge, rough idle or starts and then stalls, go to step 10 . If engine runs okay, go to next step.
6. Connect a test light between terminals No. 4 and No. 16 of DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, repair ground circuit.
7. Check for open or shorted CLASS II DATA BUS circuit between DLC and PCM, and also between PCM and ABS module if equipped with ABS. Repair as necessary. If circuit is okay, go to next step.
8. If vehicle is equipped with ABS, go to next step. If vehicle is not equipped with ABS, PCM and/or connections are faulty. Repair as necessary.
9. Disconnect ABS module harness connector. If scan tool communicates with PCM, replace ABS controller. If scan tool does not communicate with PCM, PCM and/or connections are faulty. Repair as necessary.
10. Turn ignition off. Disconnect 24-pin PCM harness connector. Turn ignition on with ignition off. If scan tool communicates with PCM, go to next step. If scan tool does not communicate with PCM, go to step 6 .
11. Check the following circuits at PCM for a short to battery positive. See appropriate wiring diagram in WIRING DIAGRAMS article. EVO low circuit (Brown wire). ECT sensor signal circuit (Yellow wire). TP sensor 5-volt reference circuit (Gray wire). TP sensor signal circuit (Dark Blue wire). EST circuit for cylinders No. 1 and 4 (White wire). EST circuit for cylinders No. 2 and 3 (Orange wire). Repair as necessary. If all circuits are okay, replace PCM.
12. Turn ignition on. Using a test light connected to ground, probe both sides of PCM 1 and PCM B fuses (10-amp), located in underhood fuse block. If test light illuminates at both sides of both fuses, go to next step. If test light does not illuminate at both sides of both fuses, go to step 15 .
13. Turn ignition off. Disconnect 32-pin PCM harness connector. Turn ignition on. Using DVOM, measure voltage between ground and ignition positive feed and battery positive feed circuits at PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage is present at each circuit, go to next step. If battery voltage is not present at each circuit, repair open or short in circuits between underhood fuse block and PCM.
14. Check all PCM ground circuits. See appropriate wiring diagram in WIRING DIAGRAMS article. If all ground circuits are okay, PCM and/or connections are faulty. Repair as necessary.
15. Repair ignition positive feed and battery positive feed circuits to underhood fuse block. Replace fuse as necessary.
16. Repair open in faulty circuit between underhood fuse block and PCM.

2.2L & 2.4L

Note. Check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT perform the following procedure if driveability conditions are not present. DO NOT turn ignition off during the following procedure or clear DTCs unless instructed to do so.

1. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
2. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Using scan tool, check for DTCs. If any LAST TEST FAIL, HISTORY or MIL request DTCs are present, go to next step. If no DTCs are present, go to step 5 .
4. Using scan tool, record FREEZE FRAME and FAILURE RECORDS information. Identify DTCs. See «DIAGNOSTIC TROUBLE CODE (DTC) DEFINITION»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__diagnostic-trouble-code-dtc-definition) . After identification, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article.
5. Observe MIL. If MIL is illuminated, go to next step. If MIL is not illuminated, go to «MIL INOPERATIVE»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
6. Using scan tool, command MIL off. If MIL turns off, go to next step. If MIL does not turn off, go to «MIL ON STEADY»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
7. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and then stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
8. Allow engine to idle. During engine warm-up, check ECT, TP, MAP, O2 sensors and IAC valve for proper operation. Compare actual scan tool data with typical scan tool data values. If values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article. If values are not within limits, go to appropriate SYSTEM & COMPONENT TESTING article.

3.0L

1. Check if MIL is illuminated with engine running. Check for driveability concerns. Also, check for faulty computer-controlled components. If a problem is found, go to next step. If no problems are found, system is okay.
2. Turn ignition off. Connect scan tool. Turn ignition on, with engine off. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Attempt to crank engine. If engine cranks, go to next step. If engine does not crank, diagnose starting and/or charging system.
4. Using scan tool, command MIL on and off. If MIL turns on and off as commanded, go to next step. If MIL does not turn on and off as commanded, diagnose using appropriate test procedure for DTC P0650. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article.
5. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
6. Check for any applicable Technical Service Bulletins (TSBs). Perform repairs as necessary. If no applicable bulletins are found, go to next step.
7. Using scan tool, check for DTCs. If DTCs are present, go to next step. If no DTCs are present, go to step 9 .
8. Using scan tool, record any FREEZE FRAME and non-FREEZE FRAME information. Identify DTCs. See «DIAGNOSTIC TROUBLE CODE (DTC) DEFINITION»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__diagnostic-trouble-code-dtc-definition) . After identification, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article.
9. With engine running, compare actual scan tool data with typical scan tool data values. If values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

3.1L & 3.4L

Note. Check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT perform the following procedure if driveability conditions are not present. DO NOT turn ignition off during the following procedure or clear DTCs unless instructed to do so.

