Engine Controls - Tests W/codes Buick Riviera VIII

INTRODUCTION

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 checks and inspections covered in appropriate BASIC TESTING article. Failure to do so may result in lost diagnostic time.

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed with DIAGNOSTIC PROCEDURE under SELF-DIAGNOSTIC SYSTEM. If no fault codes are present and driveability problems exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.). If only intermittent codes are present, see INTERMITTENTS in TESTS W/O CODES article.

SELF-DIAGNOSTIC SYSTEM

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

There are 4 types of DTC category

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

HARD FAILURES

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

If a sensor fails, PCM/VCM 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 go out about 10 seconds after intermittent fault goes away. Corresponding DTC, however, will be retained in PCM/VCM memory. If related fault does not reoccur within 50 engine starts, trouble code will be erased from control module memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article.

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 scan tool. See tester operator's manual for additional information.

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

Used to search for a specific type of stored DTC information. There are 7 choices in this mode. Technician may be instructed to test DTC(s) 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.

DTC STATUS

This selection will display any DTC(s) 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. DTC test which run and passed will cause that affected DTC to be removed from scan tool screen.

FAIL THIS IGN.

This selection will display all DTCs that have failed during the present ignition cycle.

HISTORY

This selection will display only DTC(s) that are stored in the control module's history memory. It will not Type "B" 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.

LAST TEST FAIL

This selection will display only DTCs that have failed the last time the test ran. The last test may have ran during the previous ignition cycle, if a type "A" or "B" DTC is displayed. For type "C" DTCs, the last failure must have occurred during the current ignition cycle to be displayed as LAST TEST FAIL.

MIL REQUEST

This selection will display only DTCs that are requesting the MIL. Type "C" DTCs cannot be displayed using this option. This selection will report type "B" DTCs only after the MIL has been requested.

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.

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.

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.

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.

NOT RUN THIS IGN.

Not Run This Ignition message indicates the selected diagnostic test has not run this ignition cycle.

TEST RAN AND PASSED

This message indicates the selected diagnostic test has

1. Passed the last test.
2. Ran and passed during this ignition cycle.
3. Ran and passed since DTCs were last cleared.
4. Test has not failed since DTCs were last cleared.

If this message is displayed, repair is done. 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 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 appropriate OBD SYSTEM CHECK procedure in appropriate BASIC TESTING article.
2. If DTC(s) were displayed, determine whether codes are hard or intermittent trouble codes. Hard codes will cause MIL to illuminate continuously while engine is running. See «HARD OR INTERMITTENT TROUBLE CODE DETERMINATION»(/buick/riviera/viii-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes__hard-or-intermittent-trouble-code-determination) . For diagnosing hard codes, proceed to appropriate DTC test. For diagnosing intermittent codes, proceed to INTERMITTENTS in appropriate TESTS W/O CODES article.
3. If no DTCs are present and a driveability problem exists, refer to SYMPTOMS in appropriate TESTS W/O CODES article. Doing so will help identify proper system or component to check in appropriate SYSTEM/COMPONENT TESTS article.
4. After necessary repairs are made, clear DTCs, verify vehicle will enter "closed loop" operation and ensure DTC does not reset.

READING TROUBLE CODES

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

TROUBLE CODE DEFINITION

TROUBLE CODE DEFINITION

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 (DTC)»(/buick/riviera/viii-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes__clearing-diagnostic-trouble-codes-dtc) .
2. Apply parking brake, and place transmission in Neutral or Park. Block drive wheels, and start engine. MIL should go out. Run warm engine at specified RPM for 2 minutes and note MIL.
3. If MIL comes on, enter diagnostic mode. Read and record DTCs. This will reveal hard failure codes. Oxygen sensor related codes may require a road test to reset hard failure after trouble codes were cleared.
4. If MIL does not come on, all stored DTCs were intermittent failures, except as noted above.

Note. DTCs will be recorded at various operating times. Some codes 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 (DTC)

To clear DTCs from memory, either to determine if malfunction will occur again or after making necessary repairs, disconnect power supply to PCM/VCM for at least 30 seconds or clear codes using a scan tool.

PCM/VCM LOCATION

On most models, 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 more precise location, see COMPONENT LOCATIONS in appropriate SYSTEM/COMPONENT TESTS 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. A scan tool plugged into 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 lights and 6 jumper wires 6" long (one wire with female connectors at both ends, one wire with male connectors at both ends and 4 wires with male and female connectors at opposite ends). 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. This is done by performing DIAGNOSTIC CIRCUIT CHECK or ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK located in appropriate BASIC TESTING article. If vehicle does not pass OBD system check, information received may be invalid.

Scan tool is a specialized tester which, when plugged into 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 cuts down diagnostic time dramatically by furnishing input data (voltage signals) which can be compared to specification parameters. See SCAN DATA . 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 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 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. See SCAN DATA .

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.

SCAN DATA

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

SPECIFICATIONS

MAP SENSOR VOLTAGE (1)

IAT TEMPERATURE-TO-RESISTANCE VALUES

ECT TEMPERATURE-TO-RESISTANCE VALUES

SUMMARY

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

DIAGNOSTIC TROUBLE CODES

Note. In following diagnostic tests, schematics are courtesy of General Motors Corp.

Note. Before clearing DTCs, perform On-Board Diagnostic (OBD) system check. See appropriate BASIC TESTING article. Record FREEZE FRAME and FAILURE RECORDS for reference during testing. Data will be erased when DTCs are cleared.

Note. If VCM/PCM is replaced, NEW VCM/PCM must be programmed using special manufacturer's equipment.

Circuit Description

Mass Airflow (MAF) sensor measures amount of air entering engine during a given time. PCM uses MAF sensor information for fuel delivery calculations. MAF sensor readings during acceleration are much higher than those during deceleration or idle.

PCM calculates what MAF sensor reading should be from sensor under certain conditions using engine speed (RPM), throttle position, and barometric pressure parameters. When these test conditions are met, PCM will compare its calculated MAF value to actual value received from sensor.

Conditions required to set DTC are

1. Vehicle driven at a steady speed.
2. MAF sensor signal higher or lower than predicted value.
3. Listed conditions present for at least 12 seconds.

Diagnostic Procedures

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If DTC P1635 is also set, go to DTC P1635. If DTC is not set, go to next step.
3. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0101 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0101 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
4. Ignition on. Observe MAP and BARO parameter on scan tool. If reading is 65-105 kPa, go to next step. If not, go to step 8).
5. Start engine. Observe MAP sensor display on scan tool with engine idling. If display is 29-48 kPa, go to next step. If not, go to step 7).
6. Observe MAP sensor display on scan tool while slowly increasing engine speed to 3000 RPM. If MAP value increases with increase in RPM, go to step 9). If not, go to step 8).
7. Check for throttle body inlet screen blockage. Check for vacuum leaks at intake manifold, throttle body, or EGR valve flange and pipes. Check for PCV valve faulty, missing or incorrectly installed. Repair faulty conditions as necessary and go to step 22). If no faulty conditions exist, go to step 9).
8. Replace MAP sensor. After repair, go to step 22).
9. Turn ignition on, throttle closed. Using scan tool, read THROTTLE AT IDLE. If scan tool displays YES, go to next step. If scan does not display YES, go to DTC P0121.
10. Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on, engine off. Using a DVOM, check voltage between MAF sensor harness connector signal circuit and chassis ground. If voltage is about 5 volts, go next step. If voltage is not as specified, go to step 12).
11. Connect a test light between MAF sensor harness connector ignition feed and ground circuits. If test light illuminates, go to step 15). If test light does not illuminate, go to step 14).
12. If voltage is less than 4.5 volts, go to step 16). If voltage is 4.5 volts or more, go to next step.
13. Turn ignition off. Disconnect PCM connectors. Turn ignition on, engine off. Check voltage between PCM harness connector MAF signal circuit and chassis ground. If voltage reading is zero volts, go to step 21). If voltage is not zero volts, go to step 19)
14. Connect test light between MAF sensor harness connector ignition feed circuit and chassis ground. If test light illuminates, go to step 17). If test light does not illuminate, go to step 18).
15. Check for faulty connection at MAF sensor. Repair connection as necessary and go to step 22). If connection is okay, go to step 20).
16. Check MAF sensor signal circuit between PCM and MAF sensor for open or short. Repair signal circuit as necessary and go to step 22). If signal circuit is okay, go to step 21).
17. Locate and repair open MAF in the sensor ground circuit and go to step 22).
18. Locate and repair open MAF sensor ignition feed circuit and go to step 22).
19. Locate and repair short to voltage in MAF sensor signal circuit and go to step 22).
20. Replace MAF sensor and go to step 22).
21. Replace PCM. Program PCM using required equipment. Go to next step.
22. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0101. If scan tool displays DTC P0101 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0101 FAILED THIS IGN, repair is complete.

Check for skewed or stuck Throttle Position (TP) sensor. Using scan tool, read TP ANGLE value with throttle closed. If value is not zero percent, check for and repair the following condition(s)

1. Throttle plate sticking or excessive deposits on throttle plate or throttle bore.
2. TP sensor signal circuit shorted to voltage.
3. Faulty connection or high resistance in TP sensor ground circuit.

If none of the listed conditions exist and TP ANGLE value is not zero percent, replace TP sensor.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Check for plugged intake air duct or dirty air filter. A wide-open throttle acceleration from a stop should cause MAF reading on scan tool to increase from about 4-7 grams per second at idle to 100 grams per second or more at time of 1-2 shift. If not, check for restriction.

Check for a skewed MAP sensor, which can cause Barometric (BARO) pressure reading to be incorrectly calculated. This condition may also cause high Idle Air Control (IAC) counts. If IAC counts are high, replace MAP sensor.

DTC P0101 Schematic. Scheme 4

DTC P0102 - MAF SENSOR CIRCUIT LOW FREQUENCY

Note. For circuit reference, see DTC P0101 schematic.

Mass Airflow (MAF) sensor measures amount of air entering engine during a given time. PCM uses MAF sensor information for fuel delivery calculations. MAF sensor readings during acceleration are much higher than those during deceleration or idle.

PCM calculates what MAF sensor reading should be received from sensor under certain conditions using engine speed (RPM), throttle position, and altitude parameters. When these test conditions are met, PCM will compare its calculated MAF value to actual value received from sensor.

1. Engine running.
2. TP sensor angle less than 50 percent.
3. MAF signal frequency less than 1200 Hz.
4. Listed conditions present for greater than 0.5 second, plus 33 crankshaft revolutions.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
2. Start engine. With engine at idle, use scan tool to read MAF FREQUENCY. If frequency is less than 1200 Hz, go to step 4). If frequency is 1002 Hz or greater, go to next step.
3. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0102 FAILED THIS IGN, go to next step. If DTC P0102 FAILED THIS IGN is not displayed, go to DIAGNOSTIC AIDS.
4. Check for MAF sensor inlet screen blockage. Check for vacuum leaks at intake manifold, throttle body or EGR valve flange and pipes. Check for PCV valve faulty, missing or incorrectly installed. Repair faulty conditions as necessary and go to step 14). If no faulty conditions exist, go to next step.
5. Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on, engine off. Using a DVOM, check voltage between MAF sensor harness connector signal circuit and chassis ground. If voltage reading is about 5 volts, go next step. If voltage reading is not about 5 volts, go to step 9).
6. Connect a test light between MAF sensor harness connector ignition feed and ground circuits. If test light illuminates, go to step 8). If test light does not illuminate, go to next step.
7. Connect test light between MAF sensor harness connector ignition feed circuit and battery ground. If test light illuminates, go to step 10). If test light does not illuminate, go to step 11).
8. Check for faulty connection at MAF sensor. Repair connection as necessary and go to step 14). If connection is okay, go to step 12).
9. Check MAF sensor signal circuit between PCM and MAF sensor for open or short. Repair signal circuit as necessary and go to step 14). If signal circuit is okay, go to step 13).
10. Locate and repair open in the MAF sensor ground circuit and go to step 14).
11. Locate and repair open MAF sensor ignition feed circuit and go to step 14).
12. Replace MAF sensor and go to step 14).
13. Replace PCM. Program PCM using required equipment. Go to next step.
14. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0102. If scan tool displays DTC P0102 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0102 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Check for plugged intake air duct or filter element. Check minimum airflow rate as follows

1. Run engine and allow it to reach operating temperature.
2. Disconnect IAC valve and install IAC Driver (J37027).
3. With engine idling, command IAC valve to fully extended position (zero counts).
4. Using scan tool, observe MASS AIRFLOW VALUE.
5. If MAF value is less than 2.27 grams per second on VIN K or less than 2.95 grams per second on VIN 1, clean or replace throttle body as necessary.

DTC P0103 - MAF SENSOR CIRCUIT HIGH FREQUENCY

Note. For circuit reference, see DTC P0101 schematic.

Mass Airflow (MAF) sensor measures amount of air entering engine during a given time. PCM uses MAF sensor information for fuel delivery calculations. MAF sensor readings during acceleration are much higher than those during deceleration or idle.

PCM calculates what MAF sensor reading should be received from sensor under certain conditions using engine speed (RPM), throttle position, and altitude parameters. When these test conditions are met, PCM will compare its calculated MAF value to actual value received from sensor.

1. Engine is running.
2. TP ANGLE is less than 50 percent.
3. MAF signal frequency greater than 10,500 Hz on VIN "K" or more than 11,500 Hz on VIN "1".
4. Listed conditions present more than 0.5 seconds, plus 33 crankshaft revolutions.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine. With engine at idle, use scan tool to read MAF FREQUENCY. If frequency is more than 10,500 Hz on VIN "K" or more than 11,500 Hz on VIN "1", go to step 4). If frequency is less than specified, go to next step.
3. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0103 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0103 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
4. Turn ignition off. Disconnect MAF sensor harness connector. Turn engine on and allow it to idle. Using scan tool, read MAF FREQUENCY. If frequency is zero Hz, go to next step. If frequency is not as specified, go to step 7).
5. Check for faulty connection at MAF sensor. Repair connection as necessary and go to step 10). If connection is okay, go to next step.
6. Replace MAF sensor and go to step 10).
7. Ensure MAF sensor harness is not routed too close to high-voltage wires, such as spark plug cables, ignition coils or other high voltage components. Reroute harness if necessary and go to step 10). If harness routing is okay, go to next step.
8. Check MAF sensor signal circuit connection at PCM. Repair connection as necessary and go to step 10). If connection is okay, go to next step.
9. Replace PCM. Program replacement PCM using required equipment. Go to next step.
10. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0103. If scan tool displays DTC P0103 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0103 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Manifold Absolute Pressure (MAP) sensor measures changes in intake manifold pressure (vacuum). A low voltage signal, 2 volts, is sent to PCM on signal circuit at closed throttle (high vacuum). A high voltage signal, 4 volts is sent at wide open throttle (low vacuum). A substantial change in MAP signal should be preceded by a change in throttle position.

Conditions required to test for DTC are

1. A/C off
2. Vehicle driven at a steady speed without stepping on brake.
3. No IAC or TP sensor DTCs are set.
4. No EGR system DTCs are set.
5. Listed conditions present for more than 67 crankshaft revolutions.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0106 FAILED THIS IGN, go to step 4). If scan tool does not display DTC P0106 FAILED THIS IGN, go to next step.
3. Check for MAP sensor seal missing or damaged, or vacuum hoses disconnected, damaged or incorrectly routed. Check for vacuum leaks at intake manifold, throttle body, or at EGR valve flange or pipes. Check for faulty, missing or incorrectly installed PCV valve. If a problem is found, repair as necessary and go to step 15). If no problem is found, go to DIAGNOSTIC AIDS.
4. Disconnect MAP sensor harness connector. Using scan tool, read MAP SENSOR VALUE. If value is about zero volts, go to next step. If value is not as specified, go to step 13).
5. Connect a test light between battery voltage and MAP sensor harness connector signal circuit. Using scan tool, read MAP SENSOR VALUE. If value is about 4.95 volts, go to next step. If value is not as specified, go to step 9).
6. Connect a jumper wire between MAP sensor harness connector 5-volt reference and signal circuits. Using scan tool, read MAP SENSOR VALUE. If value is about 4.95 volts, go to next step. If value is not as specified, go to step 8).
7. Turn ignition off. Disconnect PCM connectors. Check sensor ground circuit for high resistance or an open between PCM and MAP sensor. Check for faulty connection at PCM. If a problem is found, repair as necessary and go to step 15). If no problem is found, go to step 11).
8. Check 5-volt reference circuit for high resistance or an open between PCM and MAP sensor. Check for faulty connection at PCM. If a problem is found, repair as necessary and go to step 15). If no problem is found, go to step 10).
9. Turn ignition off. Disconnect PCM connectors. Check MAP sensor signal circuit for high resistance, an open, a short to ground, or a short to sensor ground circuit. If a problem is found, repair as necessary and go to step 15). If no problem is found, go to next step.
10. Check MAP sensor signal circuit for faulty connection at PCM. If a problem is found, repair as necessary and go to step 15). If connection is okay, go to step 14).
11. Check for faulty connection at MAP sensor. If a problem is found, repair as necessary and go to step 15). If connection is okay, go to next step.
12. Replace MAP sensor and go to step 15).
13. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Check MAP sensor signal circuit for short to voltage or short to 5-volt reference circuit. If problem is found, repair as necessary and go to step 15). If no problem is found, go to next step.
14. Replace PCM. Program replacement PCM using required equipment. Go to next step.
15. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0106. If scan tool displays DTC P0106 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0106 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0106 Schematic. Scheme 5

DTC P0107 - MAP SENSOR CIRCUIT LOW VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Manifold Absolute Pressure (MAP) sensor measures changes in intake manifold pressure (vacuum). A low voltage signal, about 2 volts, is sent to PCM on signal circuit at closed throttle (high vacuum) idle. A high voltage signal, about 4 volts, is sent at wide open throttle (low vacuum).

1. Engine running.
2. TP sensor angle greater than 0% with engine speed less than 1000 RPM, or greater than 6% with engine speed greater than 1000 RPM.
3. MAP sensor signal voltage less than 0.1 volt.
4. No TP sensor DTCs are set
5. Listed conditions present for more than 67 crankshaft revolutions.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read LAST TEST FAIL. If scan tool displays DTC P0107 and DTC P1406, inspect and repair common circuit(s). If scan tool does not display P0107 and DTC P1406, go to next step.
3. Turn ignition off. Turn ignition on, engine off. Using scan tool, read MAP sensor voltage. If voltage is about zero volts, go to step 5). If voltage is not about zero volts, go to next step.
4. With ignition on, engine off, use scan tool to read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0107 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0107 FAILED THIS IGN, see DIAGNOSTIC AIDS.
5. Disconnect MAP sensor harness connector. Connect a jumper wire between MAP sensor harness connector 5-volt reference circuit and signal circuit. If scan tool voltage is about 4.95 volts, go to step 11). If voltage is not about 4.95 volts, go to next step.
6. Turn ignition off. Remove jumper wire. Connect a test light between MAP sensor harness connector signal circuit and battery voltage. Turn ignition on. If voltage is now about 4.95 volts, go to next step. If voltage is not about 4.95 volts, go to step 9).
7. Turn ignition off. Disconnect PCM connectors. Check PCM harness connector 5-volt reference circuit for open or short to ground. If open or short is found, repair as necessary and go to step 13). If no open or short is found, go to next step.
8. Check for faulty connection of 5-volt reference circuit at PCM. If faulty connection is found, repair as necessary and go to step 13). If connection is okay, go to step 12).
9. Turn ignition off. Disconnect PCM connectors. Check PCM harness connector MAP signal circuit for open or short to ground. If open or short is found, repair as necessary and go to step 13). If no open or short is found, go to next step.
10. Check for faulty connection of MAP signal circuit at PCM. If faulty connection is found, repair as necessary and go to step 13). If connection is okay, go to step 12).
11. Replace MAP sensor and go to step 13).
12. Replace PCM. Program replacement PCM using required equipment. Go to next step.
13. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0107. If scan tool displays DTC P0107 FAILED THIS IGN, return to step 3). If scan tool does not display DTC P0107 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0108 - MAP SENSOR CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Manifold Absolute Pressure (MAP) sensor measures changes in intake manifold pressure (vacuum). A low voltage signal, 2 volts, is sent to PCM on signal circuit at closed throttle (high vacuum). A high voltage signal, 4 volts, is sent at wide open throttle (low vacuum).

1. Engine running for predetermined time depending on coolant temperature at start-up. Predetermined time ranges from 0.5 second with ECT more than 86°F (30°C) to 2 minutes with ECT -22°F (-30°C).
2. Engine at idle with engine speed less than 900 RPM.
3. MAP sensor voltage more than 4.2 volts.
4. No TP sensor DTCs are set.
5. Listed conditions present for more than 67 crankshaft revolutions.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read LAST TEST FAIL. If scan tool displays DTC P0123 and DTC P1406, check and repair common circuits. If scan tool does not display P0123 and DTC P1406, go to next step.
3. Correct any engine idle or vacuum problems before proceeding. Turn engine on and allow it to idle. Using scan tool, read MAP sensor voltage. If voltage is more than 3.5 volts, go to step 5). If voltage is 3.5 volts or less, go to next step.
4. With ignition still on, engine off, use scan tool to read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0108 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0108 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
5. Turn ignition off. Disconnect MAP sensor harness connector. Turn ignition on. If voltage is zero volts, go to next step. If voltage is more than zero volts, go to step 7).
6. Connect a test light between MAP sensor harness connector ground circuit and battery voltage. If test light illuminates, go to step 8). If test light does not illuminate, go to step 10).
7. Check MAP sensor harness connector signal circuit for short to voltage. If short to voltage is found, repair as necessary and go to step 17). If short to voltage is not found, go to step 12).
8. Check for faulty connection of ground circuit at MAP sensor. If faulty connection is found, repair as necessary and go to step 17). If connection is okay, go to next step.
9. Check for plugged or leaking vacuum supply to MAP sensor. If vacuum supply is okay, go to step 13). If vacuum supply is not okay, go to step 16).
10. Check for faulty MAP sensor ground circuit connection at PCM. If faulty connection is found, repair as necessary and go to step 17). If connection is okay, go to next step.
11. Check continuity of MAP sensor ground circuit. If resistance is 5 ohms or more, repair circuit as necessary and go to step 17). If resistance is less than 5 ohms, go to step 12).
12. Replace PCM. Program replacement PCM using required equipment. Go to step 17).
13. Turn ignition off. Disconnect PCM connectors. Turn ignition on, engine off. Check PCM harness connector 5-volt reference circuit for short to voltage. If short is found, repair as necessary and go to step 17). If no short is found, go to next step.
14. Check for faulty connection at MAP sensor. If faulty connection is found, repair as necessary and go to step 17). If connection is okay, go to next step.
15. Replace MAP sensor and go to step 17).
16. Repair faulty vacuum source and go to next step.
17. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0108. If scan tool displays DTC P0108 FAILED THIS IGN, return to step 3). If scan tool does not display DTC P0108 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Intake Air Temperature (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 will set when PCM sees an IAT sensor voltage of less than 0.82 volt for 10 seconds after engine runs for 100 seconds.

1. Vehicle driven at 25 MPH or more.
2. No VSS, ECT or MAF sensor DTCs are set.
3. Engine running more than 10 seconds.
4. IAT more than 282°F (139°C).
5. Listed conditions are present for at least 20 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read INTAKE AIR TEMP. If temperature is more than 266°F (130°C), go to step 4). If temperature is 266°F (130°C) or less, go to next step.
3. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0112 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0112 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
4. Disconnect IAT sensor harness connector. Using scan tool, read INTAKE AIR TEMP. If IAT sensor temperature is less than -36°F (-39°C), go to step 6). If temperature is -36°F (-39°C) or more, go to next step.
5. Turn ignition off. Disconnect PCM connectors. Check IAT sensor signal circuit for short to ground. If short is found, go to step 7). If no short is found, go to step 8).
6. Replace IAT sensor and go to step 9).
7. Repair IAT sensor signal circuit and go to step 9).
8. Replace PCM. Program replacement PCM using required equipment. Go to next step.
9. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0112. If scan tool displays DTC P0112 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0112 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed IAT sensor. See IAT TEMPERATURE-TO-RESISTANCE VALUES.

