Engine Controls - Tests W/codes - 3.1l Engine Chevrolet Monte Carlo V

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»(/chevrolet/monte-carlo/v-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-31l-engine__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)»(/chevrolet/monte-carlo/v-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-31l-engine__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.

PCM CONNECTORS

Note. For additional terminal identification and wiring diagram information, refer to ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article.

Scheme 7

CONNECTOR C1

Note. For terminal identification (Scheme 7)

Scheme 8

Scheme 9

CONNECTOR C2

Note. For terminal identification (Scheme 7)

Scheme 10

Scheme 11

Note. For terminal identification (Scheme 7)

Scheme 12

Scheme 13

Scheme 14

Scheme 15

Note. For terminal identification (Scheme 7)

Scheme 16

Scheme 17

Note. For terminal identification (Scheme 7)

Scheme 18

Scheme 19

Scheme 20

Note. For terminal identification (Scheme 7)

Scheme 21

Scheme 22

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

This test determines if MAF sensor is providing proper readings to the PCM. MAF sensor is a high-frequency device that measures the rate of airflow through the throttle body. MAF sensor outputs a series of pulses that varies in frequency with airflow. PCM uses this signal for fuel control.

MAF sensor readings during acceleration will be much higher than those during deceleration or idle. PCM calculates what MAF sensor reading should be received from the 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 the actual value received from the sensor. The calculated MAF reading is obtained by comparing MAP sensor, RPM and IAT sensor values. If difference between calculated MAF and actual MAF is too great, DTC will set.

Diagnostic Procedures

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Using scan tool, check for stored DTCs. If DTC P1635 or P1374 is also set, diagnose that DTC first. If not, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Select SPECIFIC DTC function then enter DTC P0101. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. DO NOT clear codes. Unplug MAF sensor. Attempt to start engine. If engine starts and continues to run, go to next step. If not, go to step 6).
5. Ignition off. Reconnect MAF sensor connector. Start engine. Monitor MAF signal on scan tool. Slowly increase engine speed to 3000 RPM. If MAF sensor signal increases with engine RPM, go to step 7). If not, go to next step.
6. Go to DTC P0106 to diagnose MAP sensor circuit.
7. Turn ignition on. Ensure throttle is closed. Using scan tool, observe THROTTLE AT IDLE display. If scan tool indicates YES, go to next step. If scan tool does not indicate YES, go to DTC P0121 to diagnose DTC as necessary.
8. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, with engine off. Using DVOM, measure voltage between ground and signal circuit at MAF harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 10).
9. Connect a test light between ignition feed circuit and ground circuit terminals at MAF sensor harness connector. Observe test light. If test light is on, go to step 13). If test light is off, go to step 12).
10. If voltage is less than 4.5 volts, go to step 14). If voltage is not less than 4.5 volts, go to next step.
11. Turn ignition off. Disconnect PCM connectors. Using DVOM, measure voltage between ground and signal circuit terminal at MAF harness connector. If voltage is zero volts, go to step 20). If voltage is more than zero volts, go to step 17).
12. Connect a test light between ground and ignition feed circuit terminal at MAF sensor harness connector. If test light is on, go to step 15). If test light is off, go to step 16).
13. Check for poor connection at MAF sensor connector. Repair as necessary. After repair is completed, go to step 20). If connector is okay, go to step 18).
14. Check MAF sensor signal circuit for excessive resistance between PCM and MAF sensor connectors. Check for excessive resistance in sensor ground circuit. Check for MAF signal circuit shorted to sensor ground circuit. Check for poor connection at PCM. Repair as necessary. After repair is completed, go to step 20). If circuits are okay, go to step 19).
15. Locate and repair open in MAF sensor ground circuit. After repair is completed, go to step 20).
16. Locate and repair open or excessive resistance in MAF sensor ignition feed circuit. After repair is completed, go to step 20).
17. Locate and repair short to voltage in MAF sensor signal circuit. After repair is completed, go to step 20).
18. Replace MAF sensor. After repair is completed, go to step 20).
19. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
20. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0101. If scan tool indicates FAILED THIS IGN, repeat step 3). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for sticking throttle plate. Check for carbon build-up on throttle plate and throttle bore. Check TP sensor. See appropriate SYSTEM/COMPONENT TESTS article. Check for poor connection at PCM. Check for misrouted MAF sensor wiring harness. Ensure harness is not close to high-voltage components.

DTC P0101 Schematic. Scheme 23

DTC P0102 - MAF SENSOR CIRCUIT LOW FREQUENCY

Note. For circuit reference, see DTC P0101 schematic.

This test determines if MAF sensor circuit failed by monitoring the MAF signal. MAF sensor is a high-frequency device that measures the rate of airflow through the throttle body. MAF sensor outputs a series of pulses that varies in frequency with airflow. PCM uses this signal for fuel control. Frequency signal will vary from about 2000 Hz at idle to 10,000 Hz at maximum engine load. DTC will set if signal from MAF sensor is less than frequency range.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Start engine and allow it to idle. Using scan tool, select ENG 1 data list. Monitor MAF FREQUENCY display. If frequency is less than 1200 Hz, go to step 4). If frequency is 1200 Hz or more, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Select SPECIFIC DTC function then enter DTC P0102. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Check air leaks at MAF sensor, throttle body spacer, intake manifold, PCV, system EGR system, oil dipstick tube and oil filler cap. Repair as necessary. After repairs are completed, go to step 14). If air leak is not found, go to next step.
5. Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on, with engine off. Using DVOM, check voltage between ground and signal circuit terminal at MAF sensor harness connector. If voltage is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 9).
6. Connect a test light between ignition feed circuit and ground circuit terminals at MAF sensor harness connector. Observe test light. If test light is on, go to step 8). If test light is off, go to next step.
7. Connect a test light between ground and ignition feed circuit terminal at MAF sensor harness connector. If test light is on, go to step 10). If test light is off, go to step 11).
8. Check for poor connection at MAF sensor connector. Repair as necessary. After repair is completed, go to step 14). If connector is okay, go to step 12).
9. Check MAF sensor signal circuit between PCM and MAF sensor for an open, short to voltage or short to ground. Repair as necessary. After repair is completed, go to step 14). If circuit is okay, go to step 13).
10. Locate and repair open in MAF sensor ground circuit. After repair is completed, go to step 14).
11. Locate and repair open in MAF ignition feed circuit. After repair is completed, go to step 14).
12. Replace MAF sensor. After repair is completed, go to step 14).
13. Replace and program replacement PCM. After repair is completed, go to next step.
14. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0102. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for misrouted MAF sensor wiring harness. Ensure harness is not close to high voltage components. Check for damaged wiring harness. Check for plugged intake air duct or filter element.

DTC P0103 - MAF SENSOR CIRCUIT HIGH FREQUENCY

Note. For circuit reference, see DTC P0101 schematic.

This test determines if MAF sensor circuit failed by monitoring the MAF signal. MAF sensor is a high-frequency device that measures the rate of airflow through the throttle body. MAF sensor outputs a series of pulses that varies in frequency with airflow. PCM uses this signal for fuel control. Frequency signal will vary from about 2000 Hz at idle to 10,000 Hz at maximum engine load. DTC will set if signal from MAF sensor is below frequency range.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Start engine and allow it to idle. Using scan tool, select ENG 1 data list. Monitor MAF FREQUENCY display. If frequency is less than 11,500 Hz, go to step 4). If frequency is 11,500 Hz or more, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Select SPECIFIC DTC function then enter DTC P0103. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Turn ignition off. Disconnect MAF sensor harness connector. Start engine. Using scan tool, monitor MAF FREQUENCY. If frequency is zero Hz, go to next step. If frequency is not zero Hz, go to step 7).
5. Check for poor connection at MAF sensor connector. Repair as necessary. After repair is completed, go to step 10). If connector is okay, go to next step.
6. Replace MAF sensor. After repair is completed, go to step 10).
7. Check for incorrect routing of MAF sensor wiring harness. Ensure harness is not near ignition coils or other high-voltage components. Reroute wiring harness as necessary. After repair is completed, go to step 10). If wiring harness is routed correctly, go to next step.
8. Check MAF signal circuit terminal connections at PCM. Repair as necessary. After repair is completed, go to step 10). If terminal connections are okay, go to next step.
9. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
10. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0103. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for misrouted MAF sensor wiring harness. Ensure harness is not close to high voltage components. Check for damaged wiring harness.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Manifold Absolute Pressure (MAP) sensor. As manifold pressure changes, monitored MAP sensor signal voltage changes. MAP sensor signal voltage should be 1.0-1.5 volts at idle and 4.5-4.8 volts at Wide Open Throttle (WOT).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Start engine and allow it to idle. Using scan tool, observe MAP sensor voltage. MAP sensor voltage should be 1.0-1.5 volt. If MAP sensor voltage varies by more than .33 volt, go to next step. If MAP sensor voltage does not vary by more than .33 volt, go to step 4).
3. Turn ignition on, with engine off. Disconnect MAP sensor connector. Using scan tool, observe MAP sensor voltage. If voltage is one volt or less, go to step 5). If voltage is more than one volt, go to step 6).
4. Observing scan tool display, wiggle, pull and twist MAP sensor connector. MAP sensor voltage should be 1.0-1.5 volt. If MAP sensor voltage varies by more than .33 volt, go to step 3). If MAP sensor voltage does not vary by more than .33 volt, go to step 7).
5. Disconnect and inspect PCM and MAP sensor connectors. If connectors are okay, go to step 9). If connector(s) are not okay, go to step 8).
6. Disconnect and inspect PCM connector. If connector is okay, go to step 12). If connector is not okay, go to step 8).
7. Ensure ignition is on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Observing scan tool display, drive vehicle at a steady speed. If MAP sensor voltage varies by more than .33 volt, go to step 3). If MAP sensor voltage does not vary by more than .33 volt, go to DIAGNOSTIC AIDS.
8. Repair connector pins and/or wiring as necessary. After repair is completed, go to step 13).
9. Check for restricted or leaking MAP sensor vacuum hose. If vacuum hose is okay, go to next step. If vacuum hose is not okay, go to step 11).
10. Replace MAP sensor. After repair is completed, go to step 13).
11. Replace MAP sensor vacuum hose as necessary. After repair is completed, go to step 13).
12. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
13. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Drive vehicle at a steady speed. Select SPECIFIC DTC function then enter DTC P0106. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
14. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Turn ignition on, with engine off. MAP sensor voltage signal should be 4.5-4.8 volts. Compare this reading with a known-good vehicle with same style MAP sensor. Voltage readings should be within .4 volt of each other.

DTC P0106 Schematic. Scheme 24

DTC P0107 - MAP SENSOR CIRCUIT LOW VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Manifold Absolute Pressure (MAP) sensor. As manifold pressure changes, monitored MAP sensor signal voltage changes. MAP sensor signal voltage should be 1.0-1.5 volts at idle and 4.5-4.8 volts at Wide Open Throttle (WOT).

Conditions required to test for DTC are

1. Engine speed less than 1200 RPM.
2. Throttle Position (TP) sensor angle more than 16 percent.
3. DTC P0122 or P0123 not set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Start and run engine at idle. Using scan tool, observe MAP sensor voltage. If voltage is less than .25 volt, go to next step. If voltage is .25 volt or greater, go to step 4).
3. Turn ignition off. Disconnect MAP sensor connector. Connect a jumper wire between signal circuit and 5-volt reference circuit terminals at MAP sensor harness connector. Turn ignition on. Observe scan tool. If voltage is more than 4.7 volts, go to step 5). If voltage is 4.7 volts or less, go to step 6).
4. Ensure ignition is on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If MAP sensor voltage is less than .25 volt, go to step 3). If MAP sensor voltage is .25 volt or more, go to DIAGNOSTIC AIDS.
5. Disconnect and inspect MAP sensor connector. If connector is okay, go to step 9). If connector is not okay, go to step 8).
6. Turn ignition off. Disconnect jumper wire from MAP sensor connector. Connect a test light between positive battery terminal and signal circuit terminal at MAP sensor harness connector. Turn ignition on. Observe scan tool. If MAP sensor voltage is more than 4 volts, go to next step. If MAP sensor voltage is 4 volts or less, go to step 12).
7. Check MAP sensor 5-volt reference circuit for an open or short to ground. If 5-volt reference circuit is okay, go to step 11). If 5-volt reference circuit is not okay, go to step 10).
8. Repair connector pins and/or wiring as necessary. After repair is completed, go to step 14).
9. Replace MAP sensor. After repair is completed, go to step 14).
10. Repair 5-volt reference circuit as necessary. After repair is completed, go to step 14).
11. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 14).
12. Check MAP sensor signal circuit for an open or short to ground. If sensor signal circuit is okay, go to step 11). If sensor signal circuit is not okay, go to next step.
13. Repair MAP sensor signal circuit as necessary. After repair is completed, go to next step.
14. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0107. If scan tool indicates TEST RAN AND PASSED, repair is complete. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).

Turn ignition on, with engine off. MAP sensor voltage signal should be 4.5-4.8 volts. Compare this reading with a known-good vehicle with same style MAP sensor. Voltage readings should be within .4 volt of each other. After repairs are completed, use scan tool and access FUEL TRIM RESET function. Reset long term fuel trim to 128.

DTC P0108 - MAP SENSOR CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Manifold Absolute Pressure (MAP) sensor. PCM monitors a signal circuit from MAP sensor. As manifold pressure changes, MAP sensor signal voltage changes. MAP sensor signal voltage should be 1.0-1.5 volts at idle and 4.5-4.8 volts at Wide Open Throttle (WOT).

1. Vehicle speed sensor less than one MPH.
2. Throttle Position (TP) sensor angle less than 16 percent.
3. DTC P0122 or P0123 not set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Start and run engine at idle. Using scan tool, observe MAP sensor voltage. If voltage is 4 volts or more, go to next step. If voltage is less than 4 volts, go to step 4).
3. Turn ignition off. Disconnect MAP sensor connector. Turn ignition on. Using scan tool, observe MAP sensor voltage. If voltage is one volt or less, go to step 5). If voltage is more than one volt, go to step 6).
4. Ensure ignition is on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If MAP sensor voltage is 4 volts or more, go to step 3). If MAP sensor voltage is less than 4 volts, go to DIAGNOSTIC AIDS.
5. Check for continuity between ground and sensor ground circuit terminal at MAP sensor harness connector. If continuity exists, go to step 7). If continuity does not exist, go to step 9).
6. Check MAP sensor signal circuit for a short to voltage or a short to MAP sensor 5-volt reference circuit. If sensor signal circuit is okay, go to step 11). If sensor signal circuit is not okay, go to step 10).
7. Check for restricted or leaking MAP sensor vacuum hose. If vacuum hose is okay, go to step 12). If vacuum hose is not okay, go to next step.
8. Replace MAP sensor vacuum hose. After repair is completed, go to step 13).
9. Repair open in MAP sensor ground circuit. After repair is completed, go to step 13).
10. Repair MAP sensor signal circuit as necessary. After repair is completed, go to step 13).
11. See DIAGNOSTIC AIDS. If no faults have been found, replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 13).
12. Replace MAP sensor. After repair is completed, go to step 13).
13. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0108. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
14. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Turn ignition on, with engine off. MAP sensor voltage signal should be 4.5-4.8 volts. Compare this reading with a known-good vehicle with same style MAP sensor. Voltage readings should be within .4 volt of each other. Check 5-volt reference for short to battery voltage. After repairs are completed, use scan tool and access FUEL TRIM RESET function. Reset long term fuel trim to 128.

Powertrain Control Module (PCM) supplies and monitors a 5-volt reference signal and a ground circuit to Intake Air Temperature (IAT) sensor. When intake air is cold, sensor resistance is high and when intake air is warm, sensor resistance low. When PCM senses a signal voltage lower (temperature higher) than the normal operating range of the sensor, DTC will set.

Conditions for setting this DTC are as follows

1. Engine run time is more than 6 minutes.
2. Vehicle speed more than 15 MPH.
3. IAT sensor signal voltage indicates IAT air temperature is more than 262°F (128°C).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe IAT sensor value. If IAT sensor value is more than 262°F (128°C), go to step 4). If IAT sensor value is 262°F (128°C) or less, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Note IAT sensor value displayed on scan tool. If IAT sensor value is more than 262°F (128°C), go to next step. If IAT value is 262°F (128°C) or less, no problem is indicated at this time. Go to DIAGNOSTIC AIDS.
4. Disconnect IAT sensor connector. Note IAT sensor value displayed on scan tool. If IAT sensor value is less than -22°F (-30°C), go to next step. If IAT sensor value is -22°F (-30°C) or more, go to step 6).
5. Replace IAT sensor. After repair is completed, go to step 9).
6. Connect a test light between positive battery terminal and signal circuit terminal at IAT sensor connector. If test light is on, go to next step. If test light is off, go to step 8).
7. Repair short to ground in IAT sensor signal circuit. After repair is completed, go to step 9).
8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
9. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0112. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
10. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If other DTCs are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If sensor temperatures are not within a few degrees of each other, test IAT sensor. See IAT TEMPERATURE-TO-RESISTANCE VALUES.

IAT TEMPERATURE-TO-RESISTANCE VALUES

DTC P0112 Schematic. Scheme 25

DTC P0113 - IAT SENSOR CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Powertrain Control Module (PCM) supplies and monitors a 5-volt reference signal and a ground circuit to Intake Air Temperature (IAT) sensor. When intake air is cold, sensor resistance is high and when intake air is warm, sensor resistance low. When PCM senses a signal voltage lower than the normal operating range of the sensor, DTC will set.

1. Engine run time is greater than 6 minutes.
2. Vehicle speed greater than 15 MPH.
3. IAT sensor signal voltage indicates air temperature is less than -22°F (-30°C).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe IAT sensor value. If IAT sensor value is less than -22°F (-30°C), go to step 4). If IAT sensor value is -22°F (-30°C) or more, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Note IAT sensor value displayed on scan tool. If IAT sensor value is less than -22°F (-30°C), go to next step. If IAT value is -22°F (-30°C) or greater, see DIAGNOSTIC AIDS.
4. Disconnect IAT sensor connector. Connect a jumper wire between signal circuit and sensor ground circuit terminals at IAT sensor harness connector. Note IAT sensor value displayed on scan tool. If IAT sensor value is greater than 266°F (130°C), go to step 6). If IAT sensor value is 266°F (130°C) or less, go to next step.
5. Connect a jumper wire between ground and signal circuit terminal at IAT sensor harness connector. Note IAT sensor value displayed on scan tool. If IAT sensor value is greater than 266°F (130°C), go to step 7). If IAT sensor value is 266°F (130°C) or less, go to step 8).
6. Disconnect and inspect IAT sensor connector. Repair connector as necessary. After repair is completed, go to step 12). If connector is okay, go to step 10).
7. Check for an open IAT sensor ground circuit. Repair wiring as necessary. After repair is completed, go to step 12). If circuit is okay, go to step 9).
8. Check for an open IAT sensor signal circuit. Repair wiring as necessary. After repair is completed, go to step 12). If circuit is okay, go to next step.
9. Check for poor IAT sensor ground or a poor IAT sensor signal circuit terminal connection at PCM. Repair as necessary. After repair is completed, go to step 12). If circuits are okay, go to step 11).
10. Replace IAT sensor. After repair is completed, go to step 12).
11. Replace PCM. Program replacement PCM using required equipment. After replacement is completed, go to next step.
12. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0113. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
13. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

An intermittent problem can be caused by misrouted harness, rubbed through wire insulation or broken wire inside insulation.

If other DTC(s) are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If temperatures are not within a few degrees of each other, test IAT sensor. See IAT TEMPERATURE-TO-RESISTANCE VALUES.

IAT TEMPERATURE-TO-RESISTANCE VALUES

Powertrain Control Module (PCM) supplies and monitors a 5-volt reference signal and a ground circuit to Engine Coolant Temperature (ECT) sensor. With engine cold, sensor resistance is high and when engine is warm, sensor resistance is low. When PCM senses a signal voltage lower than the normal operating range of the sensor, DTC will set.

1. Engine run time is greater than 2 minutes.
2. ECT sensor signal voltage indicates engine coolant temperature is greater than 280°F (138°C).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe ECT sensor value. If ECT sensor value is greater than 266°F (130°C), go to step 4). If ECT sensor value is 266°F (130°C) or less, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, observe ECT sensor value. If ECT sensor value is greater than 266°F (130°C), go to next step. If ECT sensor value is 266°F (130°C) or less, see DIAGNOSTIC AIDS.
4. Disconnect ECT sensor connector. Observe ECT sensor value. If ECT sensor value is less than -22°F (-30°C), go to step 6). If ECT sensor value is -22°F (-30°C) or greater, go to next step.
5. Check for short to ground in ECT sensor signal circuit. Repair wiring as necessary. After repair is completed, go to step 8). If circuit is okay, go to step 7).
6. Replace ECT sensor. After repair is completed, go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
8. Using scan tool, select CLEAR DTCs or CLEAR INFO function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0117. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, return to step 2).
9. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If other DTC(s) are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If temperatures are not within a few degrees of each other, test ECT sensor. See ECT TEMPERATURE-TO-RESISTANCE VALUES table.

ECT TEMPERATURE-TO-RESISTANCE VALUES

DTC P0117 Schematic. Scheme 26

DTC P0118 - ECT SENSOR CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0117 schematic.

