Engine Controls - Self-Diagnostics - 3.2L & 3.5L: Diagnosis Isuzu Rodeo II

DIAGNOSTIC TROUBLE CODE DEFINITIONS

Note. Not all DTCs are relevant to all models.

If scan tool displays any DTCs that are not listed, scan tool data may be faulty. Notify scan tool manufacturer of any DTCs displayed that are not included in DTC IDENTIFICATION table.

DTC IDENTIFICATION

SELF-DIAGNOSTIC SYSTEM

Note. If PCM requires replacement, PCM must be reprogrammed using a Tech II or other OBD-II compatible scan tool and special manufacturer equipment.

Note. See PIN VOLTAGE CHARTS and WIRING DIAGRAMS articles for PCM harness connector, wire terminal and wire color identification.

Note. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm impedance unless stated otherwise in test procedure.

Diagnostic Aids

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation at PCM and Idle Air Control (IAC) DC motor. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Check for objects blocking DC motor or throttle bore. Check for sticking throttle valve. Check for objects blocking AP sensor or pedal arm with spring or excessive deposits in acceleration pedal arm or pedal.

Diagnostic Procedure

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) . After performing OBD-II system check, go to next step.
2. Check for throttle body tampering, restricted or collapsed air intake duct, restricted air filter or any foreign objects blocking air intake system. Check for any objects blocking throttle passage or throttle bore, excessive deposits in throttle passage or on throttle plate. Check for smooth movement of throttle lever. Throttle spring should not bind or have excessive play. Throttle lever should move with only 9 INCH Lbs (1.0 N.m) of force applied. Turn ignition on and ensure that throttle lever operation is smooth when accelerator pedal is depressed. Repair as necessary. If no problems were found, go to next step.
3. Check for accelerator pedal tampering or objects that may block free movement of pedal. Check for smooth accelerator pedal, and ensure that pedal arm does not have excessive free play. Repair as necessary. If no problems were found, go to next step.
4. Check for loose or poor connections at throttle body harness or Acceleration Position Sensor (APS) harness connectors. Repair any problems found as necessary. Retest system. If no problems were found, go to next step.
5. Use DVOM to check for open, short circuit to ground or voltage, or high resistance in throttle valve DC motor electrical circuit between DC motor and PCM. Check resistance of DC motor. DC motor resistance should be between 0.3 and 100 ohms. If faulty circuit or high resistance in DC motor is present, repair or replace as necessary. Retest system. If no problems were found, go to next step. NOTE: Varying APS sensor values are checked by depressing gas pedal.
6. Turn ignition on, engine off. Using scan tool, check values for all Throttle Position Sensor (TPS) and Acceleration Position Sensor (APS). At idle, APS1 should be 11-13 percent, APS2 and APS3 should be 87-88 percent, TPS1 should be 3-13 percent, and TPS2 should be 87-89 percent. At WOT, APS1 should be 85-89 percent, APS2 should be 11-15 percent, APS3 should be 32-36 percent, TPS1 should be 87-89 percent, and TPS2 should be 3-13 percent. Ensure that all sensor resistance values change smoothly as throttle position goes from closed to WOT. If problems were not found, go to next step. If any problems were found with any TPS or APS readings, go to step 10 . NOTE: Varying APS sensor values are checked by depressing gas pedal.
7. Replace throttle body. Go to step 3 .
8. Check for open circuit, short to voltage and/or ground or poor connection at PCM of following circuits: APS circuit 1. APS circuit 2. APS circuit 3. APS resistance. If problem is present, repair as necessary. Go to step 11 . If problem is not present, go to next step.
9. Replace Accelerator Position Sensor (APS).
10. Check for stored DTC's P1125, P1290, P1295 or P1299. See appropriate DTC under «DIAGNOSTIC TESTS»(ref-97343-S23284716092001050100000) . Repair as necessary. If problem is still present, go to next step.
11. Repair any opens, short to voltage, short to ground or poor connections found in any APS electrical circuits. Retest system.
12. Check for DTCs P1271, P1272, P1273, P1514, P1515, P1516 or P1523. If any DTCs are present, see appropriate DTC under «DIAGNOSTIC TESTS»(ref-97343-S23284716092001050100000) . Repair as necessary. If DTCs are not present, go to next step.
13. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

DIAGNOSTIC TESTS

Note. If Powertrain Control Module (PCM) requires replacement, PCM must be reprogrammed using Tech II or equivalent OBD-II compatible scan tool and special manufacturer equipment.

Note. To identify terminals referenced in testing, see PIN VOLTAGE CHARTS article. To identify circuits and wire colors referenced in testing, see WIRING DIAGRAMS article.

Circuit Description

Mass Air Flow (MAF) sensor measures amount of air which passes through it into engine during a given time. PCM uses MAF information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle. MAF sensor produces a frequency signal which can be monitored using a scan tool. Frequency will vary within about 4-7 grams/sec. at idle to about 25-40 grams/sec. at maximum engine load. DTC P0101 will be set if signal from MAF sensor does not match a predicted value based on throttle position and engine RPM.

Conditions for setting DTC are

1. Engine is running.
2. No Throttle Position (TP) sensor and Manifold Absolute Pressure (MAP) sensor DTCs are set.
3. No MAF frequency DTCs are set.
4. System voltage is between 11.5 and 16.0 volts.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Also, check for vacuum or PCV system leaks, incorrect PCV valve, engine oil dipstick not fully seated or engine oil filler cap loose or missing. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition off. Disconnect Mass Airflow (MAF) sensor harness connector. Connect test light between MAF sensor harness connector 12-volt signal circuit and ground circuit. Turn ignition on, with engine off. If test light does not come on, go to next step. If test light comes on, go to step 6 .
3. Turn ignition on, engine off. Using DVOM, check 12-volt signal circuit at MAF sensor harness connector for correct voltage. If voltage is not as specified, go to next step. If about 11.5-12.5 volts are present, go to step 5 .
4. Turn ignition off. Check 12-volt signal circuit for an open circuit or short to ground. Repair circuit as necessary.
5. Check MAF sensor ground circuit for an open circuit or short to voltage. Repair circuit as necessary.
6. Turn ignition off. Check MAF sensor signal circuit between PCM and MAF sensor for an open circuit or short to ground or voltage. Repair circuit as necessary. If circuit is okay, go to next step.
7. Reconnect MAF sensor connector. Connect scan tool. Place transmission in Park or Neutral and apply parking brake. Start and idle engine. Select MAF parameter on scan tool. If scan tool displays 4-7 grams/sec., go to next step. If scan tool does not display 4-7 grams/sec., go to step 9 .
8. Observe scan tool while increasing engine RPM to its upper limit. If scan tool does not display 25-40 grams/set., go to next step. If scan tool displays 25-40 grams/sec., go to step 10 .
9. Replace MAF sensor. Verify system operation.
10. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Verify system operation.