1. Turn ignition on, with engine off. Observe MIL. If MIL illuminates, go to next step. If MIL does not illuminate, go to «MIL INOPERATIVE»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
2. Turn ignition off. Connect scan tool. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
4. Using scan tool, display LAST TEST FAIL information. If any DTCs are stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. If DTCs are indicated as last test failed, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not indicated, go to next step.
5. Using scan tool, display DTC FAILURE RECORDS information. If DTC failure records are stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. If failure records are stored, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If failure records are not stored, go to next step.
6. Compare PCM data values displayed on scan tool to typical engine scan data values. If values are within limits, system is okay. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

3.5L

Note. Check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT perform the following procedure if driveability conditions are not present. DO NOT turn ignition off during the following procedure or clear DTCs unless instructed to do so.

1. Check if MIL is illuminated with engine running. Check for driveability concerns. Also, check for faulty computer-controlled components. If a problem is found, go to next step. If no problems are found, system is okay.
2. Turn ignition off. Connect scan tool. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Check starter operation. If starter is inoperative, or starter operates with ignition on, diagnose starter circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If starter operates okay, go to next step.
4. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
5. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTCs are stored, go to next step. If DTCs are not present, go to step 7 .
6. Using scan tool, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article.
7. Using scan tool, command MIL on and off. If MIL turns on and off as commanded, go to next step. If MIL does not turn on and off as commanded, check MIL circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
8. Compare PCM data values displayed on scan tool with typical control system data values. If values are within limits, go to appropriate TROUBLE SHOOTING - NO CODES article. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

3.8L

Note. Check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT perform the following procedure if driveability conditions are not present. DO NOT turn ignition off during the following procedure or clear DTCs unless instructed to do so.

1. Turn ignition on, with engine off. Observe MIL. If MIL illuminates, go to next step. If MIL does not illuminate, go to «MIL INOPERATIVE»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
2. Turn ignition off. Connect scan tool. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
4. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTCs are stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, go to next step.
5. Compare PCM data values displayed on scan tool with typical control system data values. If values are within limits, system is okay. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

4.0L

1. Check for one or more of the following conditions: MIL illuminates with engine running. Performance/driveability concern. Suspected fault in powertrain component or system. If one or more of the listed conditions are present, go to next step. If none of the listed conditions are present, system is okay.
2. Ensure battery is fully charged. Turn ignition off. Connect scan tool. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
4. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTCs are stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, go to next step.
5. Compare PCM data values displayed on scan tool with typical control system data values. If values are within limits, system is okay. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

4.3L, 5.0L, 5.7L (VIN R) & 7.4L

Note. Check for applicable Technical Service Bulletins (TSBs) before proceeding. Perform the following procedure only if a driveability complaint exists, or if you were sent here from another procedure or article. DO NOT turn ignition off during the following procedure or clear DTCs unless instructed to do so.

1. Connect scan tool. Turn ignition on, with engine off. Observe MIL. If MIL illuminates, go to next step. If MIL does not illuminate, go to «MIL CIRCUIT CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
2. Using scan tool, attempt to communicate with VCM. If scan tool displays VCM data, go to next step. If scan tool does not display VCM data, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTC is stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, go to next step.
4. Using scan tool, monitor SERIAL DATA CLASS II messages. If all other control modules are communicating with scan tool, go to next step. If all other control modules do not communicate with scan tool, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
5. Attempt to start engine. If engine starts and continues to run, go to step 7 . If engine does not start, or starts and then stalls, go to next step.
6. Using scan tool, check for any Passlock® DTCs. If DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If no DTCs are present, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
7. Using scan tool, command MIL to turn off. If MIL turns off, go to next step. If MIL does not turn off, go to «MIL CIRCUIT CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
8. Compare scan tool engine data with typical control system data values. If values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

4.6L

1. Check if MIL is illuminated with engine running. Check for driveability concerns, or faulty computer-controlled components. If a problem is found, go to next step. If no problems are found, system is okay.
2. Ensure battery is fully charged. Turn ignition off. Connect scan tool. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
4. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If no DTCs are present, go to next step.
5. Compare scan tool engine data with typical control system data values. If data values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article. If data values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

4.8L, 5.3L & 6.0L

Note. Ensure battery is fully charged and check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT turn ignition off during the following procedure unless instructed to do so.

1. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
2. If scan tool displays PCM data, go to step 4 . If scan tool does not display PCM data, go to next step.
3. Using scan tool, select DIAGNOSTIC CIRCUIT CHECK and CLASS 2 MESSAGE MONITOR. If scan tool displays any other modules as ACTIVE, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) . If scan tool does not display any other modules as ACTIVE, check scan tool connection. Check circuits between DLC and control module which does not communicate with scan tool. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
4. Using scan tool, monitor IGNITION 1 voltage while cranking engine. If voltage is near battery voltage, go to next step. If voltage is not as specified, diagnose system using appropriate test for DTC P0562. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article.
5. If engine starts and continues to run, go to step 8 . If engine does not start, or starts and then stalls, go to next step.
6. If any PCM, BCM or VTD DTCs related to vehicle theft deterrent system are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If no DTCs are present, go to next step.
7. Using scan tool in BODY mode, monitor PCM/VCM FUEL CONTINUE parameter while cranking engine. If scan tool displays FUEL CONTINUE as NO, diagnose theft deterrent system. See appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT. If scan tool does not display FUEL CONTINUE as NO, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
8. Using scan tool, capture DTC FREEZE FRAME and/or FAILURE RECORDS information. Monitor DTC information. If DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, go to next step.
9. Compare scan tool engine data with typical control system data values. If data values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article. If data values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

5.7L (VIN G - Camaro & Firebird)

Note. Check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT turn ignition off during the following procedure unless instructed to do so.

1. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
2. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Attempt to start engine. If engine starts and continues to run, go to step 5 . If engine does not start or starts and then stalls, go to next step.
4. Using scan tool, check for DTCs. If DTC P1626 is present, diagnose using appropriate test for DTC P1626. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If no DTCs are present, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
5. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTC is stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, go to next step.
6. Compare scan tool engine data with typical control system data values. If data values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article. If data values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

5.7L (VIN G - Corvette)

Note. Check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT turn ignition off during the following procedure unless instructed to do so.

1. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
2. If scan tool displays PCM data, go to step 4 . If scan tool does not display PCM data, go to next step.
3. Using scan tool, select DIAGNOSTIC CIRCUIT CHECK and CLASS 2 MESSAGE MONITOR. If scan tool displays any other modules as ACTIVE, go to «DLC DIAGNOSIS OR NO SCAN TOOL DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) . If scan tool does not display any other modules as ACTIVE, check scan tool connection. Check circuits between DLC and control module which does not communicate with scan tool. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
4. Attempt to start engine. If engine starts and continues to run, go to step 6 . If engine does not start or starts and then stalls, go to next step.
5. Using scan tool, check for DTCs. If DTC P1626 or P1631 is present, diagnose using appropriate test for DTC P1626 or P1631. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If no DTCs are present, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
6. Using scan tool, monitor COLUMN LOCK parameters: FUEL DISABLE-BCM DTC, PCM-BCM COM and FUEL DISABLE-ABS DTC. If any of the listed parameters indicate a problem with column lock system, diagnose body control system and/or anti-lock brake system. If no problem is indicated, go to next step.
7. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTC is stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, go to next step.
8. Compare scan tool engine data with typical control system data values. If data values are within limits, see appropriate TROUBLE SHOOTING - NO CODES article. If data values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. If MIL is illuminated, go to next step. If MIL is not illuminated, go to step 4 .
3. Check for poor connections at battery feed circuit and ignition positive voltage 2 circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. After repairs, go to step 22 . If circuits are okay, go to step 5 .
4. Attempt to start engine. If engine starts, go to step 6 . If engine does not start, go to step 7 .
5. Check for poor PCM ground connections at PCM and engine block. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. After repairs, go to step 22 .
6. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a test light connected to ground, probe MIL control circuit at PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If MIL illuminates, go to step 8 . If MIL does not illuminate, go to step 9 .
7. Check ignition and battery feed fuses. If fuses are okay, go to step 10 . If fuses are open, go to step 11 .
8. Check for poor battery feed, ignition positive voltage 2 or MIL control circuit connections. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. After repairs, go to step 22 . If circuits are okay, go to step 12 .
9. If test light illuminates, go to step 13 . If test light does not illuminate, go to step 14 .
10. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a test light connected to ground, probe ignition positive voltage 2 circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 15 . If test light does not illuminate, go to step 16 .
11. Check for short to ground in fuse circuit that was open. Repair as necessary and replace fuse. After repairs, go to step 22 .
12. Replace PCM. Perform PCM relearn procedures. After repairs, go to step 22 .
13. Repair short to voltage in MIL control circuit. After repairs, go to step 22 .
14. Check for open or poor connection in MIL control circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. After repairs, go to step 22 . If circuit is okay, go to step 17 .
15. Using a test light connected to ground, probe PCM battery positive feed circuit at PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 18 . If test light does not illuminate, go to step 19 .
16. Repair open in ignition positive voltage 2 circuit. After repairs, go to step 22 .
17. Check for open in battery positive or ignition positive voltage 2 circuits. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. After repairs, go to step 22 . If circuits are okay, go to step 20 .
18. Check for poor connections at battery positive voltage or ignition positive voltage 2 circuit. Repair as necessary. After repairs, go to step 22 . If circuits are okay, go to step 21 .
19. Repair open in PCM battery positive voltage circuit. After repairs, go to step 22 .
20. Replace Instrument Panel Cluster (IPC). After IPC replacement, go to step 22 .
21. Check for poor PCM ground connections at PCM and engine block. Repair as necessary. After repairs, go to next step. If connections are okay, go to step 12 .
22. Start engine and allow it to reach normal operating temperature. Using scan tool, check for DTCs. If DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, system is okay.

Note. After any repairs are completed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 6 .
3. Check instrument cluster ignition feed fuse. If fuse is okay, go to next step. If fuse is open, go to step 15 .
4. Turn ignition on. Using a test light connected to ground, backprobe ignition feed circuit at instrument cluster harness connector . See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
5. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a fused jumper wire, jumper MIL driver circuit at PCM harness connector to ground. See appropriate wiring diagram in WIRING DIAGRAMS article. If MIL illuminates, go to step 10 . If MIL does not illuminate, go to step 11 .
6. Check PCM ignition feed and battery feed fuses. If fuses are okay, go to next step. If fuses are open, go to step 14 .
7. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit at PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
8. Using a test light connected to ground, probe battery feed circuit at PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
9. Check for poor PCM ground or PCM ground connection. Repair as necessary. If ground and ground connection are okay, go to next step.
10. Check for poor PCM harness connection. Repair as necessary. If connection is okay, go to step 16 .
11. Check for open in MIL driver circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, go to step 17 .
12. Repair open in ignition feed circuit to instrument cluster. Repair as necessary.
13. Locate and repair open in PCM battery feed circuit or PCM ignition feed circuit. Repair as necessary.
14. Locate and repair short to ground in PCM battery feed circuit or PCM ignition feed circuit. Repair as necessary.
15. Locate and repair short to ground in instrument cluster ignition feed circuit. Repair as necessary.
16. Replace PCM. Perform PCM relearn procedures.
17. Check MIL driver circuit for poor connection at instrument cluster. Repair as necessary. If connection is okay, diagnose instrument cluster.