Powertrain Control Module (PCM) supplies and monitors a 5-volt reference signal and a ground circuit to Engine Coolant Temperature (ECT) sensor. With engine cold, sensor resistance is high and when engine is warm, sensor resistance is low. When PCM senses a signal voltage lower than the normal operating range of the sensor, DTC will set.

1. Engine run time is more than 2 minutes.
2. ECT sensor signal voltage indicates engine coolant temperature is less than -22°F (-30°C).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe ECT sensor value. If ECT sensor value is less than -22°F (-30°C), go to step 4). If ECT sensor value is -22°F (-30°C) or more, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, observe ECT sensor value. If ECT sensor value is less than -22°F (-30°C), go to next step. If ECT sensor value is -22°F (-30°C) or more, go to DIAGNOSTIC AIDS.
4. Disconnect ECT sensor connector. Connect a jumper wire between signal circuit and sensor ground circuit terminals at ECT sensor harness connector. If ECT sensor value is more than 266°F (130°C), go to step 6). If ECT value is 266°F (130°C) or less, go to next step.
5. Connect a jumper wire between ground and signal circuit terminal at ECT sensor harness connector. If ECT sensor value is more than 266°F (130°F), go to step 7). If ECT sensor value is 266°F (130°C) or less, go to step 8).
6. Disconnect and inspect ECT sensor connector. Repair connector as necessary. After repair is completed, go to step 12). If connector is okay, go to step 10).
7. Check for open ECT sensor ground circuit. Repair as necessary. After repair is completed, go to step 12). If circuit is okay, go to step 9).
8. Check for open ECT sensor signal circuit. Repair wiring as necessary. After repair is completed, go to step 12). If circuit is okay, go to next step.
9. Check for poor ECT sensor ground or a poor ECT sensor signal circuit terminal connection at PCM. Repair as necessary. After repair is completed, go to step 12). If circuits are okay, go to step 11).
10. Replace ECT sensor. After repair is completed, go to step 12).
11. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
12. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0118. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
13. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. If other DTCs are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If temperatures are not within a few degrees of each other, test ECT sensor. See ECT TEMPERATURE-TO-RESISTANCE VALUES table.

ECT TEMPERATURE-TO-RESISTANCE VALUES

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Throttle Position (TP) sensor, and a signal circuit to monitor changes in throttle angle. TP sensor signal voltage should be about .5 volt at idle and 4.5 volts or more at wide open throttle.

Conditions for setting DTC are as follows

1. No active TP sensor or MAP sensor DTC.
2. Engine is running.
3. MAP sensor reading is less than 55 kPa.
4. Predicted throttle angle is not close to actual throttle angle.
5. TP sensor angle is more than 60 percent at 1600 RPM.

1. Perform On-Board Diagnostic (OBD) System Check. CHECK. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, select ENG 1 data list. Monitor MAP sensor reading. If MAP sensor value is less than 55 kPa, go to next step. If MAP sensor scan tool value is 55 kPa or more, go to step 6).
3. Disconnect MAP sensor connector. Connect a test light between 5-volt reference circuit and signal circuit terminals at MAP sensor harness connector. If MAP sensor value is less than 55 kPa, go to step 5). If MAP sensor value is 55 kPa or more, go to next step.
4. Check for an open or short to ground in MAP sensor signal circuit. Repair as necessary. After repair is completed, go to step 13). If circuit is okay, go to step 12).
5. Replace MAP sensor. After repair is completed, go to step 13).
6. Observing scan tool, depress accelerator to floor, then slowly release pedal. TP sensor angle value should increase steadily to 100 percent when pedal is depressed and decrease steadily to zero percent when pedal is released. If TP sensor angle value is as specified, see DIAGNOSTIC AIDS. If TP sensor angle value is not as specified, go to next step.
7. Disconnect TP sensor connector. Observe TP sensor display on scan tool. If TP sensor voltage is less than .5 volt, go to next step. If TP sensor voltage is .5 volt or more, go to step 9).
8. Connect at test light between 5-volt reference circuit and signal circuit terminals at TP sensor harness connector. If scan tool voltage is about 5 volts, go to step 11). If voltage is not about 5 volts, go to step 10).
9. Check TP signal circuit for short to voltage. Check TP sensor ground circuit for high resistance between PCM and TP sensor. Check TP sensor ground circuit for poor connection. Repair as necessary. After repair is completed, go to step 13). If circuits are okay, go to step 12).
10. Check TP sensor signal circuit or 5-volt reference circuit for high resistance between PCM and TP sensor. Check TP sensor signal circuit or 5-volt reference circuit for a poor connection. Repair as necessary. After repair is completed, go to step 13). If circuit is okay, go to next step.
11. Replace TP sensor. After repair is completed, go to step 13).
12. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
13. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0121. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. If other DTC(s) are set that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM. Also, using FREEZE FRAME data may aid in determining conditions when DTC was set. Check MAP sensor. See appropriate SYSTEM/COMPONENT TESTS article.

DTC P0121 Schematic. Scheme 27

DTC P0122 - TP SENSOR CIRCUIT LOW VOLTAGE

Note. For circuit reference, see DTC P0121 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Throttle Position (TP) sensor, and a signal circuit to monitor throttle angle. TP sensor signal voltage should be about .5 volt at idle and 4.5 volts or greater at wide open throttle.

Condition for setting DTC is follows

1. Engine running and TP sensor reads less than .19 volt.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off (throttle closed). Using scan tool, observe TP sensor voltage. If voltage is less than .2 volt, go to step 4). If voltage is .2 volt or greater, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If TP sensor voltage is less than .2 volt, go to next step. If TP sensor voltage is .2 volt or greater, go to step 12).
4. Disconnect TP sensor connector. Connect a jumper wire between signal circuit and 5-volt reference circuit terminals at TP sensor harness connector. Observe TP sensor voltage. If voltage is greater than 4 volts, go to step 10). If voltage is 4 volts or less, go to next step.
5. Connect a test light between battery voltage and signal circuit terminal at TP sensor harness connector. If voltage is greater than 4 volts, go to next step. If voltage is 4 volts or less, go to step 8).
6. Check 5-volt reference circuit for an open or short to ground. Repair wiring as necessary. After repair is completed, go to step 12). If circuit is okay, go to next step.
7. Check 5-volt reference circuit terminal for poor connection at PCM. Repair as necessary. After repair is completed, go to step 12). If circuit terminal is okay, go to step 11).
8. Check TP sensor signal circuit for an open or short to ground. Repair as necessary. After repair is completed, go to step 12). If circuit is okay, go to next step.
9. Check for poor TP sensor signal circuit terminal connection at PCM. Repair as necessary. After repair is completed, go to step 12). If circuit is okay, go to step 11).
10. Replace TP sensor. After repair is completed, go to step 12).
11. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
12. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0122. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
13. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If other DTC(s) are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM. Also, using FREEZE FRAME data may aid in determining conditions when DTC was set.

DTC P0123 - TP SENSOR CIRCUIT HIGH VOLTAGE

Note. For circuit reference, see DTC P0121 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Throttle Position (TP) sensor, and a signal circuit to monitor throttle angle. TP sensor signal voltage should be about .5 volt at idle and 4.5 volts or more at wide open throttle.

1. TP sensor voltage is more than 4 volts for 5 seconds.
2. Engine speed less than 1500 RPM.
3. DTC P0107 and/or P0108 not set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off (throttle closed). Using scan tool, observe TP sensor voltage. If TP sensor voltage is more than one volt, go to step 4). If voltage is one volt or less, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. If TP sensor voltage is greater than 3.9 volts, go to next step. If not, go to step 12).
4. Disconnect TP sensor connector. Observe TP sensor voltage. If voltage is less than .2 volt, go to next step. If voltage is .2 volt or more, go to step 6).
5. Connect a test light between positive battery terminal and sensor ground circuit terminal at TP sensor connector. If test light is on, go to step 7). If test light is off, go to step 9).
6. Check for short to voltage in signal circuit. Repair as necessary. Go to step 12). If circuit is okay, go to step 11).
7. Check for short to voltage in 5-volt reference circuit. Repair as necessary. Go to step 12). If circuit is okay, go to next step.
8. Disconnect and inspect TP sensor connector. Repair as necessary. Go to step 12). If connector is okay, go to step 11).
9. Check for open in ground circuit. Repair as necessary. Go to step 12). If circuit is okay, go to step 11).
10. Replace TP sensor. Go to step 12).
11. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
12. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0123. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
13. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. If other DTC(s) are set for components that share the same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

DTC P0125 - ECT EXCESSIVE TIME TO REACH CLOSED LOOP

Note. For circuit reference, see DTC P0117 schematic.

Fuel delivery system will operate in open loop when engine coolant temperature is less than 68°F (20°C). During open loop, PCM ignores oxygen sensor signal and calculates air/fuel ratio based on inputs from Engine Coolant Temperature (ECT) sensor, Throttle Position (TP) sensor and Manifold Absolute Pressure (MAP) sensor.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Allow engine to cool to ambient temperature. Start engine and allow it to idle. Using scan tool, monitor ENG COOL TEMP display for 9 minutes. If value increases to greater than 70°F (21°C), see DIAGNOSTIC AIDS. If value does not increase to greater than 70°F (21°C), go to next step.
3. If any ECT sensor DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, go to next step.
4. Allow engine to cool. Turn ignition on. Observe cooling fans operation. If fans are off, go to next step. If fans are on, repair cooling fans system as necessary.
5. Check cooling system coolant level. If fluid level is low, go to step 9). If fluid level is okay, go to next step.
6. Check thermostat operation. If thermostat is operating properly, go to next step. If thermostat is not operating properly, go to step 9).
7. Using scan tool, compare ENG COOL TEMP display with actual coolant temperature measured with a thermometer. If temperature values are close, go to step 9). If temperature values are not close, go to next step.
8. Check for high resistance is ECT sensor wiring harness. Also, check for poor connections at ECT sensor connector and PCM connector. If a problem is found, go to step 10). If wiring is okay, go to step 11).
9. Check cooling system and repair as necessary. After repair is completed, go to step 12).
10. Repair faulty wiring or terminals as necessary. After repair is completed, go to step 12).
11. Replace ECT sensor. After repair is completed, go to next step.
12. Allow engine to cool completely. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Monitor ENG COOL TEMP display for 9 minutes. If value increases to greater than 70°F (21°C), repair is complete. If value does not increase to greater than 70°F (21°C), repeat step 2).

Check for poor connection at PCM. Check for damaged wiring harness.

Powertrain Control Module (PCM) supplies about .45 volt to Heated Oxygen Sensor 1 (HO2S 1). The HO2S 1 varies voltage from about one volt when exhaust is rich to about .10 volt when exhaust is lean. PCM monitors and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If PCM detects HO2S 1 voltage is less than predetermined voltage, DTC will set.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor MAP, sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. Closed loop air/fuel ratio is 14.4:1-14.9:1.
3. TP sensor angle is 5-40 percent.
4. HO2S 1 remains at less than 300 mV during normal closed loop operation.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, observe HO2S 1 voltage. If voltage stays at less than 300 mV, go to step 4). If voltage does not stay at less than 300 mV, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within the conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0131 until DTC P0131 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect HO2S 1 connector. Connect a jumper wire between ground and ground circuit terminal at HO2S 1 harness connector. If voltage is about 450 mV, see DIAGNOSTIC AIDS. If voltage is not about 450 mV, go to next step.
5. Turn ignition off. Disconnect PCM connector. Check for a short to ground or short to sensor ground circuit in HO2S 1 signal circuit. If circuit is shorted, go to next step. If circuit is okay, go to step 7).
6. Repair wiring as necessary. After repair is completed, go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
8. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0131 until DTC P0131 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check oxygen sensor pigtail wire for breaks, contamination or grounding on exhaust manifold. Check for intermittent ground in signal wire between sensor connector and sensor. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor. Check for fuel contamination, improper fuel pressure or exhaust leak, especially near oxygen sensor. Check for vacuum or crankcase leak, causing a lean condition. Check MAF sensor.

DTC P0131 Schematic. Scheme 28

DTC P0132 - HO2S CIRCUIT HIGH VOLTAGE SENSOR 1

Note. For circuit reference, see DTC P0131 schematic.

Powertrain Control Module (PCM) supplies about .45 volt to Heated Oxygen Sensor 1 (HO2S 1). The HO2S 1 varies voltage from about one volt when exhaust is rich to about .10 volt when exhaust is lean. PCM monitors and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If PCM detects HO2S 1 voltage is greater than predetermined voltage, DTC will set.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor, MAP sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. HO2S 1 remains at greater than 950 mV during normal closed loop operation.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, observe HO2S 1 voltage. If voltage stays at greater than 950 mV, go to step 5). If voltage does not stay at greater than 950 mV, go to next step.
3. Operate vehicle in DECEL FUEL MODE (vehicle speed greater than 25 MPH, TP angle less than 3 percent) while monitoring HO2S 1 on scan tool. If voltage stays at greater than 800 mV, go to step 5). If voltage does not stay at greater than 800 mV, go to next step.
4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0132 until DTC P0132 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
5. Disconnect HO2S 1 connector. Connect a jumper wire between ground and ground circuit terminal at HO2S 1 harness connector. If voltage is about 450 mV, see DIAGNOSTIC AIDS. If voltage is not about 450 mV, go to next step.
6. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM measure voltage between ground and signal circuit terminal at HO2S 1 harness connector. If voltage is greater than 600 mV, go to next step. If voltage is 600 mV or less, go to step 8).
7. Repair short to voltage is HO2S 1 signal circuit. After repair is completed, go to step 9).
8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
9. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0132 until DTC P0132 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate, FAILED THIS IGN, repair is complete.

Check fuel pressure. Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM/COMPONENT TESTS article. Check for leaking fuel pressure regulator by removing vacuum hose and checking for fuel presence. If fuel is present, replace regulator. Check EVAP canister for fuel saturation. Check MAF sensor. See appropriate SYSTEM/COMPONENT TESTS article.

DTC P0133 - HO2S SLOW RESPONSE SENSOR 1

Note. For circuit reference, see DTC P0131 schematic.

Powertrain Control Module (PCM) continuously monitors Heated Oxygen Sensor 1 (HO2S 1) activity for 100 seconds. During monitor period, PCM counts number of times HO2S 1 switches from rich to lean and from lean to rich. PCM then adds amount of time HO2S 1 took to complete all switches. With this information, an average time for all switches can be determined. Whenever average time to switch is too slow, a DTC P0133 will set.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor, MAP sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. Engine has been running for greater than 2 minutes.
3. Average HO2S 1 response times are 54 milliseconds or less for rich to lean or lean to rich sweeps.
4. Engine speed is 1000-3000 RPM.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step. NOTE: If other DTCs are present, diagnose affected DTC(s) before proceeding.
2. Start engine. Ensure engine is at normal operating temperature. Operate vehicle within the conditions required for setting this DTC. Monitor SPECIFIC DTC info for DTC P0133 until DTC P0133 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
3. If scan tool also indicates DTC P1133 or P1134, go to step 8). If scan tool does not also indicate DTC P1133 or P1134, go to next step.
4. Check for exhaust leaks. Repair as necessary. After repair is completed, go to step 13). If exhaust is okay, go to next step.
5. Perform the following: Check for proper HO2S 1 installation. Check HO2S 1 connector and wiring for corrosion or damage. Check HO2S 1 ground circuit. If a problem is found, go to step 9). If no problems were found, go to next step.
6. Disconnect HO2S 1 connector. Connect a jumper wire between ground and ground circuit terminal at HO2S 1 harness connector. Turn ignition on. Using scan tool, monitor HO2S 1 voltage. If voltage is about 450 mV, go to next step. If voltage is not about 450 mV, go to step 10).
7. Connect a jumper wire between ground and signal circuit terminal at HO2S 1 harness connector. If voltage is less than 300 mV, go to step 12). If voltage is 300 mV or greater, go to step 11).
8. Replace oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After repair is completed, go to step 13).
9. Repair or replace wiring or terminal as necessary. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor. After repair is completed, go to step 13).
10. Repair open in HO2S 1 ground circuit or grounded HO2S 1 signal circuit. After repair is completed, go to step 13).
11. Repair open in HO2S 1 signal circuit. If circuit is okay, check PCM connections. After repair is completed or if repairs are not required, go to step 13).
12. Replace HO2S 1. After repair is completed, go to next step.
13. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0133 until DTC P0133 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for damaged wiring harness.

DTC P0134 - HO2S INSUFFICIENT ACTIVITY SENSOR 1

Note. For circuit reference, see DTC P0131 schematic.

Powertrain Control Module (PCM) supplies about .45 volt to Heated Oxygen Sensor 1 (HO2S 1). The HO2S 1 generates a voltage that varies from about one volt when exhaust is rich to about .10 volt when exhaust is lean. PCM monitors and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If PCM detects HO2S 1 voltage remains at or near .45 volt for an extended period of time, DTC will set.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor, MAP sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. Engine has been running for greater than 30 seconds.
3. HO2S 1 signal voltage remains 400-500 mV for greater than 10 seconds.
4. Engine coolant temperature is greater than 149°F (65°C).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Ensure engine is at normal operating temperature. Start engine. Increase engine speed to 1200 RPM for 2 minutes. Using scan tool, monitor HO2S 1 voltage. If voltage is varying outside the range of 400-500 mV, go to next step. If voltage is within 400-500 mV range, go to step 4).
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0134 until DTC P0134 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Turn ignition on, with engine off. Disconnect HO2S 1 connector. Connect a jumper wire between ground and sensor signal circuit terminal at HO2S 1 harness connector. If voltage is less than 150 mV, go to step 8). If voltage is 150 mV or greater, go to next step.
5. Turn ignition on, with engine off. Disconnect jumper wire. Using DVOM, measure voltage between heater ground circuit and sensor signal circuit terminals at HO2S 1 harness connector. If voltage is greater than 450 mV, go to next step. If not, go to step 7).
6. Turn ignition off. Disconnect PCM connector. Check continuity of ground circuit between PCM connector and HO2S 1 harness connector. If resistance is 5 ohms or less, go to step 9). If resistance is greater than 5 ohms, repair open in ground circuit. After repair is completed, go to step 13).
7. Turn ignition off. Disconnect PCM connector. Check continuity of signal circuit between PCM and HO2S 1 harness connectors. If resistance is 5 ohms or less, go to step 10). If resistance is greater than 5 ohms, repair open in ground circuit. After repair is completed, go to step 13).
8. Turn ignition off. Disconnect and inspect HO2S 1 connector. Inspect for damaged pins, corrosion and loose wires. Repair as necessary. After repair is completed, go to step 13). If connector is okay, go to step 11).
9. Check for poor HO2S 1 ground circuit terminal connection at PCM connector. Repair terminal as necessary. After repair is completed, go to step 13). If connector is okay, go to step 12).
10. Check for poor HO2S 1 signal circuit terminal connection at PCM connector. Repair terminal as necessary. After repair is completed, go to step 13). If connector is okay, go to step 12).
11. Replace oxygen sensor. After repair is completed, go to step 13).
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0134 until DTC P0134 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for damaged wiring harness. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation.

Turn ignition on, with engine off. Using scan tool, monitor HO2S 1 voltage. Voltage should gradually drop to less than 250 mV or rise to greater than 600 mV. If voltage is not as specified, disconnect HO2S 1 connector/ Connector a test light between ignition feed circuit and heater ground circuit terminals at HO2S 1 harness connector. If test light is off, repair open ignition feed circuit. If test light is on, replace HO2S 1.

DTC P0135 - HO2S HEATER CIRCUIT SENSOR 1

Note. For circuit reference, see DTC P0131 schematic.

Powertrain Control Module (PCM) runs heater test only after a cold start and only once during an ignition cycle. When engine is started, PCM monitors HO2S 1 voltage. When HO2S 1 voltage indicates a sufficiently active sensor, PCM looks at how much time has elapsed since start-up. If PCM determines that too much time was required for HO2S 1 to become active, DTC will set.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor, MAP sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. Engine coolant temperature and intake air temperature is less than 212°F (100°C) at start-up.
3. HO2S 1 signal voltage remains within 150 mV of bias voltage (about 450 mV) for a longer amount of time than it should.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Allow engine to completely cool down before proceeding. Turn ignition on, with engine off. Using scan tool, monitor HO2S 1 voltage. If voltage changes from about 450 mV to 600 mV or from about 450 mV to 300 mV, see DIAGNOSTIC AIDS. If voltage does not change as indicated, go to next step.
3. Remove and inspect fuse for HO2S 1 ignition feed circuit. If fuse is blown, go to step 15). If fuse is okay, go to next step.
4. Turn ignition off. Disconnect HO2S 1 connector. With test light connected to ground, probe ignition feed circuit terminal at HO2S 1 harness connector. If test light is off, go to step 7). If test light is on, go to next step.
5. Connect a test light between heater ground circuit and ignition feed circuit terminals at HO2S 1 harness connector. If test light is on, go to next step. If test light is off, go to step 8).
6. Allow HO2S 1 to cool for a minimum of 10 minutes. Using DVOM, measure resistance between ignition feed circuit and heater ground circuit terminals at HO2S 1 pigtail. If resistance is 3-10 ohms, go to step 9). If resistance is not 3-10 ohms, go to step 14).
7. Repair open in HO2S 1 ignition feed circuit. After repair is completed, go to step 16).
8. Repair open in HO2S 1 heater ground circuit. After repair is completed, go to step 16).
9. Check for poor connection at HO2S 1 harness terminals. Repair as necessary. After repair is completed, go to step 16). If terminals are okay, go to next step.
10. Turn ignition off. Disconnect PCM connector. Measure resistance of signal circuit and ground circuit between PCM and HO2S 1 harness connector. If both readings are less than 5 ohms, go to next step. If one or both readings are 5 ohms or greater, repair open in appropriate circuit. After repair is completed, go to step 16).
11. Check for poor signal circuit or ground circuit terminal connection at HO2S 1 harness connector. Repair as necessary. After repair is completed, go to step 16). If terminals are okay, go to next step.
12. Check for poor HO2S 1 ground circuit terminal at PCM. Repair as necessary. After repair is completed, go to step 16). If terminal is okay, go to next step.
13. Check for poor HO2S 1 signal circuit terminal at PCM. Repair as necessary. After repair is completed, go to step 16). If terminal is okay, go to next step.
14. Replace oxygen sensor. After repair is completed, go to step 16).
15. Locate and repair short to ground in HO2S 1 ignition feed circuit. Replace fuse. After repair is completed, go to next step.
16. Allow engine to completely cool down before proceeding. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, monitor HO2S 1 voltage. If voltage changes from about 450 mV to 600 mV or from about 450 mV to 300 mV, repair is complete. If voltage does not change as indicated, repeat step 2).