Mass Air Flow (MAF) sensor measures amount of air which passes through it into engine during a given time. The PCM uses MAF information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle. MAF sensor produces a frequency signal which can be monitored using a scan tool. Frequency will vary within about 4-7 grams/sec. at idle to about 25-40 grams/sec. at maximum engine load. DTC P0102 will be set if signal from MAF sensor is below possible range of a normally operating MAF sensor. Conditions for setting DTC are

1. Engine is running more than 500 RPM for more than 10 seconds.
2. System voltage is more than 11.5 volts.
3. MAF signal frequency is less than 1.6 grams/sec. for a total of 50 percent of last 1,000 samples monitored. Sample is taken every cylinder event.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Also, a plugged or restricted air intake can cause intermittent failure. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. With engine at idle, monitor MAF FREQUENCY parameter on scan tool. If display is less than 1.6 grams/sec., go to next step. If display is 1.6 grams/sec. or more, go to step 5 .
3. With ignition on, engine off, review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0102 FAILED THIS IGNITION, go to next step. If scan tool does not display P0102, see «DIAGNOSTIC AIDS»(ref-97343-S22182109342001050100000) .
4. Turn ignition off. Disconnect Mass Airflow (MAF) sensor harness connector. Turn ignition on. Measure voltage between ground and MAF sensor signal circuit at MAF sensor harness connector. If reading is about 5 volts, go to next step. If reading is not about 5 volts, go to step 8 .
5. Connect test light between sensor ground circuit and voltage supply circuit at MAF sensor harness connector. If test light does not come on, go to next step. If test light comes on, go to step 13 .
6. Connect test light between ground and voltage supply circuit at MAF sensor connector. If test light does not come on, go to next step. If test light comes on, go to step 12 .
7. Check for poor connection at MAF sensor. Repair as necessary and retest system. If connections are okay, go to step 11 .
8. Turn ignition off. Disconnect PCM harness connector related to MAF sensor circuit. Turn ignition on. Measure voltage between ground and MAF sensor signal terminal at PCM harness connector. If less than 4 volts are present, go to next step. If 4 volts or more are present, go to step 11 .
9. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a voltmeter, check MAF sensor signal circuit for short to voltage. Repair as necessary. Retest system.
10. Turn ignition off. Disconnect PCM harness connectors. Check MAF sensor signal circuit between MAF sensor harness connector and PCM for an open, short to ground or short to sensor ground circuit. Repair as necessary. Retest system. If circuit is okay, go to step 13 .
11. Locate and repair open in sensor ground circuit between MAF sensor harness connector and PCM. Retest system.
12. Locate and repair open in ignition feed circuit between MAF sensor harness connector and PCM. Verify repair and retest system.
13. Replace MAF sensor. Retest system. If DTC P0102 resets, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Mass Air Flow (MAF) sensor measures amount of air which passes through it into engine during a given time. The PCM uses MAF information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle. MAF sensor produces a frequency signal which can be monitored using a scan tool. Frequency will vary within about 4-7 grams/sec. at idle to about 25-40 grams/sec. at maximum engine load. DTC P0103 will be set if signal from MAF sensor is below possible range of a normally operating MAF sensor. Conditions for setting DTC are

1. Engine is running more than 500 RPM for more than 10 seconds.
2. System voltage is more than 11.5 volts
3. MAF signal frequency is more than 1.6 grams/sec. for a total of 50 percent of last 200 samples monitored. Sample is taken every cylinder event.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Also, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0103 FAILED THIS IGNITION, go to next step. If scan tool display is not as indicated, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S25147504012001050100000) .
3. Start engine and allow it to reach normal operating temperature. With engine at idle, monitor MAF FREQUENCY parameter on scan tool. If display is more than 40 grams/sec., go to next step. If display is 40 grams/sec. or less, go to step 7 .
4. Turn ignition off. Disconnect Mass Airflow (MAF) sensor harness connector. Start engine and let idle. Using scan tool, monitor MAF FREQUENCY parameter. If display is zero grams/sec., go to next step. If display is not zero grams/sec., go to step 6 .
5. Replace MAF sensor. Retest system. If DTC P0103 resets, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. If DTC P0103 does not reset, repair is complete.
6. Check MAF sensor harness for incorrect routing near high voltage components (solenoids, relays or motors). Repair as necessary. If MAF sensor harness is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
7. With engine at idle, monitor MAF FREQUENCY parameter on scan tool. Snap throttle wide open and release while observing scan tool display. If display reading was greater than 40 grams/sec., go to step 5 . If scan tool display was not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). MAP sensor signal voltage to PCM varies from less than 2 volts at idle (high vacuum) to more than 4 volts at Wide Open Throttle (low vacuum) at sea level. MAP sensor is used to determine: manifold pressure changes while linear Exhaust Gas Recirculation (EGR) flow test diagnostic is being run, see DTC P0401: EGR FLOW INSUFFICIENT , engine vacuum level for some other diagnostics and Barometric (BARO) pressure. PCM compares MAP sensor signal to a calculated MAP based on throttle position and various engine load factors. If the PCM detects a MAP signal that varies excessively more than or less than calculated value, DTC P0106 will set. Conditions for setting DTC are

1. No Throttle Position (TP) sensor DTCs are present.
2. Engine speed is steady, changing less than 100 RPM.
3. Engine speed is between 1000 and 4000 RPM.
4. Throttle position is steady, throttle angle changes less than one percent.
5. EGR flow rate is steady, changing less than 4 percent.
6. No change in brake , A/C clutch, Torque Converter Clutch, or Power Steering Pressure (PSP) switch status.
7. Above conditions are met for more than one second.
8. Actual MAP value varies more than 10 kPa.
9. MAP value must vary for a total of 10 seconds over a 20 second period of time that samples were monitored.
10. Failure must occur over two consecutive trip cycles.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. Also, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If DTC P0106 is set, go to step 4 . If DTC P0106 is not set, go to next step.
3. Check for the following conditions: Vacuum hoses disconnected, damaged or misrouted. Intake manifold leaks. Vacuum leaks at throttle body or EGR valve and/or piping. PCV valve improperly installed, damaged or missing. Repair as necessary. Retest system. If no problems are found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S01378879542001050100000) .
4. Turn ignition off. Disconnect Manifold Absolute Pressure (MAP) sensor harness connector. Turn ignition on. Observe MAP sensor parameter on scan tool. If display is about 11 kPa, go to next step. If display is not as specified, go to step 12 .
5. Connect a test light between battery positive terminal and sensor signal circuit at MAP sensor harness connector. If display on scan tool is about 105 kPa, go to next step. If display is not as specified, go to step 9 .
6. Using a fused jumper wire, connect 5-volt reference circuit and signal circuit together at MAP sensor harness connector. If display on scan tool is about 104 kPa, go to next step. If display is not as specified, go to step 8 .
7. Turn ignition off. Disconnect PCM harness connectors. Check MAP sensor ground circuit for high resistance, open or poor connection between PCM harness connector and MAP sensor harness connector. Repair as necessary. Retest system. If wire is okay, go to step 11 .
8. Turn ignition off. Check MAP sensor 5-volt reference circuit for high resistance, open or poor connection between PCM harness connector and MAP sensor harness connector. Repair as necessary. Retest system. If wire is okay, go to step 10 .
9. Turn ignition off. Disconnect PCM harness connectors. Check MAP sensor signal circuit for high resistance, open or short circuit. Repair as necessary. Retest system. If wire is okay, go to next step.
10. Check MAP sensor signal circuit for poor connection at PCM. Repair as necessary. If wire is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
11. Check for poor connection at MAP sensor. Repair as necessary. If connection is okay, replace MAP sensor. Retest system.
12. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a voltmeter, check MAP sensor signal circuit for a short to battery voltage or 5-volt reference circuit. Repair as necessary. If wire is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). MAP sensor signal voltage to PCM varies from less than 2 volts at idle (high vacuum) to more than 4 volts with ignition on, engine off or at Wide Open Throttle (low vacuum) at sea level. MAP sensor is used to determine: manifold pressure changes while linear Exhaust Gas Recirculation (EGR) flow test diagnostic is being run, see DTC P0401: EGR FLOW INSUFFICIENT , engine vacuum level for some other diagnostics and Barometric (BARO) pressure. PCM monitors MAP sensor signals for voltages outside normal range of MAP sensor. If PCM detects a MAP signal voltage that is excessively low, DTC P0107 will set. Conditions for setting DTC are

1. Throttle angle is more than one percent if engine speed is less than 1,000 RPM.
2. Throttle angle is more than 2 percent if engine speed is more than 1,000 RPM.
3. MAP sensor indicates manifold absolute pressure at or less than 11 kpa for a total of about 10 seconds over a 16 second period.
4. Ignition voltage is more than 11 volts.