Note. After any repairs are completed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Using scan tool, check for DTCs. If any DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If no DTCs are present, go to next step.
3. Check fuses for PCM battery and ignition feed circuits. If fuses are okay, go to next step. If fuses are open, go to step 9 .
4. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
5. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit at PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
6. Using a test light connected to ground, probe battery feed circuit at PCM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
7. Check for poor PCM ground or PCM ground connection. Repair as necessary.
8. Locate and repair open in PCM battery feed or ignition feed circuits. Repair as necessary.
9. Locate and repair short to ground in PCM battery feed or ignition feed circuits. Repair as necessary.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Turn engine off for 15 seconds. Turn ignition on, with engine off. If MIL illuminates, go to next step. If MIL does not illuminate, go to step 5 .
3. Using scan tool, command MIL on and off. If MIL turns on and off as commanded, see appropriate TROUBLE SHOOTING - NO CODES article. If MIL does not turn on and off as commanded, go to next step.
4. Turn ignition off. Disconnect VCM harness connector C4. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on. If MIL does not illuminate, go to step 19 . If MIL illuminates, go to step 13 .
5. Check for open gauge, battery or ignition feed fuses. If any fuses are open, go to step 14 . If all fuses are okay, go to next step.
6. Turn ignition off. Disconnect VCM harness connector C4. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on, with engine off. Using a fused jumper wire connected to ground, probe MIL control circuit at VCM harness connector C4. If MIL illuminates, go to step 16 . If MIL does not illuminate, go to next step.
7. Check fused jumper wire. If fuse is open, go to step 15 . If fuse is okay, go to next step.
8. Check for open in MIL control circuit. Repair as necessary. After repairs, go to step 20 . If circuit is okay, go to next step.
9. Check for open in circuit between MIL and GAUGE fuse (10-amp). Repair as necessary. After repairs, go to step 20 . If circuit is okay, go to next step.
10. Check for faulty MIL bulb. Repair as necessary. After repairs, go to step 20 . If MIL bulb is okay, go to next step.
11. Check harness connections at instrument cluster. Repair as necessary. After repairs, go to step 20 . If harness connections are okay, go to next step.
12. Replace instrument cluster. After repairs, go to step 20 .
13. Repair short to ground in MIL control circuit. After repairs, go to step 20 .
14. Check for a short to ground in circuit associated with circuit of open fuse. Repair as necessary. Replace open fuse. After repairs, go to step 20 .
15. Repair short to voltage in MIL control circuit between MIL and VCM. After repairs, go to step 20 .
16. Disconnect VCM harness connector C3. See appropriate wiring diagram in WIRING DIAGRAMS article. Using a test light connected to ground, probe both VCM ground circuits at VCM harness connector. If test light illuminates at both circuits, go to step 18 . If test light does not illuminate at both circuits, go to next step.
17. Repair open in VCM ground circuit. After repairs, go to step 20 .
18. Check for poor connections at VCM. Repair as necessary. After repairs, go to step 20 . If connections are okay, go to next step.
19. Replace VCM. Perform appropriate relearn procedures for VCM, CKP and anti-theft systems. After repairs, go to next step.
20. Turn ignition off for 15 seconds. Turn ignition on, with engine off. If MIL illuminates, go to next step. If MIL does not illuminate, go to step 2 .
21. Using scan tool, command MIL on and off. If MIL turns on and off as commanded, system is okay. If MIL does not turn on and off as commanded, go to step 2 .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. If MIL illuminates, go to next step. If MIL does not illuminate, go to «MIL INOPERATIVE»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Connect scan tool. Using scan tool, command MIL on and off. If MIL turns on and off as commanded, go to step 8 . If MIL does not turn on and off as commanded, go to next step.
4. Turn ignition off. Disconnect PCM connectors. Turn ignition on. If MIL does not illuminate, go to step 7 . If MIL illuminates, go to next step.
5. Check for short to ground in MIL control circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to next step.
6. Replace instrument cluster. After repairs, go to step 8 .
7. Replace PCM. Perform PCM relearn procedures. After repairs, go to next step.
8. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to step 1 .
9. Allow engine to reach normal operating temperature. Using scan tool, check for DTCs. If DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, system is okay.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. If MIL illuminates, go to next step. If MIL does not illuminate, go to «MIL INOPERATIVE»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction) .
3. Connect scan tool. If scan tool powers up, go to next step. If scan tool does not power up, go to step 6 .
4. Using scan tool, attempt to communicate with Body Control Module (BCM) and Electronic Brake Control Module (EBCM). If scan tool communicates with both control modules, go to step 11 . If scan tool does not communicate with both control modules, go to next step.
5. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on, with engine off. Using scan tool, attempt to communicate with BCM and EBCM. If scan tool communicates with both control modules, go to step 13 . If scan tool does not communicate with both control modules, go to step 12 .
6. Using a DVOM, measure voltage between ground and DLC battery feed circuit at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is near battery voltage, go to next step. If voltage is not as specified, go to step 8 .
7. Using a DVOM, measure voltage between battery positive and both DLC ground circuits at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is near battery voltage at both circuits, go to step 9 . If voltage is not as specified, go to step 10 .
8. Repair poor connection, open or short to ground in battery feed circuit. After repairs, go to step 17 .
9. Check for open battery feed fuse and poor connections at DLC. Repair as necessary. After repairs, go to step 17 . If no problem is found, go to step 14 .
10. Repair open or poor connections in DLC ground circuits. After repairs, go to step 17 .
11. Check class 2 serial data line for an open or poor connection between PCM and circuit splice. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. After repairs, go to step 17 . If circuit is okay, go to step 13 .
12. Check class 2 serial data line for an open, short to power, short to ground or poor connection between PCM and DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. After repairs, go to step 17 . If circuit is okay, go to step 14 .
13. Turn ignition off. Replace PCM. Perform PCM relearn procedures. After repairs, go to step 16 .
14. Install scan tool on another vehicle equipped with class 2 serial data and check for proper operation. If scan tool operates properly, go to appropriate TROUBLE SHOOTING - NO CODES article. If scan tool does not operate properly, go to next step.
15. Scan tool is malfunctioning. Refer to scan tool manufacturer's instructions. After repairs, go to step 17 .
16. Ensure PCM and CKP relearn procedures were performed if PCM was replaced. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and then stalls, go to step 2 .
17. Allow engine to reach normal operating temperature. Using scan tool, check for DTCs. If DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, system is okay.