Check for poor connection at PCM. Check for damaged wiring harness. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

The Heated Oxygen Sensor 2 (HO2S 2), located rear of catalytic converter produces an output signal relative to oxygen storage capacity of catalytic converter. HO2S 2 signal is less active than signal produced by front oxygen sensor.

1. Engine coolant temperature is greater than 167°F (75°C).
2. Engine run time is greater than 3 minutes.
3. TP sensor angle is 5-40 percent.
4. Air/fuel ratio is 14.4:1-14.9:1.
5. Engine is in closed loop.
6. HO2S 2 voltage is less than 100 mV for greater than 2 minutes.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe HO2S 2 voltage. If voltage is less than 100 mV, go to step 4). If voltage is 100 mV or greater, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0137 until DTC P0137 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect HO2S 2 connector. Connect a jumper wire between ground and ground circuit terminal at HO2S harness connector. If voltage is about 450 mV, see DIAGNOSTIC AIDS. If voltage is not about 450 mV, go to next step.
5. Turn ignition off. Disconnect PCM connectors. Check HO2S 2 signal circuit for a short to ground or a short to sensor ground circuit. If a problem is found, go to next step. If circuit is okay, go to step 7).
6. Repair HO2S 2 signal circuit. After repair is completed, go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
8. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0137 until DTC P0137 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Inspect exhaust system for leaks. Check oxygen sensor pigtail wire for breaks, contamination or grounding on exhaust manifold. Check fuel pressure. Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in SYSTEM/COMPONENT TESTS article. Repair as necessary. Check for vacuum leaks. Check for exhaust leaks. Check MAF sensor. See SYSTEM/COMPONENT TESTS article. Check for fuel contamination.

DTC P0137 Schematic. Scheme 29

DTC P0138 - HO2S CIRCUIT HIGH VOLTAGE SENSOR 2

Note. For circuit reference, see DTC P0137 schematic.

The Heated Oxygen Sensor 2 (HO2S 2), located rear of catalytic converter produces an output signal relative to oxygen storage capacity of catalytic converter. HO2S 2 signal is less active than signal produced by front oxygen sensor.

1. Engine coolant temperature is greater than 167°F (75°C).
2. Engine run time is greater than 25 seconds.
3. TP sensor angle is 5-40 percent.
4. Air/fuel ratio is 14.5:1-14.7:1.
5. Engine is in closed loop.
6. HO2S 2 voltage is greater than 999 mV for greater than 2 minutes.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe HO2S 2 voltage. If voltage is greater than 999 mV, go to step 4). If voltage is 999 mV or less, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0138 until DTC P0138 test runs. If scan tool indicates FAILED THIS IGNITION, go to next step. If scan tool does not indicated FAILED THIS IGNITION, see DIAGNOSTIC AIDS.
4. Disconnect HO2S 2 connector. Connect a jumper wire between ground and sensor ground circuit terminal at HO2S 2 harness connector. If voltage is about 450 mV, see DIAGNOSTIC AIDS. If voltage is not about 450 mV, go to next step.
5. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and HO2S 2 signal circuit terminal at PCM connector. 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. After repair is completed, go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
8. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0138 until DTC P0138 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check if fuel pressure is too high. PCM can compensate for some increase, however, if fuel pressure is too high, DTC will set. Check for leaking injector(s) or faulty fuel pressure regulator. See SYSTEM/COMPONENT TESTS article. Check EVAP system for fuel saturation. Check MAF sensor. Check for oxygen sensor silicone contamination. Check TP sensor. See SYSTEM/COMPONENT TESTS article.

DTC P0140 - HO2S INSUFFICIENT ACTIVITY SENSOR 2

Note. For circuit reference, see DTC P0137 schematic.

The Heated Oxygen Sensor 2 (HO2S 2), located rear of catalytic converter, produces an output signal relative to oxygen storage capacity of catalytic converter. HO2S 2 signal is less active than signal produced by front oxygen sensor.

1. Engine coolant temperature is greater than 149°F (65°C).
2. Engine run time is greater than 30 seconds.
3. Engine is in closed loop.
4. HO2S 2 voltage is 400-500 mV for greater one minute.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Ensure engine is at normal operating temperature. Start engine. Increase engine speed to 1200 RPM for 2 minutes. Observe HO2S voltage. If voltage is 400-500 mV, go to step 4). If voltage is not 400-500 mV, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0140 until DTC P0140 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Turn ignition on, with engine off. Disconnect HO2S 2 connector. Connect a jumper wire between ground and sensor signal circuit and ground circuit terminals at HO2S 2 harness connector. If voltage is less than 150 mV, go to step 8). If voltage is 150 mV or greater, go to next step.
5. Remove jumper wire. Using DVOM, measure voltage between signal circuit and heater ground circuit terminals at HO2S 2 harness connector. If voltage is about 450 mV, go to next step. If voltage is not about 450 mV, go to step 7).
6. Turn ignition off. Disconnect PCM connector. Check continuity of HO2S 2 ground circuit between PCM and HO2S 2 connector. If resistance is less than 5 ohms, go to step 9). If resistance is 5 ohms or greater, repair open circuit. After repair is completed, go to step 13).
7. Turn ignition off. Disconnect PCM connector. Check continuity of HO2S 2 signal circuit between PCM and HO2S 2 connector. If resistance is less than 5 ohms, go to step 10). If resistance is 5 ohms or greater, repair open circuit. After repair is completed, go to step 13).
8. Check for poor HO2S 2 signal or ground circuit terminal connection at HO2S 2 connector. Repair as necessary. After repair is completed, go to step 13). If connection is okay, go to step 11).
9. Check for poor HO2S 2 ground circuit terminal connection at PCM connector. Repair as necessary. After repair is completed, go to step 13). If connection is okay, go to step 12).
10. Check for poor HO2S 2 signal circuit terminal connection at PCM connector. Repair as necessary. After repair is completed, go to step 13). If connection is okay, go to step 12).
11. Replace HO2S 2. After repair is completed, go to step 13).
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0140 until DTC P0140 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check oxygen sensor pigtail wire for breaks and contamination. An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for intermittent open in HO2S 2 signal circuit wire. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

DTC P0141 - HO2S HEATER CIRCUIT SENSOR 2

Note. For circuit reference, see DTC P0137 schematic.

Powertrain Control Module (PCM) runs heater test only after a cold start and only once during an ignition cycle. When engine is started, PCM monitors HO2S 2 voltage. When HO2S 2 voltage indicates a sufficiently active sensor, PCM looks at how much time has elapsed since start-up. If PCM determines that too much time was required for HO2S 2 to become active, DTC will set.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor, MAP sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. Engine coolant temperature and intake air temperature is less than 212°F (100°C) at start-up.
3. HO2S 2 signal voltage remains within 150 mV of bias voltage (about 450 mV) for a longer amount of time than it should.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Allow engine to completely cool down before proceeding. Turn ignition on, with engine off. Using scan tool, monitor HO2S 2 voltage. If voltage changes from about 450 mV to 600 mV, or from about 450 mV to 300 mV, see DIAGNOSTIC AIDS. If voltage does not change from about 450 mV to 600 mV or from about 450 mV to 300 mV, go to next step.
3. Remove and inspect fuse for HO2S 2 ignition feed circuit. If fuse is blown, go to step 15). If fuse is okay, go to next step.
4. Turn ignition off. Disconnect HO2S 2 connector. With test light connected to ground, probe ignition feed circuit terminal at HO2S 2 harness connector. If test light is off, go to step 7). If test light is on, go to next step.
5. Connect a test light between heater ground circuit and ignition feed circuit terminals at HO2S 2 harness connector. If test light is on, go to next step. If test light is off, go to step 8).
6. Allow HO2S 2 to cool for a minimum of 10 minutes. Using DVOM, measure resistance between ignition feed circuit and heater ground circuit terminals at HO2S 2 pigtail. If resistance is 3-10 ohms, go to step 9). If resistance is not 3-10 ohms, go to step 14).
7. Repair open in HO2S 2 ignition feed circuit. After repair is completed, go to step 16).
8. Repair open in HO2S 2 heater ground circuit. After repair is completed, go to step 16).
9. Check for poor connection at HO2S 2 harness terminals. Repair as necessary. After repair is completed, go to step 16). If terminals are okay, go to next step.
10. Turn ignition off. Disconnect PCM connector. Measure resistance of signal circuit and ground circuit between PCM and HO2S 2 harness connector. If both readings are less than 5 ohms, go to next step. If one or both readings are 5 ohms or greater, repair open in appropriate circuit. After repair is completed, go to step 16).
11. Check for poor signal circuit or ground circuit terminal connection at HO2S 2 harness connector. Repair as necessary. After repair is completed, go to step 16). If terminals are okay, go to next step.
12. Check for poor HO2S 2 ground circuit terminal at PCM. Repair as necessary. After repair is completed, go to step 16). If terminal is okay, go to next step.
13. Check for poor HO2S 2 signal circuit terminal at PCM. Repair as necessary. After repair is completed, go to step 16). If terminal is okay, go to next step.
14. Replace oxygen sensor. After repair is completed, go to step 16).
15. Locate and repair short to ground in HO2S 2 ignition feed circuit. Replace fuse. After repair is completed, go to next step.
16. Allow engine to completely cool down before proceeding. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, monitor HO2S 2 voltage. If voltage changes from about 450 mV to 600 mV, or from about 450 mV to 300 mV, repair is complete. If voltage does not change as described, repeat step 2).

Check for poor connection at PCM. Check for damaged wiring harness. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

PCM monitors oxygen sensor signal voltage and adjusts fuel delivery based on signal voltage. A change made to fuel delivery is indicated by the long and short term fuel trim values. Ideal fuel trim value is about 128 (zero percent).

A fuel trim value more than 128 indicates that PCM is adding fuel to compensate for a lean condition. A fuel trim value less than 128 indicates that PCM is reducing amount of fuel to compensate for rich condition. DTC will set if PCM detects an excessively lean condition.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor, MAP sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. Engine coolant temperature is 68-110°F (20-110°C).
3. TP sensor angle is less than 90 percent.
4. Vehicle speed is less than 75 MPH.
5. Engine speed is 550-5000 RPM.
6. Long Term (L.T.) fuel trim is about 16 percent.
7. Short Term (S.T.) fuel trim is about 20 percent.
8. BARO is more than 70 kPa.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
3. Start and warm engine to normal operating temperature. Ensure system is in closed loop. Using scan tool, select ENG 1 data list. Observe L.T. FUEL TRIM and S.T. FUEL TRIM. If L.T. FUEL TRIM is about +16 percent and S.T. FUEL TRIM is about +20 percent, go to step 5). If fuel trim is not as specified, go to next step.
4. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0171 until DTC P0171 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
5. Inspect vacuum hoses for splits, kinks and faulty connections. Repair as necessary. After repair is completed, go to step 22). If vacuum hoses are okay, go to next step.
6. Inspect Positive Crankcase Ventilation (PCV) valve for proper installation. Repair as necessary. After repair is completed, go to step 22). If PCV valve is okay, go to next step.
7. Inspect throttle body inlet screen for damage or blockage. Repair as necessary. After repair is completed, go to step 22). If inlet screen is okay, go to next step.
8. Start engine and check idle quality. If idle is high or rough, go to next step. If idle is okay, go to step 11).
9. Allow engine to idle. Using scan tool, observe IDLE AIR CONTROL display. If counts are more than 5, go to step 11). If counts are 5 or less, go to next step.
10. Inspect throttle body, intake manifold, EGR valve and EGR feed pipe for vacuum leaks. Repair as necessary. After repair is completed, go to step 22). If no vacuum leak is present, go to next step.
11. Check Idle Air Control (IAC) valve. See appropriate SYSTEM/COMPONENT TESTS article. Repair as necessary. After repair is completed, go to step 22). If IAC valve is functioning properly, go to next step.
12. Check for fuel contamination. If fuel is contaminated, replace fuel. After repair is completed, go to step 22). If fuel is not contaminated, go to next step.
13. Inspect injector grounds, power grounds and sensor grounds. Ensure connections are clean and tight and in their proper locations. Repair as necessary. After repair is completed, go to step 22). If grounds are okay, go to next step.
14. Disconnect MAF sensor connector. Start engine and allow it to idle. Ensure system is in closed loop. Using scan tool, observe S.T. FUEL TRIM display. If S.T. FUEL TRIM decreases to about zero percent, go to step 21). If S.T. FUEL TRIM does not decrease to about zero percent, go to next step.
15. Check fuel system. See BASIC FUEL SYSTEM CHECKS (A-7) in appropriate BASIC TESTING article. Repair as necessary. After repair is completed, go to step 22). If fuel system is okay, go to next step.
16. Check canister purge valve operation. See appropriate SYSTEM/COMPONENT TESTS article. Repair as necessary. After repair is completed, go to step 22). If canister purge valve is okay, go to next step.
17. Inspect intake manifold, injector "O" rings, EGR adapter, EGR valve and EGR feed pipes for vacuum leaks. Repair as necessary. After repair is completed, go to step 22). If no vacuum leaks are present, go to next step.
18. Check exhaust system for leaks. Repair as necessary. After repair is completed, go to step 22). If exhaust system is okay, go to next step.
19. Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM/COMPONENT TESTS article. Repair as necessary. After repair is completed, go to step 22). If no problem is found, go to next step.
20. Check HO2S for proper installation. Check HO2S wiring harness for damage and proper routing. Ensure harness is not contacting exhaust. Repair as necessary. After repair is completed, go to step 22). If no problem is found, see DIAGNOSTIC AIDS.
21. Replace MAF sensor. After repair is completed, go to next step.
22. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0171 until DTC P0171 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for damaged wiring harness. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

PCM monitors oxygen sensor signal voltage and adjusts fuel delivery based on signal voltage. A change made to fuel delivery is indicated by the long and short term fuel trim values. Ideal fuel trim value is about 128 (zero percent).

A fuel trim value more than 128 indicates that PCM is adding fuel to compensate for a lean condition. A fuel trim value less than 128 indicates that PCM is reducing amount of fuel to compensate for rich condition. DTC will set if PCM detects an excessively rich condition.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor, MAP sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. Engine coolant temperature is 68-110°F (20-110°C).
3. Intake air temperature is 0-140°F (-18 to 65°C).
4. TP sensor angle is less than 90 percent.
5. Vehicle speed is less than 75 MPH.
6. Engine speed is 550-5000 RPM.
7. Long Term (L.T.) fuel trim is about -23 percent.
8. Short Term (S.T.) fuel trim is about -11 percent.
9. BARO is 18-80 kPa.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
3. Start and warm engine to normal operating temperature. Ensure system is in closed loop. Using scan tool, select ENG 1 data list. Observe L.T. FUEL TRIM and S.T. FUEL TRIM. If L.T. FUEL TRIM is about -23 percent and S.T. FUEL TRIM is about -11 percent, go to step 5). If fuel trim is not as specified, go to next step.
4. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0171 until DTC P0171 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
5. Inspect air filter element. Repair as necessary. After repair is completed, go to step 21). If air filter element is okay, go to next step.
6. Check for collapsed or restricted air intake duct. Repair as necessary. After repair is completed, go to step 21). If air duct is okay, go to next step.
7. Inspect throttle body inlet screen for damage or blockage. Repair as necessary. After repair is completed, go to step 21). If inlet screen is okay, go to next step.
8. Start engine and check idle quality. If idle is high or rough, go to next step. If idle is okay, go to step 11).
9. Allow engine to idle. Using scan tool, observe IDLE AIR CONTROL display. If counts are less than 100, go to step 11). If counts are 100 or more, go to next step.
10. Turn ignition off. Inspect throttle body bore, throttle plate and IAC passages for coking and foreign objects. Repair as necessary. After repair is completed, go to step 22). If no problem is found, go to next step.
11. Check Idle Air Control (IAC) valve operation. See appropriate SYSTEM/COMPONENT TESTS article. Repair as necessary. After repair is completed, go to step 21). If IAC valve is functioning properly, go to step 13).
12. Disconnect fuel pressure regulator vacuum hose. Check vacuum hose for presence of fuel. If fuel is present, replace fuel pressure regulator. After repair is completed, go to step 21). If fuel pressure regulator is okay, go to next step.
13. Turn ignition on, with engine off. Using scan tool, monitor TP ANGLE display while slowly depressing accelerator pedal. If reading increases steadily from minimum value to maximum value at wide open throttle, go to next step. If reading does not increase steadily from minimum value to maximum value at wide open throttle, go to step 19).
14. Disconnect MAF sensor connector. Start engine and allow it to idle. Ensure system is in closed loop. Using scan tool, observe S.T. FUEL TRIM and L.T. FUEL TRIM display. If both values change to about zero percent, go to step 20). If one or both values do not change to about zero percent, go to next step.
15. Perform BASIC FUEL SYSTEM CHECKS (A-7) in appropriate BASIC TESTING article. Repair fuel system as necessary. After repair is completed, go to step 21) If fuel system is okay, go to next step.
16. Check fuel evaporation system for proper operation. Ensure canister purge solenoid is functioning properly. See appropriate SYSTEM/COMPONENT TESTS article. Repair as necessary. After repair is completed, go to step 21). If fuel evaporation system is functioning properly, go to next step.
17. Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM/COMPONENT TESTS article. Repair as necessary. After repair is completed, go to step 21). If no problem is found, go to next step.
18. Remove and inspect Heated Oxygen Sensor 1 (HO2S 1) for silicon contamination. If contamination exists, a powdery White deposit on portion of sensor exposed to exhaust system will be present. If silicone contamination is present, locate and repair source of silicon contamination. Replace HO2S 1. After repair is completed, go to step 21). If no contamination exists, go to DIAGNOSTIC AIDS.
19. Check Throttle Position (TP) sensor mounting screws. Tighten or replace sensor screws as necessary. After repair is completed, go to step 21). If mounting screws are okay, replace TP sensor. After repair is completed, go to step 21).
20. Replace MAF sensor. After repair is completed, go to next step.
21. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0172 until DTC P0172 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for damaged wiring harness. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

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.

Powertrain Control Module (PCM) monitors Crankshaft Position (CKP) sensor and Camshaft Position (CMP) sensor to detect if engine is misfiring. PCM looks for a sudden drop in crankshaft speed. Under light misfire conditions, it may take more than one trip to set a DTC. Severe misfire will flash Malfunction Indicator Light (MIL) indicating that catalytic converter damage is possible.