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 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 all Manifold Absolute Pressure (MAP) sensor circuits are okay, check related 5-volt reference circuits. If it is determined that DTC is intermittent, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. With throttle fully closed, observe MAP sensor parameter on scan tool. If display is not as specified, go to next step. If display is 11 kPa at sea level, go to step 4 .
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0107 failed, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S12442749202001050100000) .
4. Turn ignition off. Disconnect MAP sensor harness connector. Using a fused jumper wire, connect sensor 5-volt reference circuit and sensor signal circuit together at MAP sensor harness connector. Turn ignition on. Observe MAP sensor parameter on scan tool. If display is about 5 volts and 104 kPa, replace MAP sensor. Retest system. If display is not as specified, go to next step.
5. Remove jumper wire. Connect a test light between battery positive terminal and sensor signal circuit at MAP sensor harness connector. If display on scan tool is about 5 volts and 104 kPa, go to next step. If display is not as specified, go to step 8 .
6. Turn ignition off. Disconnect PCM harness connectors. Check 5-volt reference circuit for an open or short to ground. Repair as necessary. Retest system. If wire is okay, go to next step.
7. Check 5-volt reference circuit for poor connection at PCM. Repair as necessary. If connection is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
8. Turn ignition off. Disconnect PCM harness connectors. Check MAP sensor signal circuit for an open, short to ground or short to sensor ground circuit. Repair as necessary. Retest system. If wire is okay, go to next step.
9. Check MAP sensor signal circuit for a poor connection at PCM or MAP sensor. Repair as necessary. If wire is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). MAP sensor signal voltage to PCM varies from less than 2 volts at idle (high vacuum) to more than 4 volts with key on, engine off or at wide open throttle (low vacuum). MAP sensor is used to determine: manifold pressure changes while linear Exhaust Gas Recirculation (EGR) flow test diagnostic is being run, see DTC P0401: EGR FLOW INSUFFICIENT , engine vacuum level for some other diagnostics and Barometric (BARO) pressure. . PCM monitors MAP sensor signals for voltages outside normal range of MAP sensor. If PCM detects a MAP signal voltage that is excessively high, DTC P0108 will set. Conditions for setting DTC are

1. No Throttle Position (TP) DTCs set.
2. Engine is running for more than 10 seconds.
3. Throttle position is less than 3 percent if engine speed is less than 1,000 RPM.
4. Throttle position is less than 10 percent if engine speed is more than 1,000 RPM.
5. MAP sensor indicates an intermittent manifold absolute pressure more than 80 kpa for a total of about 10 seconds over a 16 second period.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If it is determined that DTC is intermittent, performing DTC P1106 diagnostics may isolate cause of fault.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step. NOTE: If idle is rough or unstable, repair idle problem first. See TROUBLE SHOOTING - NO CODES article.
2. Start engine and allow it to reach normal operating temperature. With engine at idle, note Manifold Absolute Pressure (MAP) sensor value on scan tool. If display is more than 90 kPa, go to step 4 . If display is 90 kPa or less, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0108 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S02982927562001050100000) .
4. Turn ignition off. Disconnect MAP sensor harness connector. Turn ignition on. Note MAP sensor voltage on scan tool. If display is zero volts and 11 kPa, go to next step. If display is not zero volts and 11 kPa, go to step 6 .
5. Connect test light between battery voltage and MAP sensor ground circuit. If test light comes on, go to step 7 . If test light does not come on, go to step 9 .
6. Using a voltmeter, check MAP sensor signal circuit for a short to battery voltage or 5-volt reference circuit. Repair as necessary. If wire is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
7. Check for poor sensor ground terminal connection at MAP sensor harness connector. Repair as necessary. Retest system. If connection is okay, go to next step.
8. Check for plugged or leaking vacuum hose to MAP sensor. Repair as necessary. If vacuum supply is okay, replace MAP sensor. Retest system.
9. Check for poor MAP sensor ground terminal connection at PCM. Repair as necessary. Retest system. If connection is okay, go to next step.
10. If MAP sensor ground is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Intake Air Temperature (IAT) sensor is a thermistor which measures temperature of air entering engine. PCM applies 5 volts through a pull-up resister to IAT sensor. When intake air is cold, sensor resistance is high and PCM will monitor a high signal voltage on IAT signal circuit. If intake air is warm, sensor resistance is lower, causing PCM to monitor a lower voltage. DTC P0112 will set when PCM detects an excessively low signal voltage on IAT sensor signal circuit. Conditions for setting DTC are

1. Engine has been running more than 15 seconds.
2. Vehicle speed is more than 30 MPH.
3. IAT signal voltage indicates intake air temperature more than 298°F (148°C), about 5 volts, for a total of 12.5 seconds over a 25-second period of time.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If it is determined that DTC is intermittent, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Using scan tool, monitor Intake Air Temperature (IAT) sensor parameter. If display is not greater than 283°F (148°C), go to next step. If display is greater than 283°F (148°C), go to step 4 .
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool displays DTC P0112 FAILED THIS IGNITION, check resistance of IAT sensor at specified temperatures. See «IAT SENSOR RESISTANCE»(ref-97343-S31949362862001050100000) table. Replace IAT sensor if it does not test as specified. If DTC P0112 is not set, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S15430526392001050100000) . IAT SENSOR RESISTANCE Temperature °F (°C) Ohms -40 (-40) 100,700 -22 (-30) 52,700 5 (-15) 21,450 23 (-5) 12,300 41 (5) 7280 59 (15) 4450 77 (25) 2796 95 (35) 1802 113 (45) 1188 140 (60) 667 176 (80) 332 212 (100) 177
4. Turn ignition off. Disconnect IAT sensor harness connector. Turn ignition on. Observe IAT parameter on scan tool. If display is less than -36°F (-38°C), replace IAT sensor. Retest system. If display is not as specified, go to next step.
5. Turn ignition off. Disconnect PCM harness connectors. Check IAT sensor signal circuit for short to ground. Repair as necessary. If wire is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Intake Air Temperature (IAT) sensor is a thermistor which measures temperature of air entering engine. PCM applies 5 volts through a pull-up resister to IAT sensor. When intake air is cold, sensor resistance is high and PCM will monitor a high signal voltage on IAT signal circuit. If intake air is warm, sensor resistance is lower, causing PCM to monitor a lower voltage. DTC P0113 will set when PCM detects an excessively high signal voltage on IAT sensor signal circuit. Conditions for setting DTC are

1. Engine has been running for over 30 seconds.
2. Vehicle speed is less than 20 MPH.
3. Engine Coolant Temperature (ECT) signal temperature is more than 140°F (60°C).
4. Mass air flow is less than 20 grams/sec.
5. IAT signal voltage indicates an intake air temperature less than -38°F (-39°C) for a total of 12.5 seconds over a 25-second period.

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 same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If it is determined that DTC is intermittent, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Using scan tool, monitor Intake Air Temperature (IAT) sensor parameter. If display is less than -36°F (-38°C), go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0113 FAILED THIS IGNITION, check resistance of IAT sensor at specified temperatures. See «IAT SENSOR RESISTANCE»(ref-97343-S31949362862001050100000) table in DTC P0112 test. Replace IAT sensor as necessary. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S34033411032001050100000) .
4. Turn ignition off. Disconnect IAT sensor harness connector. Connect fused jumper wire between IAT sensor harness connector terminals. Turn ignition on. Observe IAT sensor parameter on scan tool. If display is 284°F (140°C), go to step 6 . If display is not as specified, go to next step.
5. Connect jumper wire between IAT sensor signal circuit and ground. If display on scan tool is 284°F (140°C), go to step 7 . If display is not 284°F (140°C), go to step 8 .
6. Check for poor connections at IAT sensor harness connector. Repair as necessary. If connections are okay, replace IAT sensor. Retest system.
7. Turn ignition off. Disconnect PCM harness connectors. Check IAT sensor ground circuit for an open. Repair as necessary. Retest system. If wire is okay, go to step 9 .
8. Turn ignition off. Disconnect PCM harness connector. Check IAT sensor signal circuit for an open. Repair as necessary. Retest system. If wire is okay, go to next step.
9. Check for a poor IAT sensor ground circuit or signal circuit connection at PCM. Repair as necessary. If wires are okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Engine Coolant Temperature (ECT) sensor is a thermistor mounted on a coolant crossover pipe at front of engine. PCM applies about 5 volts through a pull-up resister to ECT signal circuit. When engine coolant is cold, sensor (thermistor) resistance is high and PCM will monitor a high signal voltage. As engine coolant warms, sensor resistance becomes less, engine coolant temperature measured at PCM drops. With a fully warmed-up engine, ECT signal voltage should measure about 1.5- 2.0 volts. Conditions for setting DTC are

1. Engine running time is more than 120 seconds.
2. ECT sensor signal indicates an engine coolant temperature more than 302°F (150°C), about 0.10 volts, for a total of 50 seconds over a 100-second period.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault.