Note. Perform On-Board Diagnostic (OBD) system check after completing any repairs. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Install scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to step 8 .
3. Attempt to start engine. If engine starts and continues to run, go to step 11 . If engine does not start, or starts and then stalls, go to next step.
4. Turn ignition off. Disconnect ECM harness connectors. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit at ECM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 6 .
5. Using a test light connected to battery positive, probe ground circuits at ECM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates for all ground circuits, go to step 15 . If test light does not illuminate for all ground circuits, go to step 7 .
6. Repair ignition feed circuit.
7. Repair short to ground in affected circuit.
8. Disconnect scan tool. Using a test light connected to chassis ground, probe battery feed circuit at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
9. Using a test light connected to battery positive, probe both ground circuits at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates for both ground circuits, go to step 17 . If test light does not illuminate for both ground circuits, go to step 13 .
10. Repair battery feed circuit to DLC.
11. Disconnect scan tool. Using a test light connected to battery positive, probe DLC ground circuits. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates for both ground circuits, go to next step. If test light does not illuminate for both ground circuits, go to step 13 .
12. Check for open, short to ground or short to voltage in serial data circuit. Repair as necessary. If circuit is okay, go to step 14 .
13. Repair open or high resistance in DLC ground circuits.
14. Connect scan tool to another vehicle and check for proper operation. If scan tool operates properly, go to next step. If scan tool does not operate properly, go to step 17 .
15. Check ECM for proper terminal tension or poor connections. Repair as necessary. If terminals and connections are okay, go to next step.
16. Replace ECM. Perform ECM relearn procedures.
17. Replace faulty scan tool.

3.1L, 3.4L & 3.8L

Note. Perform On-Board Diagnostic (OBD) system check after completing any repairs. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Connect a test light between DLC battery feed circuit and ground circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 4 . If test light does not illuminate, go to next step.
3. Using a test light connected to ground, probe DLC battery feed circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 10 .
4. Turn ignition on, with engine off. Using DVOM connected to ground, probe class 2 serial data circuit at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. DVOM should read zero volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 7 .
5. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on, with engine off. Using DVOM connected to battery positive, probe class 2 serial data circuit at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. DVOM should read zero volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8 .
6. Check for open in class 2 serial data circuit between DLC and PCM. Repair as necessary. If circuit is okay, go to step 11 .
7. Check for short to voltage in class 2 serial data circuit. Repair as necessary. If circuit is okay, go to step 11 .
8. Locate and repair short to ground in class 2 serial data circuit.
9. Locate and repair open in DLC ground circuits.
10. Locate and repair open or short to ground in DLC battery feed circuit.
11. Replace PCM. Perform PCM relearn procedures.