1. Misfire total is 12 counts or more.
2. TP sensor angle has not changed more than 8 percent in one second.
3. Engine run time is more than 15 seconds.
4. Engine speed is 450-5800 RPM.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If DTC P1200 is also set, diagnose DTC as necessary before proceeding. If DTC P1200 is not set, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, select MISFIRE DATA LIST function and monitor MISFIRE CUR. COUNTERS (one counter per cylinder). If any MISFIRE CURRENT counters are incrementing, go to next step. If MISFIRE CURRENT counters are not incrementing, see DIAGNOSTIC AIDS.
4. If MISFIRE HIST display indicates a large value for more than one cylinder, go to next step. If MISFIRE HIST display does not indicate a large value for mote than one cylinder, go to step 14).
5. Inspect vacuum hoses for splits, kinks and proper routing. Repair as necessary. After repair is completed, go to step 30). If vacuum hoses are okay, go to next step.
6. Inspect Positive Crankcase Ventilation (PCV) valve for proper installation and damaged "O" rings. Repair as necessary. After repair is completed, go to step 30). If vacuum hoses are okay, go to next step.
7. Inspect throttle body inlet screen for damage or blockage. Repair as necessary. After repair is completed, go to step 30). If inlet screen is okay, go to next step.
8. Check fuel pressure. See BASIC FUEL SYSTEM CHECKS (A-7) in BASIC TESTING article. Repair as necessary. After repair is completed, go to step 30). If fuel pressure is okay, go to next step.
9. Check for fuel contamination. If fuel is contaminated, replace contaminated fuel. After repair is completed, go to step 30). If fuel is not contaminated, go to next step.
10. Inspect injector grounds, power grounds and sensor grounds. Ensure connections are clean and tight and in their proper locations. Repair as necessary. After repair is completed, go to step 30). If grounds are okay, go to next step.
11. Disconnect MAF sensor connector. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, select MISFIRE DATA LIST function and monitor MISFIRE CUR. COUNTERS (one counter per cylinder). If any MISFIRE CURRENT counters are incrementing, go to next step. If MISFIRE CURRENT counters are not incrementing, go to step 27).
12. Inspect intake manifold, injector "O" rings, EGR valve and EGR feed pipe for vacuum leaks. Repair as necessary. After repair is completed, go to step 30). If no vacuum leak is present, go to next step.
13. Remove EGR valve. Inspect valve for sticking pintle and carbon build-up. Repair as necessary. After repair is completed, go to step 30). If EGR valve is okay, go to next step.
14. Check for proper injector operation. Install Injector Test Harness (J-34730-380) and Adapter Harness (J-34730-385) to injector 10-way harness connector. Attempt to start engine. If all LEDs flash, go to next step. If not, go to step 16).
15. Perform fuel injector coil test using Injector Tester (J-39021) and DVOM. Injector should indicate 5.7-6.6 volts. If repairs are necessary, repair and go to step 30). If no repairs are required, go to step 17).
16. Check affected injector driver circuit between PCM and injector harness for opens, shorts to ground or poor connections. If a repair is necessary, repair and go to step 30). If no repairs are required, go to step 29).
17. Inspect spark plug wires for correct installation and damage. Repair as necessary. After repair is completed, go to step 30). If plug wires are okay, go to next step.
18. Install Spark Tester (J-26792) on spark plug wire (plug end) for cylinder indicated by MISFIRE CURRENT counters or MISFIRE HIST counters as having most severe misfire (largest number of counts). Jumper spark plug wire end of companion cylinder (same coil shared) to engine ground. Crank engine and observe spark tester. If spark is present, go to step 23). If spark is not present, go to next step.
19. Remove and inspect ignition coil(s) for cracks and carbon tracking. Replace coil(s) as necessary. After repair is completed, go to step 30). If coils(s) are okay, go to next step.
20. Remove ignition coil for cylinder that did not have spark. Measure secondary resistance of coil. If resistance is 5000-7000 ohms, go to next step. If resistance is not 5000-8000 ohms, replace coil. After repair is completed, go to step 30).
21. Visually and physically inspect ignition wires associated with misfiring cylinders. If a problem is found, repair and go to step 30). If no repairs are required, go to next step.
22. Measure spark plug wire resistance. If resistance is more than 30,000 ohms, replace plug wire. After repair is completed, go to step 30). If no repairs are required, go to step 28).
23. Remove and inspect spark plugs. If plugs are fouled, check for a basic engine problem (engine worn out). Repair as necessary. If plugs are okay, go to next step.
24. Check spark plugs for cracked insulators, carbon tracking or other damage. Replace plugs as necessary. After repair is completed, go to step 30). If plugs are okay, go to next step.
25. Check for a basic engine mechanical problem (incorrect valve timing, leaking head gasket, excessive valve deposits, worn camshaft, etc.). Repair as necessary and go to step 30). If engine is okay, go to next step.
26. Check transaxle operation. If transaxle is functioning properly, see DIAGNOSTIC AIDS. If transaxle is not functioning properly, repair as necessary. After repair is completed, go to step 30).
27. Replace MAF sensor. After repair is completed, go to step 30).
28. Replace Ignition Control Module (ICM). After repair is completed, go to next step.
29. Replace PCM. Program replacement PCM using required equipment. After repairs, go to step 30).
30. Ensure FREEZE FRAME data had been recorded. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Using scan tool, monitor MISFIRE CURRENT counters for each cylinder. If any MISFIRE CURRENT counters are incrementing, repeat step 2). If MISFIRE CURRENT counters are not incrementing, repair is complete.

Scan tool provides information that can be useful in identifying the misfire cylinder. If DTC P0300 is currently stored as TEST FAILED SINCE LAST CODE CLEAR, misfire history counters (MISFIRE HIST NO. 1-6) will still contain a value that represents level of misfire for each cylinder. Counter values can help determine is misfire is isolated to a single cylinder or to pair of cylinders.

If largest amount of activity is isolated to a pair or cylinders, check resistance of spark plug wires. Resistance should be less than 30 k/ohms. Check resistance of ignition coil. Resistance should be 5000-7000 ohms. If coil resistance is okay, try a known-good coil.

If misfire is random, check system grounds. Check MAF sensor. See SYSTEM/COMPONENT TESTS article. Check for vacuum leaks. Check fuel pressure. Check fuel injectors. Check EGR valve.

Knock Sensor (KS) is used to detect engine detonation. PCM will retard spark timing based on signals from KS module. The KS produces an AC signal voltage that is sent to the KS module. The amount of AC voltage produced is proportional to the amount of knock.

1. Engine speed is 550-850 RPM.
2. Engine has been running for a minimum of 5 seconds.
3. Engine coolant temperature is greater than 149°F (65°C).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step. NOTE: If an engine knock can be heard, repair engine mechanical condition before proceeding.
2. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, monitor SPECIFIC DTC info for DTC P0325 until DTC P0325 test runs. If scan tool indicates FAILED THIS IGN, go to step 4). If scan tool does not indicate FAILED THIS IGN, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0325. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Check KS signal circuit wires for incorrect wiring near secondary wires. Repair as necessary. After repair is completed, go to step 8). If wires are routed properly, go to next step.
5. Check if KS module is mounted properly. Repair as necessary. After repair is completed, go to step 8). If KS module is mounted properly, go to next step.
6. Replace KS module. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, monitor SPECIFIC DTC info for DTC P0325 until DTC P0325 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
8. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0325 until DTC P0325 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for damaged or improperly installed KS module. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0325 Schematic. Scheme 30

DTC P0326 - KNOCK SENSOR HIGH VOLTAGE

Note. For circuit reference, see DTC P0325 schematic.

Knock Sensor (KS) is used to detect engine detonation. PCM will retard spark timing based on signals from KS module. The KS produces an AC signal voltage that is sent to the KS module. The amount of AC voltage produced is proportional to the amount of knock.

1. Engine speed is 2200-2500 RPM.
2. Throttle angle is greater than 10 percent.
3. Engine has been running for a minimum of 10 seconds.
4. Engine coolant temperature is greater than 149°F (65°C).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step. NOTE: If an engine knock can be heard, repair engine mechanical condition before proceeding.
2. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, monitor SPECIFIC DTC info for DTC P0326 until DTC P0326 test runs. If scan tool indicates FAILED THIS IGN, go to step 4). If scan tool does not indicate FAILED THIS IGN, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0326. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect KS connector. Using DVOM, measure voltage between ground and KS signal circuit terminal at KS harness connector. If voltage is 5 volts, go to next step. If voltage is not 5 volts, go to step 9).
5. Measure resistance between engine block and KS terminal. If resistance is about 100 k/ohms, go to next step. If resistance is not about 100 k/ohms, go to step 10).
6. Set DVOM to 2 volt A/C scale. With engine idling, measure voltage between ground and bank 1 KS terminal. If any voltage is indicated, go to step 10). If no voltage is indicated, go to next step.
7. With DVOM still connected between ground and KS terminal, tap on engine lift bracket. If any voltage is indicated, go to next step. If no voltage is indicated, go to step 10).
8. Check KS signal circuit wires for incorrect wiring near secondary wires. Repair as necessary. After repair is completed, go to step 14). If wires are routed properly, go to step 11).
9. Turn ignition off. Disconnect PCM. Turn ignition on. Check KS signal circuit between PCM and KS connector for an open, short to voltage or a short to ground. Repair as necessary. After repair is completed, go to step 14). If circuit is okay, go to step 11).
10. Replace KS. Repair as necessary. After repair is completed, go to step 14).
11. Turn ignition off. Disconnect PCM. Turn ignition on. Check KS signal circuit for poor connection at PCM. Repair as necessary. After repair is completed, go to step 14). If circuit is okay, go to next step.
12. Replace KS module. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, monitor SPECIFIC DTC info for DTC P0326 until DTC P0326 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate 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. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0326 until DTC P0326 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for damaged or improperly installed KS module. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0327 - KNOCK SENSOR LOW VOLTAGE

Note. For circuit reference, see DTC P0325 schematic.

Knock Sensor (KS) is used to detect engine detonation. PCM will retard spark timing based on signals from KS module. The KS produces an AC signal voltage that is sent to the KS module. The amount of AC voltage produced is proportional to the amount of knock.

1. Engine speed is 2200-2500 RPM.
2. Throttle angle is more than 10 percent.
3. Engine has been running for a minimum of 10 seconds.
4. Engine coolant temperature is more than 149°F (65°C).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step. NOTE: If an engine knock can be heard, repair engine mechanical condition before proceeding.
2. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, monitor SPECIFIC DTC info for DTC P0327 until DTC P0327 test runs. If scan tool indicates FAILED THIS IGN, go to step 4). If scan tool does not indicate FAILED THIS IGN, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0327. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect KS connector. Using DVOM, measure voltage between ground and KS signal circuit terminal at KS harness connector. If voltage is about 5 volts, go to next step. If voltage is not 5 volts, go to step 8.
5. Measure resistance between engine block and KS terminal. If resistance is about 100 k/ohms, go to next step. If resistance is not about 100 k/ohms, go to step 12).
6. Set DVOM to 2 volt A/C scale. With engine idling, tap on engine lift bracket. If any voltage is indicated, go to next step. If no voltage is indicated, go to step 9).
7. Check KS signal circuit for poor terminal connection at KS. Repair as necessary. After repair is completed, go to step 14). If terminal connection is okay, go to step 10).
8. Turn ignition off. Disconnect PCM. Turn ignition on. Check KS signal circuit between PCM and KS connector for an open, short to voltage or a short to ground. Repair as necessary. After repair is completed, go to step 14). If circuit is okay, go to step 10).
9. Replace KS. Repair as necessary. After repair is completed, go to step 14).
10. Turn ignition off. Disconnect PCM. Turn ignition on. Check KS signal circuit for poor connection at PCM. Repair as necessary. After repair is completed, go to step 14). If circuit is okay, go to next step.
11. Check for improperly installed KS module. Repair as necessary. After repair is completed, go to step 14). If KS module is mounted properly, go to next step.
12. Replace KS module. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, monitor SPECIFIC DTC info for DTC P0327 until DTC P0327 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate 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. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0327 until DTC P0327 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for damaged or improperly installed KS module. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

24X reference signal is produced by Ignition Control Module (ICM). The ICM calculates 24X signal by filtering Crankshaft Position (CKP) sensor 24X pulses when engine is running and CKP sync pulses are also being received. PCM uses 24X signal to calculate engine RPM and crankshaft position at engine speeds less than 1200 RPM. PCM constantly monitors number of pulses on 24X reference circuit and compares them with number of 3X reference pulses and CAM signal pulses being received. If PCM receives an incorrect number of pulses on 24X circuit, DTC P0336 will set and PCM will use 3X reference signal circuit for fuel and ignition control.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to NO START DIAGNOSIS (A-3) in BASIC TESTING article.
3. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Check for DTCs. If DTC P0336 is set, go to next step. If DTC P0336 is not set, see DIAGNOSTIC AIDS.
4. Using DVOM, check for battery voltage at crankshaft and camshaft position sensor battery feed terminals. If about battery voltage is present, go to next step. If about battery voltage is not present, go to step 6).
5. Unplug PCM. Using fused jumper wire, apply battery voltage to PCM harness cam/crank sensor feed circuit terminal. Check for voltage on PCM harness camshaft and crankshaft sensor reference signal high circuit terminals. If about battery voltage is present, go to step 12) If about battery voltage is not present, go to step 7).
6. Check for open or short to ground in sensor feed circuit from PCM. Check connections at camshaft and crankshaft position sensors and PCM. Repair as necessary. After repairs, go to next step. If no repairs are required, go to step 8).
7. Check connections at PCM and replace terminals if necessary. After repairs, go to step 15). If no repairs are required, go to next step.
8. Check connections at crankshaft position sensor reference signal terminals. Repair if necessary and go to step 15). If no repairs are required, go to next step.
9. Check reference signal circuit for open or short to ground. Repair as necessary and go to step 15). If no repairs are required, go to next step.
10. Unplug 24X crankshaft position sensor connector and camshaft position sensor connector. Check for continuity between 24X crankshaft position sensor connector reference low (sensor ground) terminal and camshaft position sensor connector reference low (sensor ground) terminal. Then, check for continuity between 24X crankshaft position sensor connector reference low terminal and 3X crankshaft position sensor connector reference low (ground) terminal. The 3X sensor (also referred to as a 7X sensor) is a 2-wire PM generator that is mounted in the side of the engine block. If continuity is not present, repair open circuit as necessary and go to step 12). If no repairs are required, go to next step.
11. Check for open in 3X crankshaft sensor reference low (ground) circuit. Check for open in splice for reference low circuit. Check PCM and sensor connections. If repairs are necessary, repair and go to step 15). If no repairs are required, go to next step.
12. Ignition off. Unplug 24X crankshaft sensor connector. Ignition on. Probe sensor low circuit with test light to battery voltage. If test light is on, go to next step. If test light is not on, go to step 14).
13. Replace 24X crankshaft position sensor. After repair, go to step 15).
14. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
15. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME data as possible. Monitor SPECIFIC DTC info for DTC P0336 until DTC P0336 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for poor connection at PCM. Check for damaged wiring harness or incorrect routing. Check if ignition coil is arcing to wiring harness or ICM. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0336 Schematic. Scheme 31

DTC P0341 - CAMSHAFT POSITION SENSOR CIRCUIT

Note. For circuit reference, see DTC P0336 schematic.

CAM signal is produced by Ignition Control Module (ICM). The ICM produces CAM signal by filtering Camshaft Position (CMP) sensor pulses when engine is running and Crankshaft Position (CKP) sync pulses are also being received. PCM uses CAM signal pulses to initiate sequential fuel injection. PCM constantly monitors number of pulses on CAM signal circuit and compares them with number of 24X reference pulses and number of 3X reference pulses being received. If PCM receives an incorrect number of pulses on CAM circuit, DTC P0341 will set. PCM will then initiate injector sequence without CAM signal with a one in 6 chance that injector sequence is correct.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0341. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
3. Ignition off. Unplug PCM connector. Using test light to battery voltage, probe PCM harness sensor feed terminal. If test light is on, go to next step. If test light is not on, go to step 6).
4. With test light still connected, unplug camshaft position sensor connector. If test light is still on, go to next step. If test light is not on, go to step 11)
5. Check for short to ground in camshaft position sensor feed wire, or short to ground in 24X crankshaft position sensor or sensor feed wire. Repair as necessary and go to step 14). If no repairs are required, see DIAGNOSTIC AIDS.
6. Connect a fuse jumper wire between battery voltage and PCM harness sensor feed terminal. Using DVOM to ground, check for voltage on PCM harness sensor signal terminal. If battery voltage is present, go to next step. If battery voltage is not present, go to step 8).
7. With fused jumper still in PCM harness sensor feed terminal, connect DVOM between 3X crankshaft sensor reference low (ground) circuit terminal and engine ground. If about battery voltage is displayed, go to step 12). If not, go to step 10).
8. Check for open in camshaft position sensor feed circuit. Repair as necessary and go to step 14). If no repairs are required, go to next step.
9. Check camshaft position sensor signal wire for open or short to ground. Repair as necessary and go to step 14). If no repairs are required, go to step 11).
10. Check camshaft position sensor for an open ground circuit. Repair as necessary and go to step 14). If no repairs are required, go to next step.
11. Replace camshaft position sensor. After repair, go to step 14).
12. Check connections and terminals at PCM. Repair as necessary and go to step 14). If no repairs are required, go to next step.
13. Replace PCM. Reprogram PCM using required equipment. After repairs, go to step 14).
14. Review and record scan tool FAIL RECORDS data. Clear DTCs. Operate vehicle within fail records conditions as recorded. Using scan tool monitor SPECIFIC DTC P0341. Run engine until DTC test runs. If scan tool indicates DTC P0341 failed this ignition, go to step 2). If not, repair is complete.

Check for poor connection at PCM. Check for damaged wiring harness or incorrect routing. Check if ignition coil is arcing to wiring harness or ICM. An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

A linear Exhaust Gas Recirculation (EGR) valve is used on this system. Powertrain Control Module (PCM) commands EGR valve to operate when necessary by controlling a ground signal through PCM.

1. Engine speed is 800-1500 RPM.
2. Engine coolant temperature is greater than 176°F (80°C).
3. Barometric Pressure (BARO) is greater than 65 kPa.
4. Manifold Absolute Pressure (MAP) changes monitored during EGR flow test indicated insufficient EGR flow.
5. Idle Air Control (IAC) has not changed greater than 4 counts.
6. TP angle is less than one percent.
7. Vehicle speed is greater than 30 MPH.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Check exhaust system for modification of original parts. Also, check for exhaust leaks. Repair as necessary. After repair is completed, go to step 5). If exhaust is okay, go to next step.
3. Remove EGR valve. Inspect EGR valve pintle, valve passages and adapter for excessive deposits or restrictions. Repair as necessary. After repair is completed, go to step 5). If no problems are found, go to next step.
4. Remove EGR inlet and outlet pipes from exhaust manifold and intake manifold. Inspect manifold EGR ports and EGR pipes for blockage. Repair as necessary. After repair is completed, go to next step. If no problems are found, see DIAGNOSTIC AIDS.
5. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Ensure engine is at normal operating temperature. Monitor EGR TEST COUNT display while operating vehicle as specified. See DIAGNOSTIC AIDS. Continue operating vehicle EGR TEST COUNT until 9-12 test samples have been taken. Select SPECIFIC DTC function then enter DTC P0401. If scan tool indicates TEST RAN AND PASSED, repair is completed. If scan tool does not indicate TEST RAN AND PASSED, go to step 2).

To verify a repair, clear info with scan tool and run EGR flow test. See the following

1. PCM will only run EGR flow test during a gradual deceleration.
2. PCM will only run EGR test during a closed throttle condition.
3. PCM will only run EGR test with vehicle speed at greater than 30 MPH.
4. Several deceleration cycles will be necessary to run a sufficient number of EGR low test samples (9-12).
5. EGR TEST COUNTER display on scan tool can be useful in determining if EGR flow test is running and to keep track of number of test samples taken. Counter will increment each time a test sample is taken.

An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0401 Schematic. Scheme 32

A 3-Way catalytic converter is used to maintain low emissions. The PCM monitors exhaust gasses from converter using Heated Oxygen Sensor (HO2S). HO2S is located in exhaust stream past the 3-way catalytic converter. HO2S produces an output signal which indicates the oxygen capacity of the catalyst. This determines the catalyst's ability to convert exhaust emissions effectively.

During normal operation, HO2S signal will be less active than that produced by the front Oxygen Sensor (O2S). Powertrain Control Module (PCM) monitors catalyst efficiency. If catalyst is not operating efficiently, DTC will set.

1. Engine speed is less than 3000 RPM.
2. Coolant temperature is greater than 167°F (75°C).
3. Intake air temperature is greater than 32°F (0°C).
4. Vehicle speed is 40-75 MPH.
5. HO2S 2 voltage varies greater than 250 mV.
6. Engine load is less than 63 percent and steady.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
3. Check for catalytic converter for damage. Ensure converter is original equipment. If a problem is found, go to step 6). If no problem is found, go to next step.
4. Inspect exhaust system for leaks, damage and loose or missing hardware. Repair as necessary. After repair is completed, go to step 6).
5. Replace catalytic converter. After repair is completed, go to step 7) If exhaust system is okay, go to next step.
6. Replace catalytic converter. After repair is completed, go to next step.
7. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Review FREEZE FRAME data and note parameters. Start engine. Allow engine to warm up until engine coolant temperature monitored on scan tool is greater than 167°F (75°C). Run engine to maintain MASS AIR FLOW range at 15 gm/s for a minimum of 2 minutes. Using scan tool, monitor TWC MONITOR TEST COUNTER while operating vehicle within conditions required for setting this DTC. Continue operating vehicle until TWC MONITOR TEST COUNTER reaches 49 and return to zero 2 times. Select SPECIFIC DTC function then enter DTC which was set. If scan tool indicates TEST RAN AND PASSED, repair is complete. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0440 - EVAP SYSTEM

Note. For circuit reference, see the appropriate WIRING DIAGRAMS article.

Evaporative leak detection strategy is based on applying vacuum to EVAP system and monitoring vacuum decay. Powertrain Control Module (PCM) monitors vacuum level by means of fuel tank vacuum sensor input. At a predetermined time, EVAP purge solenoid and EVAP vent solenoid are turned on. This allows engine vacuum to draw a small vacuum on entire EVAP system. Whenever a sufficient vacuum level cannot be achieved, a large leak or faulty EVAP purge solenoid is indicated.

Conditions for setting this DTC are as follows

1. No TP sensor, ODM, IAT sensor, or MAP sensor DTCs present.
2. Start-up ECT between 40-86°F (4-30°C).
3. Start-up ECT is not greater than 14°F (8°C) greater than start-up IAT.
4. Start-up IAT is not greater than 4°F (2°C) of start-up ECT.
5. Fuel tank level is 15-85 percent.
6. BARO is greater than 75 kPa.
7. Vehicle has been driven at least 11 miles.
8. EVAP system is unable to achieve or maintain vacuum during diagnostic test.