If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set. If it is determined that DTC is intermittent, performing DTC P1114 diagnostics may isolate cause of fault.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Using scan tool, select ENG COOL TEMP. If display is less than 282°F (139°C), go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0117 FAILED THIS IGNITION, check resistance of Engine Coolant Temperature (ECT) sensor at specified temperatures. See «ECT SENSOR RESISTANCE»(ref-97343-S20195180012001050100000) table. Replace ECT sensor as necessary. If DTC P0117 is not set, check for an intermittent problem. See TROUBLE SHOOTING - NO CODES article. ECT SENSOR RESISTANCE Temperature °F (°C) Ohms -40 (-40) 100,700 -22 (-30) 52,700 5 (-15) 21,450 23 (-5) 12,300 41 (5) 7280 59 (15) 4450 77 (25) 2796 95 (35) 1802 113 (45) 1188 140 (60) 667 176 (80) 332 212 (100) 177
4. Turn ignition off. Disconnect ECT sensor harness connector. Turn ignition on. Observe ENG COOL TEMP on scan tool. If display is -36°F (-38°C), replace ECT sensor. Retest system. If display is not as specified, go to next step.
5. Turn ignition off. Disconnect PCM harness connectors. Check ECT sensor signal circuit for short to sensor ground circuit. Repair as necessary. If wire is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Engine Coolant Temperature (ECT) sensor is a thermistor mounted on a coolant crossover pipe at front of engine. PCM applies about 5 volts through a pull-up resister to ECT signal circuit. When engine coolant is cold, sensor (thermistor) resistance is high and PCM will monitor a high signal voltage. As engine coolant warms, sensor resistance becomes less, engine coolant temperature measured at PCM drops. With a fully warmed-up engine, ECT signal voltage should measure about 1.5- 2.0 volts. Conditions for setting DTC are

1. Engine running time is more than 90 seconds.
2. ECT sensor signal indicates an engine coolant temperature of -38°F (-39°C) or less (about 5 volts) for a total of 50 seconds over a 100-second period.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set. If it is determined that DTC is intermittent, performing DTC P1115 diagnostics may isolate cause of fault.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Using scan tool, select ENG COOL TEMP. If display is less than -38°F (-39°C), go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0118 FAILED THIS IGNITION, check resistance of Engine Coolant Temperature (ECT) sensor at specified temperatures. See «ECT SENSOR RESISTANCE»(ref-97343-S20195180012001050100000) table in DTC P0117. Replace ECT sensor if it does not test as specified. If DTC P0118 is not set, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S38505956182001050100000) . See TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect ECT sensor harness connector. Using a fused jumper wire, connect terminals of ECT sensor harness connector together. Turn ignition on. Observe ENG COOL TEMP value on scan tool. If display is 284°F (140°C), go to step 6 . If display is not as specified, go to next step.
5. Connect fused jumper wire between ECT sensor harness connector signal circuit and ground. If display on scan tool is 284°F (140°C), go to step 7 . If display is not as specified, go to step 8 .
6. Check for poor connections at ECT sensor harness connector. Repair as necessary. If connections are okay, replace ECT sensor. Retest system.
7. Turn ignition off. Disconnect PCM harness connectors. Check ECT sensor ground circuit for an open. Repair as necessary. Retest system. If wire is okay, go to step 9 .
8. Turn ignition off. Disconnect PCM harness connector. Check ECT sensor signal circuit for an open. Repair as necessary. Retest system. If wire is okay, go to next step.
9. Check for a poor ECT sensor ground circuit or signal circuit connection at PCM. Repair as necessary. If wires are okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Throttle Position (TP) sensor circuit provides a voltage signal that changes relative to throttle plate angle. Signal voltage will vary from about 0.6 volts at closed throttle to about 4.5 volts at Wide Open Throttle (WOT). TP signal is used by PCM to control fuel and other PCM-controlled outputs. PCM monitors and compares actual throttle position to a predicted TP value calculated from engine speed. If PCM detects an out-of-range condition, DTC P0121 will set. Conditions for setting DTC

1. Engine is running.
2. No MAP DTCs, or P0121, P0122, P1122, P01123 are set.
3. MAP reading is less than 55 kpa.
4. Throttle is steady, throttle angle is changing less than one percent.
5. Predicted throttle angle is not close to actual throttle angle.
6. Above conditions are present for a total of 12.5 seconds over a 25 second period.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault.

Low MAP reading can cause PCM to incorrectly calculate Throttle Position (TP) sensor value. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set. If it is determined that DTC is intermittent, performing DTCs P1121 and DTC P1122 diagnostics may isolate cause of fault.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Observe MAP sensor parameter on scan tool. If display is less than 65 kPa, go to next step. If display is not as specified, go to step 6 .
3. Turn ignition off. Disconnect MAP sensor harness connector. Connect a test light between MAP sensor 5-volt reference circuit and MAP sensor signal circuit at harness connector. Turn ignition on. If display on scan tool is less than 65 kPa, replace MAP sensor. Retest system. If display is not as specified, go to next step.
4. Turn ignition off. Check for an open, short to ground or short to MAP sensor ground circuit. Repair as necessary. If wire is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
5. Observe TP sensor angle on scan tool while slowly opening throttle. If display shows a steady increase from zero percent to 100 percent, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S00796974242001050100000) . If display is not as specified, go to next step.
6. Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Observe TP sensor parameter on scan tool. If display is zero volts, go to next step. If display is not as specified, go to step 8 .
7. Turn ignition off. Connect a test light between 5-volt reference circuit (Red wire) and sensor signal circuit (Blue wire) at TP sensor harness connector. Turn ignition on. If display is 5 volts, replace TP sensor. Retest system. If display is not as specified, go to step 9 .
8. Check for the following items: TP sensor signal circuit shorted to voltage. High resistance or open in TP sensor ground circuit. Repair as necessary. If no problems are found, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
9. Check for the following items: Poor connection in TP sensor signal circuit or 5-volt reference circuit. High resistance in TP sensor 5-volt reference circuit.

Repair as necessary. If no problems are found, replace and reprogram PCM. See EEPROM PROGRAMMING PROCEDURE under PROGRAMMING. Retest system.

Throttle Position (TP) sensor circuit provides a voltage signal that changes relative to throttle plate angle. Signal voltage will vary from about 0.6 volts at closed throttle to about 4.5 volts at Wide Open Throttle (WOT). TP signal is used by PCM to control fuel and other PCM-controlled outputs. PCM monitors and compares actual throttle position to a predicted TP value calculated from engine speed. If PCM detects an out-of-range condition, DTC P0122 will set. Conditions for setting DTC

1. Ignition is on.
2. TP sensor signal voltage is less than 0.22 volts for a total of 0.78 seconds over a 1.5 second period.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault.

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

If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set. If it is determined that DTC is intermittent, performing DTC P1122 diagnostics may isolate cause of fault.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. With throttle closed, observe Throttle Position (TP) sensor parameter on scan tool. If display is less than 0.22 volt, go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If DTC P0122 is set, go to next step. If DTC P0122 is not set, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S20440057322001050100000) .
4. Turn ignition off. Disconnect TP sensor harness connector. Using a fused jumper wire, connect 5-volt reference circuit to sensor signal circuit at harness connector. Turn ignition on. Observe display on scan tool. If display is 5 volts, go to step 10 . If display is not as specified, go to next step.
5. Remove jumper wire. Connect a test light between battery positive terminal and sensor signal circuit at TP sensor harness connector. If display on scan tool is 5 volts, go to next step. If display is not as specified, go to step 8 .
6. Turn ignition off. Disconnect PCM harness connectors. Check for an open or short to ground in 5-volt reference circuit. Repair as necessary. Retest system. If wire is okay, go to next step.
7. Check 5-volt reference circuit for poor connection at PCM. Repair as necessary. If connection is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
8. Turn ignition off. Disconnect PCM harness connectors. Check TP sensor signal circuit for an open, short to ground or short to sensor ground circuit. Repair as necessary. Retest system. If wire is okay, go to next step.
9. Check TP sensor signal circuit for poor connection at PCM. Repair as necessary. If connection is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
10. Check TP sensor signal circuit for poor connection at TP sensor. Repair as necessary. If connection is okay, replace TP sensor. Retest system.