IAT TEMPERATURE-TO-RESISTANCE VALUES

DTC P0112 Schematic. Scheme 6

DTC P0113 - IAT SENSOR CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Intake Air Temperature (IAT) sensor is a thermistor that varies resistance based on temperature. As temperature of sensor increases, resistance decreases. Low temperature will result in a high signal voltage. DTC will set when PCM sees an IAT sensor voltage of greater than 5 volts.

1. Engine running for greater than 3 minutes.
2. Vehicle speed is less than 35 MPH.
3. No ECT or MAF sensor DTCs are set.
4. No VSS DTCs are set.
5. MAF value is less than 12 grams per second.
6. ECT is greater than 140°F (60°C)
7. IAT less than -38°F (-39°C).
8. Listed conditions present for at least 20 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read INTAKE AIR TEMP. If temperature is less than -38°F (-39°C), go to step 4). If temperature is -38°F (-39°C) or greater, go to next step.
3. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0113 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0113 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
4. Disconnect IAT sensor harness connector. Connect a jumper wire between IAT sensor harness connector signal and ground circuits. Using scan tool, read INTAKE AIR TEMP. If temperature is 284°F (140°C), go to step 6). If temperature is not as specified, go to next step.
5. Connect jumper wire between chassis ground and IAT sensor harness connector signal circuit. Using scan tool, read INTAKE AIR TEMP. If temperature is 284°F (140°C), go to step 7). If temperature is not as specified, go to step 8).
6. Check for faulty connection at IAT sensor. If faulty connection is found, repair as necessary and go to step 12). If connection is okay, go to step 10).
7. Turn ignition off. Disconnect PCM connectors. Check IAT sensor ground circuit for an open. If open is found, repair as necessary and go to step 12). If no open is found, go to step 9).
8. Turn ignition off. Disconnect PCM connectors. Check IAT signal circuit for an open. If open is found, repair circuit as necessary and go to step 12). If no open is found, go to next step.
9. Check for faulty IAT signal or ground circuit connection at PCM. If problem is found, repair as necessary and go to step 12). If no problem is found, go to step 11).
10. Replace IAT sensor and go to step 12).
11. Replace PCM. Program replacement PCM using required equipment. Go to next step.
12. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0113. If scan tool displays DTC P0113 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0113 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Check for skewed IAT sensor. See IAT TEMPERATURE-TO-RESISTANCE VALUES.

IAT TEMPERATURE-TO-RESISTANCE VALUES

DTC P0117 - ECT SENSOR CIRCUIT LOW VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Engine Coolant Temperature (ECT) 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 will set when PCM sees an excessively low ECT sensor voltage signal.

1. Engine running greater than 3 seconds.
2. ECT greater than 282°F (139°C).
3. Listed conditions present for at least 10 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read ENG COOL TEMP. If temperature is less than 282°F (139°C), go to step 4). If temperature is 282°F (139°C) or greater, go to next step.
3. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0117 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0117 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect ECT sensor harness connector. Using scan tool, read ENG COOL TEMP. If temperature is -38°F (-39°C), go to step 6). If temperature is not as specified, go to next step.
5. Turn ignition off. Disconnect PCM connectors. Check ECT sensor signal circuit for short to ground. If short is found, repair as necessary and go to step 8). If no short is found, go to step 7).
6. Replace ECT sensor and go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. Go to next step.
8. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0117. If scan tool displays DTC P0117 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0117 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed ECT sensor. See ECT TEMPERATURE-TO-RESISTANCE VALUES table.

ECT TEMPERATURE-TO-RESISTANCE VALUES

DTC P0118 - ECT SENSOR CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Engine Coolant Temperature (ECT) sensor is a thermistor that varies resistance based on temperature. As temperature of sensor increases, resistance decreases. Low temperature will result in a high signal voltage. DTC will set when PCM sees an excessively high ECT sensor voltage signal.

1. Engine running more than 3 seconds.
2. ECT less than -36°F (-38°C).
3. Listed conditions present for at least one minute.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read ENG COOL TEMP. If temperature is -36°F (-38°C) or less, go to step 4). If not, go to next step.
3. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0118 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0118 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
4. Disconnect ECT sensor harness connector. Connect a jumper wire between ECT sensor harness connector signal and ground circuits. Using scan tool, read ENG COOL TEMP. If temperature is 284°F (140°C), go to step 6). If temperature is not as specified, go to next step.
5. Connect jumper wire between chassis ground and ECT sensor harness connector signal circuit. Using scan tool, read ENG COOL TEMP. If temperature is 284°F (140°C), go to step 7). If temperature is not as specified, go to step 8).
6. Check for faulty connection at ECT sensor. If faulty connection is found, repair as necessary and go to step 12). If connection is okay, go to step 10).
7. Turn ignition off. Disconnect PCM connectors. Check ECT sensor ground circuit for an open. If open is found, repair as necessary and go to step 12). If no open is found, go to step 9).
8. Turn ignition off. Disconnect PCM connectors. Check ECT signal circuit for an open. If open is found, repair as necessary and go to step 12). If no open is found, go to next step.
9. Check for faulty ECT signal or ground circuit connection at PCM. If problem is found, repair as necessary and go to step 12). If no problem is found, go to step 11).
10. Replace ECT sensor and go to step 12).
11. Replace PCM. Program replacement PCM using required equipment. Go to next step.
12. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0118. If scan tool displays DTC P0118 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0118 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed ECT sensor. See ECT TEMPERATURE-TO-RESISTANCE VALUES table.

ECT TEMPERATURE-TO-RESISTANCE VALUES

DTC P0121 - TP SENSOR SYSTEM PERFORMANCE

Note. For circuit reference, see DTC P0106 schematic.

Throttle Position (TP) sensor measures amount of throttle opening. PCM uses TP sensor information for fuel delivery calculations. TP sensor readings during acceleration are much higher than those during deceleration or idle.

1. Engine running and throttle steady.
2. No MAP or TP sensor DTCs are set
3. Predicted throttle angle not close to actual throttle angle.
4. Listed conditions present more than 10 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If DTC P1635 is also set, go to that DTC. If not, turn ignition on, engine off. Using scan tool, read MAP value. If value is less than 65 kPa, go to next step. If not, go to step 6).
3. Disconnect MAP sensor harness connector. Connect a test light between MAP sensor harness connector 5-volt reference and signal circuits. Using scan tool, read MAP value. If value is less than 65 kPa, go to step 5). If not, go to next step.
4. Check MAP sensor signal circuit for open or short between PCM and MAP sensor. If problem is found, repair as necessary and go to step 13). If no problem is found, go to step 12).
5. Replace MAP sensor and go to step 13).
6. Observe scan tool TP ANGLE value while moving throttle from closed to wide open throttle. If value increases steadily and evenly from closed to open throttle, go to DIAGNOSTIC AIDS. If value does not increase as specified, go to next step.
7. Disconnect TP sensor harness connector. If TP voltage is zero volts, go to next step. If not, go to step 9).
8. Connect a test light between TP sensor harness connector 5-volt reference and signal circuits. Using scan tool, read TP sensor voltage. If scan tool voltage is 5 volts, go to step 11). If voltage is not as specified, go to step 10).
9. Check TP sensor signal circuit for short to ground, ground circuit for high resistance and poor connection. If a problem is found, repair as necessary and go to step 13). If no problem is found, go to step 12).
10. Check TP sensor 5-volt reference circuit for poor connection or high resistance between PCM and TP sensor. If a problem is found, repair as necessary and go to step 13). If no problem is found, go to step 12).
11. Replace TP sensor and go to step 13).
12. Replace PCM. Program replacement PCM using required equipment. Go to next step.
13. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0117. If scan tool displays DTC P0117 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0117 FAILED THIS IGN, repair is complete.

Check for and repair the following condition(s)

1. Throttle plate sticking or excessive deposits on throttle plate or throttle bore.
2. Check TP sensor harness connector terminals for damage.
3. A steady throttle movement from a stop should cause TP ANGLE value reading on scan tool to increase smoothly as throttle is opened.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed MAP signal or faulty MAP sensor.

DTC P0122 - TP SENSOR CIRCUIT LOW VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Throttle Position (TP) sensor measures amount of throttle opening. PCM uses TP sensor information for fuel delivery calculations. TP sensor readings during acceleration are much higher than those during deceleration or idle.

Condition required to test for DTC is

1. Engine running.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read LAST TEST FAIL. If scan tool displays DTC P0107 and DTC P1406, check and repair common circuits. If scan tool does not display P0107 and DTC P1406, go to next step.
3. Turn ignition off. Turn ignition on, engine off. With throttle closed, use scan tool to read TP sensor voltage. If voltage is less than 0.16 volt, go to step 5). If voltage is 0.16 volt or greater, go to next step.
4. With ignition still on, engine off, use scan tool to read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0122 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0122 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
5. Disconnect TP sensor harness connector. Connect a jumper wire between TP sensor harness connector 5-volt reference and signal circuits. If scan tool voltage is 5 volts, go to step 11). If voltage is not 5 volts, go to next step.
6. Turn ignition off. Remove jumper wire. Connect a test light between TP sensor harness connector signal circuit and battery voltage. If scan tool voltage is 5 volts, go to next step. If voltage is not 5 volts, go to step 9).
7. Turn ignition off. Disconnect PCM connectors. Check PCM harness connector 5-volt reference circuit for open or short to ground. If open or short is found, repair as necessary and go to step 14). If no open or short is found, go to next step.
8. Turn ignition off. Check for faulty connection of 5-volt reference circuit at PCM. If faulty connection is found, repair connection as necessary and go to step 14). If connection is okay, go to step 13).
9. Turn ignition off. Disconnect PCM connectors. Check PCM harness connector TP signal circuit for open or short to ground. If open or short is found, repair as necessary and go to step 14). If no open or short is found, go to next step.
10. Check for faulty connection of TP signal circuit at PCM. If faulty connection is found, repair as necessary and go to step 14). If connection is okay, go to step 13).
11. Check for faulty connection of TP signal circuit at TP sensor. If faulty connection is found, repair as necessary and go to step 14). If connection is okay, go to step 13).
12. Replace TP sensor and go to step 14).
13. Replace PCM. Program replacement PCM using required equipment. Go to next step.
14. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0122. If scan tool displays DTC P0122 FAILED THIS IGN, return to step 3). If scan tool does not display DTC P0122 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0123 - TP SENSOR CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Throttle Position (TP) sensor measures amount of throttle opening. PCM uses TP sensor information for fuel delivery calculations. TP sensor readings during acceleration are much higher than those during deceleration or idle.

1. Ignition on.
2. TP sensor signal voltage more than 4.71 volts.
3. Listed conditions present more than one second.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read LAST TEST FAIL. If scan tool displays DTC P0108 and DTC P1406, check and service common circuits. If scan tool does not display P0108 and DTC P1406, go to next step.
3. Turn ignition on, engine off. Using scan tool, read TP sensor voltage. If voltage is more than 4.71 volts, go to step 5). If voltage is 4.71 volts or less, go to next step.
4. With ignition still on, engine off, use scan tool to read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0123 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0123 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
5. Disconnect TP sensor harness connector. If voltage is about volt, go to next step. If voltage is not as specified, go to step 7).
6. Connect a test light between TP sensor harness connector ground circuit and battery voltage. If test light illuminates, go to step 8). If test light does not illuminate, go to step 9).
7. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Check TP sensor harness connector signal circuit for short to voltage. If short to voltage is found, repair as necessary and go to step 14). If short to voltage is not found, go to step 13).
8. Turn ignition on. While monitoring scan tool TP SENSOR display, disconnect each component (one at a time) that shares common 5-volt reference circuit. If display changes, replace component that causes change and go to step 14). If display does not change, go to next step.
9. Turn ignition off. Disconnect PCM connectors. Turn ignition on, engine off. Check PCM harness connector 5-volt reference circuit for short to voltage. If short is found, repair as necessary and go to step 14). If no short is found, go to next step.
10. Check for faulty connection at TP sensor. If faulty connection is found, repair as necessary and go to step 14). If connection is okay, go to next step.
11. Turn ignition off. Disconnect PCM connectors. Check for faulty TP sensor ground circuit connection at PCM. If faulty connection is found, repair as necessary and go to step 14). If connection is okay, go to next step.
12. Replace TP sensor and go to step 14).
13. Replace PCM. Program replacement PCM using required equipment. Go to next step.
14. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0123. If scan tool displays DTC P0123 FAILED THIS IGN, return to step 3). If scan tool does not display DTC P0123 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Turn ignition on, engine off. Using scan tool TP SENSOR display, slowly depress accelerator to wide open throttle. If voltage is more than 4.71 volts at any time, replace TP sensor.

DTC P0125 - ECT SENSOR EXCESSIVE TIME TO REACH CLOSED LOOP

Note. For circuit reference, see DTC P0112 schematic.

While engine is warming, PCM reads Engine Coolant Temperature (ECT) sensor to determine how long it takes coolant to reach temperature required for closed loop operation. PCM compares actual time required to a predetermined time.

1. No ECT or IAT DTCs are set.
2. Vehicle speed greater than 5 MPH.
3. IAT greater than 50°F (10°C).
4. ECT greater than 32°F (0°C).
5. Start-up ECT less than 70°F (21°C).
6. Closed loop operation temperature of 68°F (20°C) not reached within 2 minutes of start-up.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Allow engine to cool completely. Turn engine on and allow it to idle. Using scan tool, monitor ENG COOL TEMP. If temperature increases to 70°F (21°C) within 2 minutes, see DIAGNOSTIC AIDS. If specified temperature is not reached within 2 minutes, go to next step.
3. If any ECT DTCs are set, diagnose affected DTC before proceeding. If no ECT DTCs are set, go to next step.
4. Allow engine to cool. Turn ignition on and observe cooling fans. If cooling fans are off, go to next step. If cooling fans are on, diagnose and repair cooling fan problem.
5. Check coolant level. If coolant level is low, go to step 9) If coolant level is okay, go to next step.
6. Check thermostat operation. If thermostat is operating correctly, go to next step. If thermostat is not operating correctly, go to step 9).
7. Compare actual coolant temperature with scan tool ECT value. If temperatures are within 5°F (3°C) of each other, go to step 9). If temperatures are not within 5°F (3°C) of each other, go to next step.
8. Check for high resistance in wiring related to ECT sensor and for poor connections at ECT sensor and PCM. If a problem is found with connections, go to step 10). If no problem is found, go to step 11).
9. Repair cooling system as necessary and go to step 12).
10. Repair as necessary and go to step 12).
11. Replace ECT sensor and go to next step.
12. Allow engine to cool completely. Using scan tool, clear DTCs. Turn engine on and allow it to idle. Using scan tool, monitor ENG COOL TEMP. If temperature increases to 70°F (21°C) within 2 minutes, repair is complete. If specified temperature is not reached within 2 minutes, return to step 2).

Check coolant level. Ensure thermostat and cooling fans are operating properly. Check for high resistance in wiring related to ECT sensor. Check for skewed ECT sensor by comparing actual coolant temperature with scan tool display, and replace ECT sensor if temperatures are not close.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

PCM provides about 0.35 volt reference to HO2S 1. HO2S 1 sensor signal voltage varies from about one volt when exhaust is rich to about 0.1 volt when exhaust is lean. PCM reads and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If HO2S 1 voltage is out of predetermined range, DTC will set.

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. Closed loop commanded air/fuel ratio is 14.5-14.8:1.
5. TP ANGLE is 3-40 percent.
6. HO2S 1 signal voltage stays less than 0.175 volt during closed loop operation.
7. HO2S 1 signal voltage stays less than 0.6 volt during power enrichment mode of fuel control operation.
8. Listed conditions present for 15 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and allow it to reach operating temperature. Operate vehicle under conditions required to set DTC. Using scan tool, read HO2S 1 voltage. If voltage stays less than 0.3 volt, go to step 4). If voltage does not stay less than 0.3 volt, go to next step.
3. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0131 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0131 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect HO2S 1 connector. Connect jumper wire between HO2S 1 harness connector ground circuit and chassis ground. If voltage is about 0.45 volt, see DIAGNOSTIC AIDS. If voltage is not as specified, go to next step.
5. Turn ignition off. Disconnect PCM connectors. Check HO2S sensor harness connector signal circuit for short to ground. If short is found, go to next step. If no short is found, go to step 7).
6. Repair circuit as necessary and go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. Go to next step.
8. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0131. If scan tool displays DTC P0131 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0131 FAILED THIS IGN, repair is complete.

Ensure HO2S 1 sensor harness is routed correctly and not contacting exhaust system. Check for faulty PCM grounds. Perform A-6, FUEL SYSTEM DIAGNOSIS under BASIC FUEL SYSTEM CHECKS in BASIC TESTING article. Perform A-7, INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM/COMPONENT TESTS article.

Check for vacuum leaks at intake manifold, throttle body, EGR system and crankcase ventilation system. Check for exhaust leaks in front of HO2S 1. Disconnect MAF sensor connector and see if lean condition is corrected. If lean condition is corrected, replace MAF sensor. Check for fuel contamination. See A-6, FUEL SYSTEM DIAGNOSIS under BASIC FUEL SYSTEM CHECKS in BASIC TESTING article. If no faults are found, replace HO2S 1.

DTC P0131 Schematic. Scheme 7

DTC P0132 - HO2S 1 CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0131 schematic.

PCM provides about 0.45 volt reference to HO2S 1. HO2S 1 sensor signal voltage varies from about one volt when exhaust is rich to about 0.1 volt when exhaust is lean. PCM reads and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If HO2S 1 voltage is out of predetermined range, DTC will set.

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. Closed loop commanded air/fuel ratio is 14.5-14.8:1.
5. TP ANGLE is 3-40%.
6. HO2S 1 signal voltage stays greater than 0.8 volt during closed loop operation.
7. HO2S 1 signal voltage stays greater than 0.11 volt during deceleration fuel mode operation.
8. Listed conditions present for 15 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and allow it to reach operating temperature. Operate vehicle under conditions required to set DTC. Using scan tool, read HO2S 1 voltage. If voltage stays greater than 0.8 volt, go to step 5). If voltage stays at 0.8 volt or less, go to next step.
3. Operate vehicle in deceleration fuel mode (vehicle speed greater than 25 MPH and TP ANGLE less than 3%) while monitoring HO2S 1 voltage. If voltage stays greater than 0.11 volt, go to step 5). If voltage stays 0.11 volt or less, go to next step.
4. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0132 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0132 FAILED THIS IGN, see DIAGNOSTIC AIDS.
5. Disconnect HO2S 1 connector. Connect a jumper wire betweenHO2S 1 harness connector ground circuit and chassis ground. If voltage is about 0.45 volt, see DIAGNOSTIC AIDS. If voltage is not as specified, go to next step.
6. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between PCM harness connector HO2S 1 signal circuit and chassis ground. If voltage is greater than 0.6 volt, go to next step. If voltage is 0.6 volt or less, go to step 8).
7. Repair short to voltage in HO2S 1 signal circuit and go to step 9).
8. Replace PCM. Program replacement PCM using required equipment. Go to next step.
9. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0132. If scan tool displays DTC P0132 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0132 FAILED THIS IGN, repair is complete.

Ensure HO2S 1 sensor harness is routed correctly and not contacting exhaust system. Check for open or short in HO2S 1 signal or ground circuits. Check for internally shorted HO2S 1. Check HO2S 1 for silicon (powdery white deposit) contamination. Check for faulty PCM grounds. Perform A-6, FUEL SYSTEM DIAGNOSIS under BASIC FUEL SYSTEM CHECKS in BASIC TESTING article. Perform A-7, INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM/COMPONENT TESTS article.

Check EVAP canister for fuel saturation. Disconnect MAF sensor connector and see if rich condition is corrected. If rich condition is corrected, replace MAF sensor. Check for fuel in fuel pressure regulator vacuum line.

DTC P0133 - HO2S 1 SLOW RESPONSE

Note. For circuit reference, see DTC P0131 schematic.

PCM provides about 0.45 volt reference to HO2S 1. HO2S 1 sensor signal voltage varies from about one volt when exhaust is rich to about 0.1 volt when exhaust is lean. PCM counts number of times a rich-to-lean and lean-to-rich response is indicated and adds amount of time it takes to complete all transitions. PCM uses this information to determine average time for each transition. If average response time is slow, DTC P0133 will set.

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. Engine running in closed loop fuel control mode for at least 2 minutes.
5. Engine speed 1000-3000 RPM.
6. ECT greater than 167°F (75°C).
7. MAF 15-29 grams per second.
8. Lean-to-rich average transition response time greater than 75 milliseconds on VIN 1, or greater than 139 milliseconds on VIN K.
9. Rich-to-lean average transition response time greater than 100 milliseconds on VIN 1, or greater than 107 milliseconds on VIN K.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any other HO2S DTCs (except P1133 or P1134) are set, diagnose affected DTCs. Start engine and allow it to reach operating temperature. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0133 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0133 FAILED THIS IGN, see DIAGNOSTIC AIDS.
3. If scan tool also displays DTC P1133 or P1134 FAILED THIS IGN, go to step 8). If scan tool does not display these DTCs, go to next step.
4. Visually inspect exhaust system for leaks near HO2S 1. If leaks are found, repair as necessary and return to step 2). If no leaks are found, go to next step.
5. Visually inspect HO2S 1 for secure installation or corrosion on terminals. Check terminal tension at HO2S 1 and PCM. Check for damaged wiring. If a problem is found, go to step 9). If no problem is found, go to next step.
6. Disconnect HO2S 1 connector. Connect a jumper wire between HO2S 1 harness connector ground circuit and chassis ground. Using scan tool, read HO2S 1 voltage. If voltage is about 0.45 volt, go to next step. If voltage is not as specified, go to step 10).
7. Connect a jumper wire between HO2S 1 harness connector signal and ground circuits, and chassis ground. If voltage is less than 0.3 volt, go to step 12). If voltage is 0.3 volt or greater, go to step 11).
8. Repair condition causing fuel, sealant, oil or coolant contamination. Replace affected HO2S and go to step 13).
9. Repair condition as necessary and go to step 13).
10. Repair open HO2S 1 ground circuit or HO2S 1 signal circuit shorted to ground, and go to step 13).
11. Repair open HO2S 1 signal circuit or faulty PCM connections as necessary, and go to step 13).
12. Replace HO2S 1 and go to next step.
13. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0133. If scan tool displays DTC P0133 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0133 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0134 - HO2S 1 CIRCUIT INSUFFICIENT ACTIVITY

Note. For circuit reference, see DTC P0131 schematic.

PCM provides about 0.45 volt reference to HO2S 1. HO2S 1 sensor signal voltage varies from about one volt when exhaust is rich to about 0.1 volt when exhaust is lean. PCM reads and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If HO2S 1 voltage is out of predetermined range, DTC will set.

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. Engine running for at least 4 minutes.
5. HO2S 1 signal voltage signal voltage stays 0.4-0.5 volt for greater than 10 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and allow it to reach operating temperature. Place gear selector in Park or Neutral, and apply parking brake. Increase engine speed to greater than 1200 RPM for 2 minutes. Using scan tool, read HO2S 1 voltage. If voltage is varying outside of 0.4-0.5 volt range, go to next step. If not, go to step 4)
3. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0134 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0134 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Connect a jumper wire between HO2S 1 harness connector signal and ground circuits, and chassis ground. If voltage is less than 0.15 volt, go to step 8). If voltage is 0.15 volt or greater, go to next step.
5. Remove jumper wire. Using DVOM, check voltage between HO2S 1 harness connector signal and heater ground circuits. If voltage is about 0.45 volt, go to next step. If voltage is not as specified, go to step 7).
6. Turn ignition off. Disconnect PCM connectors. Check resistance of HO2S 1 harness connector ground circuit. If resistance is greater than 5 ohms, repair open or faulty connection and go to step 13). If resistance is 5 ohms or less, go to step 9).
7. Turn ignition off. Disconnect PCM connectors. Check resistance of HO2S 1 harness connector signal circuit. If resistance is greater than 5 ohms, repair open or faulty connection as necessary and go to step 13). If resistance is 5 ohms or less, go to step 10).
8. Check for faulty connection at HO2S 1. If faulty connection is found, repair as necessary and go to step 13). If no faulty connection is found, go to step 11).
9. Check for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 13). If no faulty connection is found, go to step 12).
10. Check for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 13). If no faulty connection is found, go to step 12).
11. Replace HO2S 1 and go to step 13).
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0134. If scan tool displays DTC P0134 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0134 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location. Check HO2S 1 heater operation.