1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 3.1L»(ref-20651) article. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Check if «DTC P1655 - EVAP PURGE SOLENOID CONTROL CIRCUIT»(/chevrolet/monte-carlo/v-1994-1999/remont/testing-diagnostics/#engine-controls-tests-wcodes-31l-engine__dtc-p1655-evap-purge-solenoid) is also set. If any of DTC(s) is present, diagnose affected DTC(s). If DTC(s) are not present, go to next step.
3. Turn ignition off. Remove fuel filler cap. Turn ignition on. Using scan tool, observe fuel tank pressure. If fuel tank pressure is zero in. H2O, go to next step. If fuel tank pressure in not zero in. H2O, diagnose evaporative system.
4. Replace fuel filler cap. Using scan tool, capture FAIL RECORD data for DTC P0440 and clear DTC. Command EVAP vent solenoid on. Connect EVAP Pressure/Purge Diagnostic Station (J 41413) to EVAP service port. Pressurize EVAP system using diagnostic station. Monitor pressure on EVAP pressure gauge on diagnostic station. If pressure is 5 in. H2O, go to next step. If not, go to step 6).
5. Maintain EVAP pressure at 5 in. H2O. Observe fuel tank pressure on scan tool. If fuel tank pressure reading on scan tool is 5 in. H2O, go to step 8). If not, go to next step.
6. Disconnect fuel tank vapor line and EVAP purge line from EVAP canister. Block canister fitting for fuel tank pressure line. Connect a hand-held vacuum pump to canister fitting for EVAP purge line. Ensure that EVAP vent solenoid is still commanded on. Apply vacuum to EVAP canister. If vacuum can be maintained at 5 in. Hg, go to step 11). If not, go to step 10).
7. Check for restriction in fuel tank vapor line or EVAP purge line. Repair as necessary. After repairs, go to step 16). If restriction is not found, diagnose EVAP system.
8. Disconnect vacuum source line at EVAP purge solenoid and plug vacuum source fitting on solenoid. Using scan tool's output tests function, select and activate SYSTEM PERF. Pressurize EVAP system to 5 in H2O. Observe EVAP pressure gauge on diagnostic station while removing plug from EVAP purge solenoid vacuum source fitting. If EVAP pressure decreases to zero in. H2O within 15 seconds while system performance is activated, go to next step. If not, go to step 13).
9. Install vacuum gauge on EVAP diagnostic station to vacuum source line. Start and operate engine to greater than 2000 RPM. Observe source vacuum level. If vacuum level is greater than 15 in. Hg, see DIAGNOSTIC AIDS. If vacuum level is not greater than 15 in. Hg, go to step 14).
10. Check for disconnected or damaged vent hose. Check for damaged EVAP canister. Repair as necessary. After repairs, go to step 16). If no problems were found, go to next step.
11. Check for faulty or missing fuel filler cap. Check for disconnected or leaking fuel tank vapor line. Check for disconnected or damaged EVAP purge line. If problem is found, repair as necessary. After repairs, go to step 16). If no problems were found, go to next step.
12. Using scan tool, command EVAP vent solenoid on. Continuously attempt to pressurize the EVAP system by leaving the EVAP diagnostic station control knob in the pressurized position. Using the Ultrasonic Leak Detector (J 41416), locate and repair leak in EVAP system. After repairs, go to step 16).
13. Replace EVAP purge solenoid. After replacing solenoid, go to step 16).
14. Check for carbon release into the EVAP system. Repair as necessary. After repairs, go to step 16).
15. Replace EVAP vent solenoid. After replacing solenoid, go to next step.
16. Turn ignition on. Using scan tool, command EVAP vent solenoid on. Using EVAP diagnostic station, pressurize EVAP system to 15 in. H2O. Move rotary switch in diagnostic station to HOLD and observe EVAP pressure gauge. If EVAP pressure decreases to less than 10 in. Hg within 2 minutes, repeat step 3). If EVAP pressure does not decrease, system is okay.

Check for the following

1. Cranked and punctured EVAP canister.
2. Damaged or disconnected source vacuum line, EVAP purge line, vent hose, for fuel tank vapor line.
3. Poor connection at PCM.
4. Inspect harness connectors for backed out terminals, improper mating, broken lock, damaged terminals, or poor wire connection.
5. Check for intermittent in circuit.
6. Check for kinked, pinched or plugged vacuum lines to EVAP purge or fuel tank vapor line. Also check for restrictions.
7. Faulty or damaged evaporative canister.

A vacuum switch in the purge line is used to detect when system is being purged. The normally closed switch will open when 5 in. H2O or greater is present in purge line. Powertrain Control Module (PCM) supplies a 5-volt reference to the switch to monitor if EVAP system is functioning properly. If switch is off (no purge detected) when PCM commands purge, DTC P0441 will set.

1. Engine speed is 550-5000 RPM.
2. Engine coolant temperature is less than 237°F (114°C) at engine start-up.
3. Barometric Pressure (BARO) is greater than 70 kPa.
4. Canister purge duty cycle is greater than 85 percent.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, select ENG 1 data list. Observe EVAP VACUUM SW while commanding EVAP purge solenoid on. If scan tool displays PURGE, go to next step. If scan tool does not display PURGE, go to step 4).
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within the conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0441 until DTC P0441 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Plug vacuum line between EVAP purge canister and EVAP vacuum switch. Start engine and allow it to idle. Using scan tool, observe EVAP VACUUM SW while commanding EVAP purge solenoid on. If PURGE is indicated, go to next step. If PURGE is not indicated, go to step 6).
5. Check vacuum line to EVAP canister for damage or improper connections. Repair as necessary. After repair is completed, go to step 20) If vacuum line is okay, go to step 14).
6. Turn ignition off. Install 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 is indicated, go to next step. If vacuum is not indicated, go to step 8).
7. Turn ignition off. Disconnect EVAP vacuum switch connector. Turn ignition on. Observe EVAP VACUUM SW on scan tool. If PURGE is indicated, go to step 15). If PURGE is not indicated, go to step 9).
8. Turn ignition off. Install vacuum gauge in vacuum source line to EVAP purge solenoid. Start engine and allow it to idle. If vacuum is greater than 12 in. Hg, go to step 10). If vacuum is 12 in. Hg or less, go to step 16).
9. Turn ignition off. Disconnect PCM. Turn ignition on. Check for a short to voltage in EVAP vacuum switch input circuit. Repair as necessary. After repair is completed, go to step 20) If circuit is okay, go to next step.
10. Turn ignition off. Disconnect EVAP purge solenoid connector. Connect a test light between EVAP purge solenoid harness connector terminals. Turn ignition on. Command EVAP purge solenoid on. If test light is on, go to step 17). If test light is off, go to next step.
11. Turn ignition off. Disconnect PCM connector. Connect a test light between EVAP purge solenoid harness connector terminals. Turn ignition on. Connect a jumper wire between ground and EVAP canister purge driver circuit terminal at PCM connector. If test light is on, go to next step. If test light is off, go to step 13).
12. Disconnect and inspect PCM connector for damaged pins, corrosion and loose wires. Repair as necessary. After repair is completed, go to step 20). If connector is okay, go to step 19).
13. Check for an open in purge solenoid driver circuit. Also, check for an open or short to ground in EVAP purge solenoid ignition feed circuit. Repair as necessary. After repair is completed, go to step 20).
14. Replace EVAP canister. After repair is completed, go to step 20).
15. Replace defective EVAP vacuum switch. After repair is completed, go to step 20).
16. Locate and repair cause of low on no vacuum. After repair is completed, go to step 20).
17. Check for poor connection at EVAP purge solenoid. After repair is completed, go to step 20). If connector is okay, go to next step.
18. Replace defective EVAP purge solenoid. After repair is completed, go to step 20).
19. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
20. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0441. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0441 Schematic. Scheme 33

The Idle Air Control (IAC) valve is controlled by the Powertrain Control Module (PCM). PCM uses the IAC to maintain a desired idle speed, which can vary depending on input to PCM. Scan tool reads IAC valve pintle position in counts. The higher the counts, the more air that is allowed to by-pass the throttle plate.

1. Barometer is greater than 65 kPa.
2. Vehicle speed is less than 3 MPH.
3. Engine coolant temperature is greater than 158°F (70°C).
4. TP angle is less than one percent.
5. Engine run time is greater than 2 minutes.
6. Idle speed is greater than 175 RPM less than desired RPM for more than 5 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, go to next step.
3. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 500 and then up to 1500 while monitoring ENGINE SPEED display. If engine speed remains within 50 RPM of desired RPM for each RPM command, no problem is detected at this time. See DIAGNOSTIC AIDS. If engine speed does not remain within 50 RPM of desired RPM for each RPM command, go to next step.
4. Disconnect IAC valve connector. Install IAC Node Light (J-37027) to IAC valve harness connector. Using scan tool, command RPM up to 1500, down to 500 and then up to 1500 while monitoring ENGINE SPEED display. If each node light cycles Red and Green (never off), go to step 6). If each node light does not cycle Red and Green, go to next step.
5. Check for an open, short to voltage or short to ground in IAC valve related circuits between IAC valve and PCM. Repair as necessary. After repair is completed, go to step 11). If circuits are okay, go to step 9).
6. Check for restricted air intake. Check for collapsed air intake duct, restricted air filter element or foreign objects blocking air intake system. Check for throttle body tampering (adjustment screw plug removed). Check for excessive deposits in IAC passage and on IAC pintle. Repair as necessary. After repair is completed, go to step 11). If no problem is found, go to next step.
7. Check for poor connection at IAC valve connector. Repair as necessary. After repair is completed, go to step 11). If no problem is found, go to next step.
8. Replace IAC valve. Repair as necessary. After repair is completed, go to step 11). If no problem is found, go to next step.
9. Check for poor connection at PCM valve connector. Repair as necessary. After repair is completed, go to step 11). If no problem is found, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
11. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 500 and then up to 1500 while monitoring ENGINE SPEED display. If engine speed remains within 50 RPM of desired RPM for each RPM command, repair is complete. See DIAGNOSTIC AIDS. If engine speed does not remain within 50 RPM of desired RPM for each RPM command, repeat step 2).

Inspect IAC valve connector for proper connection. Inspect throttle linkage for signs of binding or excessive wear. A slow or unstable idle may be caused by one of the following

1. Fuel system too rich or too lean.
2. Foreign material in throttle body bore or in air induction system.
3. Leaking or restricted intake manifold.
4. Excessive engine overloading.
5. Too high a viscosity engine oil.

Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0506 Schematic. Scheme 34

DTC P0507 - IAC SYSTEM RPM HIGH

Note. For circuit reference, see DTC P0506 schematic.

The Idle Air Control (IAC) valve is controlled by the Powertrain Control Module (PCM). PCM uses the IAC to maintain a desired idle speed, which varies depending on input to PCM. Scan tool reads IAC valve pintle position in counts. The higher the counts, the more air that is allowed to by-pass the throttle plate.

1. Barometer is more than 65 kPa.
2. Vehicle speed is less than 3 MPH.
3. Engine coolant temperature is more than 158°F (70°C).
4. TP angle is less than one percent.
5. Engine run time is more than 2 minutes.
6. Idle speed is more than 175 RPM less than desired RPM for more than 5 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, go to next step.
3. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 500 and then up to 1500 while monitoring ENGINE SPEED display. If engine speed remains within 50 RPM of desired RPM for each RPM command, no problem is detected at this time. See DIAGNOSTIC AIDS. If engine speed does not remain within 50 RPM of desired RPM for each RPM command, go to next step.
4. Disconnect IAC valve connector. Install IAC Node Light (J-37027) to IAC valve harness connector. Using scan tool, command RPM up to 1500, down to 500 and then up to 1500 while monitoring ENGINE SPEED display. If each node light cycles Red and Green but never off, go to step 6). If each node light does not cycle Red and Green, go to next step.
5. Check for an open, short to voltage or short to ground in IAC valve related circuits between IAC valve and PCM. Repair as necessary. After repair is completed, go to step 11). If circuits are okay, go to step 9).
6. Check for vacuum leaks. Check for binding throttle plate or throttle shaft. Check for misadjusted throttle and cruise control cables. Check PCV system operation. Repair as necessary. After repair is completed, go to step 11). If no problem is found, go to next step.
7. Check for poor connection at IAC valve connector. Repair as necessary. After repair is completed, go to step 11). If no problem is found, go to next step.
8. Replace IAC valve. Repair as necessary. After repair is completed, go to step 11). If no problem is found, go to next step.
9. Check for poor connection at PCM valve connector. Repair as necessary. After repair is completed, go to step 11). If no problem is found, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
11. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 500 and then up to 1500 while monitoring ENGINE SPEED display. If engine speed remains within 50 RPM of desired RPM for each RPM command, repair is complete. See DIAGNOSTIC AIDS. If engine speed does not remain within 50 RPM of desired RPM for each RPM command, repeat step 2).

Inspect IAC valve connector for proper connection. Inspect throttle linkage for signs of binding or excessive wear. A slow or unstable idle may be caused by one of the following

1. Fuel system too rich or too lean.
2. Foreign material in throttle body bore or in air induction system.
3. Leaking or restricted intake manifold.
4. Excessive engine overloading.
5. Too high a viscosity engine oil.

Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

Powertrain Control Module (PCM) supplies and monitors a 5-volt reference signal to A/C pressure sensor. PCM uses A/C pressure sensor signal to turn on engine cooling fans when A/C pressure is too high and to keep compressor disengaged when A/C pressure is too low. When signal is out of range for a prolonged period of time, DTC will set.

1. A/C pressure sensor signal is more than 4.94 volts with A/C on.
2. A/C pressure sensor signal is more than 3.98 volts with A/C off.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, check A/C pressure sensor voltage. If voltage is less than .1 volt, go to step 5). If voltage is .1 volt or more, go to next step.
3. If A/C pressure sensor voltage is more than 4.8 volts, go to next step. If voltage is not more than 4.8 volts, see DIAGNOSTIC AIDS.
4. Observe A/C pressure sensor voltage on scan tool, and disconnect pressure sensor connector. If voltage is about zero volts, go to step 12). If voltage is more than zero volts, so to step 11).
5. Disconnect A/C pressure sensor connector. Connect a jumper wire between signal circuit and 5-volt reference circuit terminals at A/C pressure sensor harness connector. If voltage is about 5 volts, go to step 16). If voltage is not about 5 volts, go to next step.
6. Using DVOM, measure voltage sensor ground circuit and 5-volt reference "B" circuit terminals at A/C pressure sensor harness connector. If voltage is about 5 volts, go to step 9). If voltage is not about 5 volts, go to next step.
7. Check for poor 5-volt reference "B" circuit terminal connection at PCM. If a poor connection exists, go to step 17). If connection is okay, go to next step.
8. Check for an open or faulty splice in 5-volt reference "B" circuit. If an open or faulty splice exists, go to step 18). If circuit is okay, go to next step.
9. Check for poor A/C pressure signal circuit terminal connection at PCM. If a poor connection exists, go to step 17). If connection is okay, go to next step.
10. Check for an open or short to ground in A/C pressure signal circuit between PCM and A/C pressure sensor. If an open or short to ground exists, go to step 18). If circuit is okay, go to step 20).
11. Check for short to voltage in A/C pressure signal circuit between PCM and A/C pressure sensor. If a short to voltage exists, go to step 18). If circuit is okay, go to step 20).
12. Check for short to voltage in 5-volt reference "B" circuit between PCM and A/C pressure sensor. Repair as necessary. After repair is completed, go to step 21). If circuit is okay, go to next step.
13. Check for poor A/C pressure sensor ground circuit terminal connection at PCM. If a poor connection exists, go to step 17). If connection is okay, go to next step.
14. Check for poor sensor ground circuit terminal connection at A/C pressure sensor harness connector. If a poor connection exists, go to step 17). If connection is okay, go to next step.
15. Check for an open or faulty splice in sensor ground circuit. If an open or faulty splice exists, go to step 18). If circuit is okay, go to next step. 16) Check for poor signal circuit or 5-volt reference circuit terminal connection at A/C pressure sensor harness connector. If a poor connection exists, go to next step. If connection is okay, go to step 19).
16. Repair wiring, connector or terminal as necessary. After repair is completed, go to step 21).
17. Locate and repair open or short circuit in wiring harness as necessary. After repair is completed, go to step 21).
18. Replace defective A/C pressure sensor. After repair is completed, go to step 21).
19. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
20. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, check A/C pressure sensor voltage. If voltage is .1-4.8 volts, repair is complete. If voltage is not .1-4.8 volts, repeat step 2).

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0530 Schematic. Scheme 35

Powertrain Control Module (PCM) monitors system voltage on ignition feed circuit terminal to PCM. If voltage is not within calibrated value, DTC will set.

1. System voltage is less than 10 volts or greater than 16 volts.
2. Engine speed is greater than 1300 RPM.
3. Fault is present for greater than 2 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If DTC P1635 is also set, diagnose DTC as necessary. If DTC P1635 is not set, go to next step.
3. Start engine. Raise engine speed to 1000 RPM. Using scan tool, select ENG 1 data list. Observe IGNITION 1 display. If voltage is 10-16 volts, go to next step. If voltage is not 10-16 volts, go to step 5).
4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0560. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
5. Connect DVOM between battery terminals. Raise engine speed to 1000 RPM. If voltage is 10-16 volts, go to next step. If voltage is not 10-16 volts, go to step 7).
6. Ensure DVOM is still connected between battery terminals. Turn headlights on and A/C blower motor to high speed. Raise engine speed to 2000 RPM. If voltage is 10-16 volts, go to step 8). If voltage is not 10-16 volts, go to next step.
7. Turn ignition off. Disconnect generator connector. Turn ignition on. Connect DVOM between ground and control circuit terminal at generator harness connector. Using scan tool, command GEN L TERM on. If battery voltage is present, go to step 12). If battery voltage is not present, go to step 10).
8. Compare IGNITION 1 voltage, displayed on scan tool with actual battery voltage. If voltage is about same, see DIAGNOSTIC AIDS. If voltage is not about same, go to next step.
9. Check ignition feed circuit for poor terminal connections at PCM and ignition switch connectors. Repair as necessary. After repair is completed, go to step 14). If circuit is okay, go to step 13).
10. Check for an open or short to ground in generator control circuit between PCM and generator. Repair as necessary. After repair is completed, go to step 14). If circuit is okay, go to next step.
11. Check generator control circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 14). If terminal connection is okay, go to step 13).
12. Check generator control circuit for poor terminal connection at generator. Repair as necessary. After repair is completed, go to step 14). If terminal connection is okay, check charging system and repair as necessary.
13. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
14. Start engine. Raise engine speed to 1000 RPM. Using scan tool, select ENG 1 data list. Observe IGNITION 1 display. If voltage is 10-16 volts, repair is complete. If voltage is not 10-16 volts, repeat step 2).

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0560 Schematic. Scheme 36

An Electronically Erasable Programmable Read Only (EEPROM) is used to contain the program information and calibrations required for engine, transmission and powertrain diagnostics operation. Powertrain Control Module (PCM) uses a value called a checksum for error detection of software. Checksum is a value that is equal to all numbers in software added together. PCM adds all values in the software and if that value does not equal the checksum value, a DTC will set.

Condition for setting this DTC is as follows

1. PCM detects more than 3 incorrect checksums.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0601. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
4. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

An Electronically Erasable Programmable Read Only (EEPROM) is used to contain the program information and calibrations required for engine, transmission and powertrain diagnostic operation. EEPROM program can be updated by reprogramming Powertrain Control Module (PCM).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If PCM was just replaced, go to next step. If PCM was not just replaced, go to step 4).
3. Program replacement PCM using required equipment. If DTC resets, attempt to reprogram PCM again (maximum of 3 times). If DTC still resets, go to next step. If DTC does not reset, go to step 5).
4. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
5. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0602. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
6. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Transaxle range switch is a multi-signal switch that sends a signal indicating gear selection to Powertrain Control Module (PCM). Transaxle range switch uses 4 circuits to pull PCM voltage low in various combinations to indicate each gear range. Voltage level of circuits is represented as "X (high voltage) or "O" (low voltage).