Throttle Position (TP) sensor circuit provides a voltage signal that changes relative to throttle plate angle. Signal voltage will vary from about 0.6 volts at closed throttle to about 4.5 volts at Wide Open Throttle (WOT). TP signal is used by PCM to control fuel and other PCM-controlled outputs. PCM monitors and compares actual throttle position to a predicted TP value calculated from engine speed. If PCM detects an out-of-range condition, DTC P0123 will set. Conditions for setting DTC

1. Engine is on.
2. TP sensor signal is more than 4.88 volts for a total of 0.78 seconds over a period of 1.5 second period.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault.

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

If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set. If it is determined that DTC is intermittent, performing DTC P1121 diagnostics may isolate cause of fault.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. With throttle closed, observe Throttle Position (TP) sensor parameter on scan tool. If display is more than 4.88 volts, go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If DTC P0123 is set, go to next step. If DTC P0123 is not set, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S42359291572001050100000) .
4. Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Observe display on scan tool. If display is about zero volts, go to next step. If display is not as specified, go to step 6 .
5. Using a test light connected to battery positive terminal, probe TP sensor ground circuit at harness connector. If test light comes on, go to step 7 . If test light does not come on, go to step 10 .
6. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a voltmeter, check TP sensor signal circuit for a short to power. Repair as necessary. If wire is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
7. Turn ignition on. Observe TP sensor parameter on scan tool while disconnecting each sensor which shares same 5-volt reference circuit. See WIRING DIAGRAMS article. If display changes while disconnecting a sensor, replace that sensor. Repair as necessary. If display does not change, go to next step.
8. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a voltmeter, check 5-volt reference circuit for short to battery voltage. Repair as necessary. Retest system. If wire is okay, go to next step.
9. Check for poor connection at TP sensor. Repair as necessary. If connection is okay, replace TP sensor. Retest system.
10. Turn ignition off. Disconnect PCM harness connectors. Check for open in TP sensor ground circuit. Repair as necessary. If wire is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

To provide best possible combination of driveability, fuel economy and emission control, a closed loop air/fuel metering system is used. When the vehicle is first started, PCM controls fuel delivery in open loop, ignoring Heated Oxygen Sensor (H02S) signals and calculating air/fuel mixture ratio and based on inputs from the Engine Coolant Temperature (ECT), Throttle Position (TP) and Mass Air Flow (MAF) sensors. PCM will begin using Bank 1 HO2S 1 and Bank 2 HO2S 1 signals for controlling fuel delivery under closed loop conditions when following have been met

1. HO2S output signals are varying, indicating that sensors are hot enough to operate properly.
2. ECT sensor indicates coolant temperature above 122°F (50°C).
3. Time since start-up is at least 16 seconds for a warm engine, or 23 seconds for a cold engine. Conditions for setting DTC: No active IAT or ECT DTCs are present. Engine is running. Vehicle speed is more than 5 MPH. Intake air temperature is more than 14°F (-10°C). Start-up engine coolant temperature is between 14°F (-10°C) and 82°F (28°C). For a warm engine, intake air temperature is more than 50°F (10°C), engine coolant temperature sufficient to allow closed loop operation 122°F (50°C) is not achieved within 2 minutes of start-up. For a cold engine, intake air temperature between 19.4°F and 50°F (-7°C and 10°C), engine coolant temperature sufficient to allow closed loop operation 122°F (50°C) is not achieved within 10 minutes of start-up. Above condition fails 20 consecutive times.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. If any Engine Coolant Temperature (ECT) sensor DTCs are set, see appropriate DTC in DIAGNOSTIC TESTS. If no DTCs are set, go to next step.
3. Allow engine to cool. Ensure coolant level is full. If coolant level is okay, go to next step. If coolant level is low, check cooling system for leaks. Repair as necessary. Retest system.
4. Start engine and let idle. Using scan tool, select ENG COOL TEMP. If display increases to more than 70°F (21°C) within 2 minutes, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S09043809532001050100000) . If display is not as specified, go to next step.
5. Check thermostat for proper operation. Replace thermostat if necessary. Retest system. If thermostat is okay, go to next step.
6. Using a thermometer, check temperature of coolant in radiator. Compare reading with display on scan tool. If readings are close, check for sticking thermostat or incorrect thermostat application. Repair as necessary. If display readings are not close, go to next step.
7. Turn ignition off. Disconnect PCM harness connectors. Measure resistance between ECT sensor signal circuit and ECT sensor ground circuit at PCM harness connector. Compare resistance reading with coolant temperature reading. See «ECT SENSOR RESISTANCE»(ref-97343-S20195180012001050100000) table under DTC P0117. If readings are as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system. If readings are not as specified, go to next step.
8. Check for high resistance in ECT sensor signal circuit or sensor ground circuit. Check for poor connections at PCM and ECT sensor. Repair as necessary. If ECT sensor circuit is okay, replace ECT sensor. Retest system.

Engine Coolant Temperature (ECT) sensor thermistor mounted on coolant crossover pipe at front of engine. This code determines if system has insufficient coolant temperatures for stable operation. Conditions for setting DTC