DTC P0135 - HO2S 1 HEATER CIRCUIT

Note. For circuit reference, see DTC P0131 schematic.

PCM provides about 0.45 volt reference to HO2S 1. HO2S 1 sensor signal voltage varies from about one volt when exhaust is rich to about 0.1 volt when exhaust is lean. When ignition is turned on, battery voltage is supplied to HO2S 1 heater to provide for faster sensor warm-up, thus allowing sensor to become active in a shorter period of time. PCM reads amount of time necessary for sensor to become active after start-up.

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. MAF less than 24 grams per second.
5. ECT and IAT less than 95°F (35°C) at start-up.
6. Difference between ECT and IAT no greater than 11°F (6°C).
7. HO2S 1 voltage remains within 0.15 volt of bias voltage for longer amount of time than it should.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step. NOTE: If engine has been operating, allow engine to cool for about 30 minutes before proceeding with tests.
2. Turn ignition on, engine off. Using scan tool, read HO2S 1 voltage. If voltage is greater than 0.6 volt or less than 0.3 volt, see DIAGNOSTIC AIDS. If voltage is not as specified, go to next step.
3. Inspect HO2S 1 ignition feed fuse. If fuse is open, go to step 15). If fuse is okay, go to next step.
4. Turn ignition off. Raise and support vehicle. Disconnect HO2S 1 harness connector. Connect a test light between ground and HO2S 1 ignition feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
5. Connect test light between HO2S 1 harness connector ignition feed and heater ground circuits. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
6. Allow HO2S 1 to cool for at least 10 minutes. Using DVOM, check resistance between ignition feed and heater ground circuits at HO2S 1. If resistance is 3-10 ohms, go to step 9). If resistance is not as specified, go to step 14).
7. Repair open HO2S 1 ignition feed circuit and go to step 16).
8. Repair open HO2S 1 heater ground circuit and go to step 16).
9. Check for faulty connection at HO2S 1. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to next step.
10. Turn ignition off. Disconnect PCM connectors. Check resistance of HO2S 1 signal and ground circuits. If resistance on either circuit is greater than 5 ohms, repair open or faulty connection as necessary and go to step 16). If resistance is 5 ohms or less, go to next step.
11. Check for faulty connection at HO2S 1 harness connector. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to next step.
12. Check for faulty ground circuit connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to next step.
13. Check for faulty HO2S 1 signal circuit connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to next step.
14. Replace HO2S 1 and go to step 16).
15. Locate and repair short to ground in HO2S 1 ignition feed circuit, replace fuse and go to next step.
16. Allow engine to cool completely. Using scan tool, clear DTCs. Turn ignition on, engine off. Read HO2S 1 voltage. If voltage is greater than 0.6 volt or less than 0.3 volt, repair is complete. If voltage is not as specified, return to step 2).

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0137 - HO2S 2 CIRCUIT LOW VOLTAGE

Note. For circuit reference, see DTC P0131 schematic.

Three-Way Catalyst (TWC) system is used to control emissions. PCM uses signal from Heated Oxygen Sensor (HO2S) located behind TWC to read efficiency of TWC. PCM will set DTC P0137 if TWC oxygen storage capacity is less than a predetermined threshold.

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. Closed loop commanded air/fuel ratio is 14.5-14.8:1.
5. TP ANGLE is 3-40%.
6. HO2S 2 signal voltage stays less than 0.075 volt during closed loop operation.
7. HO2S 2 signal voltage stays less than 0.6 volt during power enrichment mode of fuel control operation.
8. Listed conditions present for 50 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and allow it to reach operating temperature. Operate vehicle under conditions required to set DTC. Using scan tool, read HO2S 2 voltage. If voltage stays less than 0.075 volt, go to step 4). If voltage stays 0.075 volt or greater, go to next step.
3. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0137 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0137 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect HO2S 2 connector. Connect a jumper wire betweenHO2S 2 harness connector ground circuit and chassis ground. If voltage is about 0.45 volt, see DIAGNOSTIC AIDS. If voltage is not as specified, go to next step.
5. Turn ignition off. Disconnect PCM connectors. Check HO2S 2 sensor harness connector signal circuit for short to ground. If short is found, go to next step. If no short is found, go to step 7).
6. Repair circuit as necessary and go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. Go to next step.
8. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0137. If scan tool displays DTC P0137 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0137 FAILED THIS IGN, repair is complete.

Ensure HO2S 2 sensor harness is routed correctly and not contacting exhaust system. Check for faulty PCM grounds. Perform A-6, FUEL SYSTEM DIAGNOSIS under BASIC FUEL SYSTEM CHECKS in BASIC TESTING article. Perform A-7, INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM/COMPONENT TESTS article.

Check for vacuum leaks at intake manifold, throttle body, EGR system and crankcase ventilation system. Check for exhaust leaks in front of HO2S 2. Disconnect MAF sensor connector and see if lean condition is corrected. If lean condition is corrected, replace MAF sensor. Check for fuel contamination. See A-6, FUEL SYSTEM DIAGNOSIS under BASIC FUEL SYSTEM CHECKS in BASIC TESTING article.

DTC P0138 - HO2S 2 CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0131 schematic.

Three-Way Catalyst (TWC) system is used to control emissions. PCM uses signal from Heated Oxygen Sensor (HO2S) behind TWC to read efficiency of TWC. PCM will set DTC P0137 if TWC oxygen storage capacity is less than a predetermined threshold.

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. Closed loop commanded air/fuel ratio is 14.5-14.8:1.
5. TP ANGLE is 3-40%.
6. HO2S 2 signal voltage stays greater than 999 mV during closed loop operation.
7. HO2S 2 signal voltage stays greater than 0.2 volt during deceleration fuel mode operation.
8. Listed conditions present for 50 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and allow it to reach operating temperature. Operate vehicle under conditions required to set DTC. Using scan tool, read HO2S 2 voltage. If voltage stays greater than 999 mV, go to step 4). If voltage stays 999 mV or less, go to next step.
3. Turn ignition on. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0138. If scan tool displays DTC P0138 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0138 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect HO2S 2 connector. Connect a jumper wire betweenHO2S 2 harness connector ground circuit and chassis ground. If voltage is about 0.45 volt, see DIAGNOSTIC AIDS. If voltage is not as specified, go to next step.
5. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between PCM harness connector HO2S 2 signal circuit and chassis ground. If voltage is greater than 999 mV, go to next step. If voltage is 999 mV or less, go to step 7).
6. Repair short to voltage in HO2S 2 signal circuit and go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. Go to next step.
8. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0138. If scan tool displays DTC P0138 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0138 FAILED THIS IGN, repair is complete.

Ensure HO2S 2 sensor harness is routed correctly and not contacting exhaust system. Check for open or short in HO2S 2 signal or ground circuits. Check for internally shorted HO2S 2. Check HO2S 2 for silicone (powdery white deposit) contamination. Check for faulty PCM grounds. Perform A-6, FUEL SYSTEM DIAGNOSIS under BASIC FUEL SYSTEM CHECKS in BASIC TESTING article. Perform A-7, INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM/COMPONENT TESTS article.

Check EVAP canister for fuel saturation. Disconnect MAF sensor connector and see if rich condition is corrected. If rich condition is corrected, replace MAF sensor. Check for fuel in fuel pressure regulator vacuum line.

DTC P0140 - HO2S INSUFFICIENT ACTIVITY SENSOR 2

Note. For circuit reference, see DTC P0131 schematic.

Three-Way Catalyst (TWC) system is used to control emissions. PCM uses signal from Heated Oxygen Sensor (HO2S) behind TWC to read efficiency of TWC. PCM will set DTC P0140 if TWC oxygen storage capacity is less than a predetermined threshold.

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. Closed loop commanded air/fuel ratio is 14.5-14.8:1.
5. Engine run time greater than 200 seconds.
6. HO2S 2 voltage stays 0.425-0.474 volt for 50 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and allow it to reach operating temperature. Place gear selector in Park or Neutral, and apply parking brake. Increase engine speed to greater than 1200 RPM for 2 minutes. Using scan tool, read HO2S 2 voltage. If voltage is not switching from greater than 0.475 to less than 0.425 volt, go to next step. If voltage is as specified, go to step 4)
3. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0140 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0140 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect HO2S 2 harness connector. Connect a jumper wire between HO2S 2 harness connector signal and ground circuits, and chassis ground. If voltage is less than 0.15 volt, go to step 8). If voltage is 0.15 volt or greater, go to next step.
5. Remove jumper wire. Using DVOM, check voltage between HO2S 2 harness connector signal and heater ground circuits. If voltage is about 0.45 volt, go to next step. If voltage is not as specified, go to step 7).
6. Turn ignition off. Disconnect PCM connectors. Check resistance of HO2S 2 harness connector ground circuit. If resistance is greater than 5 ohms, repair open or faulty connection as necessary and go to step 13). If resistance is 5 ohms or less, go to step 9).
7. Turn ignition off. Disconnect PCM connectors. Check resistance of HO2S 2 harness connector signal circuit. If resistance is greater than 5 ohms, repair open or faulty connection as necessary and go to step 13). If resistance is 5 ohms or less, go to step 10).
8. Check for faulty connection at HO2S 2. If faulty connection is found, repair as necessary and go to step 13). If connection is okay, go to step 11).
9. Check for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 13). If connection is okay, go to step 12).
10. Check for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 13). If connection is okay, go to step 12).
11. Replace HO2S 2 and go to step 13).
12. Replace PCM. Program replacement PCM using required equipment. Go to next step.
13. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0140. If scan tool displays DTC P0140 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0140 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location. Check HO2S 2 heater operation.

DTC P0141 - HO2S 2 HEATER CIRCUIT

Note. For circuit reference, see DTC P0131 schematic.

When ignition is turned on, battery voltage is supplied to HO2S 2 heater to provide for faster sensor warm-up, thus allowing sensor to become active in a shorter period of time. PCM reads amount of time necessary for sensor to become active after start-up.

1. No ECT, IAT, MAF, MAP or TP sensor DTCs set.
2. No EVAP system DTC set.
3. No fuel injector circuit, fuel trim, misfire or transaxle DTCs set.
4. MAF less than 24 grams per second.
5. ECT and IAT less than 95°F (35°C) at start-up.
6. Difference between ECT and IAT no greater than 11°F (6°C).
7. HO2S 2 voltage remains within 0.15 volt of bias voltage (about 0.45 volt) for longer amount of time than it should.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step. NOTE: If engine has been operating, allow engine to cool for about 30 minutes before proceeding with tests.
2. Turn ignition on, engine off. Using scan tool, read HO2S 2 voltage. If voltage is greater than 0.6 volt or less than 0.3 volt, see DIAGNOSTIC AIDS. If voltage is not as specified, go to next step.
3. Inspect HO2S 2 ignition feed fuse. If fuse is open, go to step 15). If fuse is okay, go to next step.
4. Turn ignition off. Raise and support vehicle. Disconnect HO2S 2 harness connector. Connect a test light between ground and HO2S 2 ignition feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
5. Connect test light between HO2S 2 harness connector ignition feed and heater ground circuits. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
6. Allow HO2S 2 to cool for at least 10 minutes. Using DVOM, check resistance between ignition feed and heater ground circuits at HO2S 2. If resistance is 3-10 ohms, go to step 9). If resistance is not as specified, go to step 14).
7. Repair open HO2S 2 ignition feed circuit and go to step 16).
8. Repair open HO2S 2 heater ground circuit and go to step 16).
9. Check for faulty connection at HO2S 2. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to next step.
10. Turn ignition off. Disconnect PCM harness connectors. Check resistance of HO2S 2 signal and ground circuits. If resistance on either circuit is greater than 5 ohms, repair open or faulty connection as necessary and go to step 16). If resistance is 5 ohms or less, go to next step.
11. Check for faulty connection at HO2S 2 harness connector. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to next step.
12. Check for faulty ground circuit connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to next step.
13. Check for faulty HO2S 2 signal circuit connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to next step.
14. Replace HO2S 2 and go to step 16).
15. Locate and repair short to ground in HO2S 2 ignition feed circuit, replace fuse and go to next step.
16. Allow engine to cool completely. Using scan tool, clear DTCs. Turn ignition on, engine off. Read HO2S 2 voltage. If voltage is greater than 0.6 volt or less than 0.3 volt, repair is complete. If voltage is not as specified, return to step 2).

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

PCM reads HO2S signal voltage and adjusts fuel delivery based on this voltage. A change made to fuel delivery is indicated by Long Term (LT) and Short Term (ST) FUEL TRIM values.

ST FUEL TRIM values change rapidly in response to HO2S signal voltages. These changes fine tune engine fueling. LT FUEL TRIM values change in response to trends in ST fuel trim. LT fuel trim makes coarse adjustments to fueling in order to re-center and restore control to ST fuel trim. LT and ST fuel trim can be read by using a scan tool.

Ideal FUEL TRIM value is about zero. Fuel trim value more than zero indicates that PCM is adding fuel to compensate for a lean condition. Fuel trim less than zero indicates that PCM is reducing amount of fuel to compensate for rich condition. DTC will set if PCM detects an excessively rich or lean condition.

1. No IAC DTCs set at idle.
2. No ECT, EGR, HO2S, IAT, MAF, MAP or TP sensor DTCs set.
3. No EVAP DTCs set.
4. No misfire or injector circuit DTCs set.
5. Engine speed 500-4000 RPM.
6. ECT 68-230°F (20-110°C).
7. IAT 0-104°F (-18-40°C).
8. BARO more than 10.7 psi (0.75 kg/cm 2 ).
9. MAP 2.6-12.8 psi (0.18-0.90 kg/cm 2 )
10. TP ANGLE less than 90%.
11. MAF 9-180 grams per second.
12. Long term fuel trim about maximum authority (16).
13. Short term fuel trim about maximum authority (20).
14. Vehicle speed less than 70 MPH.
15. Listed conditions met in FUEL TRIM CELLS 0, 1, 2, 6, and/or 7.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Operate vehicle in closed loop mode while using scan tool to read LT and ST FUEL TRIM values. If LT FUEL TRIM value is about 16 and ST FUEL TRIM value is about 20, go to step 5). If values are not as specified, go to next step.
4. Using scan tool, read and record FAIL RECORDS data. Clear DTCs and operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC while operating vehicle. Continue operating vehicle until DTC P0171 test runs. If scan tool displays DTC P0171 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0171 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
5. Check vacuum hoses for splits, kinks and proper routing. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
6. Check PCV valve for proper installation. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
7. Check throttle body inlet screen for blockage or foreign objects which may partially block airflow sample through MAF sensor. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
8. Start engine. If high or unsteady idle condition exists, go to next step. If Idle is okay, go to step 11).
9. Using scan tool, read IDLE AIR CONTROL (IAC) value. If value is more than 5 counts, go to step 11). If value is 5 counts or less, go to next step.
10. Check throttle body, intake manifold, and EGR valve for vacuum leaks. If a problem is found, repair as necessary and go to step 22) If no problem is found, go to next step.
11. Check IAC valve for proper operation. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
12. Check for fuel contamination. If fuel is contaminated, repair condition causing contamination and go to step 22). If fuel is okay, go to next step.
13. Check PCM injector, power and sensor grounds for clean and tight connection, and for proper location. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
14. Disconnect MAF sensor harness connector. Operate vehicle in closed loop mode while monitoring scan tool ST FUEL TRIM. If ST FUEL TRIM decreases to about zero, go to step 21). If ST FUEL TRIM does not decrease to about zero, go to next step.
15. Perform FUEL SYSTEM PRESSURE TEST under BASIC FUEL SYSTEM CHECKS in appropriate BASIC TESTING article. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
16. Perform EVAP SYSTEM CHECK. See FUEL EVAPORATION CONTROL, under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM/COMPONENT TESTS article. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
17. Check intake manifold, injector "O" rings, EGR adapter, EGR valve, and EGR feed pipes for vacuum leaks. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
18. Check exhaust system for corrosion, loose or missing hardware. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
19. Perform A-7, INJECTOR BALANCE TEST under FUEL SYSTEM in appropriate SYSTEM/COMPONENT TESTS article. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to next step.
20. Ensure HO2S is installed securely, and connector and harness are not contacting exhaust manifold or ignition wires. If a problem is found, repair as necessary and go to step 22). If no problem is found, go to DIAGNOSTIC AIDS.
21. Replace MAF sensor and go to next step.
22. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0171. If scan tool displays DTC P0171 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0171 FAILED THIS IGN, repair is complete.

Ensure HO2S wiring is routed correctly and not contacting exhaust system. Check for faulty PCM-to-engine ground connections. Check fuel pressure. Check fuel injector operation. Check for vacuum and exhaust leaks. Disconnect MAF sensor connector and see if lean condition is corrected. If lean condition is corrected, replace MAF sensor.

Check for fuel contamination. See A-6, FUEL SYSTEM DIAGNOSIS under BASIC FUEL SYSTEM CHECKS in appropriate BASIC TESTING article. Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool HO2S 1 display while moving all related harness and connectors. A change in scan tool display indicates fault location.

PCM reads HO2S signal voltage and adjusts fuel delivery based on this voltage. A change made to fuel delivery is indicated by Long Term (LT) and Short Term (ST) FUEL TRIM values.

ST FUEL TRIM values change rapidly in response to HO2S signal voltages. These changes fine tune engine fueling. LT FUEL TRIM values change in response to trends in ST fuel trim. LT fuel trim makes coarse adjustments to fueling in order to re-center and restore control to ST fuel trim. LT and ST fuel trim can be read by using a scan tool.

Ideal FUEL TRIM value is about zero. Fuel trim value more than zero indicates that PCM is adding fuel to compensate for a lean condition. Fuel trim less than zero indicates that PCM is reducing amount of fuel to compensate for rich condition. DTC will set if PCM detects an excessively rich or lean condition.

1. No IAC DTCs set at idle.
2. No ECT, EGR, HO2S, IAT, MAF, MAP or TP sensor DTCs set.
3. No EVAP DTCs set.
4. No misfire or injector circuit DTCs set.
5. Engine speed 500-4000 RPM.
6. ECT 68-230°F (20-110°C).
7. IAT 0-104°F (-18-40°C).
8. BARO more than 10.7 psi (0.75 kg/cm 2 ).
9. MAP 2.6-12.8 psi (0.18-0.90 kg/cm 2 )
10. TP ANGLE less than 90%.
11. MAF 9-180 grams per second.
12. Long term fuel trim about maximum authority (-25).
13. Short term fuel trim about maximum authority (-11).
14. Vehicle speed less than 70 MPH.
15. Listed conditions met in FUEL TRIM CELLS 0, 1, 2, 6, and/or 7.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Operate vehicle in closed loop mode while using scan tool to read LT and ST FUEL TRIM values. If LT FUEL TRIM value is about -25 and ST FUEL TRIM value is about -11, go to step 5). If values are not as specified, go to next step.
4. Using scan tool, read and record FAIL RECORDS data. Clear DTCs and operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC while operating vehicle. Continue operating vehicle until DTC P0172 test runs. If scan tool displays DTC P0172 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0172 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
5. Check air filter element condition. Replace air filter element if necessary and go to step 21). If air filter element is okay, go to next step.
6. Check air intake duct for being collapsed or restricted. If a problem is found, repair as necessary and go to step 21). If no problem is found, go to next step.
7. Check throttle body inlet screen for blockage or foreign objects which may partially block airflow sample through MAF sensor. If a problem is found, repair as necessary and go to step 21). If no problem is found, go to next step.
8. Start engine. If high or unsteady idle condition exists, go to next step. If Idle is okay, go to step 11).
9. Using scan tool, read IDLE AIR CONTROL (IAC) value. If value is less than 100 counts, go to step 11). If value is 100 counts or more, go to next step.
10. Turn ignition off. Check throttle body bore, throttle plate and IAC passages for coking and foreign objects. If a problem is found, repair as necessary and go to step 21) If no problem is found, go to next step.
11. Check IAC valve for proper operation. If a problem is found, repair as necessary and go to step 21). If no problem is found, go to next step.
12. Disconnect vacuum hose from fuel pressure regulator and check it for presence of fuel. If fuel is present, replace fuel pressure regulator and go to step 21). If no fuel is present, go to next step.
13. Turn ignition on, engine off. Using scan tool, read TP ANGLE while slowly depressing accelerator pedal. If TP ANGLE increases steadily from 0% at closed throttle to 100% at wide open throttle, go to next step. If TP ANGLE does not increase as specified, to step 19).
14. Disconnect MAF sensor harness connector. Operate vehicle in closed loop mode while monitoring scan tool LT and ST FUEL TRIM. If both FUEL TRIM values decrease to about 0, go to step 20). If FUEL TRIM values do not decrease to about 0, go to next step.
15. Perform FUEL SYSTEM PRESSURE TEST under BASIC FUEL SYSTEM CHECKS in appropriate BASIC TESTING article. If a problem is found, repair as necessary and go to step 21). If no problem is found, go to next step.
16. Perform EVAP SYSTEM CHECK. See FUEL EVAPORATION CONTROL, under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM/COMPONENT TESTS article. If a problem is found, repair as necessary and go to step 21). If no problem is found, go to next step.
17. Perform A-7, INJECTOR BALANCE TEST under FUEL SYSTEM in appropriate SYSTEM/COMPONENT TESTS article. If a problem is found, repair as necessary and go to step 21). If no problem is found, go to next step.
18. Remove HO2S 1 and check it for silicone (powdery white deposit) contamination. If HO2S 1 is contaminated, replace HO2S 1 and go to step 21). If HO2S 1 is not contaminated, go to DIAGNOSTIC AIDS.
19. Check and tighten TP sensor mounting screws. If mounting screws are tight, replace TP sensor and go to step 21).
20. Replace MAF sensor and go to next step.
21. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0172. If scan tool displays DTC P0172 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0172 FAILED THIS IGN, repair is complete.

Check fuel pressure. Check fuel injector operation. Disconnect MAF sensor connector and see if rich condition is corrected. If rich condition is corrected, replace MAF sensor.

Check for faulty TP sensor operation. Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool HO2S 1 display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0300-P0308 - ENGINE MISFIRE DETECTED

Note. DTC P0300 is set when the ECM recognizes a general misfire in the engine. If the ECM determines the cylinder causing the misfire it will set a specific DTC P0301-P0308, to indicate the number of the cylinder causing the misfire. If a DTC P0301-P0308 is retrieved, use this procedure to diagnose the misfire condition in the indicated cylinder.

Misfire is detected using Camshaft Position (CMP) and Crankshaft Position (CKP) sensors. When PCM senses CKP deceleration not associated with normal engine speed reduction, CMP is used to determine misfiring cylinder. PCM determines misfires on each cylinder and evaluates a random misfire and set DTC.