Note. Perform On-Board Diagnostic (OBD) system check after completing any repairs. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Check all PCM power and ground connections and circuits. Repair as necessary. If connections and circuits are okay, go to next step.
3. Ensure battery is fully charged. Using DVOM, measure voltage between DLC battery feed circuit and DLC ground circuits. See appropriate wiring diagram in WIRING DIAGRAMS article. Voltage reading for both circuits should be 10 volts or greater. If voltage is as specified, go to step 7 . If voltage is not as specified, go to next step.
4. Using DVOM, measure voltage between ground and DLC battery feed circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Voltage reading should be 10 volts or greater. If voltage is as specified, go to next step. If voltage is not as specified, go to step 6 .
5. Repair open in DLC ground circuit that had low or no voltage. After repairs, go to step 7 .
6. Repair open or short to ground in DLC battery feed circuit. Replace open fuse as necessary. After repairs, go to next step.
7. Turn ignition on. If scan tool displays PCM data, perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . If scan tool does not display PCM data, go to next step.
8. Connect scan tool to another vehicle and check for proper operation. If scan tool operates properly, go to next step. If scan tool does not operate properly, go to step 13 .
9. Reconnect scan tool to original vehicle and enter fluid life information. Turn ignition off and wait 30 seconds. Disconnect PCM harness connector C1. Using DVOM, measure resistance of class 2 serial data circuit between PCM and DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If resistance is greater than 5 ohms, go to step 11 . If resistance is not greater than 5 ohms, go to next step.
10. Disconnect Remote Accessory Control (RAC) module harness connector. Using DVOM, measure resistance of DLC class 2 serial data circuit to ground. See appropriate wiring diagram in WIRING DIAGRAMS article. If resistance is less than 10,000 ohms, go to step 12 . If resistance is 10,000 ohms or greater, go to step 14 .
11. Repair open in class 2 serial data circuit.
12. Repair short to ground in class 2 serial data circuit.
13. Replace faulty scan tool.
14. Reconnect PCM harness connectors. Check for PCM data with RAC module disconnected. If scan tool displays PCM data, go to step 17 . If scan tool does not display PCM data, go to next step.
15. Check connections at PCM harness connector C1. Repair as necessary. If connections are okay, go to next step.
16. Replace PCM. Perform PCM relearn procedures.
17. Replace RAC module.

Note. Perform On-Board Diagnostic (OBD) system check after completing any repairs. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Connect scan tool to a known-good vehicle. If scan tool displays VCM data, go to step 4 . If scan tool does not display VCM data, go to next step.
3. Repair scan tool or scan tool cables.
4. Reconnect scan tool to original vehicle. If scan tool powers up, go to next step. If scan tool does not power up, go to step 9 .
5. Using scan tool, select correct vehicle application. If vehicle information is correct, go to next step. If vehicle information is not correct, perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) .
6. Turn ignition on. Using scan tool, monitor class 2 serial data. If any modules on serial data circuit are communicating, go to step 13 . If no modules communicate, go to next step.
7. Turn ignition off. Disconnect components sharing serial data circuit, leaving VCM connected. Turn ignition on, with engine off. If scan tool displays VCM data, diagnose class 2 serial data circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If scan tool does not display VCM data, go to next step.
8. Turn ignition off. Disconnect VCM harness connector C4. See appropriate wiring diagram in WIRING DIAGRAMS article. Using a test light connected to battery positive, probe class 2 serial data circuit at DLC (terminal No. 2). If test light illuminates, go to step 20 . If test light does not illuminate, go to step 13 .
9. Using a test light connected to ground, probe battery positive feed circuit at DLC (terminal No. 16). See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
10. Using a test light connected to battery positive, probe ground circuit at DLC (terminal No. 4). See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 16 .
11. Using a test light connected to battery positive, probe ground circuit at DLC (terminal No. 5). See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step 18 . If test light does not illuminate, go to step 16 .
12. Inspect fuse associated with battery feed circuit. If fuse is open, go to step 14 . If fuse is okay, go to step 15 .
13. Check for open or poor connection in class 2 serial data circuit. If a problem is found, go to step 17 . If circuit is okay, go to step 19 .
14. Check for short to ground in battery feed circuit. Repair as necessary and replace fuse. After repairs, go to step 23 .
15. Repair open in battery feed circuit. After repairs, go to step 23 .
16. Repair open in DLC ground circuit. After repairs, go to step 23 .
17. Repair open or poor connection in class 2 serial data circuit. After repairs, go to step 23 .
18. Check for poor connections at DLC. If a problem is found, go to step 21 . If connections are okay, see appropriate TROUBLE SHOOTING - NO CODES article.
19. Check class 2 serial data circuit for poor connections at VCM and DLC. If a problem is found, go to step 21 . If circuit connections are okay, go to step 22 .
20. Repair short to ground in class 2 serial data circuit. After repairs, go to step 23 .
21. Repair circuit as necessary. After repairs, go to step 23 .
22. Replace VCM. Perform VCM, Passlock® and CKP system relearn procedures. After repairs, go to next step.
23. Using scan tool, check for DTCs. If any additional DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If no DTCs are present, system is okay.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Check all PCM power and ground connections and circuits. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If connections and circuits are okay, go to next step.
3. Ensure battery is fully charged. Using DVOM, measure voltage between DLC battery feed circuit and DLC ground circuits. See appropriate wiring diagram in WIRING DIAGRAMS article. Voltage reading for both circuits should be 10 volts or greater. If voltage is as specified, go to step 7 . If voltage is not as specified, go to next step.
4. Using DVOM, measure voltage between ground and DLC battery feed circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Voltage reading should be 10 volts or greater. If voltage is as specified, go to next step. If voltage is not as specified, go to step 6 .
5. Repair open in DLC ground circuit that had low or no voltage. After repairs, go to step 7 .
6. Repair open or short to ground in DLC battery feed circuit. Replace blown fuse as necessary. After repairs, go to next step.
7. Turn ignition on. If scan tool displays PCM data, perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . If scan tool does not display PCM data, go to next step.
8. Connect scan tool to another vehicle and check for proper operation. If scan tool operates properly, go to next step. If scan tool does not operate properly, go to step 13 .
9. Reconnect scan tool to original vehicle and enter on-board diagnostics. If on-board diagnostics is entered, go to next step. If on-board diagnostics cannot be entered, diagnose vehicle computer system.
10. Using on-board diagnostics display, check all control modules for DTCs. If DTCs are present, diagnose DTCs. See DIAGNOSTIC TESTS in appropriate TESTS W/CODES article. If DTCs are not present, go to next step.
11. Check for open in class 2 serial data circuit between DLC and PCM. Repair as necessary. If circuit is okay, go to next step.
12. Check DLC terminal connection. Repair as necessary. Exit on-board diagnostics. Reconnect scan tool. If scan tool displays PCM data, perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . If scan tool does not display PCM data, go to step 14 .
13. Replace faulty scan tool.
14. Replace PCM. Perform PCM relearn procedures.