1. Engine running.
2. No Intake Air Temperature (IAT), Engine Coolant Temperature (ECT) and Mass Air Flow (MAF) DTCs set.
3. No Vehicle Speed Sensor (VSS) DTC set. Warm case: (Ambient temperature is between 50°F and 128°F.) Time for coolant to reach stabilized closed loop value is less than 239 seconds. Cold case: (Ambient temperature is between 20°F and 50°F.) Time for coolant to reach stabilized Thermostat regulation temperature is more than 263 seconds.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Visually check air duct and water pipe for splits, kinks, proper connections and routing. Repair as necessary. If no problem was found, go to next step.
3. Remove and inspect air filter for restrictions. Replace as necessary. If air filter is okay, go to next step.
4. Remove and inspect thermostat for proper operation. Replace thermostat if necessary. If no problem was found, go to next step.
5. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0128 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, go to «DIAGNOSTIC AIDS»(ref-97343-S21449465142001050100000) .
6. Observe ENG COOL TEMP on scan tool. If display is less than 282°F (139°C), go to «DIAGNOSTIC AIDS»(ref-97343-S21449465142001050100000) . If scan tool display is not as specified, go to next step.
7. Turn ignition off. Disconnect PCM harness connectors. Check ECT signal circuit for short to ground or to sensor ground circuit. Repair as necessary. Retest system. If no problem was found, go to next step.
8. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Using scan tool, observe HO2S-1 Bank 1 parameter on scan tool. If display remains less than 22 millivolts, go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0131 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S12238749252001050100000) .
4. Turn ignition off. Disconnect PCM harness connectors. Check HO2S-1 Bank-1 high and low circuits for a short to ground or short to heater ground circuit. Repair as necessary. Retest system. If wires are okay, go to next step.
5. Disconnect HO2S-1 Bank-1 harness connector. Check for continuity between high and low signal circuits at harness connector. If continuity is present, check for short between wires and repair as necessary. Retest system. If continuity is not present, go to next step.
6. Reconnect PCM, leaving sensor disconnected. Turn ignition on. If HO2S-1 Bank-1 parameter on scan tool is 425-475 millivolts, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S12238749252001050100000) . If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Using scan tool, observe HO2S-1 Bank-1 parameter. If display remains more than 952 millivolts, go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0132 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S13506297272001050100000) .
4. Turn ignition off. Disconnect HO2S-1 Bank-1 harness connector. Turn ignition on. Measure voltage of high and low signal circuits at HO2S-1 Bank-1 harness connector (PCM side). If reading is 3-4 volts at each wire, repair signal circuit for short to voltage. If reading is not as specified, go to next step.
5. Turn ignition on. Use fused jumper wires to connect both high and low signal circuits of HO2S harness connector (PCM side) to ground. If display on scan tool is less than 10 millivolts, go to next step. If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
6. Disconnect jumper wires from signal circuits. Using scan tool, observe replace HO2S-1 Bank-1 parameter. If display remains between 425 and 475 millivolts, see «DIAGNOSTIC AIDS»(ref-97343-S13506297272001050100000) . If display is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach operating temperature. Operate vehicle within conditions required to set DTC: Engine in closed loop. Engine running for at least 90 seconds. Engine RPM is 1500-3000. Canister purge duty cycle is more than 2 percent. MAF is 18-42 grams per second. All conditions present for 3 seconds or more. Rich-to-Lean transition is longer than 105 milliseconds. Lean-to-Rich transition is longer than 94 milliseconds. Using scan tool, observe SPECIFIC DTC parameter. If scan tool displays DTC P0133 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0133 FAILED THIS IGN, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S31190519652001050100000) .
3. If scan tool also displays DTC P0153, P1133, P1134, P1153 or P1154 FAILED THIS IGN, replace affected HO2S. Retest system. If scan tool does not display these DTCs, go to next step.
4. Visually inspect exhaust system for leaks near HO2S-1 Bank-1. If leaks are found, repair as necessary and return to step 2 . If no leaks are found, go to next step.
5. Visually inspect HO2S-1 Bank-1 for proper installation. Check for corrosion on terminals. Check terminal tension at HO2S-1 Bank-1 and PCM. Repair as necessary. If no problem is found, go to next step.
6. Disconnect HO2S-1 Bank-1 harness connector. Measure voltage between high signal circuit and ground, then low signal circuit and ground. If reading is 3-4 volts, go to next step. If reading is not as specified, go to step 8 .
7. Using fused jumper wires, connect high and low signal circuits of HO2S-1 Bank-1 harness connector (PCM side) to ground. Turn ignition on. Using scan tool, monitor voltage. If reading is less than 10 millivolts and immediately returns to about 450 millivolts when jumper wire is removed, replace HO2S-1 Bank-1. If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
8. Inspect PCM connections and terminals for damage. Repair as necessary. Retest system. If PCM connections and terminals are okay, go to next step.
9. Repair open, short or grounded HO2S-1 Bank-1 high or low signal circuits. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Apply parking brake and increase engine speed to more than 1200 RPM for 2 minutes. Using scan tool, observe HO2S-1 Bank-1 parameter. If reading varies outside 400-500 millivolts range, turn engine off and go to next step. If reading does not vary outside 400-500 millivolts range, go to step 4 .
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0134 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S15518398042001050100000) .
4. Inspect sensor harness for damage. Repair as necessary. If harness is okay, go to next step.
5. Check for poor high and low signal circuit connections at HO2S-1 Bank-1 harness connector. Repair as necessary. Retest system. If connection is okay, go to next step.
6. Check for poor HO2S-1 Bank-1 high and low signal circuit connections at PCM harness connectors. Repair as necessary. Retest system. If connections are okay, go to next step.
7. Turn ignition off. Disconnect PCM connectors. Measure resistance of HO2S-1 Bank-1 high signal circuit between PCM and HO2S. If resistance is more than 5 ohms, repair open circuit or poor connection. Retest system. If wire is okay, go to next step.
8. Measure resistance of HO2S-1 Bank-1 low signal circuit between PCM and HO2S. If resistance is greater than 5 ohms, repair open or poor connection. Retest system. If wire is okay, reconnect PCM connectors and go to next step.
9. Disconnect HO2S-1 Bank-1 connector. Turn ignition on. Using fused jumper wires, connect high and low signal circuits to ground. If scan tool display is 0-10 millivolts, replace HO2S-1 Bank-1. If display is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Allow engine to cool. Disconnect fuel pump relay. Connect fused jumper between fuel pump relay socket positive battery terminal and relay wire that goes to fuel pump and HO2S fuses. Turn ignition off. Install scan tool. Turn ignition on. Observe HO2S-1 Bank-1 parameter on scan tool for several minutes. If display is more than 650 millivolts or less than 250 millivolts, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S15518398042001050100000) . If display is not as specified, go to next step.
3. Inspect O2 SENS HEATER (20-amp) fuse in engine compartment fuse box. If fuse is blown, locate and repair short in HO2S ignition feed circuit and replace fuse. Retest system. If fuse is okay, go to next step.
4. Turn ignition off. Raise and support vehicle. Disconnect HO2S-1 Bank-1 harness connector. Turn ignition on. Using a test light connected to ground, probe HO2S-1 Bank-1 ignition feed circuit at connector (PCM side). If test light comes on, go to next step. If test light does not come on, go to step 7 .
5. Connect test light between HO2S-1 Bank-1 ignition feed circuit and HO2S-1 Bank-1 heater ground circuit at harness connector (PCM side). If test light comes on, go to next step. If test light does not come on, go to step 8 .
6. Turn ignition off. Ensure HO2S-1 Bank-1 is cool. Measure resistance between HO2S-1 Bank-1 heater ignition feed circuit and heater ground circuit at HO2S-1 Bank-1 harness connector (sensor side). If resistance is 3-6 ohms, go to step 9 . If resistance is not as specified, go to step 10 .
7. Repair open in HO2S-1 Bank-1 ignition feed circuit. Retest system.
8. Repair open in HO2S-1 Bank-1 ground circuit. Retest system.
9. Check for poor connection at HO2S-1 Bank-1 harness connector terminals. Repair as necessary. Retest system. If harness connector is okay, go to next step.
10. Check for poor connection at HO2S-1 Bank-1 high or low circuit terminal connections at harness connector. Repair as necessary. Retest system. If connections are okay, go to next step.
11. Turn ignition off. Disconnect PCM connector. Measure resistance of HO2S-1 Bank-1 high and low signal circuits between PCM harness connector and HO2S-1 Bank-1 harness connector. If either circuit resistance is more than 5 ohms, repair open circuit or poor connection. Repair as necessary. If wires are okay, go to next step.