Conditions required to set code are

1. No transaxle or VSS DTCs set.
2. No CKP, CMP, ECT, MAF or TP sensor DTCs set.
3. Engine speed 450-5800 RPM.
4. ECT 19-248°F (-7-120°C).
5. Throttle steady.
6. PCM detects crankshaft RPM variation, indicating a misfire which could cause catalytic convertor damage or high emissions.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If DTC P1200 is also set, go to DTC P1200. If DTC P1200 is not set, go to next step.
3. Start engine and allow it to idle. Using scan tool, read and record FREEZE FRAME data. Operate vehicle within conditions noted in FREEZE FRAME data. Using scan tool, read MISFIRE CUR # display for each cylinder. If MISFIRE CUR # is increasing (indicating a misfire currently occurring) for any cylinder, go to next step. If MISFIRE CUR # is not increasing, see DIAGNOSTIC AIDS.
4. If MISFIRE HIST # displays a very large number for more than one cylinder, go to next step. If MISFIRE HIST # does not display a very large number for more than one cylinder, go to step 14).
5. Check vacuum hoses for splits, kinks, or improper connections. If a problem is found, repair as necessary and go to step 27). If no problem is found, go to next step.
6. Check PCV valve for improper installation or damaged "O" rings. If a problem is found, go to step 27). If no problem is found, go to next step.
7. Check throttle body inlet screen for blockage or foreign objects which may partially block airflow sample through MAF sensor. If a problem is found, repair as necessary and go to step 27). If no problem is found, go to next step.
8. Perform A-7, INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM/COMPONENT TESTS article. If a problem is found, repair as necessary and go to step 27). If no problem is found, go to next step.
9. Check for fuel contamination. If fuel is contaminated, repair condition causing contamination and go to step 27). If fuel is okay, go to next step.
10. Check PCM injector, power and sensor grounds for clean and tight connection, and for proper location. If a problem is found, repair as necessary and go to step 27). If no problem is found, go to next step.
11. Disconnect MAF sensor harness connector. Operate vehicle within conditions noted in FREEZE FRAME data. Using scan tool, read MISFIRE CUR # display for each cylinder. If MISFIRE CUR # is increasing (indicating a misfire currently occurring) for any cylinder, go to next step. If MISFIRE CUR # is not increasing, go to step 25).
12. Check intake manifold, injector "O" rings, EGR adapter, EGR valve, and EGR feed pipes for vacuum leaks. If a problem is found, repair as necessary and go to step 27). If no problem is found, go to next step.
13. Remove EGR valve and inspect valve, seat and passages for damage. Inspect valve pintle to ensure it is not sticking partially open. If a problem is found, repair as necessary and go to step 27). If no problem is found, go to next step.
14. Perform A-4, INJECTOR CIRCUIT TEST under FUEL SYSTEM DIAGNOSIS in BASIC TESTING article. If a problem is found, repair as necessary and go to step 27). If no problem is found, go to next step.
15. Check ignition wire(s) associated with cylinder(s) that is misfiring. If a problem is found, repair as necessary and go to step 27). If no problem is found, go to next step.
16. Install a spark tester on spark plug wire at spark plug end for cylinder indicating most severe misfire. Connect a jumper wire between engine ground and companion cylinder spark plug wire at spark plug end. Companion cylinders are 1 and 4, 2 and 5, and 3 and 6. Crank engine and check for crisp, Blue spark at tester. Repeat procedure for each affected cylinder. If spark is okay on all cylinders, go to step 21). If spark is not okay on any cylinder, go to next step.
17. Remove ignition coil(s) associated with misfiring cylinder(s). Check ignition coils for cracks or carbon tracking. If a problem is found, replace damaged coil(s) and go to step 27). If no problem is found, go to next step.
18. Check ignition coil secondary resistance. If resistance is not 5000-8000 ohms, replace ignition coil and go to step 27). If resistance is as specified, go to next step.
19. Remove ignition wire(s) associated with misfiring cylinder(s). Check ignition wire(s) boot for carbon tracking or damaged insulation. If a problem is found, replace faulty ignition wire(s) and go to step 27). If no problem is found, go to next step.
20. Check resistance of ignition wire(s) associated with misfiring cylinder(s). If resistance is more than 30,000 ohms, replace ignition wire(s) and go to step 27). If resistance is 30,000 ohms or less, go to step 26).
21. Remove spark plug(s) associated with misfiring cylinder(s). Check spark plugs for excessive fouling. If spark plugs are excessively fouled, diagnose and repair mechanical engine problem. If spark plugs are not excessively fouled, go to next step.
22. Check spark plug insulation for cracks, carbon tracking or other damage. If a problem is found, replace faulty spark plug(s) and go to step 27). If no problem is found, go to next step.
23. Diagnose mechanical engine problem. If a problem is found, repair as necessary and go to step 27). If no problem is found, go to next step.
24. Check for transmission DTCs. If a problem is found, repair as necessary and go to step 27). If no problem is found, see DIAGNOSTIC AIDS.
25. Replace MAF sensor and go to step 27).
26. Replace ignition control module and go to next step.
27. Using scan tool, read and record FREEZE FRAME data. Clear DTCs. Start engine and allow it to idle. Operate vehicle within conditions noted in FREEZE FRAME data. Using scan tool, read MISFIRE CUR # display for each cylinder. If MISFIRE CUR # is increasing (indicating a misfire currently occurring) for any cylinder, return to step 2). If MISFIRE CUR # is not increasing, repair is complete.

Check secondary ignition wires. Check for damaged or faulty ignition coil. Substitute a known-good ignition coil. Check system grounds. Check MAF sensor, air induction system, fuel pressure, injectors, and EGR valve.

Extended idle periods or short trip driving could leave deposits on HO2S. Deposits could cause HO2S to respond slowly, affecting fuel control and causing misfire at idle.

DTC P0300 Schematic. Scheme 8

Knock Sensor (KS) module is located in PCM and is replaceable. KS module reads KS to determine if excessive detonation (knock) is present. If excessive knock is present, PCM will retard timing until knock goes away. When KS module is missing or malfunctioning, PCM will set DTC P0325.

1. No fuel injector, misfire or TP sensor DTCs set.
2. Engine running at least 10 seconds.
3. ECT greater than 149°F (65°C).
4. PCM detects problem with KS module causing knock to be indicated continuously.
5. Listed conditions present for up to 2.5 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If engine knock can be heard, repair engine mechanical problem before proceeding with test. Operate vehicle within conditions required to set DTC. Using scan tool, select DTC, SPECIFIC function and enter DTC P0325. If scan tool displays DTC P0325 FAILED THIS IGN, go to step 4). If scan tool does not display DTC P0325 FAILED THIS IGN, go to next step.
3. Turn engine off. Turn ignition on, engine off. Read and record FAIL RECORDS data for DTC P0325. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0325 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0325 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Ensure KS harness is not routed too close to high-voltage wires, such as spark plug cables, ignition coils or other high-voltage components. Reroute harness if necessary and go to step 8). If harness routing is okay, go to next step.
5. Ensure KS module is fully seated and installed properly. If a problem is found, repair as necessary and go to step 8). If no problem is found, go to next step.
6. Replace KS module. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. Monitor scan tool until DTC P0325 test runs. If scan tool displays DTC P0325 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0325 FAILED THIS IGN, go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. Go to next step.
8. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0325. Monitor scan tool until DTC P0325 test runs. If scan tool displays DTC P0325 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0325 FAILED THIS IGN, repair is complete.

Check for faulty connection at PCM. Check KS connector for damage. Insure KS is installed properly.

DTC P0325 Schematic. Scheme 9

DTC P0326 - KNOCK SENSOR CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0325 schematic.

Knock Sensor (KS) is used to detect engine detonation (knock). If excessive knock is present, PCM will retard timing until knock goes away. When KS module in PCM determines that an abnormally high noise channel voltage exists, PCM will set DTC P0326.

1. No active TP or ECT sensor DTCs set.
2. ECT greater than 149°F (65°C).
3. Engine running at least 10 seconds.
4. TP ANGLE greater than 1.5%.
5. Engine speed is 2500-2900 RPM.
6. Noise channel voltage level greater than 5 volts.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If engine knock can be heard, repair engine mechanical problem before proceeding with test. Operate vehicle within conditions required to set DTC. Using scan tool, select DTC, SPECIFIC function and enter DTC P0326. If scan tool displays DTC P0326 FAILED THIS IGN, go to step 4). If scan tool does not display DTC P0326 FAILED THIS IGN, go to next step.
3. Turn engine off. Turn ignition on, engine off. Read and record FAIL RECORDS data for DTC P0326. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0326 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0326 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect KS connector. Using a DVOM, check voltage between engine ground and terminal at each KS. If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step 9).
5. Using DVOM in 400 k/ohm scale, check resistance between engine ground and terminal at each KS. If resistance is about 100 k/ohms, go to next step. If resistance is not as specified, go to step 10).
6. Turn ignition off. Using DVOM in 2-volt AC scale, check voltage between engine ground and bank 1 KS terminal. Start engine and allow it to idle. Repeat procedure for bank 2 KS. If any signal is present for either KS, go to step 10). If signal is not present, go to next step.
7. With DVOM still connected between KS terminal and engine ground, tap on engine while observing DVOM. If any signal is present, go to next step. If signal is not present, go to step 10).
8. Check KS harness connector signal circuit for incorrect routing near secondary wires or faulty terminal connection at KS. If a problem is found, repair as necessary and go to step 14). If no problem is found, go to step 11).
9. Turn ignition off. Disconnect PCM connectors. Turn ignition on and check KS signal circuit between PCM and KS harness connector for open, short to voltage or short to ground. If a problem is found, repair as necessary and go to step 14). If no problem is found, go to step 11).
10. Replace affected KS and go to step 14).
11. Turn ignition off. Disconnect PCM connectors. Check KS signal circuit for proper terminal connection at PCM. Repair or replace terminal as necessary and go to step 14). If terminal is okay, go to next step.
12. Replace KS module. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. Monitor scan tool until DTC P0326 test runs. If scan tool displays DTC P0326 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0326 FAILED THIS IGN, go to step 14).
13. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
14. Read and record FAIL RECORDS data for DTC P0326. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0326 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0326 FAILED THIS IGN, repair is complete.

Check for faulty connection at PCM. Check KS and PCM connectors for damage. Ensure KS harness is not routed too close to high-voltage wires, such as spark plug cables, ignition coils or other high-voltage components. Insure KS is installed properly.

DTC P0327 - KNOCK SENSOR CIRCUIT LOW VOLTAGE

Note. For circuit reference, see DTC P0325 schematic.

Knock Sensor (KS) is used to detect engine detonation (knock). When KS module in PCM determines that an abnormally high noise channel voltage exists, PCM will set DTC P0327.

1. No active TP or ECT sensor DTCs set.
2. ECT more than 149°F (65°C).
3. Engine running at least 10 seconds.
4. TP ANGLE more than 1.5%.
5. Engine speed is 2500-2900 RPM.
6. Difference between KS minimum learned noise and noise channel is less than 0.4 volt.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Operate vehicle within conditions required to set DTC. Using scan tool, select DTC, SPECIFIC function and enter DTC P0327. If scan tool displays DTC P0327 FAILED THIS IGN, go to step 4). If scan tool does not display DTC P0327 FAILED THIS IGN, go to next step.
3. Turn engine off. Turn ignition on, engine off. Read and record FAIL RECORDS data for DTC P0327. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0327 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0327 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
4. Disconnect both KS connectors. Using a DVOM, check voltage between engine ground and terminal at each KS. If voltage is 5 volts for both KS, go to next step. If voltage is not as specified, go to step 9).
5. Using DVOM in 400 k/ohm scale, check resistance between engine ground and terminal at each KS. If resistance is about 100 k/ohms for both KS, go to next step. If resistance is not as specified, go to step 10).
6. Connect DVOM to bank 1 KS terminal and ground. Select 2-volt AC scale on DVOM. Engine idling, observe DVOM. Repeat for bank 2 KS. If voltage is indicated on DVOM for either KS, go to step 10). If not, go to next step.
7. With DVOM still connected between KS terminal and engine ground, tap on engine while observing DVOM. If any signal is present, go to next step. If signal is not present, go to step 10).
8. Check KS harness connector for incorrect routing or faulty terminal connection at KS. If a problem is found, repair as necessary and go to step 14). If no problem is found, go to step 11).
9. Turn ignition off. Disconnect PCM connectors. Turn ignition on and check KS signal circuit between PCM and KS harness connector for open, short to voltage or short to ground. If a problem is found, repair as necessary and go to step 14). If no problem is found, go to step 11).
10. Replace affected KS and go to step 14).
11. Turn ignition off. Disconnect PCM connectors. Check KS signal circuit for proper terminal connection at PCM. Repair or replace terminal as necessary and go to step 14). If terminal is okay, go to next step.
12. Replace KS module. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. Monitor scan tool until DTC P0327 test runs. If scan tool displays DTC P0327 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0327 FAILED THIS IGN, go to step 14).
13. Replace PCM. Program replacement PCM using required equipment. Go to next step.
14. Read and record FAIL RECORDS data for DTC P0327. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0327 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0327 FAILED THIS IGN, repair is complete.

Check for faulty connection at PCM. Check KS and PCM connectors for damage. Ensure KS harness is not routed too close to high-voltage wires, such as spark plug cables, ignition coils or other high-voltage components. Insure KS is installed properly.

Ignition Control Module (ICM) produces 18X reference signal. ICM calculates 18X reference signal by filtering Crankshaft Position (CKP) sensor 18X pulses when engine is running and CKP pulses are also being received. PCM uses this information to calculate engine speed and CKP at engine speeds less than 1200 RPM. PCM compares number of 18X reference pulses to 3X reference pulses and Camshaft Position (CMP) pulses. If PCM receives incorrect number of pulses, DTC P0336 will set.

1. Engine running and PCM receiving 3X reference pulses.
2. Ratio of 18X reference pulses to 3X reference pulses received by PCM does not equal 6.
3. Ratio of 3X reference pulses to CMP pulses received by PCM equals 6.
4. Above conditions occur 80 times.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start and run, see ENGINE DOES NOT START in BASIC TESTING article.
3. Using scan tool, clear DTC P0336. Start engine and allow to idle for one minute. Read DTCs. If DTC P0336 resets, go to next step. If DTC does not reset, go to DIAGNOSTIC AIDS.
4. Disconnect ICM and PCM connectors. Check for open or short to ground in 18X reference circuit between ICM and PCM harness connectors. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to next step.
5. Reconnect ICM connector. Using DVOM, check voltage on 18X reference circuit at PCM harness connector while cranking engine. If voltage is about 3 volts, go to step 8). If voltage is not as specified, go to next step.
6. Check for faulty connections at ICM. If a faulty connection is found, repair as necessary and go to step 11). If connections are okay, go to next step.
7. Replace ICM and go to step 11).
8. Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to next step.
9. Check for faulty connections at PCM. If faulty connection is found, repair as necessary and go to step 11). If connections are okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. Go to next step.
11. Read and record FAIL RECORDS data for DTC P0336. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0336 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0336 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe a voltmeter connected to 18X reference circuit at PCM harness connector while moving all related harness and connectors. A change in voltage indicates fault location.

Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness.

DTC P0336 Schematic. Scheme 10

DTC P0341 - CAMSHAFT POSITION SENSOR CIRCUIT PERFORMANCE

Note. For circuit reference, see DTC P0336 schematic.

DTC P0341 will set if Camshaft Position (CMP) sensor pulses are not in proper ratio to 18X and 3X pulses.

1. Engine running and PCM receiving 3X reference pulses.
2. Ratio of 3X reference pulses to CMP pulses received by PCM does not equal 6.
3. Ratio of 18X reference pulses to 3X reference pulses received by PCM does not equal 6.
4. Listed conditions occur 80 times.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read and record FAIL RECORDS data for DTC P0341. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0341 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0341 FAILED THIS IGN, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect PCM connectors. Using DVOM, check voltage on CMP sensor signal circuit at PCM harness connector. Turn ignition on. If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step 5).
4. Remove CMP sensor, but leave harness connector connected. Place a magnet on CMP sensor. If voltage is now about zero volts, go to step 16). If voltage is not as specified, go to step 8).
5. If voltage is greater than 5 volts, go to step 7). If voltage is 5 volts or less, go to next step.
6. Turn ignition off. Disconnect Ignition Control Module (ICM) connector. Leave PCM connector disconnected. Turn ignition on. Connect a test light between battery voltage and ICM harness connector CMP sensor signal and CMP sensor input circuits. If test light illuminates, locate and repair short to ground in CMP sensor signal or input circuit and go to step 24). If test light does not illuminate, go to step 13).
7. Turn ignition off. Disconnect Ignition Control Module (ICM) connector. Leave PCM connector disconnected. Turn ignition on. Connect a test light between engine ground and ICM harness connector CMP sensor input circuit. If test light illuminates, locate and repair short to voltage in CMP sensor input circuit and go to step 24). If test light does not illuminate, go to step 18).
8. Disconnect CMP sensor. Check voltage between CMP sensor harness connector sensor feed and sensor ground circuit. If voltage is about battery voltage, go to next step. If voltage is not as specified, go to step 12).
9. Check voltage CMP sensor harness connector sensor signal and sensor ground circuits. If voltage is 5-7 volts, go to next step. If voltage is not as specified, go to step 11).
10. Check voltage on PCM harness connector CMP sensor input signal circuit. Connect a test light to CMP sensor harness connector sensor signal circuit. Repeatedly touch other end of test light to engine ground. If voltage switches from zero to 5 volts, go to step 15). If voltage does not switch, go to step 14).
11. Turn ignition off. Disconnect Ignition Control Module (ICM) connector. Leave CMP sensor connector disconnected. Turn ignition on. Check CMP sensor signal circuit for open or short to voltage. Check CMP sensor input signal circuit for short to voltage. If a problem is found, repair as necessary and go to step 24). If no problem is found, go to step 14).
12. Turn ignition off. Disconnect ICM and CMP sensor connectors. Check sensor feed and sensor ground circuits for open between ICM and CMP sensor. If a problem is found, repair as necessary and go to step 24). If no problem is found, go to step 14).
13. Check for open in CMP sensor input signal circuit between ICM and PCM. If open is found, repair as necessary and go to step 24). If open is not found, go to next step.
14. Check for faulty connection at ICM. If faulty connection is found, repair as necessary and go to step 24). If ICM connection is okay, go to step 17).
15. Check for faulty connection at CMP sensor. If faulty connection is found, repair as necessary and go to step 24). If connection is okay, go to step 19).
16. Check for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 24). If PCM connection is okay, go to step 20).
17. Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness. If a problem is found, repair as necessary and go to step 24). If no problem is found, go to next step.
18. Replace ICM and go to step 24).
19. Replace CMP sensor and go to step 24).
20. Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness. If a problem is found, repair as necessary and go to step 24). If no problem is found, go to next step.
21. Reinstall CMP sensor. Using DVOM, check voltage on CMP sensor input signal circuit while cranking engine. If voltage switches from zero to 4 volts, go to next step. If voltage does not switch, go to step 23).
22. Replace PCM. Program replacement PCM using required equipment. After repairs are completed, go to step 24).
23. Replace faulty or missing CMP sensor and go to next step.
24. Read and record FAIL RECORDS data for DTC P0341. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0341 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0341 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe a voltmeter connected to CMP sensor input circuit at PCM harness connector while moving all related harness and connectors. A change in voltage indicates fault location.

Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness.

PCM tests Exhaust Gas Recirculation (EGR) valve by momentarily commanding valve on while monitoring engine MAP. PCM will illuminate MIL and store DTC P0401 if expected increase is not seen under certain conditions during deceleration.

1. No ECT, IAT, MAP, or TP sensor DTCs set.
2. No misfire, linear EGR (pintle position) or vehicle speed sensor DTCs set.
3. BARO is greater than 10 psi (0.7 kg/cm 2 ).
4. ECT greater than 180°F (80°C).
5. Vehicle speed greater than 25 MPH.
6. Engine speed is 800-1400 RPM.
7. IAC position steady.
8. TP ANGLE less than 1%.
9. Commanded state of A/C relay is steady.
10. MAP changes monitored during EGR flow test indicate insufficient EGR flow.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Inspect exhaust system for modifications or leaks. If a problem is found, repair as necessary and go to step 5). If no problem is found, go to next step.
3. Remove EGR valve and check pintle, valve and passages and adapter for excessive deposits or restriction. Check EGR valve gasket and pipes for leaks. If a problem is found, repair as necessary and go to step 5). If no problem is found, go to next step.
4. Remove EGR inlet and outlet pipes from exhaust and intake manifolds. Inspect manifold EGR ports and pipes for blockage or damage. If a problem is found, repair as necessary and go to next step. If no problem is found, see DIAGNOSTIC AIDS.
5. Read and record FAIL RECORDS data for DTC P0401. Clear DTCs and monitor EGR TEST COUNT while operating vehicle within conditions noted in DIAGNOSTIC AIDS until 9-12 test counts have been taken. Read SPECIFIC DTC. If scan tool displays DTC P0401 TEST RAN AND PASSED, repair is complete. If scan tool does not display DTC P0401 TEST RAN AND PASSED, return to step 2).

PCM will only run EGR flow test during gradual deceleration, a closed throttle condition and with vehicle speed greater than 25 MPH. Accelerate vehicle to greater than 25 MPH, and gradually decelerate 9-12 times.

Check for faulty connections or damaged harness. Inspect PCM harness connector EGR control circuit for backed-out terminal. Observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

If EGR valve shows signs of excessive heat, check exhaust system for blockage or plugged catalytic converter.

Three-Way Catalyst (TWC) system is used to control emission. PCM uses signal from Heated Oxygen Sensors (HO2S) to read efficiency of TWC. PCM will set DTC P0420 if TWC oxygen storage capacity is less than a predetermined threshold.

1. Converter warm-up test passed.
2. No CKP, ECT, HO2S, IAC, IAT, MAF, MAP, or TP sensor DTCs set.
3. No EGR flow or pintle position, EVAP purge, fuel trim, injector circuit or misfire DTCs set.
4. Engine speed 1000-3000 RPM.
5. PCM determines TWC oxygen storage capacity less than predetermined threshold.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Diagnose any other DTCs present before proceeding. If no other DTCs are present, go to next step.
3. Ensure TWC is an original equipment part. Check TWC for dents or discoloration caused by excessive heat. Ensure no internal damaged catalyst rattle exists. If a problem is found, repair as necessary and go to step 6). If no problems are found, go to next step.
4. Check exhaust system for leaks, damage, loose or missing hardware. If a problem is found, repair as necessary and go to step 7). If no problems are found, go to next step.
5. Ensure HO2S 2 is securely installed and that harness is not damaged or contacting exhaust. If a problem is found, repair as necessary and go to step 7). If no problems are found, go to next step.
6. Replace TWC. Check for possible engine misfire DTC or engine mechanical problem, and go to next step.
7. Read and record FAIL RECORDS data for DTC P0401. Clear DTCs. Start engine and allow it to reach 167°F (75°C). Run engine while monitoring scan tool IAC RPM control function to maintain MAF at 12-15 grams per second for at least 2 minutes. Using scan tool, monitor TWC MONITOR TEST COUNTER while operating vehicle within conditions required to set DTC. Continue operating vehicle until TWC MONITOR TEST COUNTER reaches 49 and returns to zero 2 times. Read SPECIFIC DTC. If scan tool displays DTC P0420 TEST RAN AND PASSED, repair is complete. If scan tool does not display DTC P0420 TEST RAN AND PASSED, return to step 2).

Check for faulty connections or damaged harness. Inspect PCM harness connector EGR control circuit for backed-out terminal. Observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Ensure engine has reached operating temperature. Place gear selector in Park. Using scan tool, monitor HO2S 1 and HO2S 2 values while using scan tool IAC RPM function to maintain MAF at 10 grams per second. Compare activity between HO2S 1 and HO2S 2 for 30 seconds. If activity between both HO2S is about equal, a problem exists. Repeat DTC P0420.

Evaporative (EVAP) emission canister purge is controlled by a solenoid valve which allows ported vacuum to purge canister when energized by PCM. A vacuum switch in purge line is used to detect when system is being purged. PCM supplies and reads a 5-volt reference to switch. If switch is closed (no purge detected) when commanded by PCM, DTC P0441 is set.