Note. Perform On-Board Diagnostic (OBD) system check after completing any repairs. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Connect scan tool. Turn ignition on, with engine off. If scan tool powers up, go to next step. If scan tool does not power up, go to step 5 .
3. Attempt to start engine. If engine starts and continues to run, go to step 6 . If engine does not start, go to next step.
4. If engine starts and then stalls, go to step 12 . If engine does not start and then stall, go to step 9 .
5. Disconnect scan tool. Turn ignition on, with engine off. Using a test light connected to ground, probe battery positive feed circuit at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 16 .
6. Using test light connected to battery positive, probe both ground circuits at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates for both circuits, go to next step. If test light does not illuminate for both circuits, go to step 8 .
7. Check for poor terminal connections at DLC. Repair as necessary. If connections are okay, go to step 12 .
8. Repair open ground circuit to DLC.
9. Turn ignition off. Disconnect PCM harness connector C1. See appropriate wiring diagram in WIRING DIAGRAMS article. Turn ignition on, with engine off. Using a test light connected to ground, probe PCM battery and PCM ignition feed circuits at PCM harness connector. If test light illuminates for each circuit, go to next step. If test light does not illuminate for each circuit, go to step 14 .
10. Turn ignition off. Disconnect PCM harness connector C2. See appropriate wiring diagram in WIRING DIAGRAMS article. Using DVOM, measure resistance between battery ground and each ground circuit at PCM harness connector. If resistance is 0-2 ohms for each circuit, go to next step. If resistance is not as specified, go to step 15 .
11. Check PCM for poor harness connections. Repair as necessary. If connections are okay, go to step 13 .
12. Check class 2 serial data circuit for an open or poor connection. Repair as necessary. If circuit is okay, go to next step.
13. Replace PCM. Perform PCM relearn procedures.
14. Repair circuit that did not illuminate test light.
15. Repair faulty PCM ground circuits.
16. Repair faulty battery positive feed circuit.

5.7L (VIN G)

Note. Perform On-Board Diagnostic (OBD) system check after completing any repairs. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Connect scan tool. If scan tool powers up, go to next step. If scan tool does not power up, go to step 5 .
3. Turn ignition off for 15 seconds. Immediately attempt to start engine. If engine is not cranked within 5 seconds after ignition is turned on, misdiagnosis could occur. If engine starts and then stalls after about 5 seconds, see appropriate BODY CONTROL MODULE article in ACCESSORIES & EQUIPMENT. If engine does not start and stall after about 5 seconds, go to next step.
4. If engine cranks but does not start, go to step 9 . If engine starts and continues to run, go to step 13 .
5. Disconnect scan tool. Turn ignition on, with engine off. Using a test light connected to ground, probe battery positive feed circuit at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 16 .
6. Using a test light connected to battery positive, probe both ground circuits at DLC. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates for both circuits, go to next step. If test light does not illuminate for both circuits, go to step 8 .
7. Inspect scan tool connections at DLC. Also, inspect DLC terminals for proper tension. Repair as necessary.
8. Repair open in ground circuits to DLC.
9. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a test light connected to battery ground, probe all PCM battery and PCM ignition feed circuits at PCM harness connectors. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates for each circuit, go to next step. If test light does not illuminate for each circuit, go to step 14 .
10. Using DVOM, measure resistance between battery ground and PCM ground circuits at PCM harness connectors. See appropriate wiring diagram in WIRING DIAGRAMS article. If resistance is equal to or less than 2 ohms for each circuit, go to next step. If resistance is not less than 5 ohms for each circuit, go to step 15 .
11. Check PCM for proper connections. Repair as necessary. If connections are okay, go to next step.
12. Replace PCM. Perform PCM relearn procedures.
13. Repair open in class 2 serial data circuit between splice pack and PCM.
14. Repair circuit that did not illuminate test light.
15. Repair faulty PCM ground circuits.
16. Repair faulty battery positive feed circuit.