1. PCM recognizes an invalid PRNDL parameter.
2. Vehicle speed is more than 5 MPH.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Place transaxle gear selector in Park. Using scan tool, observe TRANS RANGE PABC display. Compare scan tool values with transaxle range switch valid input combination values. See GEAR SELECTOR POSITION table. In Park, if all values are as specified, go to next step. If any value is not as specified, go to step 4).
3. Observe TRANS RANGE PABC display and move gear selector through all gear selections. Compare scan tool values with transaxle range switch valid input combination values. If all values are as specified, see DIAGNOSTIC AIDS. If any value is not as specified, go to step 10).
4. If all TRANS RANGE PABC values are indicated as "X" (high voltage), go to next step. If all values are not indicated as "X", go to step 7).
5. Check if transaxle range switch is disconnected. Repair as necessary. After repair is completed, go to step 17). If switch is not disconnected, go to next step.
6. Check transaxle range switch ground circuit for an open or poor connection. Repair as necessary. After repair is completed, go to step 17). If circuit is okay, go to step 13).
7. If all TRANS RANGE PABC values are indicated as "O" (low voltage), go to next step. If all values are not indicated as "O", go to step 10).
8. Disconnect transaxle range switch connector. Observe TRANS RANGE PABC display. If all TRANS RANGE PABC values are indicated as "O" (low voltage), go to next step. If all values are not indicated as "O", go to step 14).
9. Turn ignition off. Disconnect PCM connector. Check transaxle range switch wiring for pinched wires or short to ground. Repair as necessary. After repair is completed, go to step 17). If wiring is okay, go to step 16).
10. Check for crossed wires in transaxle range switch connector. Repair as necessary. After repair is completed, go to step 17). If connector is wired properly, go to next step.
11. Turn ignition off. Disconnect transaxle range switch and PCM connectors. Turn ignition on. Check for an open, short to ground or short to voltage in circuit that caused incorrect value reading in step 3). Repair as necessary. After repair is completed, go to step 17). If no problem is found, go to next step.
12. Reconnect transaxle range switch connector. Connect a test light between positive battery terminal and circuit terminal that caused incorrect value reading in step 3). Observe and note state of test light while moving gear selector through all gears. Compare test light state in each gear selection with transaxle range switch valid input combination values. If test light is on when value should be "O" and off when value should be "X", go to step 15). If test light is not as specified, go to next step.
13. Check for poor terminal connections at transaxle range switch connectors. Repair as necessary. After repair is completed, go to step 17). If terminal connections are okay, go to next step.
14. Replace defective transaxle range switch. After repair is completed, go to step 17).
15. Disconnect and inspect PCM connector for damaged pins, corrosion and loose wires. After repair is completed, go to step 17). If terminal connections are okay, go to next step.
16. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
17. Observe TRANS RANGE PABC display and move gear selector through all gear selections. Compare scan tool values with transaxle range switch valid input combination values. If all values are as specified, repair is complete. If any value is not as specified, repeat step 2).

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0705 Schematic. Scheme 37

Transaxle Range Switch Valid Input Combination Values. Scheme 38

DTC P0706 - TRANSMISSION RANGE SWITCH PERFORMANCE

Note. For circuit and TR PABC switch status display reference, see DTC P0705 schematic.

Transaxle range switch is a multi-signal switch that sends a signal indicating gear selection to Powertrain Control Module (PCM). Transaxle range switch uses 4 circuits to pull PCM voltage low in various combinations to indicate each gear range. Voltage level of circuits is represented as "X (high voltage) or "O" (low voltage).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. If DTC P0705 is also set, go to that DTC for diagnosis. If DTC P0705 is not set, go to next step.
3. Ignition on. Place gear selector in Park. If scan tool display indicates Park or Neutral, go to next step. If not, go to step 5).
4. Place gear selector in Neutral. If scan tool display indicates Park or Neutral, see DIAGNOSTIC AIDS. If not, go to next step.
5. Observe scan tool TR P A B C display. If scan tool display indicates P=0, A=0, B=0 and C=0, go to next step. If not, go to step 8).
6. Unplug transaxle range switch 4-wire connector. If scan tool display does not changed, go to next step. If display has changes, go to step 8).
7. Ignition off. Unplug PCM. Check transaxle range switch wiring harness for damage (short to ground). Repair as necessary and go to step 12). If no repairs are required, go to step 11).
8. Attempt to adjust transaxle range switch. If scan tool transaxle input now reads Park or Neutral with transaxle gear selector in Park or Neutral, go to step 12). If not, go to next step.
9. Using appropriate wiring diagram (see WIRING DIAGRAMS article), check for improperly wired transaxle range switch. Repair as necessary and go to step 12). If no repairs are required, go to next step.
10. Replace transaxle range switch. After repairs, go to step 12).
11. Replace PCM. Reprogram PCM using required equipment. After repairs, go to step 12).
12. Clear DTCs. Monitor scan tool TR switch parameter and write down gear status while selecting each transaxle gear using gear selector. See DTC P0705 for correct TR PABC display. If display is correct, system is okay. If not, go to step 2).

DTC P0706 indicates a misadjusted Transaxle Range (TR) switch (park/neutral position switch). DO NOT drive vehicle with TR switch disconnected as idle quality may be affected. Reviewing FAIL RECORDS vehicle mileage since diagnostic last failed. This may help determine how often the condition to cause the DTC occurs. This may assist in diagnosis.

DTC P1106 - MAP SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Manifold Absolute Pressure (MAP) sensor. As manifold pressure changes, MAP sensor output voltage changes. MAP sensor output voltage should be 1.0-1.5 volts at idle and 4.5-4.8 volts at Wide Open Throttle (WOT).

Condition for setting DTC are as follows

1. Ignition on.
2. Throttle Position (TP) sensor angle less than 5 percent if engine speed is greater than 3000 RPM.
3. Throttle Position (TP) sensor angle less than 30 percent if engine speed is less than 3000 RPM.
4. MAP sensor indicates an intermittent manifold absolute pressure of greater than 90 kPa.
5. No Throttle Position (TP) sensor DTCs set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. If DTC P0108 is set, diagnose DTC as necessary. If DTC P0108 is not set, go to next step.
3. If DTC P1111, P1115 and/or P1121 is set, go to step 6). If DTC P1111, P1115 and/or P1121 is not set, go to next step.
4. Check for poor sensor ground circuit terminal connection at MAP sensor harness connector. If poor connection exists, go to step 9). If connection is okay, go to next step.
5. Check for an intermittent short to voltage in signal circuit between MAP sensor and PCM. If a short to voltage exists, go to step 10). If circuit is okay, go to step 8).
6. Check for an intermittent short to voltage in 5-volt reference "A" circuit between PCM and MAP sensor, EGR valve or TP sensor. If a short to voltage exists, go to step 10). If circuit is okay, go to next step.
7. Check for poor sensor ground circuit terminal connection at PCM. If poor connection exists, go to step 9). If connection is okay, go to next step.
8. Check for an intermittent open or a faulty splice in MAP sensor ground circuit. If a problem is found, go to step 10). If circuit is okay, see DIAGNOSTIC AIDS.
9. Repair MAP sensor ground circuit as necessary. After repair is completed, go to step 11).
10. Locate and repair intermittent open or short circuit in wiring harness. After repair is completed, go to next step.
11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1106. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1107 - MAP SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

Note. For circuit reference, see DTC P0106 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Manifold Absolute Pressure (MAP) sensor. As manifold pressure changes, MAP sensor output voltage changes. MAP sensor output voltage should be 1.0-1.5 volts at idle and 4.5-4.8 volts at Wide Open Throttle (WOT).

1. Ignition on.
2. Throttle Position (TP) sensor angle more than 5 percent with engine speed more than 1000 RPM.
3. MAP sensor indicates an intermittent manifold absolute pressure of less than 2 kPa.
4. No Throttle Position (TP) sensor DTCs set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. If DTC P0107 is set, diagnose DTC as necessary. If DTC P0107 is not set, go to next step.
3. If DTC P1122 is also set, go to step 6). If DTC P1122 is not set, go to next step.
4. Check for poor 5-volt reference "A" circuit or MAP signal circuit terminal connection at MAP sensor harness connector. If poor connection exists, go to step 9). If connection is okay, go to next step.
5. Check for an intermittent open or short to ground in signal circuit between MAP sensor and PCM. If a problem is found, go to step 10). If circuit is okay, go to step 8).
6. Check for an intermittent short to ground in 5-volt reference "A" circuit between PCM and MAP sensor, EGR valve or TP sensor. If a short to ground exists, go to step 10). If circuit is okay, go to next step.
7. Check for poor 5-volt reference "A" circuit terminal connection at PCM. If poor connection exists, go to step 9). If connection is okay, go to next step.
8. Check for an intermittent open or a faulty splice in 5-volt reference "A" circuit. If a problem is found, go to step 10). If circuit is okay, see DIAGNOSTIC AIDS.
9. Repair 5-volt reference "A" circuit as necessary. After repair is completed, go to step 11).
10. Locate and repair intermittent open or short circuit in wiring harness. After repair is completed, go to next step.
11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1107. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1111 - IAT SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Intake Air Temperature (IAT) sensor. When intake air is cold, sensor resistance is high and when intake air is warm, sensor resistance low. When PCM senses an intermittently high signal voltage on IAT sensor signal circuit, DTC will set.

1. Engine run time is greater than 10 seconds.
2. Vehicle speed less than 35 MPH.
3. IAT sensor signal voltage indicates IAT air temperature is less than -38°F (-39°C).

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. If DTC P0113 is set, diagnose DTC as necessary. If DTC P0113 is not set, go to next step.
3. If DTC P1106, P1115 and/or P1121 is also set, go to step 6). If DTC P1106, P1115 and/or P1121 is not set, go to next step.
4. Check for poor sensor ground circuit terminal connection at IAT sensor harness connector. Repair as necessary. After repair is completed, go to step 10). If connection is okay, go to next step.
5. Check for poor signal circuit terminal connection at IAT sensor harness connector. Repair as necessary. After repair is completed, go to step 10). If connection is okay, go to next step.
6. Check for an intermittent open in signal circuit between PCM and IAT sensor harness connector. Repair as necessary. After repair is completed, go to step 10). If circuit is okay, go to next step.
7. Check for an intermittent short to voltage in signal circuit between IAT sensor and PCM. Repair as necessary. After repair is completed, go to step 10). If circuit is okay, go to next step.
8. Check for poor sensor ground circuit terminal connection at PCM. Repair as necessary. After repair is completed, go to step 10). If connection is okay, go to next step.
9. Check for an intermittent open circuit or faulty splice in sensor ground circuit. Repair as necessary. After repair is completed, go to next step. If circuit is okay, see DIAGNOSTIC AIDS.
10. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1111. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1112 - IAT SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

Note. For circuit reference, see DTC P0112 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Intake Air Temperature (IAT) sensor. When intake air is cold, sensor resistance is high and when intake air is warm, sensor resistance low. When PCM senses an intermittently low signal voltage on IAT sensor signal circuit, DTC will set.

1. Engine run time is more than 10 seconds.
2. Vehicle speed less is greater than 25 MPH.
3. IAT sensor signal voltage is intermittently less than .14 volt.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. If DTC P0112 is set, diagnose DTC as necessary. If DTC P0112 is not set, go to next step.
3. Check for an intermittent short to ground in signal circuit between IAT sensor and PCM. Repair as necessary. After repair is completed, go to next step. If circuit is okay, see DIAGNOSTIC AIDS.
4. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1112. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1114 - ECT SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

Note. For circuit reference, see DTC P0117 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Engine Coolant Temperature (ECT) sensor. With engine cold, sensor resistance is high and when engine is warm, sensor resistance is low. When PCM senses an ECT signal that is intermittently less than the normal operating range of the sensor, DTC will set.

1. Engine run time is more than 3 seconds.
2. ECT sensor signal voltage is intermittently less than .14 volt.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. If DTC P0117 is set, diagnose DTC as necessary. If DTC P0117 is not set, go to next step.
3. Check for an intermittent short to ground in signal circuit between ECT sensor and PCM. Repair as necessary. After repair is completed, go to next step. If circuit is okay, see DIAGNOSTIC AIDS.
4. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1114. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1115 - ECT SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE

Note. For circuit reference, see DTC P0117 schematic.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Engine Coolant Temperature (ECT) sensor. With engine cold, sensor resistance is high and when engine is warm, sensor resistance is low. When PCM senses an ECT signal that is intermittently more than the normal operating range of the sensor, DTC will set.

1. Engine run time is more than 3 seconds.
2. ECT sensor signal voltage is intermittently greater than 4.8 volts.

1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. If DTC P0118 is set, diagnose DTC as necessary. If DTC P0118 is not set, go to next step.
3. If DTC P1106, P1111 and/or P1121 is also set, go to step 8). If DTC P1106, P1111 and/or P1121 is not set, go to next step.
4. Check for poor sensor ground circuit terminal connection at ECT sensor harness connector. Repair as necessary. After repair is completed, go to step 10). If connection is okay, go to next step.
5. Check for poor ECT signal circuit terminal connection at ECT sensor harness connector. Repair as necessary. After repair is completed, go to step 10). If connection is okay, go to next step.
6. Check for an intermittent open in ECT signal circuit between ECT sensor and PCM. Repair as necessary. After repair is completed, go to step 10). If circuit is okay, go to next step.
7. Check for an intermittent short to voltage in ECT signal circuit between ECT sensor and PCM. Repair as necessary. After repair is completed, go to step 10). If circuit is okay, go to next step.
8. Check for poor sensor ground circuit terminal connection at PCM. Repair as necessary. After repair is completed, go to step 10). If circuit is okay, go to next step.
9. Check for an intermittent open or a faulty splice in sensor ground circuit. Repair as necessary. After repair is completed, go to next step. If circuit is okay, see DIAGNOSTIC AIDS.
10. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1115. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs. 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.

Powertrain Control Module (PCM) supplies a 5-volt reference signal and a ground circuit to Throttle Position (TP) sensor. TP sensor signal voltage should be about .5 volt at idle and 4.5 volts or greater at wide open throttle.

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

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. If DTC P0123 is set, diagnose DTC as necessary. If DTC P0123 is not set, go to next step.
3. If DTC P1106, P1111 and/or P1115 is also set, go to step 6). If DTC P1106, P1111 and/or P1115 is not set, go to next step.
4. Check for poor sensor ground circuit terminal connection at TP sensor harness connector. If a problem is found, go to step 9). If connection is okay, go to next step.
5. Check for an intermittent short to voltage in signal circuit between TP sensor and PCM. If a problem is found, go to step 10). If circuit is okay, go to next step.
6. Check for an intermittent short to voltage in 5-volt reference "A" circuit between PCM and MAP sensor, EGR valve or TP sensor. If a problem is found, go to step 10). If circuit is okay, go to next step.
7. Check for poor sensor ground circuit terminal connection at PCM. Repair as necessary. If a problem is found, go to step 9). If connection is okay, go to next step.
8. Check for an intermittent open circuit or faulty splice in sensor ground circuit. If a problem is found, go to step 10). If circuit is okay, see DIAGNOSTIC AIDS.
9. Repair sensor ground circuit as necessary. After repair is completed, go to step 11).
10. Repair intermittent open or short circuit in wiring harness as necessary. After repair is completed, go to next step.
11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1121. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1122 - TP SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE

Note. For circuit reference, see DTC P0121 schematic.

Powertrain Control Module (PCM) supplies 5-volt reference, signal and ground circuits to Throttle Position (TP) sensor. TP sensor signal voltage should be about .5 volt at idle and 4.5 volts or greater at wide open throttle.

1. TP sensor voltage is intermittently less than .16 volt.
2. Ignition on.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. If DTC P0122 is set, diagnose DTC as necessary. If DTC P0122 is not set, go to next step.
3. If DTC P1107 is also set, go to step 6). If DTC P1107 is not set, go to next step.
4. Check for poor 5-volt reference "A" circuit or signal circuit terminal connection at TP sensor harness connector. If a problem is found, go to step 9). If connection is okay, go to next step.
5. Check for an intermittent open or short to ground in signal circuit between TP sensor and PCM. If a problem is found, go to step 10). If circuit is okay, go to next step.
6. Check for an intermittent short to ground in 5-volt reference "A" circuit between PCM and MAP sensor, EGR valve or TP sensor. If a problem is found, go to step 10). If circuit is okay, go to next step.
7. Check for poor 5-volt reference "A" circuit terminal connection at PCM. Repair as necessary. If a problem is found, go to step 9). If connection is okay, go to next step.
8. Check for an intermittent open circuit or faulty splice in 5-volt reference "A" circuit. If a problem is found, go to step 10). If circuit is okay, see DIAGNOSTIC AIDS.
9. Repair 5-volt reference circuit and/or TP signal circuit as necessary. After repair is completed, go to step 11).
10. Repair intermittent open or short circuit in wiring harness as necessary. After repair is completed, go to next step.
11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1122. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1133 - HO2S INSUFFICIENT SWITCHING SENSOR 1

Note. For circuit reference, see DTC P0131 schematic.

Powertrain Control Module (PCM) continuously monitors Heated Oxygen Sensor 1 (HO2S 1) activity for 100 seconds. During monitor period, PCM counts number of times HO2S 1 switches from rich to lean and from lean to rich. PCM then adds amount of time HO2S 1 took tolete all switches. If PCM determines HO2S 1 did not switch enough times, DTC P1133 will set.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor, MAP sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. PCM monitors less than 50 rich to lean and 50 lean to rich switches for HO2S 1.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step. NOTE: If other DTCs are present, diagnose affected DTC(s) before proceeding.
2. Start engine. Ensure engine is at normal operating temperature. Operate vehicle within the conditions required for setting this DTC. Monitor SPECIFIC DTC info for DTC P1133 until DTC P1133 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
3. Check for exhaust leaks. Repair as necessary. After repair is completed, go to step 11). If exhaust is okay, go to next step.
4. Inspect the following: Check for proper HO2S 1 installation. Check HO2S 1 connector and wiring for corrosion or damage. Check HO2S 1 ground circuit. If a problem is found, go to step 8). If no problems were found, go to next step.
5. Disconnect HO2S 1 connector. Connect a jumper wire between ground and ground circuit terminal at HO2S 1 harness connector. Turn ignition on. Using scan tool, monitor HO2S 1 voltage. If voltage is about 450 mV, go to next step. If voltage is not about 450 mV, go to step 9).
6. Connect a jumper wire between ground and signal circuit terminal at HO2S 1 harness connector. If voltage is less than 300 mV, go to next step. If voltage is 300 mV or greater, go to step 10).
7. Replace the affected oxygen sensor. After repairs, go to step 11).
8. Repair as necessary. After repair is completed, go to step 11).
9. Repair open in HO2S 1 ground circuit or short to ground in HO2S 1 signal circuit. After repair is completed, go to step 11).
10. Repair open in HO2S 1 signal circuit or faulty PCM connections. After repair is completed, go to step 11).
11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1133 until DTC P1133 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check HO2S 1 heater circuits for intermittent fault or poor connections. If connections and wiring are okay and DTC P1133 continues to set, replace HO2S 1. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1134 - HO2S TRANSITION TIME RATIO SENSOR 1

Note. For circuit reference, see DTC P0131 schematic.

Powertrain Control Module (PCM) continuously monitors Heated Oxygen Sensor 1 (HO2S 1) activity for 100 seconds. During monitor period, PCM counts number of times HO2S 1 switches from rich to lean and from lean to rich. PCM then adds amount of time HO2S 1 took to complete all switches. With this information, an average time for all switches can be determined. Whenever average time to switch is no within preset range, a DTC P0134 will set.

1. No active misfire, fuel injector circuit, TP sensor, EVAP, IAT sensor, MAP sensor, fuel trim, EGR, ECT sensor, MAF sensor or CKP sensor DTCs set.
2. HO2S 1 transition time ratio is less than .7 or greater than 2.5.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step. NOTE: If other DTCs are present, diagnose affected DTC(s) before proceeding.
2. Start engine. Ensure engine is at normal operating temperature. Operate vehicle within the conditions required for setting this DTC. Monitor SPECIFIC DTC info for DTC P1134 until DTC P1134 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
3. Check for exhaust leaks. Repair as necessary. After repair is completed, go to step 11). If exhaust is okay, go to next step.
4. Inspect the following: Check for proper HO2S 1 installation. Check HO2S 1 connector and wiring for corrosion or damage. Check HO2S 1 ground circuit. If a problem is found, go to step 7). If no problem is found, go to next step.
5. Disconnect HO2S 1 connector. Connect a jumper wire between ground and ground circuit terminal at HO2S 1 harness connector. Turn ignition on. Using scan tool, monitor HO2S 1 voltage. If voltage is about 450 mV, go to next step. If voltage is not about 450 mV, go to step 8).
6. Connect a jumper wire between ground and signal circuit terminal at HO2S 1 harness connector. If voltage is less than 300 mV, go to step 10). If voltage is 300 mV or greater, go to step 9).
7. Repair as necessary. After repair is completed, go to step 11).
8. Repair open in HO2S 1 ground circuit or short to ground in HO2S 1 signal circuit. After repair is completed, go to step 11).
9. Repair open in HO2S 1 signal circuit or faulty PCM connections. After repair is completed, go to step 11).
10. Replace oxygen sensor. After repair is completed, go to next step.
11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1133 until DTC P1133 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check HO2S 1 heater circuits for intermittent fault or poor connections. If connections and wiring are okay and DTC P1134 continues to set, replace HO2S 1. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

Powertrain Control Module (PCM) controls fuel injector circuit using a General FED Driver (GFD). The GFD has the ability to detect an electrical fault on any injector ignition feed or driver circuits.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Start engine and allow it to idle. Using scan tool, monitor SPECIFIC DTC info for DTC P1200 until DTC P1200 test runs. If scan tool indicates FAILED THIS IGN, go to step 4). If scan tool does not indicate FAILED THIS IGN, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1200 until DTC P1200 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Install Injector Test Harness (J-34730-380) and Adapter Harness (J 34730-385) to injector 10-way connector. Attempt to start engine. If ALL injector test LEDs flash, go to next step. If not, go to step 6).
5. Using Fuel Injector Coil Tester (J-39021), check injector coil voltage and repair as necessary. After repairs, go to step 12).
6. If some of the injector LEDs flashed, go to step 8). If none flashed, go to next step.
7. Check injector feed circuit between fuse and 10-way connector for open or short to ground. Repair as necessary and go to step 12). If no repairs are required, go to step 9).
8. Check injector drive circuits for injectors which did not flash LED for open, short to ground, or short to voltage. Repair as necessary and go to step 12). If no repairs are required, go to step 10).
9. Check for poor terminal connections. Repair as necessary and go to step 12).
10. Check for poor terminal connections at injectors. Repair as necessary and go to step 12). If no repairs are required, go to next step.
11. Replace PCM. Reprogram PCM using required equipment. After repairs, go to step 12).
12. Review and record scan tool FAIL RECORDS data. Clear DTCs. Operate vehicle under conditions which set DTC. Monitor scan tool SPECIFIC DTC info for DTC P1200. If scan tool indicates DTC failed this ignition, go to step 2). If not, repair is complete. If driveability symptom exists, go to TESTS W/O CODES article.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1200 Schematic. Scheme 39

Ignition Control Module (ICM) sends signals that Powertrain Control Module (PCM) requires for fuel control and spark advance calculations. An open in IC circuit or a short to voltage in by-pass circuit at engine start-up will cause PCM to monitor IC pulses during cranking, when ICM should be grounding IC circuit. This condition will cause a DTC P1350 to set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTC P1350. Start engine and allow it to idle for 2 minutes. Check for DTCs. If DTC P1350 is set, go to next step. If DTC P1350 is not set, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure resistance between IC circuit and reference low circuit terminals at PCM connector. If resistance is less than 300 ohms, go to step 6). If resistance is 300 ohms or greater, go to next step.
4. Turn ignition off. Disconnect ICM connector. Check for an open IC circuit. Repair as necessary. After repair is completed, go to step 10). If circuit is okay, go to next step.
5. Check IC circuit terminal for poor connection at ICM. Repair as necessary. After repair is completed, go to step 10). If connection is okay, go to step 8).
6. Check IC circuit terminal for poor connection at PCM. Repair as necessary. After repair is completed, go to step 10). If connection is okay, go to next step.
7. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 10).
8. Turn ignition on. Check for a short to voltage in by-pass circuit between ICM and PCM. Repair as necessary. After repair is completed, go to step 10). If circuit is okay, go to next step.
9. Replace ICM. After repair is completed, go to next step.
10. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1350 until DTC P1350 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1350 Schematic. Scheme 40

DTC P1361 - IGNITION CONTROL CIRCUIT NOT TOGGLING

Note. For circuit reference, see DTC P1350 schematic.