1. No ECT, IAT, MAF, MAP, TP sensor DTCs set.
2. BARO greater than 10 psi (0.7 kg/cm 2 ).
3. ECT less than 237°F (114°C).
4. IAT 32-158°F (0-70°C).
5. Difference between ECT and IAT less than 18°F (10°C).
6. Engine speed 650-5000 RPM.
7. Canister Pulse Width Modulation (PWM) greater than 75 percent.
8. EVAP vacuum switch remains closed (12-volt signal at PCM).
9. Listed conditions present greater than 4 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn engine on and allow it to idle. Using scan tool, command EVAP purge solenoid on, while monitoring EVAP VACUUM SW on ENG 2 data list. If scan tool displays PURGE, go to next step. If scan tool does not display PURGE, go to step 4).
3. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data for DTC P0441. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0441 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0441 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Plug vacuum line between EVAP purge canister and EVAP vacuum switch. Turn engine on and allow it to idle. Using scan tool, command EVAP purge solenoid on, while monitoring EVAP VACUUM SW on ENG 2 data list. If scan tool displays PURGE, go to next step. If scan tool does not display PURGE, go to step 6).
5. Check vacuum line to canister for damage or improper connections. If a problem is found, repair as necessary and go to step 20). If no problem is found, go to step 14).
6. Turn ignition off. Connect a vacuum gauge between EVAP purge solenoid and vacuum switch. Start engine and allow it to idle. Using scan tool, command EVAP purge solenoid on. If vacuum gauge reads 12 in. Hg, go to next step. If vacuum is not as specified, go to step 8).
7. Turn ignition off. Disconnect vacuum switch harness connector. turn ignition on. Observe EVAP VACUUM SW. If scan tool displays PURGE, go to step 15). If scan tool does not display PURGE, go to step 9).
8. Turn ignition off. Connect a vacuum gauge to EVAP purge solenoid vacuum source. Start engine and allow it to idle. If vacuum gauge reads 12 in. Hg, go to step 10). If vacuum is not as specified, go to step 16).
9. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Check for short to voltage in EVAP vacuum switch input circuit. If a problem is found, repair as necessary and go to step 20). If no problem is found, go to step 19).
10. Turn ignition off. Disconnect EVAP purge solenoid harness connector. Connect a test light across EVAP purge solenoid harness connector signal and ground circuits. Turn ignition on. Using scan tool, command EVAP solenoid on. If test light illuminates, go to step 17). If test light does not illuminate, go to next step.
11. Turn ignition off. Disconnect PCM connectors. Connect a test light across EVAP purge solenoid harness connector signal and ground circuits. Turn ignition on. Connect a jumper wire between EVAP purge solenoid harness connector driver circuit and PCM harness connector ground circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
12. Check for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 20). If connection is okay, go to step 19)
13. Repair EVAP purge solenoid ignition feed circuit for open or short to ground, or EVAP purge solenoid driver circuit for open and go to step 20).
14. Replace EVAP canister and go to step 20).
15. Replace EVAP vacuum switch and go to step 20).
16. Locate and repair cause of no vacuum and go to step 20).
17. Check for faulty connection at EVAP purge solenoid. If faulty connection is found, repair as necessary and go to step 20). If connection is okay, go to next step.
18. Replace EVAP purge solenoid and go to step 20).
19. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
20. Read and record FAIL RECORDS data for DTC P0441. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0441 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P0441 FAILED THIS IGN, repair is complete.

Check vacuum canister and hoses for damage. Check for faulty connections or damaged harness. Observe scan tool EVAP VACUUM SW display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0441 Schematic. Scheme 11

PCM controls idle speed with an Idle Air Control (IAC) valve to a calculated RPM based on sensor inputs and actual engine RPM. PCM moves IAC valve in or out to vary amount of airflow into intake manifold and thus decrease or increase idle RPM.

PCM commands IAC in counts. A higher count, allows more air to by-pass throttle plate (higher idle).

1. No CKP, ECT, IAT, MAF, MAP, TP or VSS sensor DTCs set.
2. No EVAP solenoid, EVAP system, fuel trim, fuel injector, EGR flow or EGR pintle position DTCs set.
3. ECT greater than 158°F (70°C).
4. Engine running greater than 5 seconds.
5. Vehicle speed less than 3 MPH.
6. IAT greater than -4°F (-20°C).
7. Throttle closed.
8. Engine speed greater than 175 RPM lower than desired idle.
9. Listed conditions met for greater than 15 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 100 RPM of desired RPM for each command, see DIAGNOSTIC AIDS. If ENGINE SPEED is not as specified, to next step.
4. Disconnect IAC harness connector. Install IAC Node Light (J37027) in IAC harness connector. Monitor node lights while commanding engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. Both node lights should cycle Green and Red, but not off as RPM changes from 500-1500 RPM. If lights flash as specified, go to step 6). If lights do not flash as specified, go to next step.
5. Check IAC "A" high and low, and "B" high and low circuits for open, short to voltage or short to ground. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to step 9).
6. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to next step.
7. Check for faulty connection at IAC harness connector. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to next step.
8. Replace IAC valve and go to step 11).
9. Check for faulty connection at PCM harness connector. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
11. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 100 RPM of desired RPM for each command, repair is complete. If ENGINE SPEED is not as specified, return to step 2).

Check for faulty connection at IAC and PCM connectors. Check for damaged harness. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Check for large vacuum leak, such as incorrectly installed PCV valve or disconnected brake booster hose. Check for restricted air intake system.

DTC P0506 Schematic. Scheme 12

DTC P0507 - IAC SYSTEM RPM HIGH

Note. For circuit reference, see DTC P0506 schematic.

PCM controls idle speed with an Idle Air Control (IAC) valve to a calculated RPM based on sensor inputs and actual engine RPM. PCM moves IAC valve in or out to vary amount of airflow into intake manifold and thus decrease or increase idle RPM.

PCM commands IAC in counts. A higher count, allows more air to by-pass throttle plate (higher idle).

1. No CKP, ECT, IAT, MAF, MAP, TP or VS sensor DTCs set.
2. No EVAP solenoid, EVAP system, fuel trim, fuel injector, EGR flow or EGR pintle position DTCs set.
3. ECT more than 158°F (70°C).
4. Engine running more than 5 seconds.
5. Vehicle speed less than 3 MPH.
6. IAT more than -4°F (-20°C).
7. Throttle closed.
8. Engine speed more than 200 RPM lower than desired idle.
9. Listed conditions met for more than 20 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 100 RPM of desired RPM for each command, go to DIAGNOSTIC AIDS. If ENGINE SPEED is not as specified, to next step.
4. Disconnect IAC harness connector. Install IAC Node Light (J 37027) in IAC harness connector. Monitor node lights while commanding engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. Both node lights should cycle Green and Red, but not OFF as RPM changes from 500-1500 RPM. If lights flash as specified, go to step 6). If lights do not flash as specified, go to next step.
5. Check IAC "A" high and low, and "B" high and low circuits for open, short to voltage or short to ground. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to step 9).
6. Check for vacuum leaks. Ensure throttle stop screw has not been tampered with. Check for throttle plate or shaft binding. Check accelerator and speed control cables for misadjustment or binding. Check for faulty, missing or incorrectly installed PCV valve. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to next step.
7. Check for faulty connection at IAC harness connector. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to next step.
8. Replace IAC valve and go to step 11).
9. Check for faulty connection at PCM harness connector. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. Go to next step.
11. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 100 RPM of desired RPM for each command, repair is complete. If ENGINE SPEED is not as specified, return to step 2).

Check for faulty connection at IAC and PCM connectors. Check for damaged harness. Check for vacuum leaks. Check throttle body bore and IAC for excessive deposits. Check throttle plate for sticking.

PCM uses input signal from A/C refrigerant pressure sensor to determine if it should turn on engine coolant fans. When signal is out of range, DTC P0530 sets and PCM will not allow A/C clutch to engage.

1. A/C refrigerant pressure sensor signal less than 0.1 volt.

Or

1. A/C refrigerant pressure sensor signal more than 4.94 volts.
2. Either listed condition present longer than 20 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read A/C refrigerant pressure sensor voltage. If voltage is less than 0.1 volt, go to step 5). If voltage is 0.1 volt or more, go to next step.
3. If voltage is more than 4.8 volts, go to next step. If voltage is 4.8 volts or less, go to DIAGNOSTIC AIDS.
4. While observing scan tool, disconnect A/C refrigerant pressure sensor connector. If voltage is about zero volts, go to step 12). If voltage is not as specified, go to step 11).
5. Disconnect A/C refrigerant pressure sensor connector. Connect a fused jumper wire between A/C refrigerant pressure sensor harness connector 5-volt reference and signal circuit. If voltage is about 5 volts, go to step 16). If voltage is not as specified, go to next step.
6. Using a DVOM, check voltage between A/C pressure sensor harness connector 5-volt reference and ground circuits. If voltage is about 5 volts, go to step 9). If voltage is not as specified, go to next step.
7. Check for faulty 5-volt reference circuit connection at PCM. If faulty connection is found, go to step 17). If connection is okay, go to next step.
8. Check for open or a faulty splice in 5-volt reference circuit. If problem is found, go to step 18). If no problem is found, go to step 13).
9. Check A/C refrigerant signal circuit for faulty connection at PCM. If faulty connection is found, go to step 17). If connection is okay, go to next step.
10. Check A/C refrigerant pressure signal circuit between A/C refrigerant pressure sensor connector and PCM for open or short to ground. If problem is found, go to step 18). If no problem is found, go to step 20)
11. Check A/C refrigerant pressure signal circuit between A/C refrigerant pressure sensor connector and PCM for short to voltage. If problem is found, go to step 18). If no problem is found, go to step 20)
12. Check 5-volt reference circuit for short to voltage. If problem is found, repair as necessary and go to step 18). If no problem is found, go to next step.
13. Check for faulty sensor ground circuit terminal connection at PCM. If faulty connection is found, go to step 17). If connection is okay, go to next step.
14. Check for faulty sensor ground circuit terminal connection at A/C refrigerant pressure sensor connector. If faulty connection is found, go to step 17). If connection is okay, go to next step.
15. Check for open or faulty splice in sensor ground circuit. If a problem is found, go to step 18). If no problem is found, go to step 19).
16. Check for faulty 5-volt reference or A/C refrigerant pressure signal circuit terminal connection at A/C refrigerant pressure sensor. If faulty connection is found, go to next step. If connections are okay, go to step 19).
17. Replace faulty harness connector terminal and go to step 21).
18. Locate and repair open/short circuit in wiring harness as necessary and go to step 21).
19. Replace A/C refrigerant pressure sensor and go to step 21).
20. Replace PCM. Program replacement PCM using required equipment. Go to next step.
21. Using scan tool, clear DTCs. Read A/C refrigerant pressure sensor voltage. If voltage is 0.1-4.8 volts, repair is complete. If voltage is not as specified, return to step 2).

Check for faulty connections or damaged harness. Observe scan tool A/C refrigerant pressure sensor display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0530 Schematic. Scheme 13

PCM monitors system voltage on PCM ignition feed circuit. If system voltage is out of range, DTC P0560 will set.

1. Engine is running.
2. System voltage monitored at PCM ignition feed circuit is less than 10 or greater than 16 volts.
3. Listed conditions present for more than 2 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If DTC P1635 is also set, diagnose DTC P1635 before proceeding. If DTC is not set, go to next step.
3. Start and run engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG. 2 DATA LIST. If voltage is 10-16 volts, go to step 5). If voltage is not as specified, go to next step.
4. Read and record FAIL RECORDS data for DTC P0560. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC while operating vehicle. Continue operating vehicle until DTC P0560 test runs. If scan tool displays DTC P0560 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0560 FAILED THIS IGN, see DIAGNOSTIC AIDS.
5. Install DVOM between battery terminals. Monitor DVOM while running engine at greater than 1000 RPM. If voltage is 10-16 volts, go to next step. If voltage is not as specified, go to step 7).
6. Turn headlights on and place A/C switch on high. Monitor DVOM while running engine at greater than 2000 RPM. If voltage is 10-16 volts, go to step 8). If voltage is not as specified, go to next step.
7. Turn ignition off. Disconnect generator electrical connector. Turn ignition on. Connect DVOM between generator harness connector control circuit and engine ground. Using scan tool, command GEN L TERM on. If voltage is 10-16 volts, go to step 12). If voltage is not as specified, go to step 10).
8. Compare IGNITION 1 voltage display on scan tool with DVOM voltage reading. If both values are close, see DIAGNOSTIC AIDS. If both values are not close, go to next step.
9. Check PCM ignition feed circuit for poor connection between ignition switch and PCM. If problem is found, repair as necessary and go to step 14). If no problem is found, go to step 13).
10. Check generator control circuit for open or short to ground between generator and PCM. If problem is found, repair as necessary and go to step 14). If no problem is found, go to next step.
11. Check generator control circuit for faulty connection at PCM. If problem is found, repair as necessary and go to step 14). If no problem is found, go to step 13).
12. Check generator control circuit for faulty connection at generator. If problem is found, repair as necessary and go to step 14). If no problem is found, see DIAGNOSTIC AIDS.
13. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
14. Clear DTCs. Start and run engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG. 2 DATA LIST. If voltage is 10-16 volts, repair is complete. If voltage is not as specified, return to step 2).

Check for faulty connections or damaged harness. Observe scan tool IGNITION 1 voltage display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0560 Schematic. Scheme 14

PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM). EEPROM contains program information and calibrations required for engine, transaxle, and powertrain diagnostics operation.

Condition required to set DTC is

1. PCM detects an internal program fault (check sum error).

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After completing repairs, repeat OBD system check.

Only possible repair is replacement and programming of PCM.

PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM). EEPROM contains program information and calibrations required for engine, transaxle, and powertrain diagnostics operation.

1. PCM does not contain correct program(s) required to operate vehicle.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using special equipment, program PCM with correct software. Using scan tool, retest for DTC P0602. If DTC P0602 sets, go to next step. If DTC does not set, repair is complete.
3. Replace PCM. Program replacement PCM using required equipment. After repair is completed, repeat OBD system check.

Transaxle Range Switch (TRS) is part of Park/Neutral Position (PNP) switch. Inputs from TRS indicate to PCM which position is selected by gear selector lever. PCM uses this information for ignition timing, EVAP canister purge, EGR and IAC valve operation.

Combination of 4 TRS input states determine PCM commanded shift pattern. Input voltage level at PCM is high when TRS is open, and low when TRS is closed. A problem which causes PCM to detect an invalid transaxle range input combination will set DTC P0705.

1. TRS inputs indicate an invalid combination for more than 10 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on, engine off. Place gear selector in Park. Using scan tool, read TR PABC display. If scan tool displays P=O A=O B=X C=X, go to next step. If display is not as specified, go to step 4).
3. Observe scan tool display while placing gear selector in each gear position. Record TR PABC status for each gear position. Compare scan tool display for each gear position with TRANSAXLE RANGE SWITCH VALID INPUT COMBINATIONS table. If scan tool display matches table entries for each gear selected, go to DIAGNOSTIC AIDS. If scan tool display does not match table entries, go to step 10).
4. If scan tool displays P=X A=X B=X C=X, go to next step. If display is not as specified, go to step 7).
5. Check if TRS 4-pin harness connector is disconnected or damaged. If a problem is found, repair as necessary and go to step 17). If no problem is found, go to next step.
6. Check for open in TRS 7-pin harness connector ground circuit. If open is found, repair as necessary and go to step 17). If no open is found, go to step 13).
7. If scan tool displays P=O A=O B=O C=O, go to next step. If display is not as specified, return to step 3).
8. Disconnect TRS 4-pin harness connector. If scan tool displays P=O A=O B=O C=O, go to next step. If display is not as specified, go to step 14).
9. Turn ignition off. Disconnect PCM. Check TRS input circuit for being pinched or shorted to ground. If a problem is found, repair as necessary and go to step 17). If no problem is found, go to step 16).
10. Ensure wires in TRS 4-pin harness connector are not crossed. If a problem is found, repair as necessary and go to step 17). If no problem is found, go to next step.
11. Turn ignition off. Disconnect PCM and TRS. Turn ignition on. Check for open, short to ground or short to voltage in circuit which caused incorrect TRS input combination. If a problem is found, repair as necessary and go to step 17). If no problem is found, go to next step.
12. Reconnect TRS. Connect a test light between battery voltage and TRS circuit which caused incorrect TRS input combination at PCM. Observe and record state of test light while selecting each gear position. Compare state of test light in each gear position with TRANSAXLE RANGE SWITCH VALID INPUT COMBINATIONS TABLE. If test light illuminates when input state should be "O" and off when input state should equal "X", go to step 15). If test light illuminates as specified, go to next step.
13. Check for faulty connection at TRS 4-pin and 7-pin connectors. If a problem is found, repair as necessary and go to step 17). If no problem is found, go to next step.
14. Replace TRS and go to step 17).
15. Check for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 17). If no problem is found, go to next step.
16. Replace PCM. Program replacement PCM using required equipment. Go to next step.
17. Clear DTCs. Observe scan tool display while placing gear selector in each gear position. Record TR PABC status for each gear position. Compare scan tool display for each gear position with TRANSAXLE RANGE SWITCH VALID INPUT COMBINATIONS table. If scan tool display matches table entries for each gear selected, repair is complete. If scan tool display does not match table entries, return to step 2).

TRANSAXLE RANGE SWITCH VALID INPUT COMBINATIONS

Check for faulty connections or damaged harness. Observe scan tool TR PABC display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0705 Schematic. Scheme 15

DTC P0706 - TRANSAXLE RANGE SYSTEM PERFORMANCE

Note. For circuit reference, see DTC P0705 schematic.

Transaxle Range Switch (TRS) is part of Park/Neutral Position (PNP) switch. Inputs from TRS indicate to PCM which position is selected by gear selector lever. PCM uses this information for ignition timing, EVAP canister purge, EGR and IAC valve operation.

Combination of 4 TRS input states determine PCM commanded shift pattern. Input voltage level at PCM is high when TRS is open, and low when TRS is closed. If PCM detects engine start-up in any gear other than Park or Neutral, DTC P0706 is set.

1. System voltage is greater than 9 volts.
2. TRS inputs indicate a gear position other than Park or Neutral during start-up.
3. Listed conditions present for more than 3 consecutive start-ups.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If DTC P0705 is also set, diagnose DTC P0705 before proceeding. If DTC is not set, go to next step.
3. Turn ignition on. Place gear selector in Park. Using scan tool, read TRANS RANGE display. If scan tool displays P-N, go to next step. If scan tool does not display P-N, go to step 5).
4. Place gear selector in Neutral. Read scan tool TRANS RANGE display. If scan tool displays P-N, see DIAGNOSTIC AIDS. If scan tool does not display P-N, go to next step.
5. Read scan tool TR PABC display. If scan tool displays P=O A=O B=O C=O, go to next step. If display is not as specified, go to step 10).
6. Disconnect TRS 4-pin harness connector. If scan tool displays P=O A=O B=O C=O, go to next step. If display is not as specified, go to step 8).
7. Turn ignition off. Disconnect PCM. Check TRS input circuit for being pinched or shorted to ground. If a problem is found, repair as necessary and go to step 12). If no problem is found, go to step 11).
8. Attempt to adjust PNP/TRS switch. Read scan tool TRANS RANGE display with Park and Neutral selected. If scan tool displays P-N, go to step 12). If scan tool does not display P-N, go to next step.
9. Ensure wires in TRS 4-pin harness connector are not crossed. If a problem is found, repair as necessary and go to step 12). If no problem is found, go to next step.
10. Replace TRS and go to step 12).
11. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
12. Clear DTCs. Observe scan tool display while placing gear selector in each gear position. Record TR PABC status for each gear position. Compare scan tool display for each gear position with TRANSAXLE RANGE SWITCH VALID INPUT COMBINATIONS table. If scan tool display matches table entries for each gear selected, repair is complete. If scan tool display does not match table entries, return to step 3).

TRANSAXLE RANGE SWITCH VALID INPUT COMBINATIONS

Check for faulty connections or damaged harness. Observe scan tool TR PABC display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1106 - MAP SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Manifold Absolute Pressure (MAP) sensor measures changes in intake manifold pressure (vacuum). A low voltage signal, 2 volts, is sent to PCM on 5-volt reference circuit at closed throttle (high vacuum). A high voltage signal, 4 volts is sent at wide open throttle (low vacuum).

1. No TP sensor DTCs set.
2. Ignition on.
3. TP ANGLE steady and less than 5% with engine speed less than 1000 RPM, or steady and less than 10% with engine speed greater than 1000 RPM.
4. MAP sensor intermittently indicates MAP greater than 12.8 psi (0.90 kg/cm 2 ).

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0108 is also set, diagnose DTC P0108 before proceeding. If DTC is not set, go to next step.
3. If DTC P1111, P1115, and/or P1121 is also set, go to step 6). If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal at MAP sensor. If problem is found, go to step 9). If no problem is found, go to next step.
5. Check MAP signal circuit between MAP sensor harness connector and PCM for intermittent short to voltage. If a problem is found, go to step 10). If no problem is found, go to step 8).
6. Check for intermittent short to voltage on 5-volt reference circuit between PCM and MAP, EGR and TP sensors. If a problem is found, go to step 10). If no problem is found, go to next step.
7. Check for faulty ground circuit terminal connection at PCM. If problem is found, go to step 9). If no problem is found, go to next step.
8. Check for intermittent open or faulty splice in sensor ground circuit. If a problem is found, go to step 10). If no problem is found, see DIAGNOSTIC AIDS.
9. Replace faulty connector terminal and go to step 11).
10. Locate and repair intermittent open/short circuit and go to next step.
11. Read and record FAIL RECORDS data for DTC P1106. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1106 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1106 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool MAP display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1107 - MAP SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Manifold Absolute Pressure (MAP) sensor measures changes in intake manifold pressure (vacuum). A low voltage signal, 2 volts, is sent to PCM on 5-volt reference circuit at closed throttle (high vacuum). A high voltage signal, 4 volts is sent at wide open throttle (low vacuum).

1. No TP sensor DTCs set.
2. Ignition on.
3. TP ANGLE steady and more than 6 percent with engine speed more than 1000 RPM.
4. MAP sensor intermittently indicates MAP less than 2.8 psi. (0.20 kg/cm 2 ).

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0107 is also set, diagnose DTC P0107 before proceeding. If DTC is not set, go to next step.
3. If DTC P1122 is also set, go to step 6). If DTC is not set, go to next step.
4. Check for faulty 5-volt reference or signal circuit connection at MAP sensor. If a problem is found, go to step 9). If no problem is found, go to next step.
5. Check signal circuit between MAP sensor and PCM for intermittent open or short to ground. If problem is found, go to step 10). If no problem is found, go to step 8).
6. Check for intermittent short to ground on 5-volt reference circuit between PCM and EGR valve, MAP and TP sensors. If a problem is found, go to step 10). If no problem is found, go to next step.
7. Check for faulty 5-volt reference circuit connection at PCM. If faulty connection is found, go to step 9). If connection is okay, go to next step.
8. Check for intermittent open or faulty splice in 5-volt reference circuit. If a problem is found, go to step 10). If no problem is found, go to DIAGNOSTIC AIDS.
9. Replace faulty connector terminal(s) and go to step 11).
10. Repair circuit as necessary and go to next step.
11. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1107. If scan tool displays DTC P1107 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1107 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool MAP display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1111 - IAT SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Intake Air Temperature (IAT) sensor is a thermistor. PCM applies and reads a 5-volt reference signal to sensor. When air is cold, sensor resistance is high and PCM will measure a high signal voltage. If air is warm, sensor resistance is low causing PCM to measure low voltage.

1. No ECT, MAF or VSS sensor DTCs set.
2. Engine running more than 3 minutes.
3. ECT greater than 140°F (60°C).
4. Vehicle speed less than 35 MPH.
5. IAT intermittently less than -38°F (-39°C).

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0113 is also set, diagnose DTC P0113 before proceeding. If DTC is not set, go to next step.
3. If DTC P1106, P1115, and/or P1121 is also set, go to step 6). If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal at IAT sensor. If problem is found, repair as necessary and go to step 10). If no problem is found, go to next step.
5. Check for faulty signal circuit connection at IAT sensor. If faulty connection is found, repair as necessary and go to step 10). If connection is okay, go to next step.
6. Check IAT signal circuit between IAT sensor harness connector and PCM for intermittent open. If open is found, repair as necessary and go to step 10). If no open is found, go to next step.
7. Check IAT signal circuit between IAT sensor harness connector and PCM for intermittent short to voltage. If short to voltage is found, repair as necessary and go to step 10). If no short to voltage is found, go to next step.
8. Check for faulty ground circuit terminal connection at PCM. If problem is found, repair as necessary and go to step 10). If no problem is found, go to next step.
9. Check for intermittent open or faulty splice in sensor ground circuit. If a problem is found, repair as necessary and go to next step. If no problem is found, see DIAGNOSTIC AIDS.
10. Read and record FAIL RECORDS data for DTC P1111. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1111 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1111 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool IAT display while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed IAT sensor. See IAT TEMPERATURE-TO-RESISTANCE VALUES.