DIAGNOSTIC TROUBLE CODE (DTC) DEFINITION

Note. Use of Tech 1 or Tech 2 scan tool is required to retrieve DTCs. Refer to user reference manual supplied with scan tool.

TROUBLE CODE DEFINITION - CARS

TROUBLE CODE DEFINITION - TRUCKS

HARD OR INTERMITTENT TROUBLE CODE DETERMINATION

During any diagnostic procedure, determine if DTC(s) are hard failure codes or intermittent failure codes. Diagnostic procedures will not always help analyze intermittent codes. To determine hard codes and intermittent codes

1. Enter diagnostic mode. Read and record all stored DTCs. Exit diagnostic mode and clear DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES (DTCS)»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__clearing-diagnostic-trouble-codes-dtcs) .
2. Apply parking brake and place transmission in Neutral or Park. Block drive wheels and start engine. MIL should turn off. Allow engine to reach normal operating temperature and continue to run for 2 minutes and note MIL.
3. If MIL illuminates, enter diagnostic mode. Read and record DTCs. This will reveal hard failure codes. Oxygen sensor related DTCs may require a road test to reset hard failures after DTCs were cleared.
4. If MIL does not illuminate, all stored DTCs were intermittent failures.

Note. DTCs will be recorded at various operating times. Some DTCs require operation of that sensor or switch for 5 seconds; others require operation for 5 minutes or longer at normal operating temperature, vehicle speed and load. Therefore, some DTCs may not set in a service bay operational mode and may require road testing vehicle in order to duplicate conditions under which code will set.

CLEARING DIAGNOSTIC TROUBLE CODES (DTCS)

To clear DTCs from memory, use scan tool, following scan tool manufacturer's instructions. Codes may also be cleared by disconnecting power supply to ECM/PCM/VCM for at least 30 seconds.

ECM/PCM/VCM LOCATION

On most models, ECM/PCM/VCM is located behind right or left side of dash, behind right or left kick panel, or on left or right side of engine compartment. For a more precise location, see COMPONENT LOCATIONS in appropriate SYSTEM & COMPONENT TESTING article.

Diagnostic Aids

Diagnostic aids are additional tips used to help diagnose trouble codes when inspected circuit is okay. Diagnostic aids may help lead to a definitive solution to trouble code problem.

SPECIAL TOOLS (DIAGNOSTIC)

Note. For scan data values, refer to scan tool manufacturer owner's manual or compare values with a known-good component or vehicle.

Note. A scan tool connected to DLC is used to read DTCs and check voltages in system on serial data line. A scan tool is required to retrieve vehicle information.

Computerized engine control system is most easily diagnosed using scan tool; however, other tools may aid in diagnosing problems. These tools are a tachometer, test light, ohmmeter, digital voltmeter with a 10-megohm input impedance (minimum), vacuum pump, vacuum gauge, fuel injector test light, and jumper wires with appropriate terminal ends and length. A test light, rather than a voltmeter, must be used when indicated by a diagnostic test. In addition, special jumper harnesses or testers may be required by manufacturer to facilitate diagnosis.

SCAN TOOL USAGE

Note. Before connecting scan tool to vehicle, diagnostic system should be checked to determine if system is operating properly and if information received will be accurate. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . If vehicle does not pass OBD system check, information received may be invalid.

Scan tool is a specialized tester which, when connected to DLC, can be used to diagnose on-board computer control systems by providing instant access to circuit voltage information without need to crawl under dash or hood to backprobe sensors and connectors.

Scan tool reduces diagnostic time dramatically by furnishing input data (voltage signals) which can be compared to specification parameters. They may also furnish information on output device (solenoids and motors) status. However, status parameters only indicate output signals have been sent to devices by ECM/PCM/VCM; they do not indicate whether devices have responded properly to signal. Verify proper response at output device using a voltmeter or test light.

A problem may exist even if DTCs are not present. About 80 percent of driveability problems occur without setting DTCs. Sensors that are out of calibration will not set a DTC but will cause driveability problems.

Using a scan tool is the easiest method of checking sensor specifications and other data parameters. Scan tool is also useful in finding intermittent wiring problems by wiggling wiring harnesses and connections (key on, engine off) while observing data parameters.

Note. If erroneous voltage signals are suspected, verify tester information using a digital voltmeter and wiring schematic. If non-existent codes are displayed, DO NOT use scan tool for diagnosis. Contact tester manufacturer for additional information.

SUMMARY

If no hard fault codes are present, driveability symptoms exist or intermittent DTC(s) exist, proceed to appropriate TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

PCM PIN VOLTAGE CHARTS

Note. Manufacturer does not supply PCM pin voltages. For PCM connector terminal identification, refer to appropriate WIRING DIAGRAMS article.

See also:
• P0100
• P0135
• P0205
• P0352
• P0453
• P0704
• P1275
• P1537
• MODEL IDENTIFICATION (CARS)
• DIAGNOSTIC PROCEDURE
• ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK
• HARD OR INTERMITTENT TROUBLE CODE DETERMINATION
• SCAN TOOL USAGE
• DIAGNOSTIC TROUBLE CODE (DTC) DEFINITION
• CLEARING DIAGNOSTIC TROUBLE CODES (DTCS)