12. Check for poor HO2S-1 Bank-1 terminal connections at PCM. Repair as necessary. If connections are okay, replace HO2S-1 Bank-1. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Observe HO2S-2 Bank-1 parameter on scan tool. If display remains less than 22 millivolts, go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0137 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S25888398912001050100000) .
4. Turn ignition off. Disconnect PCM connectors. Check HO2S-2 Bank-1 high and low signal circuits for a short to ground or short to heater ground circuit. Repair as necessary. Retest system. If wires are okay, go to next step.
5. Disconnect HO2S-2 Bank-1 harness connector. Check for continuity of high and low signal circuits between PCM harness connector and HO2S-2 Bank-1 harness connector. If continuity is present, check for short between wires and repair as necessary. Retest system. If continuity is not present, go to next step.
6. Reconnect PCM harness connectors, leaving HO2S disconnected. Turn ignition on. If HO2S-2 Bank-1 parameter on scan tool is about 425-475 millivolts, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S25888398912001050100000) . If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle under following conditions: Ensure that no other related DTCs are stored. Closed loop commanded air/fuel ratio is between 14.5 and 14.8. ECT is above 140°F (60°C). TP sensor angle is between 3 and 19 percent. Observe HO2S-2 Bank-1 parameter on scan tool. If display remains more than 952 millivolts during normal closed loop operation for a total of 106 seconds over a 125 second period, go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0138 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S19319035372001050100000) .
4. Turn ignition off. Disconnect HO2S-2 Bank-1. Turn ignition on. Measure voltage at high and low signal circuits at HO2S-2 harness connector (PCM side). If reading is more than 3-4 volts at either wire, repair appropriate signal circuit for short to voltage. If reading is not as specified, go to next step.
5. Turn ignition on. With HO2S-2 Bank-1 disconnected, connect fused jumper wires to both ground and high and low signal circuits at HO2S-2 harness connector (PCM side). If display on scan tool is less than 10 millivolts, go to next step. If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
6. Disconnect jumpers. With HO2S connector disconnected, observe HO2S-2 Bank-1 parameter on scan tool. If voltage is 425-475 millivolts, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S19319035372001050100000) . If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Apply parking brake and increase engine speed to more than 1200 RPM for 2 minutes. Using scan tool, observe HO2S-2 Bank-1 parameter. If reading stays between 425 and 475 millivolts, go to step 4 . If reading is not as specified, turn engine off and go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0140 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S02641222892001050100000) .
4. Check for poor high or low signal circuit connections at HO2S-2 Bank-1 harness connector. Check for damaged wiring harness. Repair as necessary. Retest system. If no problem was found, go to next step.
5. Turn ignition off. Disconnect PCM harness connectors. Check for poor HO2S-2 Bank-1 high or low signal circuit connections at PCM harness connectors or damaged harness. Repair as necessary. Retest system. If connections are okay, go to next step.
6. Turn ignition off. Measure resistance of HO2S-2 Bank-1 high and low signal circuits between PCM harness connector and HO2S-2 harness connector. If resistance is more than 5 ohms in each wire, repair open circuit or poor connection. Retest system. If wire is okay, go to next step.
7. Turn ignition on. Disconnect HO2S-2 Bank-1 harness connector. Connect fused jumper wires between high and low signal circuits of HO2S-2 Bank-1 (PCM side) and ground. If scan tool display is 0-10 millivolts, replace HO2S-2 Bank-1. If display is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Allow engine to cool. Disconnect fuel pump relay. Connect fused jumper wire between fuel pump relay socket positive battery terminal and relay wire that goes to fuel pump and HO2S fuses. Turn ignition off. Install scan tool. Turn ignition on. Observe HO2S-2 Bank-1 parameter on scan tool. If display is more than 650 millivolts or less than 250 millivolts, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S38727931712001050100000) . If display is not as specified, go to next step.
3. Inspect O2 SENS HEATER (20-amp) fuse in engine compartment fuse box. If fuse is blown, locate and repair short in HO2S ignition feed circuit and replace fuse. Retest system. If fuse is okay, go to next step.
4. Turn ignition off. Raise and support vehicle. Disconnect HO2S-2 Bank-1 harness connector. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit at HO2S-2 Bank-1 harness connector (PCM side). If test light comes on, go to next step. If test light does not come on, go to step 7 .
5. Connect test light between HO2S-2 Bank-1 harness connector (PCM side) ignition feed circuit and heater ground circuit. If test light comes on, go to next step. If test light does not come on, go to step 8 .
6. Turn ignition off. Ensure HO2S-2 Bank-1 is cool. Measure resistance between HO2S-2 Bank-1 ignition feed circuit and ground circuit at HO2S-2 Bank-1 harness connector (sensor side). If resistance is 3-6 ohms, go to step 9 . If resistance is not as specified, go to step 10 .
7. Repair open in HO2S-2 Bank-1 ignition feed circuit. Retest system.
8. Repair open in HO2S-2 Bank-1 heater ground circuit. Retest system.
9. Check for poor connection at HO2S-2 Bank-1 harness connector terminals. Repair as necessary. Retest system. If harness is okay, go to next step.
10. Turn ignition off. Disconnect PCM harness connectors. Measure resistance of HO2S-2 Bank-1 high and low signal circuits between HO2S-2 Bank-1 harness connector and PCM harness connector. If either circuit resistance is more than 5 ohms, locate and repair open circuit or poor connection. If wires are okay, go to next step.
11. Check for poor HO2S-2 Bank-1 high and low signal circuit terminal connections at PCM. Repair as necessary. If connections are okay, replace HO2S-2 Bank-1. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Using scan tool, observe HO2S-1 Bank-2 parameter on scan tool. If display remains less than 22 millivolts, go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0151 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S31747985112001050100000) .
4. Turn ignition off. Disconnect PCM harness connectors. Using ohmmeter, check HO2S-1 Bank-2 high and low signal circuits for a short to ground or short to heater ground circuit. Repair as necessary. Retest system. If wires are okay, go to next step.
5. Disconnect HO2S-1 Bank-2 harness connector. Check for continuity between HO2S-1 Bank-2 high and low signal circuits. If continuity is present, locate and repair short circuit between wires as necessary. Retest system. If continuity is not present, go to next step.
6. Reconnect PCM harness connectors, leaving HO2S-1 Bank-2 harness connector disconnected. Turn ignition on. If HO2S-1 Bank-2 parameter on scan tool is 425-475 millivolts, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S31747985112001050100000) . If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Using scan tool, observe HO2S-1 Bank-2 parameter. If display remains more than 952 millivolts, go to step 4 . If display is not as specified, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0152 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S14147648772001050100000) .
4. Turn ignition off. Disconnect HO2S-1 Bank-2. Turn ignition on. Using a voltmeter, measure voltage of high and low signal circuits at HO2S-1 Bank-2 harness connector (PCM side). If reading is 3-4 volts at either wire, repair signal circuit for short to power. If reading is not as specified, go to next step.
5. Turn ignition on. Connect fused jumper wires between HO2S-1 Bank-2 harness connector (PCM side) high and low signal circuits and ground. If display on scan tool is less than 10 millivolts, go to next step. If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
6. Disconnect jumper wires. Using scan tool, observe HO2S-1 Bank-2 voltage. If voltage is between 425 and 475 millivolts, see «DIAGNOSTIC AIDS»(ref-97343-S14147648772001050100000) . If voltage is not between 425 and 475 millivolts, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach operating temperature. Operate vehicle within conditions required to set DTC: ECT is more than 122°F (50°C) for A/T, 167°F (75°C) for M/T vehicles. Engine in closed loop. Engine running for one minute or more. Engine RPM is 1500-3000. Canister purge duty cycle is 2 percent or more. MAF is between 18 and 42 grams per second. All conditions met for 3 seconds or more. Rich-to-lean transition is longer than 105 milliseconds. Lean-to-Rich transition is longer than 94 milliseconds. Using scan tool, observe SPECIFIC DTC parameter. If scan tool displays DTC P0153 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0153 FAILED THIS IGN, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S30300265382001050100000) .
3. If scan tool also displays DTC P0153, P1133, P1134, P1153 or P1154 FAILED THIS IGN, replace affected HO2S. Retest system. If scan tool does not display these DTCs, go to next step.
4. Visually inspect for exhaust leaks near HO2S-1 Bank-2. Repair as necessary, then return to step 2 . If no leaks are found, go to next step.
5. Visually inspect HO2S-1 Bank-2 for proper installation. Check for corrosion or poor terminal contact at HO2S-1 Bank-2 and PCM. Repair as necessary. If no problem is found, go to next step.
6. Disconnect HO2S-1 Bank-2 harness connector. Measure voltage at HO2S-1 Bank-2 harness connector between high signal circuit and ground, then between low signal circuit and ground. If reading is 3-4 volts, go to next step. If reading is not 3-4 volts, go to step 8 .