IAT TEMPERATURE-TO-RESISTANCE VALUES

DTC P1112 - IAT SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Intake Air Temperature (IAT) sensor is a thermistor. PCM applies and reads a 5-volt reference signal to sensor. When air is cold, sensor resistance is high and PCM will measure a high signal voltage. If air is warm, sensor resistance is low causing PCM to measure low voltage.

1. No ECT, MAF, or VSS sensor DTCs set.
2. Vehicle speed greater than 25 MPH.
3. Engine running longer than 10 seconds.
4. IAT sensor voltage intermittently less than 0.14 volt.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0112 is also set, diagnose DTC P0112 before proceeding. If DTC is not set, go to next step.
3. Check IAT signal circuit between IAT sensor harness connector and PCM for intermittent short to ground. If short to ground is found, repair as necessary and go to next step. If no short to ground is found, see DIAGNOSTIC AIDS.
4. Read and record FAIL RECORDS data for DTC P1112. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1112 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1112 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool IAT display while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed IAT sensor. See IAT TEMPERATURE-TO-RESISTANCE VALUES.

IAT TEMPERATURE-TO-RESISTANCE VALUES

DTC P1114 - ECT SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Engine Coolant Temperature (ECT) 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 will set when PCM sees an ECT sensor voltage intermittently less than 0.14 volt.

1. Engine running for 3 seconds.
2. ECT voltage intermittently less than 0.14 volt.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0117 is also set, diagnose DTC P0117 before proceeding. If DTC is not set, go to next step.
3. Check ECT signal circuit between ECT sensor harness connector and PCM for intermittent short to ground. If short to ground is found, repair as necessary and go to next step. If no short to ground is found, see DIAGNOSTIC AIDS.
4. Read and record FAIL RECORDS data for DTC P1114. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1114 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1114 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool IAT display while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed ECT sensor. See ECT TEMPERATURE-TO-RESISTANCE VALUES table.

ECT TEMPERATURE-TO-RESISTANCE VALUES

DTC P1115 - ECT SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Engine Coolant Temperature (ECT) 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 will set when PCM sees an ECT sensor voltage intermittently greater than 4.8 volts.

1. Engine running for 3 seconds.
2. ECT voltage intermittently greater than 4.8 volts.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0118 is also set, diagnose DTC P0118 before proceeding. If DTC is not set, go to next step.
3. If DTC P1106, P1111, and/or P1121 is also set, go to step 8). If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal at ECT sensor. If problem is found, repair as necessary and go to step 10). If no problem is found, go to next step.
5. Check for faulty signal circuit connection at ECT sensor. If faulty connection is found, repair as necessary and go to step 10). If connection is okay, go to next step.
6. Check ECT signal circuit between ECT sensor harness connector and PCM for intermittent open. If open is found, repair as necessary and go to step 10). If no open is found, go to next step.
7. Check ECT signal circuit between ECT sensor harness connector and PCM for intermittent short to voltage. If short to voltage is found, repair as necessary and go to step 10). If no short to voltage is found, go to next step.
8. Check for faulty ground circuit terminal connection at PCM. If problem is found, repair as necessary and go to step 10). If no problem is found, go to next step.
9. Check for intermittent open or faulty splice in sensor ground circuit. If a problem is found, repair as necessary and go to next step. If no problem is found, see DIAGNOSTIC AIDS.
10. Read and record FAIL RECORDS data for DTC P1115. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1115 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1115 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool ECT display while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed ECT sensor. See ECT TEMPERATURE-TO-RESISTANCE VALUES table.

ECT TEMPERATURE-TO-RESISTANCE VALUES

DTC P1121 - TP SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

Note. For circuit reference, see DTC P0121 schematic.

Throttle Position (TP) sensor measures amount of throttle opening. PCM uses TP sensor information for fuel delivery calculations. TP sensor readings during acceleration are much higher than those during deceleration or idle. DTC P1121 sets if PCM senses TP sensor voltage intermittently greater than 4.7 volts.

1. Ignition is on.
2. TP signal voltage is intermittently greater than 4.7 volts.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0123 is also set, diagnose DTC P0123 before proceeding. If DTC is not set, go to next step.
3. If DTC P1106, P1111, and/or P1115 is also set, go to step 6). If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal at TP sensor. If problem is found, go to step 9). If no problem is found, go to next step.
5. Check TP signal circuit between TP sensor harness connector and PCM for intermittent short to voltage. If a problem is found, go to step 10). If no problem is found, go to step 8).
6. Check for intermittent short to voltage on 5-volt reference circuit between PCM and MAP, EGR and TP sensors. If a problem is found, go to step 10). If no problem is found, go to next step.
7. Check for faulty ground circuit terminal connection at PCM. If problem is found, go to step 9). If no problem is found, go to next step.
8. Check for intermittent open or faulty splice in sensor ground circuit. If a problem is found, go to step 10). If no problem is found, see DIAGNOSTIC AIDS.
9. Replace faulty connector terminal and go to step 11).
10. Locate and repair intermittent open/short circuit and go to next step.
11. Read and record FAIL RECORDS data for DTC P1121. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1121 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1121 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool TP display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1122 - TP SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

Note. For circuit reference, see DTC P0121 schematic.

Throttle Position (TP) sensor measures amount of throttle opening. PCM uses TP sensor information for fuel delivery calculations. TP sensor readings during acceleration are much higher than those during deceleration or idle. DTC P1121 sets if PCM senses TP sensor voltage intermittently less than 0.15 volt.

1. Ignition on.
2. TP signal voltage is intermittently less than 0.15 volt.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0122 is also set, diagnose DTC P0122 before proceeding. If DTC is not set, go to next step.
3. If DTC P1107 is also set, go to step 6). If DTC is not set, go to next step.
4. Check for faulty 5-volt reference or signal circuit connection at TP sensor. If a problem is found, go to step 9). If no problem is found, go to next step.
5. Check signal circuit between TP sensor and PCM for intermittent open or short to ground. If problem is found, go to step 10). If no problem is found, go to step 8).
6. Check for intermittent short to ground on 5-volt reference circuit between PCM and EGR valve, MAP and TP sensors. If a problem is found, go to step 10). If no problem is found, go to next step.
7. Check for faulty 5-volt reference circuit connection at PCM. If faulty connection is found, go to step 9). If connection is okay, go to next step.
8. Check for intermittent open or faulty splice in 5-volt reference circuit. If a problem is found, go to step 10). If no problem is found, see DIAGNOSTIC AIDS.
9. Replace faulty connector terminal(s) and go to step 11).
10. Repair circuit as necessary and go to next step.
11. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1122. If scan tool displays DTC P1122 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1122 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool TP display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1133 - HO2S INSUFFICIENT SWITCHING SENSOR 1

Note. For circuit reference, see DTC P0131 schematic.

PCM monitors Heated Oxygen Sensor (HO2S) activity for 100 seconds. PCM determines if HO2S 1 is functioning properly by counting number of HO2S 1 Lean/Rich (L/R) and Rich/Lean (R/L) switches. If PCM determines that HO2S 1 did not switch enough times, DTC 1133 is set.

1. No fuel trim, injector or HO2S 1 heater circuit DTCs set.
2. No ECT, IAT, MAF, MAP, or TP sensor DTCs set.
3. No EGR or EVAP DTCs set.
4. Engine operating in closed loop mode.
5. Listed conditions present during 100 second monitoring period.
6. TP ANGLE value 10-20%.
7. L/R and R/L switches less than 50 on VIN 1.
8. L/R and R/L switches less than 40 on VIN K.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If any DTC other than P1133 or P1134 sets, diagnose affected DTC before proceeding. If no other DTC sets, start engine and allow it to idle. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1133 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1133 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
3. Check exhaust system for leaks. If exhaust leak is found, repair as necessary and go to step 11). If no exhaust leak is found, go to next step.
4. Visually inspect HO2S 1 for secure installation or corrosion on terminals. Check terminal tension at HO2S 1 and PCM. Check for damaged wiring. If a problem is found, go to step 8). If no problem is found, go to next step.
5. Disconnect HO2S 1 connector. Connect a jumper wire betweenHO2S 1 harness connector ground circuit and chassis ground. Using scan tool, read HO2S 1 voltage. If voltage is about 0.45 volt, go to next step. If voltage is not as specified, go to step 9).
6. Connect a jumper wire between HO2S 1 harness connector signal and ground circuits, and chassis ground. If voltage is less than 0.3 volt, go to next step. If voltage is 0.3 volt or greater, go to step 10).
7. Repair condition causing fuel, sealant, oil or coolant contamination. Replace affected HO2S and go to step 11).
8. Repair condition as necessary and go to step 11).
9. Repair open HO2S 1 ground circuit or HO2S 1 signal circuit shorted to ground, and go to step 11).
10. Repair open HO2S 1 signal circuit or faulty PCM connections as necessary, and go to step 11).
11. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1133. If scan tool displays DTC P1133 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1133 FAILED THIS IGN, repair is complete.

Check HO2S 1 heater operation. If HO2S 1 heater operation is okay, replace HO2S 1.

DTC P1134 - HO2S TRANSITION TIME RATIO SENSOR 1

Note. For circuit reference, see DTC P0131 schematic.

PCM reads Heated Oxygen Sensor (HO2S) activity for 100 seconds. During this period, PCM counts the number of Lean/Rich (L/R) and Rich/Lean (R/L) switches.

With this information, an average time for all transitions can be determined. PCM then divides R/L average by L/R rich average to obtain a ratio. If HO2S ratio is not within range, DTC P1134 will set.

1. No fuel trim, injector or HO2S 1 heater circuit DTCs set.
2. No ECT, IAT, MAF, MAP, or TP sensor DTCs set.
3. No EGR or EVAP DTCs set.
4. Engine operating in closed loop mode.
5. Listed conditions present during 100 second monitoring period.
6. TP ANGLE value 10-20 percent.
7. Ratio of average response times not 3.00-0.75 on VIN 1.
8. Ratio of average response times not 4.5-0.5 on VIN K.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If any DTC other than P1133 or P1134 sets, diagnose affected DTC before proceeding. If no other DTC sets, start engine and allow it to idle. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1133 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1133 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
3. Check exhaust system for leaks. If exhaust leak is found, repair as necessary and go to step 11). If no exhaust leak is found, go to next step.
4. Visually inspect HO2S 1 for secure installation or corrosion on terminals. Check terminal tension at HO2S 1 and PCM. Check for damaged wiring. If a problem is found, go to step 8). If no problem is found, go to next step.
5. Disconnect HO2S 1 connector. Connect a jumper wire betweenHO2S 1 harness connector ground circuit and chassis ground. Using scan tool, read HO2S 1 voltage. If voltage is about 0.45 volt, go to next step. If voltage is not as specified, go to step 9).
6. Connect a jumper wire between HO2S 1 harness connector signal and ground circuits, and chassis ground. If voltage is less than 0.3 volt, go to next step. If voltage is 0.3 volt or greater, go to step 10).
7. Repair condition causing fuel, sealant, oil or coolant contamination. Replace affected HO2S and go to step 11).
8. Repair condition as necessary and go to step 11).
9. Repair open HO2S 1 ground circuit or HO2S 1 signal circuit shorted to ground, and go to step 11).
10. Repair open HO2S 1 signal circuit or faulty PCM connections as necessary, and go to step 11).
11. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1133. If scan tool displays DTC P1133 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1133 FAILED THIS IGN, repair is complete.

Check HO2S 1 heater operation. If HO2S 1 heater operation is okay, replace HO2S 1.

PCM controls fuel injector driver circuit using a General FET Driver (GFD). GFD has ability to detect electrical faults on any injector feed or driver circuits. If an electrical fault is detected, GFD signals PCM to set DTC P1200.

1. Incorrect voltage level detected on injector driver circuit(s).
2. Listed condition present for more than 5 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and allow it to idle. Using scan tool, select SPECIFIC DTC INFO for DTC P1200. If scan tool displays DTC P1200 FAILED THIS IGN, go to step 4). If scan tool does not display DTC P1200 FAILED THIS IGN, go to next step.
3. Turn engine off. Turn ignition on, engine off. Read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1200. If scan tool displays DTC P1200 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1200 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between each injector driver circuit and engine ground. If voltage is 9-16 volts on each circuit, go to next step. If voltage is not as specified on any circuit, go to step 9).
5. Perform INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM/COMPONENT TESTS article. If injectors are okay, go to next step. If an injector problem is found, go to step 17).
6. Turn ignition off. Disconnect all injector connectors. Turn ignition on. Using DVOM, check voltage between each injector driver circuit at PCM harness connector and engine ground. If voltage is zero volts on each circuit, go to next step. If voltage is not as specified, go to step 16).
7. Check harness ignition feed circuits between injector fuse and injectors for intermittent open. Check injector driver circuits between PCM and injectors for intermittent open or short to ground. If a problem is found, repair as necessary and go to step 19). If no problem is found, go to next step.
8. Check for faulty connection at injector connectors. Check injector driver circuits for faulty connection at PCM connectors. If a problem is found, go to step 19). If no problem is found, go to step 18).
9. Turn ignition off. Disconnect affected injector connector(s). Turn ignition on. Check voltage between ignition feed circuit at affected injector connector(s) and engine ground. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 14).
10. Connect a test light between affected injector connector(s) and battery voltage. If test light illuminates, go to step 15). If test light does not illuminate, go to next step.
11. Turn ignition off. Connect a fused jumper cable between affected injector connector(s) ignition feed and driver circuits. Turn ignition on. Connect test light between affected injector(s) driver circuit at PCM and engine ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
12. Check for faulty connection at injector connector(s). If faulty connection is found, repair as necessary and go to step 19). If connection(s) are okay, go to step 17).
13. Locate and repair open in affected injector driver circuit(s) and go to step 19).
14. Locate and repair open or short to ground in affected ignition feed circuit(s) and go to step 19).
15. Locate and repair short to ground in affected injector driver circuit(s) and go to step 19).
16. Locate and repair short to voltage in affected injector driver circuit(s) and go to step 19).
17. Replace faulty injector(s) and go to step 19).
18. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
19. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1200. If scan tool displays DTC P1200 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1200 FAILED THIS IGN, repair is complete.

If DTC P0300 is also set, start engine and allow it to idle. Using scan tool, read and record FREEZE FRAME data. Operate vehicle within conditions noted in FREEZE FRAME data. Using scan tool, read MISFIRE CUR # display for each cylinder. An increasing MISFIRE CUR # (indicating a misfire currently occurring) for any cylinder indicates location of faulty circuit or injector.

DTC P1200 Schematic. Scheme 16

Normally PCM commands Boost Control solenoid to operate at 100% (on) Pulse Width Modulation (PWM) to allow for full intake boost upon demand. If Reverse is selected, PCM detects rapid deceleration, or engine is load is extremely high, PCM commands BC solenoid to operate at 0% (off) PWM.

1. IAT greater than 14°F (-10°C)
2. Engine torque exceeds maximum predetermined torque threshold value.
3. Listed conditions are present for more than 6 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If any other DTCs set, diagnose affected DTCs before proceeding. If no other DTCs set, go to next step.
3. Disconnect BC solenoid harness connector. Turn ignition on. Connect a test light across BC solenoid harness connector terminals. If test light illuminates, go to step 9). If test light does not illuminate, go to next step.
4. Disconnect inlet vacuum signal hose from bypass valve actuator. Connect a vacuum gauge to bypass valve actuator. Start engine and allow it to idle in Park. If vacuum is greater than 12 in. Hg, go to next step. If vacuum is 12 in. Hg or less, go to step 12).
5. Reconnect BC solenoid harness connector and inlet vacuum signal hose. Disconnect boost signal hose between BC solenoid and by-pass valve actuator. Connect vacuum gauge to bypass valve actuator. Using scan tool, turn BC solenoid off. If vacuum is greater than 12 in. Hg, go to next step. If vacuum is 12 in. Hg or less, go to step 12).
6. Check for restriction in boost signal hose between BC solenoid and bypass valve actuator. If restriction is found, repair as necessary and go to step 15). If no restriction is found, go to next step.
7. Check for binding bypass valve, sticking or misadjusted by-pass valve actuator linkage. If problem is found, repair as necessary and go to step 15). If no problem is found, go to next step.
8. Replace bypass valve actuator and go to step 15).
9. Turn ignition off. Disconnect PCM. Turn ignition on. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
10. Locate and repair short to ground in BC solenoid driver circuit and go to step 15).
11. Repair restriction in inlet vacuum signal hose, or blocked inlet vacuum source and go to step 15).
12. Check for restriction in boost source hose to BC solenoid. If restriction is found, repair as necessary and go to step 15). If no restriction is found, go to step 12).
13. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 15).
14. Replace BC solenoid and go to next step.
15. Read and record FAIL RECORDS data for DTC P1257. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1257 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1257 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Connect a DVOM between BC solenoid driver circuit at PCM harness connector and engine ground. With ignition on, observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

Check BC solenoid driver circuit for short to ground. Check for binding bypass valve. Check for sticking or misadjusted bypass valve actuator.

DTC P1257 Schematic. Scheme 17

DTC P1350 - IGNITION CONTROL (IC) CIRCUIT

Note. For circuit reference, see DTC P0336 schematic.

Ignition Control Module (ICM) sends signals that PCM requires for fuel control and spark advance calculations. At start of engine crank, ICM controls spark advance (by-pass mode). When second 3X signal is recognized by PCM, it applies 5 volts to bypass circuit, commanding ICM to switch Ignition Control (IC) of spark advance to PCM (IC mode). An open in IC circuit, or a short to voltage in bypass circuit will set DTC 1350.

1. PCM monitors IC pulses during crank while by-pass mode spark advance is commanded.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, clear DTCs. Start engine and allow it to idle for 2 minutes. Read DTCs. If DTC P1350 sets, go to next step. If DTC does not set, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check resistance between PCM harness connector IC and ground circuits. If resistance is less than 500 ohms, go to step 6). If resistance is greater than specified, go to next step.
4. Turn ignition off. Disconnect ICM connector. Check IC circuit for open. If open is found, repair as necessary and go to step 10). If no open is found, go to next step.
5. Check for faulty IC circuit connection at ICM. If faulty connection is found, repair as necessary and go to step 10). If connection is okay, go to step 8).
6. Check for faulty IC circuit connection at PCM. If faulty connection is found, repair as necessary and go to step 10). If connection is okay, go to next step.
7. Replace PCM. Program replacement PCM using required equipment. Go to step 10).
8. Turn ignition on. Check bypass circuit for short to voltage. If short to voltage is found, repair as necessary and go to step 10). If short to voltage is not found, go to next step.
9. Replace ICM and go to next step.
10. Read and record FAIL RECORDS data for DTC P1350. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1350 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1350 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect ICM. Connect a DVOM between ICM harness connector IC circuit and battery voltage. With ignition on, observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1361 - IGNITION CONTROL (IC) CIRCUIT NOT TOGGLING

Note. For circuit reference, see DTC P0336 schematic.

Ignition Control Module (ICM) sends signals that PCM requires for fuel control and spark advance calculations. At start of engine crank, ICM controls spark advance (by-pass mode). When second 3X signal is recognized by PCM, it applies 5 volts to by-pass circuit, commanding ICM to switch Ignition Control (IC) of spark advance to PCM (IC mode). A short in IC circuit, or an open or short ground in by-pass circuit will set DTC 1361.

1. PCM monitors IC pulses during crank while by-pass mode spark advance is commanded.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, clear DTCs. Start engine and allow it to idle for 2 minutes. Read DTCs. If DTC P1361 sets, go to next step. If DTC does not set, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Connect a test light between battery voltage and PCM harness connector bypass circuit. If test light illuminates, go to step 8). If test light does not illuminate, go to next step.
4. Turn ignition on. with test light still connected between battery voltage and PCM harness connector by-pass circuit, use a DVOM to check resistance between PCM harness connector IC circuit and reference low circuit. If resistance is more than 6000 ohms, go to step 9). If resistance is 6000 ohms or less, go to next step.
5. Turn ignition off. Disconnect ICM 14-pin connector. Check resistance between ICM 14-pin harness connector IC circuit and engine ground. If resistance is infinite, go to next step. If resistance is not infinite, go to step 10).
6. Check by-pass circuit for open. If open is found, repair as necessary and go to step 15). If open is not found, go to next step.
7. Check by-pass circuit for faulty connection at ICM. If faulty connection is found, repair as necessary and go to step 15). If connection is okay, go to step 14).
8. Turn ignition off. Disconnect ICM 14-pin connector. Turn ignition on. If test light illuminates, go to step 11). If test light does not illuminate, go to step 14).
9. Turn ignition off. Disconnect ICM connectors. Turn ignition on. Check IC circuit for short to voltage. If short to voltage is found, repair as necessary and go to step 15). If no short to voltage is found, go to step 12).
10. Locate and repair short to ground in IC circuit, and go to step 15).
11. Locate and repair short to ground in by-pass circuit, and go to step 15).
12. Check by-pass circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 15). If connection is okay, go to next step.
13. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 15).
14. Replace ICM and go to next step.
15. Read and record FAIL RECORDS data for DTC P1361. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1361 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1361 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect ICM. Connect a DVOM between ICM harness connector IC circuit and battery voltage. With ignition on, observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1374 - 3X REFERENCE CIRCUIT

Note. For circuit reference, see DTC P0336 schematic.

3X reference circuit is produced by Ignition Control Module (ICM). PCM uses 3X reference signal pulses to calculate engine speed (RPM) and crankshaft position at engine speed more than 1200 RPM. PCM uses pulses on this circuit to initiate injector pulses. If PCM receives incorrect number of pulses on 3X reference circuit, DTC P1374 will set.

1. Engine running and PCM is receiving 18X reference signal pulses.
2. Ratio of 18X reference signal pulses to 3X reference signal pulses received by PCM do not equal 6.
3. Ratio of 18X reference signal pulses to camshaft reference signal pulses received by PCM equals 36.
4. Listed conditions occur 80 times.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start and run, see ENGINE DOES NOT START in BASIC TESTING article.
3. Using scan tool, read and record FAILS RECORD DATA. Operate vehicle within conditions noted in FAILED RECORDS DATA. Read SPECIFIC DTC. If scan tool displays DTC P1374 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1374 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
4. Connect a test light to any injector harness connector. Turn ignition on. Connect repeatedly touch test light lead to 3X reference signal circuit while observing test light. If test light blinks, go to step 8). If test light does not flash, go to next step.
5. Turn ignition off. Disconnect PCM. Check 3X reference signal circuit for open or short to ground. If a problem is found, go to step 11). If no problem is found, go to next step.
6. Check for faulty 3X reference signal circuit connection at PCM. If a faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to next step.
7. Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to step 10).
8. Check for faulty connections at ICM. If faulty connection is found, repair as necessary and go to step 11). If connections are okay, go to next step.
9. Replace ICM and go to step 11).
10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
11. Read and record FAIL RECORDS data for DTC P1374. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1374 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1374 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe a voltmeter connected to 3X reference circuit at PCM harness connector while moving all related harness and connectors. A change in voltage indicates fault location.

Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness.

PCM detects engine misfire by detecting variations in crankshaft deceleration between firing strokes. For accurate detection of engine misfire, PCM must be able to distinguish between crankshaft deceleration caused by actual misfire or deceleration caused by rough road conditions.

Electronic Brake Control Module (EBCM) transmits rough road information based on wheel acceleration/deceleration data supplied by the wheel speed sensors. If ABS system detects rough road above a predetermined threshold, information is sent to PCM through serial data circuit.

1. ENGINE LOAD less than 87 percent.
2. Engine speed less than 5000 RPM.
3. Vehicle speed greater than 10 MPH.
4. A misfire DTC is occurring and requesting MIL to be illuminated.
5. PCM detects rough road data error for more than 10 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, select CHASSIS APPLICATION and attempt to display ABS DATA. If ABS DATA is displayed, go to next step. If ABS DATA is not displayed, go to step 4).
3. Check serial data circuit for open or faulty connection between EBCM and PCM. If a problem is found, repair as necessary. Repair is complete. If no open is found, see DIAGNOSTIC AIDS.
4. Turn ignition off. Disconnect EBCM connector. Turn ignition on. Using a DVOM, check voltage on EBCM harness connector serial data circuit. If voltage is 1-5 volts, go to next step. If voltage is not as specified, go to step 6).
5. Check for faulty connection at EBCM. If faulty connection is found, repair as necessary and go to step 7). If connection is okay, go to next step.
6. Check for open serial data circuit to EBCM. If open is found, repair as necessary and go to next step. If no open is found, perform ABS system diagnosis. See appropriate ANTI-LOCK BRAKE SYSTEM article in the BRAKES section.
7. Turn ignition on. Using scan tool, select CHASSIS APPLICATION and attempt to display ABS DATA. If ABS DATA is displayed, repair is complete. If ABS DATA is not displayed, return to step 4).