Ignition Control Module (ICM) sends signals that Powertrain Control Module (PCM) requires for fuel control and spark advance calculations. A short in IC circuit or an open or short to ground in by-pass circuit at engine start-up will cause PCM to monitor no IC pulses after PCM has switched by-pass circuit on. This condition will cause a DTC P1361 to set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTC P1361. Start engine and allow it to idle for 2 minutes. Check for DTCs. If DTC P1361 is set, go to next step. If DTC P1361 is not set, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect PCM connector. With test light connected to positive battery terminal, probe by-pass circuit terminal at PCM connector. If test light is on, go to step 8). If test light is off, go to next step.
4. Turn ignition on. Connect a jumper wire between positive battery terminal and by-pass circuit terminal at PCM connector. Using a DVOM, measure resistance between IC circuit and reference low circuit terminals at PCM connector. 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 Ignition Control Module (ICM) connector. Probe IC circuit with a test light to battery voltage. If test light is on, go to step 10). If not, go to next step.
6. Check for an open in by-pass circuit. Repair as necessary. After repair is completed, go to step 15). If circuit is okay, go to next step.
7. Check by-pass circuit for poor terminal connection at ICM. Repair as necessary. After repair is completed, go to step 15). If circuit is okay, go to step 14).
8. Disconnect Ignition Control Module (ICM) connector. Turn ignition on. With test light connected to positive battery terminal, probe by-pass circuit terminal at PCM connector. If test light is on, go to step 11). If test light is off, go to step 14).
9. Turn ignition off. Disconnect ICM connector. Turn ignition on. Check for short to voltage in IC circuit. Repair as necessary. After repair is completed, go to step 15) If circuit is okay, go to step 12).
10. Locate and repair short to ground in IC circuit. After repair is completed, go to step 15).
11. Locate and repair short to ground in by-pass circuit. After repair is completed, go to step 15).
12. Check by-pass circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 15). If circuit 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. After repair is completed, go to next step.
15. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1361 until DTC P1361 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1374 - 3X REFERENCE CIRCUIT

Note. For circuit reference, see DTC P1350 schematic.

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

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to NO START DIAGNOSIS (A-3) in BASIC TESTING article.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1374 until DTC P1374 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Ignition off. Unplug ICM 14-way connector. Install an injector test light at any injector harness connector. With test light connected to ground, repeatedly touch test light to 3X reference (high) circuit terminal at ICM harness connector. If test light flashes, go to step 8). If test light does not flash, go to next step.
5. Turn ignition off. Disconnect PCM connector. Check 3X reference circuit for an open or short circuit. Repair as necessary. After repair is completed, go to step 11) If circuit is okay, go to next step.
6. Check 3X reference circuit for poor terminal connection at PCM connector. Repair as necessary. After repair is completed, go to step 11) If connection is okay, go to next step.
7. Check ICM wiring harness routing. Ensure harness is not close to high voltage components. Check if ignition coil is arcing to wiring harness or ICM. Repair as necessary. After repair is completed, go to step 11). If no problems are found, go to step 10).
8. Check for poor terminal connections at ICM connector. Repair as necessary. After repair is completed, go to step 11). If no problems are found, go to next step.
9. Replace ICM. After repair is completed, go to step 11).
10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1374 until DTC P1374 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1406 - EGR VALVE PINTLE POSITION CIRCUIT

Note. For circuit reference, see DTC P0401 schematic.

Powertrain Control Module (PCM) monitors EGR valve pintle position. If PCM detects a pintle position signal voltage that is out of normal range, or a signal voltage that is not acceptable for proper EGR system operation, DTC P1406 will set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. If any other DTCs are set, diagnose DTCs as necessary. If multiple sensor DTCs are set, check for open or shorts in circuits common to all sensors (5-volt reference and sensor ground circuits). If no other DTCs are set, go to next step.
3. Start engine and allow it to idle. Using scan tool, select EGR data list. Observe EGR ACTUAL POS display. If reading is zero percent, go to next step. If reading is greater than zero percent, go to step 11).
4. Using scan tool, select MISC TESTS. Select EGR CONTROL function. Command EGR valve open to 30, 50, 80 and 100 percent while comparing EGR DESIRED POS to EGR ACTUAL POS. If EGR DESIRED POS remain close to EGR ACTUAL POS at all commanded positions, go to next step. If EGR DESIRED POS does not remain close to EGR ACTUAL POS at all commanded positions, go to step 6).
5. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1406 until DTC P1406 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
6. Disconnect EGR valve connector. Connect DVOM between ignition feed circuit and control circuit terminals at EGR valve harness connector. Observe scan tool and command EGR valve open to 30, 50, 80 and then 100 percent. If voltage is zero volts with EGR valve at zero percent and increases to battery voltage with EGR valve at 100 percent, go to step 17). If voltage is not as specified, go to next step.
7. With test light connected to ground, probe ignition feed circuit terminal at EGR valve harness connector. If test light is on, go to step 9). If test light is off, go to next step.
8. Remove and inspect fuse for EGR valve ignition feed circuit. If fuse is blown, locate and repair short to ground in ignition feed circuit. Replace fuse. After repair is completed, go to step 31). If fuse is okay, go to step 24).
9. Turn ignition off. Disconnect PCM connector. Check for an open in EGR control circuit. Repair as necessary. After repair is completed, go to step 31). If circuit is okay, go to next step.
10. Check EGR control circuit for poor terminal connection at PCM connector. Repair as necessary. After repair is completed, go to step 31). If connection is okay, go to step 30).
11. Disconnect EGR valve connector. Using scan tool, observe EGR ACTUAL POS display. If reading is zero percent, go to step 13). If reading is greater than zero percent, go to next step.
12. Turn ignition off. Disconnect PCM connector. Turn ignition on. Measure voltage between ground and EGR pintle position circuit terminal at PCM connector. If voltage is about zero volts is present, go to step 30). If voltage is greater than zero volts, go to step 26).
13. With test light connected to ground, probe sensor ground circuit terminal at EGR valve harness connector. If test light is on, go to step 15). If test light is off, go to next step.
14. Check sensor ground circuit for poor terminal connection at PCM. Repair as necessary. If terminal connection is okay, check for an open in sensor ground circuit between PCM and EGR valve connector. Repair as necessary. After repair is completed, go to step 31). If connection is okay, go to step 30).
15. With test light connected to positive battery terminal, probe control circuit at EGR valve terminal harness connector. If test light is on, go to next step. If test light is off, go to step 27).
16. Turn ignition off. Disconnect PCM connector. Turn ignition on. With test light connected to positive battery terminal, probe control circuit terminal at PCM connector. If test light is on, go to step 28). If test light is off, go to step 30).
17. Connect DVOM between sensor ground circuit and 5-volt reference circuit terminals at EGR valve harness connector. If voltage is 5 volts, go to next step. If voltage is not 5 volts, go to step 23).
18. With test light connected to positive battery terminal, probe pintle position circuit terminal at EGR valve harness connector. If test light is on, go to step 21). If test light is off, go to next step.
19. Connect a jumper wire between 5-volt reference "A" circuit and pintle position circuit terminals at EGR valve harness connector. Using scan tool, observe EGR ACTUAL POS display. If reading is 100 percent, go to step 22). If reading is not 100 percent, go to next step.
20. Turn ignition off. Disconnect PCM connector. Check pintle position circuit for an open circuit or poor terminal connection at PCM connector. Repair as necessary. After repair is completed, go to step 31). If circuit is okay, go to step 30).
21. Turn ignition off. Disconnect PCM connector. With test light connected to positive battery terminal, probe pintle position circuit terminal at PCM connector. If test light is on, go to step 29). If test light is off, go to step 30).
22. Check for poor terminal connections at EGR valve harness connector. Repair as necessary. After repair is completed, go to step 31). If connections are okay, go to step 27).
23. Check for an open or short to ground in 5-volt reference "A" circuit. Repair as necessary. After repair is completed, go to step 31). If circuit is okay, go to step 25).
24. Locate and repair open in ignition feed circuit. After repair is completed, go to step 31).
25. Check EGR 5-volt reference "A" circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 31). If connection is okay, go to step 30).
26. Locate and repair short to voltage in pintle position circuit. After repair is completed, go to step 31).
27. Replace EGR valve. After repair is completed, go to step 31).
28. Locate and repair short to ground in EGR control circuit. After repair is completed, go to step 31).
29. Locate and repair short to ground in EGR pintle position circuit. After repair is completed, go to step 31).
30. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
31. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1406 until DTC P1406 test runs. If scan tool indicates FAILED THIS IGN, repeat step 3). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for deposits that may interfere with EGR valve pintle extending completely or cause pintle to stick. Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1441 - EVAP SYSTEM FLOW DURING NON-PURGE

Note. For circuit reference, see DTC P0440 schematic.

Evaporative Emission (EVAP) canister purge valve allows manifold vacuum to purge canister. Powertrain Control Module (PCM) supplies a ground to energize the solenoid (purge on). EVAP canister purge valve is turned on and off several times a second. The duty cycle (pulse width) is determined by engine operating conditions including load, throttle position, coolant temperature and ambient temperature. Duty cycle is calculated by PCM and the output is commanded when appropriate conditions have been met.

EVAP purge vacuum switch is a normally closed switch. EVAP purge switch will open when vacuum increases to more than 5 inches of water in purge line. PCM monitors EVAP purge vacuum switch signal to determine if EVAP system is functioning properly.

1. Barometric Pressure (BARO) is more than 70 kPa.
2. Engine coolant temperature is less than 237°F (113°C).
3. Intake air temperature is 32-158°F (0-70°C).
4. Engine speed is 550-5000 RPM.
5. EVAP purge is Pulse Width Modulated (PWM) is less than 3 percent.

1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, select ENG 1 data list. Observe EVAP VACUUM SW display. If reading indicates no purge, go to next step. If reading does not indicate closed, go to DTC P1442. Diagnose DTC as necessary.
3. Start engine and allow it to idle. Observe EVAP VACUUM SW display and command EVAP purge solenoid off. If reading indicates no purge, go to next step. If reading does not indicate no purge, go to step 5).
4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1441 until DTC P1441 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
5. Disconnect EVAP purge solenoid connector. Start engine and allow it to idle. Observe EVAP VACUUM SW display. If reading indicates no purge, go to next step. If reading does not indicate no purge, go to step 7).
6. Turn ignition off. Disconnect PCM connector. Check for short to ground in EVAP canister purge driver (control) circuit. Repair as necessary. After repair is completed, go to step 12). If circuit is okay, go to step 8).
7. Disconnect vacuum signal hose from EVAP purge vacuum switch. Connect a vacuum gauge to vacuum signal hose. Start engine and allow it to idle. If vacuum is more than 12 in. Hg, go to step 9). If vacuum is 12 in. Hg or less, go to step 11).
8. Replace PCM. Reprogram replacement PCM. After repair is completed, go to step 12).
9. Check for incorrect vacuum hose routing or switched vacuum hoses at EVAP purge solenoid. Repair as necessary. After repair is completed, go to step 12). If vacuum hoses are okay, go to next step.
10. Replace EVAP purge solenoid. Repair as necessary. After repair is completed, go to step 12).
11. Replace EVAP vacuum switch. Repair as necessary. After repair is completed, go to next step.
12. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1441 until DTC P1441 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Check for incorrect vacuum hose routing. Ensure EVAP purge solenoid vacuum hoses are not switched. Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1442 - EVAP VACUUM SWITCH CIRCUIT

Note. For circuit reference, see DTC P0441 schematic.

Evaporative Emission (EVAP) canister purge valve allows manifold vacuum to purge canister. Powertrain Control Module (PCM) supplies a ground to energize the solenoid (purge on). EVAP canister purge valve is turned on and off several times a second. The duty cycle (pulse width) is determined by engine operating conditions including load, throttle position, coolant temperature and ambient temperature. Duty cycle is calculated by PCM and the output is commanded when appropriate conditions have been met.

EVAP purge vacuum switch is a normally closed switch. EVAP purge switch will open when vacuum increases to greater than 5 in. H(2)O in purge line. PCM monitors EVAP purge vacuum switch signal to determine if EVAP system is functioning properly.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, select ENG 1 data list. Observe EVAP VACUUM SW display. If reading indicates closed, go to next step. If reading does not indicate closed, go to step 4).
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1442 until DTC P1442 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
4. Disconnect EVAP purge switch connector. Connect a jumper wire between EVAP purge switch connector terminals. Observe EVAP VACUUM SW display. If reading indicates no purge, go to step 6). If reading does not indicate no purge, go to next step.
5. Check for an open or short to ground in EVAP vacuum switch signal circuit between EVAP vacuum switch and PCM. Check for an open EVAP vacuum switch ignition feed circuit. Check for poor EVAP vacuum switch signal circuit connection at PCM. Repair as necessary. After repair is completed, go to step 9). If not problem is found, go to step 7).
6. Check for poor connection at EVAP vacuum switch connector. Repair as necessary. After repair is completed, go to step 9). If connection is okay, go to step 8).
7. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 9).
8. Replace EVAP vacuum switch. After repair is completed, go to step 9).
9. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, select ENG 1 data list. Observe EVAP VACUUM SW display. If reading indicates no purge, repair is complete. If reading does not indicate no purge, repeat step 2).

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

Stepper Motor Cruise Control (SMCC) module sends cruise status input to Powertrain Control Module (PCM) to indicate when cruise control is engaged. PCM monitors cruise status signal while commanding cruise control to be disengaged by grounding cruise inhibit circuit.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe CRUISE ENGAGED display. If reading indicates yes, go to next step. If reading does not indicate yes, go to step 5).
3. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and cruise status circuit terminal at PCM connector. If voltage is greater than 7 volts, go to next step. If voltage is 7 volts or less, go to step 9).
4. Check cruise status circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 14). If connection is okay, go to step 12).
5. Turn ignition off. Disconnect SMCC module. Turn ignition on. With test light connected to positive battery terminal, probe cruise inhibit circuit terminal at SMCC module harness connector. If test light is on, go to next step. If test light is off, go to step 7).
6. Turn ignition off. Disconnect PCM connector. Observe test light. With test light connected to positive battery terminal, probe cruise inhibit circuit terminal at PCM connector. If test light is on, go to step 13). If test light is off, go to step 12).
7. Turn ignition off. Reconnect SMCC module connector. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and cruise status circuit terminal at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 11).
8. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTC P1554. Start engine and allow it to idle for 2 minutes. Check for DTCs. If DTC P1554 is set, go to step 12). If DTC P1554 is not set, see DIAGNOSTIC AIDS.
9. Check for an open or short to ground in cruise status circuit. Repair as necessary. After repair is completed, go to step 14). If circuit is okay, go to next step.
10. Check cruise status circuit for poor connection at SMCC module harness connector. Check for an open inhibit circuit. Repair as necessary. After repair is completed, go to step 14) If circuits are okay, go to next step.
11. Replace SMCC module. After repair is completed, 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. After repair is completed, go to next step.
14. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTC P1554. Start engine and allow it to idle for 2 minutes. Check for DTCs. If DTC P1554 is set, repeat step 2). If DTC P1554 is not set, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1554 Schematic. Scheme 41

Vehicle Theft Deterrent (VTD) module produces a theft deterrent fuel enable signal when ignition is on and proper key resistor pellet is sensed by VTD module. Powertrain Control Module (PCM) monitors fuel enable signal during cranking. If PCM detects fuel enable signal is not present or incorrect, DTC P1626 will set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Ensure battery is fully charged. Attempt to start engine. If engine cranks, go to next step. If engine does not crank, see appropriate ANTI-THEFT SYSTEM article in the ACCESSORIES/SAFETY EQUIPMENT section.
3. Turn ignition off. Disconnect VTD module. Turn ignition on. Using DVOM, measure voltage between ground circuit and fuel enable circuit at VTD module harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 6).
4. Turn ignition off. Reconnect VTD module connector. Turn ignition on. Backprobing connector, measure frequency between ground and fuel enable circuit terminal at VTD module connector. If frequency is 40-60 Hz, go to next step. If frequency is not 40-60 Hz, go to step 8).
5. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTC P1626. Attempt to start engine. If engine starts and continues to run, see DIAGNOSTIC AIDS. If engine does not start or starts but does not continue to run, go to step 7).
6. Check for an open, short to ground or short to voltage in fuel enable circuit. Repair as necessary. After repair is completed, go to step 11). If circuit is okay, go to next step.
7. Check fuel enable circuit for poor terminal connection at PCM connector. Repair as necessary. After repair is completed, go to step 11). If connection is okay, go to step 9).
8. Check for poor terminal connections at VTD module connector. Repair as necessary. After repair is completed, go to step 11). If terminals are okay, go to step 10).
9. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 11).
10. Replace VTD module. After repair is completed, go to next step.
11. Using scan tool, CLEAR INFO or CLEAR DTCS function to clear DTC P1554. Using scan tool, select ENG 2 data list. Observe VTD FUEL DISABLE display. If reading indicates inactive, repair is complete. If reading does not indicate inactive, repeat step 2).

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1626 Schematic. Scheme 42

DTC P1629 - THEFT DETERRENT SYSTEM CRANKING SIGNAL MALFUNCTION

Note. For circuit reference, see DTC P1626 schematic.

Vehicle Theft Deterrent (VTD) module produces a theft deterrent fuel enable signal when ignition is on and proper key resistor pellet is sensed by VTD module. Powertrain Control Module (PCM) monitors fuel enable signal during cranking. If PCM detects fuel enable signal is not present or incorrect during cranking, DTC P1629 will set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Ensure battery is fully charged. Attempt to start engine. If engine cranks, go to next step. If engine does not crank, see appropriate ANTI-THEFT SYSTEM article in the ACCESSORIES/SAFETY EQUIPMENT section.
3. Turn ignition off. Disconnect VTD module. Turn ignition on. Using DVOM, measure voltage between ground circuit and fuel enable circuit at VTD module harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 6).
4. Turn ignition off. Reconnect VTD module connector. Turn ignition on. Backprobing connector, measure frequency between ground and fuel enable circuit terminal at VTD module connector. If frequency is 40-60 Hz, go to next step. If frequency is not 40-60 Hz, go to step 8).
5. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTC P1629. Attempt to start engine. If engine starts and continues to run, see DIAGNOSTIC AIDS. If engine does not start or starts but does not continue to run, go to step 7).
6. Check for an open, short to ground or short to voltage in fuel enable circuit. Repair as necessary. After repair is completed, go to step 11). If circuit is okay, go to next step.
7. Check fuel enable circuit for poor terminal connection at PCM connector. Repair as necessary. After repair is completed, go to step 11). If connection is okay, go to step 9).
8. Check for poor terminal connections at VTD module connector. Repair as necessary. After repair is completed, go to step 11). If terminals are okay, go to step 10).
9. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 11).
10. Replace VTD module. After repair is completed, go to next step.
11. Using scan tool, CLEAR INFO or CLEAR DTCS function to clear DTC P1554. Using scan tool, select ENG 2 data list. Observe VTD FUEL DISABLE display. If reading indicates inactive, repair is complete. If reading does not indicate inactive, repeat step 2).