Check for faulty connections or damaged harness. If connections and harness appear okay, observe ABS DATA on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1381 Schematic. Scheme 18

PCM monitors Exhaust Gas Recirculation (EGR) valve pintle position sensor to ensure valve is responding to commands from PCM.

1. EGR feedback is less than 0.14 volt at any time.
2. EGR feedback is 0.4 volt greater or less than EGR closed valve pintle position when desired EGR position is commanded to 0%.
3. Actual EGR position is 10 greater or less than EGR desired position.
4. Any listed condition present for more than 20 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn engine on and allow it to idle. Using scan tool, read EGR ACTUAL POS. If scan tool displays 0%, go to next step. If scan tool does not display 0%, go to step 11).
3. Ignition on. Select MISC TESTS on scan tool. Increment EGR valve from the 10% through the 100% positions while comparing the desired position with the actual position. If desired is close to actual, go to next step. If not, go to step 6).
4. Ignition off. Unplug PCM. Ignition on. Probe EGR ignition filter circuit at PCM connector with a test light to ground. If test light is on, go to next step. If not, go to step 33)
5. Ignition off. Reconnect PCM. Ignition on. Review and record FAIL RECORDS data. Operate vehicle within fail records conditions. Monitor SPECIFIC DTC for DTC P1406 until DTC test runs. If scan tool indicates this code failed this ignition, go to step 22). If not, see DIAGNOSTIC AIDS.
6. Disconnect EGR valve harness connector. Connect a DVOM between EGR harness connector control and ignition feed circuits. Using scan tool, command EGR duty cycle to 100% position. If about battery voltage is present at 100%, go to step 17). If not, go to next step.
7. Connect a test light between engine ground and EGR valve harness connector ignition feed circuit. If test light illuminates, go to step 9). If test light does not illuminate, go to next step.
8. Check EGR valve ignition feed circuit fuse. If fuse is blown, locate and repair short to ground in ignition feed circuit and go to step 34). If fuse is okay, go to step 24).
9. Turn ignition off. Disconnect PCM connectors. Check EGR control circuit for open. If open is found, repair as necessary and go to step 34). If no open is found, go to next step.
10. Check for faulty EGR control circuit terminal connection at PCM. If faulty connection is found, repair as necessary and go to step 34). If connection is okay, go to step 32).
11. Disconnect EGR valve harness connector. Using scan tool, read EGR ACTUAL POS. If scan tool displays 0%, go to step 13). If scan tool does not display 0, go to next step.
12. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Check voltage between engine grounds and EGR pintle position circuit. If voltage is about zero volts, go to step 31). If voltage is not as specified, go to step 26).
13. Connect a test light between battery voltage and EGR harness connector sensor ground circuit. If test light illuminates, go to step 15). If test light does not illuminate, go to next step.
14. Check sensor ground circuit for faulty connection at PCM or open between PCM and EGR valve. If a problem is found, repair as necessary and go to step 34). If no problem is found, go to step 32).
15. Connect a test light between battery voltage and EGR harness connector control circuit. If test light illuminates, go to step 16). If test light does not illuminate, go to step 22).
16. Turn ignition off. Disconnect PCM. Turn ignition on. Connect test light between battery voltage and EGR control circuit. If test light illuminates, go to step 28). If test light does not illuminate, go to step 30).
17. Check voltage between EGR valve harness connector sensor ground and 5-volt reference circuits. If voltage is 5 volts, go to next step. If voltage is not as specified, go to step 23).
18. Connect test light between battery voltage and EGR valve harness connector pintle position circuit. If test light illuminates,go to step 21). If test light does not illuminate, go to next step.
19. Connect a jumper wire between EGR valve connector 5-volt reference and pintle position circuits. Using scan tool, read EGR ACTUAL POS. If scan tool displays 100, go to step 22). If scan tool does not display 100, go to next step.
20. Turn ignition off. Disconnect PCM connectors. Check pintle position circuit for open or faulty connection at PCM. If a problem is found, repair as necessary and go to step 34). If no problem is found, go to step 32).
21. Turn ignition off. Disconnect PCM connectors. Connect test light between battery voltage and pintle position circuit. If test light illuminates, go to step 29). If test light does not illuminate, go to step 30).
22. Check for faulty connection at EGR valve. If faulty connection is found, repair as necessary and go to step 33). If connection is okay, go to step 27).
23. Check for open or short to ground in EGR 5-volt reference circuit. If a problem is found, go to step 34). If no problem is found, go to step 25).
24. Locate and repair open ignition feed circuit and go to step 34).
25. Check EGR 5-volt reference circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 34). If connection is okay, go to step 32).
26. Locate and repair short to voltage in pintle position circuit and go to step 34).
27. Replace EGR valve and go to step 34).
28. Locate and repair short to ground in EGR control circuit and go to step 34).
29. Locate and repair short to ground in pintle position circuit and go to step 34).
30. Check pintle position circuit or EGR control circuit for short to sensor ground. Repair as necessary and go to step 34). If no repairs are required, go to step 32).
31. Check EGR pintle position circuit for short to 5-volt reference circuit. Repair as necessary and go to step 34). If no repairs are required, go to next step.
32. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
33. Locate and repair open in EGR ignition filter circuit and go to next step.
34. Read and record FAIL RECORDS data for DTC P1406. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1406 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1406 FAILED THIS IGN, repair is complete.

Check for excessive deposits on EGR valve pintle or seat. Check for faulty EGR valve. Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool EGR ACTUAL POS display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1406 Schematic. Scheme 19

DTC P1441 - EVAP EMISSIONS SYSTEM FLOW DURING NON-PURGE

Note. For circuit reference, see DTC P0441 schematic.

Evaporative (EVAP) emissions canister purge is controlled by a solenoid valve which allows ported vacuum to purge canister when energized (purge on) by PCM. A vacuum switch in purge line is used to detect when system is being purged. PCM supplies and reads EVAP purge vacuum switch signal. If switch is open (purge detected) when not commanded by PCM, DTC P1441 is set.

1. No IAT, MAP, ODM, or TP sensor DTCs set.
2. BARO more than 10 psi (0.70 kg/cm 2 ).
3. Engine speed 650-5000 RPM.
4. ECT less than 237°F (114°C).
5. IAT less than 50-158°F (10-70°C).
6. Difference between ECT and IAT less than 18°F (10°C).
7. EVAP canister Pulse Width Modulation (PWM) less than 3%.
8. EVAP purge vacuum switch open.
9. Listed conditions present for more than 4 seconds.

1. Perform OBD-II System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on, engine off. Using scan tool, read EVAP VACUUM SW. If scan tool displays NO PURGE, go to next step. If scan tool does not display NO PURGE, go to step 13).
3. Turn engine on and allow it to idle. Using scan tool, read EVAP VACUUM SW. If scan tool displays NO PURGE, go to next step. If scan tool does not display NO PURGE, go to step 5).
4. Turn ignition on, engine off. Using scan tool, read and record FAILS RECORD DATA. Operate vehicle within conditions noted in FAILED RECORDS DATA. Read SPECIFIC DTC. If scan tool displays DTC P1441 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1441 FAILED THIS IGN, go to DIAGNOSTIC AIDS.
5. Disconnect EVAP purge solenoid harness connector. Allow engine to idle. Read EVAP VACUUM SW. If scan tool displays NO PURGE, go to next step. If scan tool does not display NO PURGE, go to step 7).
6. Turn ignition off. Disconnect PCM connectors. Check EVAP purge solenoid driver circuit for short to ground. If short to ground is found, repair as necessary and go to step 18). If no short is found, go to step 17).
7. Leave EVAP purge solenoid harness connector disconnected. Disconnect vacuum signal hose from EVAP purge vacuum switch. Connect a vacuum gauge to signal hose. Allow engine to idle. If vacuum is more than 5 in H(2)O, go to next step. If vacuum is 5 in H(2)O or less, go to step 10).
8. Check for incorrect vacuum hose routing or switched vacuum lines at EVAP purge solenoid. If a problem is found, go to step 17). If no problem is found, go to next step.
9. Replace EVAP purge solenoid and go to step 17).
10. Check EVAP purge hose for restriction between EVAP canister and vacuum switch. If restriction is found, repair as necessary and go to step 17). If no restriction is found, go to next step.
11. Check fuel tank vapor line for restriction between EVAP canister and fuel tank. If restriction is found, repair as necessary and go to step 17). If no restriction is found, go to step 15).
12. Disconnect EVAP vacuum switch harness connector. Connect a jumper wire across vacuum switch harness connector terminals. If scan tool displays NO PURGE, go to step 14). If scan tool does not display NO PURGE, go to next step.
13. Check EVAP vacuum switch signal circuit for open or short to ground between EVAP vacuum switch and PCM. Check for open EVAP vacuum switch ignition feed circuit. Check for faulty signal circuit connection at EVAP vacuum switch. If problem is found, go to step 17). If no problem is found, go to step 16).
14. Check for faulty connection at EVAP vacuum switch. If faulty connection is found, repair as necessary and go to step 17). If connection is okay, go to next step.
15. Replace EVAP vacuum switch and go to step 17).
16. Replace PCM. Replacement PCM requires special equipment for programming procedures. Go to next step.
17. Read and record FAIL RECORDS data for DTC P1441. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1441 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1441 FAILED THIS IGN, repair is complete.

Check EVAP canister for damage or blockage. Check vacuum hoses for damage or incorrect routing. Check for restrictions in fuel vapor line, purge hose, or EVAP canister vent. Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool EVAP VACUUM SW display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1442 - EVAP EMISSION SYSTEM VACUUM SWITCH CIRCUIT

Note. For circuit reference, see DTC P0441 schematic.

Evaporative (EVAP) emission canister purge is controlled by a solenoid valve which allows ported vacuum to purge canister when energized by PCM. A vacuum switch in purge line is used to detect when system is being purged. PCM supplies and reads a 5-volt reference to switch. If switch is open (purge detected) when commanded by PCM, DTC P0442 is set.

1. EVAP purge vacuum switch is open during initial key on (before engine is cranked).

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on, engine off. Using scan tool, command EVAP purge solenoid on, while monitoring EVAP VACUUM SW on ENG 2 data list. If scan tool displays NO PURGE, go to next step. If scan tool does not display NO PURGE, go to step 4).
3. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data for DTC P1442. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1442 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1442 FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect EVAP vacuum switch harness connector. Connect a jumper wire across EVAP vacuum switch harness connector terminals. Using scan tool, read EVAP VACUUM SW. If scan tool displays NO PURGE, go to step 6). If scan tool does not display NO PURGE, go to next step.
5. Check for open or short to ground in EVAP vacuum switch signal circuit between EVAP vacuum switch and PCM. Check for open EVAP vacuum switch ignition feed circuit. Check for faulty EVAP vacuum switch signal circuit connection at PCM. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to step 7).
6. Check for faulty connection at EVAP vacuum switch. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 11).
8. Check EVAP purge hose for restriction between EVAP canister and EVAP vacuum switch. If restriction is found, repair as necessary and go to step 11). If no restriction is found, go to next step.
9. Check fuel tank vapor line for restriction between EVAP canister and fuel tank. If restriction is found, repair as necessary and go to step 11). If no restriction is found, go to next step.
10. Replace EVAP vacuum switch and go to next step.
11. Clear DTCs. Turn ignition on, engine off. Using scan tool, monitor EVAP VACUUM SW on ENG 2 data list. If scan tool displays NO PURGE, repair is complete. If scan tool does not display NO PURGE, return to step 2).

Check vacuum canister, lines and hoses for damage. Check for faulty connections or damaged harness. Observe scan tool EVAP VACUUM SW display while moving all related harness and connectors. A change in scan tool display indicates fault location.

PCM can disable Cruise Control (C/C) if conditions are detected which make C/C operation undesirable. If C/C status signal indicates C/C is engaged when PCM is inhibiting C/C operation, DTC P1554 is set.

1. PCM is inhibiting C/C operation
2. C/C status signal indicates C/C is engaged.
3. Listed conditions present for more than one second.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read CRUISE ENGAGED status. If scan tool displays YES, go to next step. If scan tool does not display YES, go to step 5).
3. Turn ignition off. Disconnect PCM. Turn ignition on. Using a DVOM, check voltage between engine ground and cruise status circuit at PCM. If voltage is greater than 7 volts, go to next step. If voltage is 7 volts or less, go to step 9).
4. Check for faulty cruise status circuit connection at PCM. If faulty connection is found, repair as necessary and go to step 14). If connection is okay, go to step 12).
5. Turn ignition of. Disconnect Stepper Motor Cruise Control (SMCC) module connector. Turn ignition on. Connect a test light between engine ground and SMCC harness connector cruise inhibit circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
6. Turn ignition off. Disconnect PCM connectors. Connect test light between battery voltage and SMCC harness connector cruise inhibit circuit. If test light illuminates, go to step 13). If test light does not illuminate, go to step 12).
7. Turn ignition off. Reconnect SMCC connector. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector cruise inhibit circuit. If DVOM voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 11).
8. Clear DTCs. Start engine and read DTCs. If DTC P1554 resets, go to step 12). If DTC does not reset, see DIAGNOSTIC AIDS.
9. Check cruise status circuit for open or short to ground. If a problem is found, repair as necessary and go to step 14). If no problem is found, go to next step.
10. Check cruise status circuit for faulty connection at SMCC module. If faulty connection is found, repair as necessary and go to step 14). If connection is okay, go to next step.
11. Replace SMCC module and go to step 14).
12. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 14).
13. Locate and repair short to ground in cruise inhibit circuit, and go to next step.
14. Clear DTCs. Start engine and read DTCs. If DTC P1554 resets, return to step 2). If DTC does not reset, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool CRUISE STATUS display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1554 Schematic. Scheme 20

DTC P1571 - TRACTION CONTROL SYSTEM DESIRED TORQUE CIRCUIT

Note. For circuit reference, see DTC P1381 schematic.

Traction Control System (TCS) uses Anti-lock Brake System (ABS) in conjunction with PCM fuel and ignition controls to limit drive wheel slippage during acceleration.

1. Desired torque signal Pulse Width Modulation (PWM) is less than 5% or greater than 95%.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read DESIRED TORQUE. If PWM is about 100%, go to step 4). If PWM is not as specified, go to next step.
3. Turn ignition off. Disconnect Electronic Brake and Traction Control Module (EBTCM) connector. Turn ignition on. Using a DVOM, check voltage between engine ground and EBTCM harness connector desired torque PWM circuit. If voltage is 5 volts, go to next step. If voltage is not as specified, go to step 6).
4. Turn ignition off. Connect ABS/TCS Pinout Box and Adapter (J39700-25) between EBTCM and EBTCM connector. Using DVOM in Hertz (Hz) scale, check frequency between engine ground and desired torque PWM circuit. Turn ignition on. If frequency is 120-135 Hz, go to next step. If frequency is not as specified, go to step 7).
5. Using DVOM in duty cycle scale, check duty cycle between engine ground and desired torque PWM circuit. Turn ignition on. If duty cycle is 5-95%, go to step 9). If duty cycle is not as specified, go to step 7).
6. Turn ignition off. Disconnect PCM. Turn ignition on. Check desired torque PWM circuit for open, short to ground or short to voltage. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to step 9).
7. Check for faulty connection at EBTCM. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to next step.
8. Replace EBTCM and go to step 11).
9. Check for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
11. Clear DTCs. Turn ignition on and observe DESIRED TORQUE PWM scan tool display. If scan tool displays about 100, repair is complete. If scan tool does not display about 100%, return to step 2)

Check for faulty connections or damaged harness. Observe scan tool DESIRED TORQUE display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1573 - EBTCM SERIAL DATA CIRCUIT

Note. For circuit reference, see Code P1381 schematic.

PCM uses Serial Data Line (SDL) circuit to communicate with various vehicle components and systems. If PCM does not receive data from Electronic Brake and Traction Control Module (EBTCM), PCM sets DTC P1573.

1. PCM detects a PCM-to-EBTCM communication error for 10 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select ABS DATA. If scan tool displays ABS DATA, go to next step. If scan tool does not display ABS DATA, go to step 4).
3. Turn ignition off. Disconnect EBTCM and PCM connectors. Check SDL circuit for open between EBTCM and PCM. If open is found, repair as necessary and go to step 8). If no open is found, go to step 5).
4. Turn ignition off, disconnect EBTCM. Turn ignition on. Using a DVOM, check voltage of SDL circuit between engine ground and EBTCM harness connector. If voltage constantly varies between zero and 5 volts, go to step 9). If voltage does not vary as specified, diagnose and repair SDL circuit.
5. Check SDL circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 8). If connection is okay, see DIAGNOSTIC AIDS.
6. Check SDL circuit for faulty connection at EBTCM. If faulty connection is found, repair as necessary and go to step 8). If connection is okay, go to next step.
7. Replace EBTCM and go to next step.
8. Read and record FAIL RECORDS data for DTC P1573. Clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1573 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1573 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool ABS DATA display while moving all related harness and connectors. A change in scan tool display indicates fault location.

Vehicle operation is disabled if incorrect key or starting procedure is used. Theft deterrent module enables crank circuit to starter and sends a signal to PCM if correct key is being used. If proper signal does not reach PCM fuel enable signal circuit, PCM will not pulse injectors on, disabling vehicle, even if crank circuit is by-passed. Signal should be 40-60 Hz and is measured using DVOM in Hertz scale.

1. Engine running.
2. PCM detects incorrect signal on Theft Deterrent System (TDS) fuel enable circuit.
3. Listed conditions are present for more than 2 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Ensure battery is fully charged. Crank engine. If engine cranks, go to next step. If engine does not crank, diagnose and repair TDS.
3. Turn ignition off. Disconnect TDS module connector. Turn ignition on. Using a DVOM, check voltage between TDS module harness connector ground and TDS fuel enable circuits. If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step 6).
4. Turn ignition off. Reconnect TDS module connector. Turn ignition on. Using DVOM in Hertz (Hz) scale, check frequency between engine ground and TDS fuel enable circuit. If frequency is 40-60 Hz, go to next step. if frequency is not as specified, go to step 8).
5. Turn ignition off. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to DIAGNOSTIC AIDS. If engine does not start, go to step 7).
6. Check TDS fuel enable circuit for open, short to ground or short to battery voltage. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to next step.
7. Check TDS fuel enable circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to step 9).
8. Check for faulty connection at TDS module. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to step 10).
9. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 11).
10. Replace TDS module and go to next step.
11. Clear DTCs. Turn ignition on and observe VTD FUEL DISABLE scan tool display. If scan tool displays INACTIVE, repair is complete. If scan tool does not display INACTIVE, return to step 2)

Check for faulty connections or damaged harness. Disconnect TDS module connector. Turn ignition on. Connect a DVOM between engine ground and TDS module harness connector fuel enable circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1626 Schematic. Scheme 21

DTC P1629 - THEFT DETERRENT SYSTEM FUEL ENABLE CIRCUIT INCORRECT SIGNAL DETECTED DURING CRANKING

Note. For circuit reference, see DTC P1626 schematic.

Vehicle operation is disabled if incorrect key or starting procedure is used. Theft deterrent module enables crank circuit to starter and sends a signal to PCM if correct key is being used. If proper signal does not reach PCM fuel enable signal circuit, PCM will not pulse injectors on, disabling vehicle, even if crank circuit is bypassed. Signal should be between 40-60 Hz and is measured using DC scale on DVOM.

1. DTC P1626 is not set.
2. An attempt is made to start engine.
3. PCM detects incorrect signal on Theft Deterrent System (TDS) fuel enable circuit.
4. Listed conditions are present for more than 2 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Ensure battery is fully charged. Crank engine. If engine cranks, go to next step. If engine does not crank, diagnose and repair TDS.
3. Turn ignition off. Disconnect TDS module connector. Turn ignition on. Using a DVOM, check voltage between TDS module harness connector ground and TDS fuel enable circuits. If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step 6).
4. Turn ignition off. Reconnect TDS module connector. Turn ignition on. Using DVOM in Hertz (Hz) scale, check frequency between engine ground and TDS fuel enable circuit. If frequency is 40-60 Hz, go to next step. if frequency is not as specified, go to step 8).
5. Turn ignition off. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to DIAGNOSTIC AIDS. If engine does not start, go to step 7).
6. Check TDS fuel enable circuit for open, short to ground or short to battery voltage. If a problem is found, repair as necessary and go to step 11). If no problem is found, go to next step.
7. Check TDS fuel enable circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to step 9).
8. Check for faulty connection at TDS module. If faulty connection is found, repair as necessary and go to step 11). If connection is okay, go to step 10).
9. Replace PCM. Program replacement PCM using required equipment. Go to step 11).
10. Replace TDS module and go to next step.
11. Clear DTCs. Turn ignition on and observe VTD FUEL DISABLE scan tool display. If scan tool displays INACTIVE, repair is complete. If scan tool does not display INACTIVE, return to step 2)

Check for faulty connections or damaged harness. Disconnect TDS module connector. Turn ignition on. Connect a DVOM between engine ground and TDS module harness connector fuel enable circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1635 - 5 VOLT-REFERENCE "A" CIRCUIT

Note. For circuit reference, see DTC P0106 schematic.

PCM uses 5-volt reference "A" circuit as a sensor feed for EGR valve pintle position, fuel tank pressure (VIN K), MAP, and TP sensors. PCM monitors voltage on this circuit. If PCM senses voltage out of tolerance, DTC P1635 sets.

1. PCM detects an out of tolerance condition on the 5-volt reference "A" circuit for 10 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Ensure PCM and engine grounds are secure and clean. If a problem is found, go to step 14). If no problem is found, go to next step.
3. Using scan tool, select DTC INFO, LAST TST FAIL. If DTC P0107, P0108, P0122, P0123, P1106, P1107, P1121, P1122 and/or P1406 also set, diagnose affected DTC before proceeding. If none of these DTCs are set, go to next step.
4. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between PCM harness connector ground and 5-volt reference "A" circuits. If voltage is more than 5.5 volts, go to next step. If voltage is 5.5 volts or less, go to step 9).
5. Using DVOM, check voltage between PCM harness connector ground and 5-volt reference "A" circuits. Disconnect EGR valve. If voltage is more than 5.5 volts, go to next step. If voltage is 5.5 volts or less, go to step 8).
6. Using DVOM, check voltage between PCM harness connector ground and 5-volt reference "A" circuits while sequentially disconnecting fuel tank pressure (VIN K), MAP and TP sensors. If voltage changes whenever any of these sensors is disconnected, locate and repair short to voltage in affected sensor signal circuit and go to step 14). If voltage does not change, go to next step.
7. Turn ignition off. Disconnect PCM connectors. Turn ignition on.Check 5-volt reference "A" circuit for short to voltage. If short to voltage is found, repair as necessary and go to step 14). If no short to voltage is found, go to step 13).
8. Replace EGR valve and go to step 14).
9. Ignition off. Reconnect PCM. Disconnect TP sensor, MAP sensor and EGR valve. Ignition on. Connect DVOM between TP sensor 5-volt reference circuit and TP sensor ground circuit. If voltage is less than 4.5 volts, go to step 12). If not, go to next step.
10. With DVOM still connected to TP sensor 5-volt reference and ground circuits, reconnect (one at a time) Map sensor and EGR valve. If voltage changes when one of the listed devices is reconnected, replace that component and go to step 14). If voltage does not change, go to next step.
11. Disconnect EGR valve. Connect DVOM between EGR connector 5-volt reference circuit and ground circuit. Reconnect TP sensor. If voltage measured on EGR connector changes, replace TP sensor and go to step 14). If not, go to step 13).
12. Turn ignition off. Disconnect PCM connectors. Turn ignition on. check 5-volt reference "A" circuit for short to ground. If short to ground is found, repair as necessary and go to step 14). If no short to ground is found, go to next step.
13. Replace PCM. Program replacement PCM using required equipment. Go to next step.
14. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1635. If scan tool displays DTC P1635 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1635 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool MAP display while moving harness and connectors related to EGR valve, fuel tank pressure (VIN K), MAP and TP sensors. A change in scan tool display indicates fault location.