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

Powertrain Control Module (PCM) monitors 5-volt reference "A" circuit. If voltage is out of tolerance, DTC P1635 will set.

1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. After performing OBD system check, go to next step.
2. Inspect PCM engine grounds. Ensure grounds are clean and tight. Repair as necessary. After repair is completed, go to step 12). If grounds are okay, go to next step.
3. Check if any other DTCs are set. If any other DTCs are set, diagnose DTCs as necessary. If multiple sensor DTCs are set, check for open or shorts in circuits common to all sensors (5-volt reference and sensor ground circuits). If no other DTCs are set, go to next step.
4. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between sensor ground circuit and 5-volt reference "A" circuit terminals at PCM connector. 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. Ensure DVOM is still connected between sensor ground circuit and 5-volt reference "A" circuit terminals at PCM connector. Observe DVOM and disconnect EGR valve connector. 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. Observe DVOM and disconnect TP sensor connector. Again, observe DVOM and disconnect MAP sensor connector. If voltage changes when one of sensors is disconnected, locate and repair short to voltage in suspect sensor signal circuit. After repair is completed, go to step 12). If voltage does not change when sensors are disconnected, go to next step.
7. Turn ignition off. Disconnect PCM connector. Turn ignition on. Check 5-volt reference "A" circuit for a short to voltage. Repair as necessary. After repair is completed, go to step 12). If circuit is okay, go to step 11).
8. Replace EGR valve. After repair is completed, go to step 12).
9. If voltage is less than 4.5 volts in step 4), go to step 10). If voltage is not less than 4.5 volts, go to step 11).
10. Turn ignition off. Disconnect PCM connector. Check for short to ground in 5-volt reference "A" circuit. Repair as necessary. After repair is completed, go to step 12). If circuit is okay, go to next step.
11. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
12. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1635 until DTC P1635 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1635 Schematic. Scheme 43

DTC P1639 - 5-VOLT REFERENCE "B" CIRCUIT

Note. For circuit reference, see DTC P1635 schematic.

Powertrain Control Module (PCM) uses 5-volt reference "B" circuit as a sensor feed to A/C pressure sensor. If voltage is out of tolerance, DTC P1639 will set.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Inspect PCM engine grounds. Ensure grounds are clean and tight. Repair as necessary. After repair is completed, go to step 12). If grounds are okay, go to next step.
3. Check if any other DTCs are set. If DTC P0530 is set, diagnose DTC as necessary. If DTC P0530 is not set, go to next step.
4. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between sensor ground circuit and 5-volt reference "B" circuit terminals at PCM connector. If voltage is more than 5.5 volts, go to next step. If voltage is 5.5 volts or less, go to step 8).
5. Ensure DVOM is still connected between sensor ground circuit and 5-volt reference "A" circuit terminals at PCM connector. Observe DVOM and disconnect A/C pressure sensor connector. If voltage is more than 5.5 volts, go to next step. If voltage is 5.5 volts or less, go to step 7).
6. Turn ignition off. Disconnect PCM connector. Turn ignition on. Check 5-volt reference "B" circuit for a short to voltage. Repair as necessary. After repair is completed, go to step 11). If circuit is okay, go to step 10).
7. Locate and repair short to voltage in A/C pressure sensor signal circuit. After repair is completed, go to step 11).
8. If voltage is less than 4.5 volts in step 4), go to step 9). If voltage is not less than 4.5 volts, go to step 10).
9. Turn ignition off. Disconnect PCM connector. Check for short to ground in 5-volt reference "B" circuit. Repair as necessary. After repair is completed, go to step 11). If circuit is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1639 until DTC P1639 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

Output Driver Modules (ODMs) are used by Powertrain Control Module (PCM) to turn on current driven devices that are needed to control various engine and transaxle functions. Each ODM can control up to 7 separate outputs by grounding the device that PCM is commanding on. ODMs can diagnose each output circuit individually. DTC P1641 indicates an improper voltage level has been detected on Malfunction Indicator Light (MIL) driver circuit.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and MIL driver circuit terminal at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
3. Set amp meter to 10-amp range. Measure current between ground and MIL driver circuit terminal at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .5-1.5 amps, go to step 11). If current is not .5-1.5 amps, go to next step.
4. Turn ignition off. Disconnect instrument cluster connector. Turn ignition on. Using DVOM, measure voltage between ground and MIL driver circuit terminal at PCM connector. 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. After repair is completed, go to step 15).
6. Remove and inspect fuse for instrument cluster indicators. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in ignition feed circuit for instrument cluster indicators. After repair is completed, go to step 15).
8. Disconnect instrument cluster connector. Turn ignition on. Measure voltage between ground and ignition feed circuit terminal at instrument cluster harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).
9. Check for an open or short to ground in MIL driver circuit. Repair as necessary. After repair is completed, go to step 15). If circuit is okay, go to next step.
10. Check MIL driver circuit and ignition feed circuit for poor terminal connection at PCM connector. Repair as necessary. After repair is completed, go to step 15). If connections are okay, check instrument cluster and repair as necessary. See appropriate INSTRUMENT PANEL article in the ACCESSORIES/SAFETY EQUIPMENT section.
11. Turn ignition off. Reconnect PCM connector. Disconnect instrument cluster connector. Turn ignition on. Connect a test light between MIL driver circuit and ignition feed circuit terminals at instrument cluster harness connector. Using scan tool, select OUTPUTS TEST function and cycle MIL on and off. If test light flashes, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
12. Check MIL driver circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 15). If connection is okay, go to step 14).
13. Locate and repair open in ignition feed circuit to instrument panel indicators. After repair is completed, go to step 15).
14. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
15. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1641 until DTC P1641 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1641 Schematic. Scheme 44

Output Driver Modules (ODMs) are used by Powertrain Control Module (PCM) to turn on current driven devices that are needed to control various engine and transaxle functions. Each ODM can control up to 7 separate outputs by grounding the device that PCM is commanding on. ODMs can diagnose each output circuit individually. DTC P1651 indicates an improper voltage level has been detected on fan 1 relay driver (control) circuit.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and fan 1 relay driver circuit terminal at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
3. Set ammeter to 10-amp range. Measure current between ground and fan 1 relay driver circuit terminal at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .5-1.5 amps, go to step 11). If current is not .5-1.5 amps, go to next step.
4. Ignition off. Disconnect fan 1 relay connector. Ignition on. Using DVOM, measure voltage between ground and fan 1 relay driver circuit at fan 1 relay harness connector. 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. After repair is completed, go to step 16).
6. Remove and inspect fuse for fan 1 relay. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in ignition feed circuit for fan 1 relay. Replace fuse. After repair is completed, go to step 16).
8. Disconnect fan 1 relay. Turn ignition on. Measure voltage between ground and ignition feed circuit terminal at fan 1 relay harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).
9. Check for an open or short to ground in fan 1 relay driver circuit. Repair as necessary. After repair is completed, go to step 16). If circuit is okay, go to next step.
10. Check fan 1 relay driver circuit and ignition feed circuit for poor terminal connection at fan 1 relay connector and at PCM connector. Repair as necessary. After repair is completed, go to step 16). If connections are okay, go to step 14).
11. Turn ignition off. Reconnect PCM connector. Disconnect fan 1 relay connector. Turn ignition on. Connect a test light between fan 1 relay driver circuit and ignition feed circuit terminals at fan 1 relay harness connector. Using scan tool, select OUTPUTS TEST function and cycle fan 1 relay on and off. If test light flashes, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
12. Check fan 1 relay driver circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 16). If connection is okay, go to step 15).
13. Locate and repair open in ignition feed circuit to fan 1 relay. After repair is completed, go to step 16).
14. Replace fan 1 relay. After repair is completed, 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, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1651 until DTC P1651 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1651 Schematic. Scheme 45

DTC P1652 - FAN 2 RELAY CONTROL CIRCUIT

Note. For circuit reference, see DTC P1651 schematic.

Output Driver Modules (ODMs) are used by Powertrain Control Module (PCM) to turn on current driven devices that are needed to control various engine and transaxle functions. Each ODM can control up to 7 separate outputs by grounding the device that PCM is commanding on. ODMs can diagnose each output circuit individually. DTC P1652 indicates an improper voltage level has been detected on fan 2 relay driver (control) circuit.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and fan 2 relay driver circuit terminal at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
3. Set ammeter to 10-amp range. Measure current between ground and fan 2 relay driver circuit terminal at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .5-1.5 amps, go to step 11). If current is not .5-1.5 amps, go to next step.
4. Ignition off. Disconnect fan 2 relay connector. Ignition on. Using DVOM, measure voltage between ground and fan 2 relay driver circuit at fan 2 relay harness connector. 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. After repair is completed, go to step 16).
6. Remove and inspect fuse for fan 2 relay. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in ignition feed circuit for fan 2 relay. Replace fuse. After repair is completed, go to step 16).
8. Disconnect fan 2 relay. Turn ignition on. Measure voltage between ground and ignition feed circuit terminal at fan 2 relay harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).
9. Check for an open or short to ground in fan 2 relay driver circuit. Repair as necessary. After repair is completed, go to step 16). If circuit is okay, go to next step.
10. Check fan 2 relay driver circuit and ignition feed circuit for poor terminal connection at fan 2 relay connector and at PCM connector. Repair as necessary. After repair is completed, go to step 16). If connections are okay, go to step 14).
11. Turn ignition off. Reconnect PCM connector. Disconnect fan 2 relay connector. Turn ignition on. Connect a test light between fan 2 relay driver circuit and ignition feed circuit terminals at fan 2 relay harness connector. Using scan tool, select OUTPUTS TEST function and cycle fan 2 relay on and off. If test light flashes, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
12. Check fan 2 relay driver circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 16). If connection is okay, go to step 15).
13. Locate and repair open in ignition feed circuit to fan 2 relay. After repair is completed, go to step 16).
14. Replace fan 2 relay. After repair is completed, 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, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1652 until DTC P1652 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

Output Driver Modules (ODMs) are used by Powertrain Control Module (PCM) to turn on current driven devices that are needed to control various engine and transaxle functions. Each ODM can control up to 7 separate outputs by grounding the device that PCM is commanding on. ODMs can diagnose each output circuit individually. DTC P1654 indicates an improper voltage level has been detected on A/C relay driver (control) circuit.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and A/C relay driver circuit terminal at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
3. Set ammeter to 10-amp range. Measure current between ground and A/C relay driver circuit terminal at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .5-1.5 amps, go to step 11). If current is not .5-1.5 amps, go to next step.
4. Ignition off. Disconnect A/C relay connector. Ignition on. Using DVOM, measure voltage between ground and A/C relay driver circuit at A/C relay harness connector. 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 A/C relay driver circuit. After repair is completed, go to step 16).
6. Remove and inspect fuse for A/C relay. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in ignition feed circuit for A/C relay. Replace fuse. After repair is completed, go to step 16).
8. Disconnect A/C relay. Turn ignition on. Measure voltage between ground and ignition feed circuit terminal at A/C relay harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).
9. Check for an open or short to ground in A/C relay driver circuit. Repair as necessary. After repair is completed, go to step 16). If circuit is okay, go to next step.
10. Check A/C relay driver circuit and ignition feed circuit for poor terminal connection at A/C relay connector and at PCM connector. Repair as necessary. After repair is completed, go to step 16). If connections are okay, go to step 14).
11. Turn ignition off. Reconnect PCM connector. Disconnect A/C relay connector. Turn ignition on. Connect a test light between A/C relay driver circuit and ignition feed circuit terminals at A/C relay harness connector. Using scan tool, select OUTPUTS TEST function and cycle A/C relay on and off. If test light flashes, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
12. Check A/C relay driver circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 16). If connection is okay, go to step 15).
13. Locate and repair open in ignition feed circuit to A/C relay. After repair is completed, go to step 16).
14. Replace A/C relay. After repair is completed, 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, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1654 until DTC P1654 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1654 Schematic. Scheme 46

DTC P1655 - EVAP PURGE SOLENOID CONTROL CIRCUIT

Note. For circuit reference, see DTC P0441 schematic.

Output Driver Modules (ODMs) are used by Powertrain Control Module (PCM) to turn on current driven devices that are needed to control various engine and transaxle functions. Each ODM can control up to 7 separate outputs by grounding the device that PCM is commanding on. ODMs can diagnose each output circuit individually. DTC P1655 indicates an improper voltage level has been detected on EVAP canister purge solenoid driver (control) circuit.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and EVAP canister purge solenoid driver circuit terminal at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
3. Set amp meter to 10-amp range. Measure current between ground and EVAP canister purge solenoid driver circuit terminal at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .5-1.5 amps, go to step 11). If current is not .5-1.5 amps, go to next step.
4. Ignition off. Disconnect EVAP canister purge solenoid connector. Ignition on. Using DVOM, check voltage between ground and EVAP canister purge solenoid driver circuit at EVAP canister purge solenoid harness connector. 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 canister purge solenoid driver circuit. After repair is completed, go to step 16).
6. Remove and inspect fuse for EVAP canister purge solenoid. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Repair short to ground in ignition feed circuit for EVAP canister purge solenoid. Replace fuse. After repair is completed, go to step 16).
8. Disconnect EVAP canister purge solenoid. Turn ignition on. Measure voltage between ground and ignition feed circuit terminal at EVAP canister purge solenoid harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).
9. Check for an open or short to ground in EVAP canister purge solenoid driver circuit. Repair wiring as necessary. After repair is completed, go to step 16). If circuit is okay, go to next step.
10. Check EVAP canister purge solenoid driver circuit and ignition feed circuit for poor terminal connection at EVAP canister purge solenoid connector and at PCM connector. Repair as necessary. After repair is completed, go to step 16). If connections are okay, go to step 14).
11. Turn ignition off. Reconnect PCM connector. Disconnect EVAP canister purge solenoid connector. Turn ignition on. Connect a test light between EVAP canister purge solenoid driver circuit and ignition feed circuit terminals at EVAP canister purge solenoid harness connector. Using scan tool, select OUTPUTS TEST function and cycle EVAP canister purge solenoid on and off. If test light flashes, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
12. Check EVAP canister purge solenoid driver circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 16). If connection is okay, go to step 15).
13. Locate and repair open in ignition feed circuit to EVAP canister purge solenoid. After repair is completed, go to step 16).
14. Replace EVAP canister purge solenoid. After repair is completed, 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, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1655 until DTC P1655 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1662 - CRUISE CONTROL INHIBIT CIRCUIT

Note. For circuit reference, see DTC P1554 schematic.

Output Driver Modules (ODMs) are used by Powertrain Control Module (PCM) to turn on current driven devices that are needed to control various engine and transaxle functions. Each ODM can control up to 7 separate outputs by grounding the device that PCM is commanding on. ODMs can diagnose each output circuit individually. DTC P1662 indicates an improper voltage level has been detected on cruise inhibit driver (control) circuit.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and cruise inhibit driver circuit terminal at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
3. Set ammeter to 10-amp range. Measure current between ground and cruise inhibit driver circuit terminal at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .5-1.5 amps, go to step 11). If current is not .5-1.5 amps, go to next step.
4. Disconnect Stepper Motor Cruise Control (SMCC) module connector. Using DVOM, measure voltage between ground and cruise inhibit driver circuit at cruise inhibit harness connector. If voltage reading is zero volts, go to step 14). If voltage reading is greater than zero volts, go to next step.
5. Locate and repair short to voltage in cruise inhibit driver circuit. After repair is completed, go to step 16).
6. Remove and inspect fuse for Stepper Motor Cruise Control (SMCC) module. If fuse is blown, go to next step. If fuse is okay, go to step 8).
7. Locate and repair short to ground in ignition feed circuit for SMCC module. Replace fuse. After repair is completed, go to step 16).
8. Disconnect SMCC module. Turn ignition on. Measure voltage between ground and ignition feed circuit terminal at SMCC module harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).
9. Check for an open or short to ground in cruise inhibit driver circuit. Repair as necessary. After repair is completed, go to step 16). If circuit is okay, go to next step.
10. Check cruise inhibit driver circuit and ignition feed circuit for poor terminal connection at SMCC module connector and at PCM connector. Repair as necessary. After repair is completed, go to step 16). If connections are okay, go to step 14).
11. Turn ignition off. Reconnect PCM connector. Disconnect SMCC module connector. Turn ignition on. Connect a test light between cruise inhibit driver circuit and ignition feed circuit terminals at SMCC module harness connector. Using scan tool, select OUTPUTS TEST function and cycle cruise inhibit on and off. If test light flashes, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
12. Check cruise inhibit driver circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 16). If connection is okay, go to step 15).
13. Locate and repair open in ignition feed circuit to SMCC module. After repair is completed, go to step 16).
14. Replace SMCC module. After repair is completed, go to step 16).
15. Replace PCM. Program replacement PCM using required equipment. After repair, go to next step.
16. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1655 until DTC P1655 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

Generator light is powered through IGN 1 fuse. Powertrain Control Module (PCM) turns on bulb, LED or driver info center indicator by supplying ground circuit.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Perform a function system check of all instrument cluster gauges and warning light indicators. If generator light is on, go to next step. If system is not functioning properly (gauges or warning lights inoperative), repair as necessary. See appropriate INSTRUMENT PANEL article in the ACCESSORIES/SAFETY EQUIPMENT section.
3. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and generator light control circuit terminal at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 7).
4. Set ammeter to 10-amp range. Measure current between ground and generator light control circuit terminal at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .5-1.5 amps, go to step 12). If current is not .5-1.5 amps, go to next step.
5. Disconnect instrument panel cluster connector. Using DVOM, check voltage between ground and generator control circuit at instrument cluster connector. If voltage reading is zero volts, go to step 15). If voltage reading is greater than zero volts, go to next step.
6. Locate and repair short to voltage in generator light control circuit. After repair is completed, go to step 3).
7. Remove and inspect fuse for generator light control circuit. If fuse is blown, go to next step. If fuse is okay, go to step 9).
8. Locate and repair short to ground in ignition feed circuit for instrument cluster indicator lights. Replace fuse. After repair is completed, go to step 3).
9. Disconnect instrument cluster connector. Turn ignition on. Measure voltage between ground and ignition feed circuit terminal at instrument panel cluster connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 14).
10. Check for an open or short to ground in generator light control circuit. Repair as necessary. After repair is completed, go to step 3). If circuit is okay, go to next step.
11. Check generator light control circuit and ignition feed circuit for poor terminal connection at instrument panel cluster connector and at PCM connector. Repair as necessary. After repair is completed, go to step 3). If connections are okay, go to step 15).
12. Turn ignition off. Reconnect PCM connector. Disconnect instrument panel cluster connector. Turn ignition on. Connect a test light between generator light control circuit and ignition feed circuit terminals at instrument cluster connector. Using scan tool, select OUTPUTS TEST function and cycle generator light on and off. If test light flashes, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
13. Check generator light control circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 3). If connection is okay, go to step 16).
14. Locate and repair open in ignition feed circuit to instrument cluster indicator lights. After repair is completed, go to step 3).
15. Replace instrument cluster. After repair is completed, go to step 3).
16. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
17. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1655 until DTC P1655 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM harness connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to set.

DTC P1663 Schematic. Scheme 47

Engine oil level switch is a float switch that grounds engine oil level switch circuit when oil level is okay. Powertrain Control Module (PCM) checks engine oil level switch circuit during engine start-up.

Note. Ensure engine oil level is not low before proceeding.

1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM connector. With test light connected to positive battery terminal, probe oil level switch signal circuit terminal at PCM connector. If test light illuminates, go to step 6). If test light does not illuminates, go to next step.
3. Turn ignition off. Reconnect PCM connector. Turn ignition on. Raise and support vehicle. Disconnect oil level switch connector. Using DVOM, measure voltage between oil level switch harness connector terminals. If battery voltage is present, go to step 7). If battery voltage is not present, go to next step.
4. Measure voltage between ground and signal circuit terminal at oil level switch harness connector. If battery voltage is present, go to step 8). If battery voltage is not present, go to next step.
5. Check for an open in oil level switch signal circuit. Repair as necessary. After repair is completed, go to step 11). If circuit is okay, see DIAGNOSTIC AIDS.
6. Check for poor terminal connections at PCM connector. Repair as necessary. After repair is completed, go to step 11). If connections are okay, go to step 10).
7. Check for poor terminal connections at PCM connector. Repair as necessary. After repair is completed, go to step 11). If connections are okay, go to step 10).
8. Locate and repair open in oil level switch ground circuit. After repair is completed, go to step 11).
9. Replace oil level switch. After repair is completed, go to step 11).
10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1672 until DTC P1672 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAIL RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P1672 Schematic. Scheme 48

See also:
• DIAGNOSTIC PROCEDURE
• HARD OR INTERMITTENT TROUBLE CODE DETERMINATION
• P0101
• P0102
• P0103
• P0107
• P0108
• P0113
• P0118
• P0122
• P0123
• P0125
• P0132
• P0133
• P0134
• P0135
• P0138
• P0140
• P0141
• P0300
• P0326
• P0327
• P0341
• P0440
• P0507
• P0706
• P1106
• P1107
• P1111
• P1112
• P1114
• P1115
• P1121
• P1122
• P1133
• P1134
• P1361
• P1374
• P1406
• P1441
• P1442
• P1629
• P1639
• P1652
• P1655
• P1662
• CLEARING DIAGNOSTIC TROUBLE CODES (DTC)
• SCAN DATA