DTC P1639 - 5 VOLT-REFERENCE "B" CIRCUIT

Note. For circuit reference, see DTC P0530 schematic.

PCM uses 5-volt reference "B" circuit as a sensor feed for A/C refrigerant pressure sensor. PCM monitors voltage on this circuit. If PCM senses voltage out of tolerance, DTC P1639 sets.

1. PCM detects an out of tolerance condition on 5-volt reference "B" circuit.
2. Above condition present for 10 seconds

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Ensure PCM and engine grounds are secure and clean. If a problem is found, go to step 11). If no problem is found, go to next step.
3. Ensure A/C is off. Observe A/C high side pressure on scan tool. If pressure displays a voltage of greater than 4.8 volts or less than 0.1 volt, go to DTC P0530 for diagnosis of pressure sensor circuit. If voltage displayed is not greater than 4.8 volts or less than 0.1 volt, go to next step.
4. Unplug A/C pressure sensor connector. Using DVOM, check voltage between sensor ground circuit and sensor 5-volt reference circuit. If voltage is greater than 5.5 volts, go to next step. If not, go to step 7).
5. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between PCM harness connector ground and 5-volt reference "B" circuits. If voltage is more than 5.5 volts, go to next step. If voltage is 5.5 volts or less, go to step 10).
6. Locate and repair short to voltage in A/C refrigerant pressure sensor signal circuit. Go to step 11).
7. If voltage is less than 4.5 volts, go to next step. If voltage is 4.5 volts or more, go to step 9).
8. Check for short to voltage in A/C pressure sensor signal circuit. Repair as necessary and go to step 11). If no repairs are required, go to step 10).
9. Ignition off. Disconnect PCM connectors. Turn ignition on. Check 5-volt reference "B" circuit for short to ground. If short to ground is found, repair as necessary and go to step 11). If no short to ground is found, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. Go to next step.
11. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1639. If scan tool displays DTC P1639 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1639 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe scan tool A/C PRESSURE display while moving harness and connectors related to A/C refrigerant pressure sensor. A change in scan tool display indicates fault location.

Output Driver Modules (ODM) are used by PCM to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including Malfunction Indicator Light (MIL) in Instrument Panel (I/P), by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually. If ODM "A" output 1 (MIL driver circuit) detects an improper voltage level, P1641 is set.

1. Ignition is on.
2. An improper voltage level has been detected on MIL driver circuit.
3. Listed condition is present for more than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector MIL driver circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 6).
3. Using DVOM in 10-amp scale, check current between engine ground and MIL driver circuit for 2 minutes. If current remains 0.05-0.50 amp go to step 11). If current does not remain as specified, go to next step.
4. Turn ignition off. With PCM connectors disconnected, disconnect I/P connectors. Turn ignition on. Using DVOM, check voltage between engine ground and MIL driver circuit. If voltage is zero volts, go to step 10). If voltage is more than zero volts, go to next step.
5. Locate and repair short to voltage in MIL driver circuit, and go to step 15).
6. Check I/P indicators ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in I/P indicators ignition feed circuit. Replace fuse and go to step 15).
8. Disconnect I/P connectors. Turn ignition on. Check voltage between engine ground and I/P indicators ignition feed circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 13).
9. Check MIL driver circuit for open or short to ground. If a problem is found, repair as necessary and go to step 15). If no problem is found, go to next step.
10. Check MIL driver and I/P indicators ignition feed circuits for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 15). If connection is okay, diagnose and repair I/P problem.
11. Turn ignition off. Reconnect PCM connectors. Disconnect I/P connectors. Turn ignition on. Connect a test light between I/P harness connector MIL driver and ignition feed circuits. Using scan tool, cycle MIL on and off. If test light flashes on and off, go to DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
12. Check MIL driver circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 15). If connection is okay, go to step 14).
13. Locate and repair open I/P indicators ignition feed circuit. Go to step 15).
14. Replace PCM. Program replacement PCM using required equipment. Go to next step.
15. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1641. If scan tool displays DTC P1641 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1641 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect PCM connector. Turn ignition on. Connect a DVOM between engine ground and PCM harness connector MIL driver circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1641 Schematic. Scheme 22

Output Driver Modules (ODM) are used by PCM to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including fuel pump Pulse Width Modulation (PWM) driver circuit, by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually. If ODM "A" output 3 (fuel pump PWM driver circuit) detects an improper voltage level, P1643 is set.

1. Ignition is on.
2. An improper voltage level has been detected on fuel pump PWM driver circuit.
3. Listed conditions are present for more than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector fuel pump PWM driver circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 6).
3. Using DVOM in 10-amp scale, check current between engine ground and fuel pump PWM driver circuit for 2 minutes. If current remains 0.1-0.5 amp, go to step 11). If current does not remain as specified, go to next step.
4. Turn ignition off. With PCM connectors disconnected, disconnect Fuel Pump Control Module (FPCM) connector. Turn ignition on. Using DVOM, check voltage between engine ground and fuel pump PWM driver circuit. If voltage is zero volts, go to step 10). If voltage is more than zero volts, go to next step.
5. Locate and repair short to voltage in fuel pump PWM driver circuit, and go to step 18).
6. Check fuel pump relay ignition feed circuit fuse. If fuse is blown, go to next step. If not, go to step 8).
7. Repair short to voltage in fuel pump PWM control circuit. After repairs, go to step 18).
8. Unplug FPCM Ignition on. Measure voltage between ground and ignition feed for module. If about battery voltage is present, go to next step. If about battery voltage is not present, go to step 13).
9. Check fuel pump PWM driver circuit for an open or short to ground. Repair as necessary and go to step 18). If no problem exists, go to step 10).
10. Check for poor FPCM control circuit connection at PCM connector or module. Check ignition feed circuit to module for poor connection at module connector. Repair as necessary and go to step 18). If no problem is present, go to step 14).
11. Turn ignition off. Reconnect PCM connectors. Disconnect FPCM connector. Turn ignition on. Connect a test light between fuel pump PWM harness connector fuel pump PWM driver and ignition feed circuits. Using scan tool, cycle fuel pump PWM on and off. If test light flashes on and off, go to DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
12. Check fuel pump PWM driver circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 18). If connection is okay, go to step 15).
13. Repair open in ignition feed circuit to fuel pump relay or between relay and module and go to step 18).
14. Replace FPCM and go to step 18).
15. Replace PCM. Program replacement PCM using required equipment. Go to next step.
16. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1643. If scan tool displays DTC P1643 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1643 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect PCM connector. Turn ignition on. Connect a DVOM between engine ground and PCM harness connector fuel pump PWM driver circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1643 Schematic. Scheme 23

Output Driver Modules (ODM) are used by PCM to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including boost control solenoid, by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually. If ODM "A" output 5 (boost control solenoid driver circuit) detects an improper voltage level, P1645 is set.

1. Ignition is on.
2. An improper voltage level has been detected on boost control solenoid driver circuit.
3. Listed conditions are present for more than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector boost control solenoid driver circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 6).
3. Using DVOM in 10-amp scale, check current between engine ground and boost control solenoid driver circuit for 2 minutes. If current remains .05-0.8 amp go to step 11). If current does not remain as specified, go to next step.
4. With PCM connectors disconnected, disconnect boost control solenoid connector. Using DVOM, check voltage between engine ground and boost control solenoid driver circuit. If voltage is zero volts, go to step 10). If voltage is more than zero volts, go to next step.
5. Locate and repair short to voltage in boost control solenoid driver circuit, and go to step 16).
6. Check boost control solenoid ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in boost control solenoid ignition feed circuit. Replace fuse and go to step 16).
8. Disconnect boost control solenoid connector. Turn ignition on. Check voltage between engine ground and boost control solenoid ignition feed circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 13).
9. Check boost control solenoid driver circuit for open or short to ground. If a problem is found, repair as necessary and go to step 16). If no problem is found, go to next step.
10. Check boost control solenoid driver and boost control solenoid ignition feed circuits for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 14).
11. Turn ignition off. Reconnect PCM connectors. Disconnect boost control solenoid connector. Turn ignition on. Connect a test light between boost control solenoid harness connector boost control solenoid driver and ignition feed circuits. Using scan tool, cycle boost control solenoid on and off. If test light flashes on and off, go to DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
12. Check boost control solenoid driver circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 15).
13. Locate and repair open boost control solenoid ignition feed circuit, and go to step 16).
14. Replace boost control solenoid and go to step 16).
15. Replace PCM. Program replacement PCM using required equipment. Go to next step.
16. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1645. If scan tool displays DTC P1645 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1645 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect PCM connector. Turn ignition on. Connect a DVOM between engine ground and PCM harness connector boost control solenoid driver circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1645 Schematic. Scheme 24

Output Driver Modules (ODM) are used by PCM to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including fan 1 relay, by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually. If ODM "B" output 1 (fan 1 relay driver circuit) detects an improper voltage level, P1651 is set.

1. Ignition is on.
2. An improper voltage level has been detected on fan 1 relay driver circuit.
3. Listed condition is present for more than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector fan 1 relay driver circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 6).
3. Using DVOM in 10-amp scale, check current between engine ground and fan 1 relay driver circuit for 2 minutes. If current remains .05-0.5 amp go to step 11). If current does not remain as specified, go to next step.
4. Ignition off. Reconnect cooling fans. With PCM connectors still disconnected, disconnect fan 1 relay connector. Ignition on. Using DVOM, check voltage between engine ground and fan 1 relay driver circuit. If voltage is zero volts, go to step 10). If voltage is more than zero volts, go to next step.
5. Locate and repair short to voltage in fan 1 relay driver circuit, and go to step 16).
6. Check fan 1 relay ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in fan 1 relay ignition feed circuit. Replace fuse and go to step 16).
8. Disconnect fan 1 relay connector. Turn ignition on. Check voltage between engine ground and fan 1 relay ignition feed circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 13).
9. Check fan 1 relay driver circuit for open or short to ground. If a problem is found, repair as necessary and go to step 16). If no problem is found, go to next step.
10. Check fan 1 relay driver and fan 1 relay ignition feed circuits for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 14).
11. Turn ignition off. Reconnect PCM connectors. Disconnect fan 1 relay connector. Turn ignition on. Connect a test light between fan 1 relay harness connector fan 1 relay driver and ignition feed circuits. Using scan tool, cycle fan 1 relay on and off. If test light flashes on and off, go to DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
12. Check fan 1 relay driver circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 15).
13. Locate and repair open fan 1 relay ignition feed circuit, and go to step 16).
14. Replace fan 1 relay and go to step 16).
15. Replace PCM. Program replacement PCM using required equipment. Go to next step.
16. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1651. If scan tool displays DTC P1651 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1651 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect PCM connector. Turn ignition on. Connect a DVOM between engine ground and PCM harness connector fan 1 relay driver circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1651 Schematic. Scheme 25

DTC P1652 - FAN 2 RELAY CONTROL CIRCUIT

Note. For circuit reference, see DTC P1651 schematic.

Output Driver Modules (ODM) are used by PCM to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including fan 2 relay, by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually. If ODM "B" output 2 (fan 2 relay driver circuit) detects an improper voltage level, P1652 is set.

1. Ignition is on.
2. An improper voltage level has been detected on fan 2 relay driver circuit.
3. Listed conditions present for more than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector fan 2 relay driver circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 6).
3. Using DVOM in 10-amp scale, check current between engine ground and fan 2 relay driver circuit for 2 minutes. If current remains .05-0.5 amp go to step 11). If current does not remain as specified, go to next step.
4. Ignition off. With PCM connectors still disconnected, disconnect series/parallel and high speed fan relays. Ignition on. Using DVOM, check voltage between engine ground and fan 2 relay driver circuit. If voltage is zero volts, go to step 10). If voltage is more than zero volts, go to next step.
5. Locate and repair short to voltage in fan 2 relay driver circuit, and go to step 18).
6. Check fan 2 relay ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in fan 2 relay ignition feed circuit. Replace fuse and go to step 18).
8. Disconnect fan 2 relay connector. Turn ignition on. Check voltage between engine ground and fan 2 relay ignition feed circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 13).
9. Check fan 2 relay driver circuit for open or short to ground. If a problem is found, repair as necessary and go to step 18). If no problem is found, go to next step.
10. Check fan 2 relay driver and fan 2 relay ignition feed circuits for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 18). If connection is okay, go to DIAGNOSTIC AIDS.
11. Turn ignition off. Reconnect PCM connectors. Disconnect high speed cooling fan relay connector. Turn ignition on. Connect a test light between fan 2 relay harness connector fan 2 relay driver and ignition feed circuits. Using scan tool, cycle fan 2 relay on and off. If test light flashes on and off, go to DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
12. Check fan 2 relay driver circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 18). If connection is okay, go to step 15).
13. Locate and repair open fan 2 relay ignition feed circuit, and go to step 18).
14. Reconnect series/parallel cooling fan relay. Using DVOM tool on 10-amp scale, check current between engine ground and fan 2 relay driver circuit for 2 minutes. If current remains less than 0.75 amp but not zero, go to step 16). If current remains 0.75 amp or more, go to step 17).
15. Replace PCM. Program replacement PCM using required equipment. Go to step 18).
16. Replace high speed cooling fan relay and go to step 18).
17. Replace series/parallel cooling fan relay and go to next step.
18. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1652. If scan tool displays DTC P1652 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1652 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect PCM connector. Turn ignition on. Connect a DVOM between engine ground and PCM harness connector fan 2 relay driver circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1653 - TRACTION CONTROL SYSTEM (TCS) DELIVERED TORQUE CONTROL CIRCUIT

Note. For circuit reference, see DTC P1381 schematic.

Electronic Brake and Traction Control Module (EBTCM) controls Pulse Width Modulation (PWM) signal on desired torque circuit while monitoring wheel speed sensors to detect slippage.

Output Driver Modules (ODM) are used by PCM to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including traction control delivered circuit, by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually. If ODM "B" output 3 (traction control delivered torque circuit) detects an improper voltage level, P1653 is set.

1. Ignition is on.
2. An improper voltage level has been detected on traction control delivered driver circuit.
3. Listed conditions present for greater than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector delivered torque circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 6).
3. Using DVOM in 10-amp scale, check current between engine ground and delivered torque circuit for 2 minutes. If current remains between .001 and 0.5 amp, go to step 11). If current does not remain as specified, go to next step.
4. Ignition off. With PCM connectors disconnected, disconnect EBTCM connector. Ignition on. Using DVOM, check voltage between engine ground and delivered torque circuit. If voltage is zero volts, go to step 10). If voltage is greater than zero volts, go to next step.
5. Locate and repair short to voltage in delivered torque circuit, and go to step 16).
6. Check EBTCM ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in EBTCM ignition feed circuit. Replace fuse and go to step 16).
8. Disconnect EBTCM connector. Turn ignition on. Check voltage between engine ground and EBTCM ignition feed circuit. If 9-16 volts exists, go to next step. If voltage is not as specified, go to step 13).
9. Check delivered torque circuit for open or short to ground. If a problem is found, repair as necessary and go to step 16). If no problem is found, go to next step.
10. Check delivered torque driver and delivered torque ignition feed circuits for faulty connection at EBTCM and PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 14).
11. Turn ignition off. Reconnect PCM connectors. Disconnect EBTCM connector. Turn ignition on. Connect a test light between EBTCM harness connector delivered torque and ignition feed circuits. Using scan tool, cycle delivered torque output on and off. If test light flashes on and off, go to DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
12. Check delivered torque circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 15).
13. Locate and repair open EBTCM ignition feed circuit, and go to step 16).
14. Replace EBTCM and go to step 16).
15. Replace PCM. Program replacement PCM using required equipment. Go to next step.
16. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1653. If scan tool displays DTC P1653 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1653 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect PCM connector. Turn ignition on. Connect a DVOM between engine ground and PCM harness connector delivered torque circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

Output Driver Modules (ODM) are used by PCM to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including A/C relay driver circuit, by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually. If ODM "B" output 4 (A/C relay driver circuit) detects an improper voltage level, P1654 is set.

1. Ignition is on.
2. An improper voltage level has been detected on A/C relay driver circuit.
3. Listed conditions present for greater than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector A/C relay driver circuit. If voltage reading is 9-16 volts, go to next step. If voltage is not 9-16 volts, go to step 6).
3. Disconnect A/C clutch connector. Using DVOM in 10 amp scale, check current between engine ground and A/C relay driver circuit for 2 minutes. If current remains .05-0.5 amp, go to step 11). If current does not remain .05-0.5 amp, go to next step.
4. Ignition off. Reconnect A/C clutch connector. With PCM connectors still disconnected, disconnect A/C relay connector. Ignition on. Using DVOM, check voltage between engine ground and A/C relay driver circuit. If voltage reading is zero volts, go to step 10). If voltage reading is greater than zero volts, go to next step.
5. Locate and repair short to voltage in A/C relay driver circuit, and go to step 16).
6. Check A/C relay ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in A/C relay ignition feed circuit. Replace fuse and go to step 16).
8. Disconnect A/C relay connector. Turn ignition on. Check voltage between engine ground and A/C relay ignition feed circuit. If voltage reading is 9-16 volts, go to next step. If voltage reading is not 9-16 volts, go to step 13).
9. Check A/C relay driver circuit for open or short to ground. If a problem is found, repair as necessary and go to step 16). If no problem is found, go to next step.
10. Check A/C relay driver and ignition feed circuits for faulty connection at A/C relay and PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 14).
11. Turn ignition off. Reconnect PCM connectors. Disconnect A/C relay connector. Turn ignition on. Connect a test light between A/C relay harness connector A/C relay driver and ignition feed circuits. Using scan tool, cycle A/C relay on and off. If test light flashes on and off, go to DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
12. Check A/C relay driver circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 15).
13. Locate and repair open A/C relay ignition feed circuit, and go to step 16).
14. Replace A/C relay and go to step 16).
15. Replace PCM. Program replacement PCM using required equipment. Go to next step.
16. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1654. If scan tool displays DTC P1654 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1654 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect PCM connector. Turn ignition on. Connect a DVOM between engine ground and PCM harness connector A/C relay driver circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1654 Schematic. Scheme 26

Output Driver Modules (ODM) are used by PCM to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including EVAP purge solenoid driver circuit, by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually. If ODM "B" output 5 (EVAP purge solenoid driver circuit) detects an improper voltage level, P1655 is set.

1. Ignition is on.
2. An improper voltage level has been detected on EVAP purge solenoid driver circuit.
3. Listed conditions present for greater than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing PBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector EVAP purge solenoid driver circuit. If voltage is 9-16 volts, go to next step. If voltage is not 9-16 volts, go to step 6).
3. Using DVOM in 10 amp scale, check current between engine ground and EVAP purge solenoid driver circuit for 2 minutes. If current remains .05-0.5 amp, go to step 11). If current does not remain .05-0.5 amp, go to next step.
4. Ignition off. With PCM connectors still disconnected, disconnect EVAP purge solenoid connector. Ignition on. Using DVOM, check voltage between engine ground and EVAP purge solenoid driver circuit. If voltage reading is zero volts, go to step 10). If voltage reading is greater than zero volts, go to next step.
5. Locate and repair short to voltage in EVAP purge solenoid driver circuit, and go to step 16).
6. Check EVAP purge solenoid ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in EVAP purge solenoid ignition feed circuit. Replace fuse and go to step 16).
8. Disconnect EVAP purge solenoid connector. Turn ignition on. Check voltage between engine ground and EVAP purge solenoid ignition feed circuit. If voltage is 9-16 volts, go to next step. If voltage is not 9-16 volts, go to step 13).
9. Check EVAP purge solenoid driver circuit for open or short to ground. If a problem is found, repair as necessary and go to step 16). If no problem is found, go to next step.
10. Check EVAP purge solenoid driver and ignition feed circuits for faulty connection at EVAP purge solenoid and PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 14).
11. Turn ignition off. Reconnect PCM connectors. Disconnect EVAP purge solenoid connector. Turn ignition on. Connect a test light between EVAP purge solenoid harness connector EVAP purge solenoid driver and ignition feed circuits. Using scan tool, cycle EVAP purge solenoid on and off. If test light flashes on and off, see DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
12. Check EVAP purge solenoid driver circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 15).
13. Locate and repair open EVAP purge solenoid ignition feed circuit, and go to step 16).
14. Replace EVAP purge solenoid and go to step 16).
15. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
16. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1655. If scan tool displays DTC P1655 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1655 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect PCM connector. Turn ignition on. Connect a DVOM between engine ground and PCM harness connector EVAP purge solenoid driver circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

DTC P1655 Schematic. Scheme 27

DTC P1662 - CRUISE CONTROL INHIBIT CIRCUIT

Note. For circuit reference, see DTC P1554 schematic.

Output Driver Modules (ODM) are used by PCM to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including cruise inhibit driver circuit, by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually. If ODM "C" output 2 (cruise inhibit driver circuit) detects an improper voltage level, P1662 is set.

1. Ignition is on.
2. An improper voltage level has been detected on cruise inhibit driver circuit.
3. Listed conditions present for greater than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector cruise inhibit driver circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 6).
3. Using DVOM in 10-amp scale, check current between engine ground and cruise inhibit driver circuit for 2 minutes. If current remains between .001 and 0.5 amp, go to step 11). If current does not remain as specified, go to next step.
4. Ignition off. With PCM connectors disconnected, disconnect cruise inhibit connector. Ignition on. Using DVOM, check voltage between engine ground and Servo Motor Cruise Control (SMCC) module cruise inhibit driver circuit. If voltage reading is zero volts, go to step 10). If voltage reading is greater than zero volts, go to next step.
5. Locate and repair short to voltage in cruise inhibit driver circuit, and go to step 16).
6. Check SMCC module ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in SMCC module ignition feed circuit. Replace fuse and go to step 16).
8. Disconnect SMCC module connector. Turn ignition on. Check voltage between engine ground and SMCC module ignition feed circuit. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 13).
9. Check cruise inhibit driver circuit for open or short to ground. If a problem is found, repair as necessary and go to step 16). If no problem is found, go to next step.
10. Check cruise inhibit driver and ignition feed circuits for faulty connection at SMCC module and PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 14).
11. Turn ignition off. Reconnect PCM connectors. Disconnect SMCC module connector. Turn ignition on. Connect a test light between SMCC module harness connector cruise inhibit driver and ignition feed circuits. Using scan tool, cycle cruise inhibit output on and off. If test light flashes on and off, see DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
12. Check cruise inhibit driver circuit for faulty connection at PCM. If faulty connection is found, repair as necessary and go to step 16). If connection is okay, go to step 15).
13. Locate and repair open SMCC module ignition feed circuit, and go to step 16).
14. Replace SMCC module and go to step 16).
15. Replace PCM. Program replacement PCM using required equipment. After repairs are completed, go to next step.
16. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1662. If scan tool displays DTC P1662 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1662 FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect PCM connector. Turn ignition on. Connect a DVOM between engine ground and PCM harness connector cruise inhibit driver circuit. Observe DVOM while moving all related harness and connectors. A change in voltage display indicates fault location.

See also:
• DIAGNOSTIC PROCEDURE
• HARD OR INTERMITTENT TROUBLE CODE DETERMINATION
• P0101
• P0102
• P0103
• P0107
• P0108
• P0113
• P0117
• P0118
• P0121
• P0122
• P0123
• P0125
• P0132
• P0133
• P0134
• P0135
• P0137
• P0138
• P0140
• P0141
• P0300
• P0326
• P0327
• P0341
• P0507
• P0706
• P1106
• P1107
• P1111
• P1112
• P1114
• P1115
• P1121
• P1122
• P1133
• P1134
• P1350
• P1361
• P1374
• P1441
• P1442
• P1571
• P1573
• P1629
• P1635
• P1639
• P1652
• P1653
• P1662
• CLEARING DIAGNOSTIC TROUBLE CODES (DTC)
• SCAN DATA