7. Connect fused jumper wires between ground and high and low signal circuits of HO2S-1 Bank-2 harness connector (PCM side). Turn ignition on. Using scan tool, monitor voltage. If reading is less than 10 millivolts, then immediately returns to about 450 millivolts when jumper wires are removed, replace HO2S-1 Bank-2. If reading is not about 450 millivolts, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
8. Inspect PCM connections and terminals for damage. Repair as necessary. Retest system. If PCM connections and terminals are okay, go to next step.
9. Repair open, short or grounded HO2S-1 Bank-2 high or low signal circuits. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Apply parking brake and increase engine speed to more than 1200 RPM for 2 minutes. Using scan tool, observe HO2S-1 Bank-2 parameter. If reading stays between 400 and 500 millivolts, go to step 4 . If reading does not stay between 400 and 500 millivolts, turn engine off and go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0154 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S07397920952001050100000) .
4. Inspect sensor harness for damage. Repair as necessary. If harness is okay, go to next step.
5. Check for poor high and low signal circuit connections at HO2S-1 Bank-2 harness connector. Repair as necessary. Retest system. If circuit is okay, go to next step.
6. Check for poor HO2S-1 Bank-2 high and low signal circuit connections at PCM harness connectors. Repair as necessary. Retest system. If circuit is okay, go to next step.
7. Turn ignition off. Disconnect PCM harness connectors. Measure HO2S-1 Bank-2 high signal circuit resistance between PCM and HO2S harness connectors. If resistance is more than 5 ohms, repair open circuit or poor connection. Retest system. If resistance is 5 ohms or less, go to next step.
8. Measure HO2S-1 Bank-2 low signal circuit resistance between PCM and HO2S harness connectors. If resistance is more than 5 ohms, repair open circuit or poor connection. Retest system. If resistance is 5 ohms or less, reconnect PCM connectors and go to next step.
9. Disconnect HO2S-1 Bank-2 connector. Turn ignition on. Connect fused jumper wires between ground and high and low signal circuits of HO2S-1 Bank-2 (PCM side). If scan tool display is 0-10 millivolts, replace HO2S-1 Bank-2. If scan tool display is not 0-10 millivolts, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Allow engine to cool. Disconnect fuel pump relay. Connect fused jumper wire between fuel pump relay socket positive battery terminal and relay wire that goes to fuel pump and HO2S fuses. Turn ignition off. Install scan tool. Turn ignition on. Observe HO2S-1 Bank-2 parameter on scan tool for several minutes. If display is more than 650 millivolts or less than 250 millivolts, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S34362666802001050100000) . If display is not more than 650 millivolts or less than 250 millivolts, go to next step.
3. Inspect O2 SENS HEATER (20-amp) fuse in engine compartment fuse box. If fuse is blown, locate and repair short in ignition feed circuit and replace fuse. Retest system. If fuse is okay, go to next step.
4. Turn ignition off. Raise and support vehicle. Disconnect HO2S-1 Bank-2 harness connector. Turn ignition on. Connect test light between ground and ignition feed circuit at HO2S-1 harness connector (PCM side). If test light comes on, go to next step. If test light does not come on, go to step 7 .
5. Connect test light between ignition feed circuit and ground circuit at HO2S-1 harness connector (PCM side). If test light comes on, go to next step. If test light does not come on, go to step 8 .
6. Turn ignition off. Ensure HO2S-1 Bank-2 is cool. Measure resistance between ignition feed circuit and heater ground circuit at HO2S-1 Bank-2 harness connector (sensor side). If resistance is 3-6 ohms, go to step 9 . If resistance is not 3-6 ohms, go to step 10 .
7. Repair open in HO2S-1 Bank-2 ignition feed circuit. Retest system.
8. Repair open in HO2S-1 Bank-2 ground circuit. Retest system.
9. Check for poor connection at HO2S-1 Bank-2 harness connector terminals. Repair as necessary. Retest system. If harness connector terminals are okay, go to next step.
10. Check for poor connection at HO2S-1 Bank-2 high or low circuit harness connector terminals. Repair as necessary. Retest system. If connector terminals are okay, go to next step.
11. Turn ignition off. Disconnect PCM harness connectors. Measure resistance of HO2S-1 Bank-2 high and low signal circuits between HO2S-1 and PCM harness connectors. If either circuit resistance is more than 5 ohms, locate and repair open circuit or poor connection. If wiring is okay, go to next step.
12. Check for poor HO2S-1 Bank-2 connections at PCM. Repair as necessary. If connections are okay, replace HO2S-1 Bank-2. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Using scan tool, observe HO2S-2 Bank-2 parameter. If display remains less than 22 millivolts, go to step 4 . If display is more than 22 millivolts, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0157 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S26611506572001050100000) .
4. Turn ignition off. Disconnect PCM harness connectors. Using an ohmmeter, check HO2S-2 Bank-2 high and low signal circuits for a short to ground or heater ground circuit. Repair as necessary. Retest system. If wires are okay, go to next step.
5. Disconnect HO2S-2 Bank-2 harness connector. Check for continuity between high and low signal circuits at HO2S-2 harness connector. If continuity is present, locate and repair short circuit between high and low signal circuits. Retest system. If continuity is not present, go to next step.
6. Reconnect PCM, leaving HO2S-2 Bank-2 harness connector disconnected. Turn ignition on. If HO2S-2 Bank-2 parameter on scan tool is 425-475 millivolts, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S26611506572001050100000) . If parameter on scan tool is not 425-475 millivolts, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Using scan tool, observe HO2S-2 Bank-2 parameter. If display remains more than 952 millivolts, go to step 4 . If display is 952 millivolts or less, go to next step.
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0158 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S21194996862001050100000) .
4. Turn ignition off. Disconnect HO2S-2 Bank-2. Turn ignition on. Measure high and low signal circuit voltage at HO2S-2 Bank-2 harness connector (PCM side). If 3-4 volts are present at each wire, repair signal circuit for short to power. If 3-4 volts are not present, go to next step.
5. Turn ignition on. Connect jumper wires between ground and HO2S-2 Bank-2 harness connector (PCM side) high and low signal circuits. Use scan tool to monitor HO2S-2 Bank-2 voltage. If less than 10 millivolts are present, go to next step. If 10 millivolts or more are present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
6. Disconnect jumper wires. Using scan tool, check HO2S-2 Bank-2 parameter. If 425-475 millivolts are present, see «DIAGNOSTIC AIDS»(ref-97343-S21194996862001050100000) . If 425-475 millivolts are not present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Start engine and allow it to reach normal operating temperature. Apply parking brake and increase engine speed to greater than 1200 RPM for 2 minutes. Using scan tool, observe HO2S-2 Bank-2 parameter. If reading is varying outside of 425-475 millivolts range, turn engine off and go to next step. If reading is staying between 425 and 475 millivolts, go to step 4 .
3. Turn ignition on. Review and record FAILURE RECORDS data on scan tool. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0160 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S21452935552001050100000) .
4. Inspect HO2S-2 Bank-2 harness for damage. Repair as necessary. If harness is okay, go to next step.
5. Check for poor high and low signal circuit connections at HO2S-2 Bank-2 harness connector. Repair as necessary. Retest system. If connection is okay, go to next step.
6. Check HO2S-2 Bank-2 high and low signal circuit connections at PCM harness connectors. Repair as necessary. Retest system. If connections are okay, go to next step.
7. Turn ignition off. Disconnect PCM harness connectors. Measure resistance of HO2S-2 Bank-2 high signal circuit between PCM and HO2S-2 harness connectors. If resistance is more than 5 ohms, locate and repair open circuit or poor connection. Retest system. If resistance is less than 5 ohms, go to next step.
8. Measure resistance of HO2S-2 Bank-2 low signal circuit between PCM and HO2S-2 harness connectors. If resistance is more than 5 ohms, repair open or poor connection. Retest system. If resistance is less than 5 ohms, reconnect PCM connectors and go to next step.
9. Disconnect HO2S-2 Bank-2 connector. Turn ignition on. Connect fused jumper wires between ground and high and low signal circuits of HO2S-2 Bank-2 (PCM side). If scan tool reads 0-10 millivolts, replace HO2S-2 Bank-2. If scan tool does not read 0-10 millivolts, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Allow engine to cool. Disconnect fuel pump relay. Connect fused jumper between fuel pump relay socket positive battery terminal and relay wire that goes to fuel pump and HO2S fuses. Turn ignition off. Install scan tool. Turn ignition on. Observe HO2S-2 Bank-2 parameter on scan tool for several minutes. If display is more than 650 millivolts or less than 250 millivolts, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S25285491372001050100000) . If display is not as specified, go to next step.
3. Inspect O2 SENS HEATER (20-amp) fuse in engine compartment fuse box. If fuse is blown, locate and repair short in ignition feed circuit and replace fuse. Retest system. If fuse is okay, go to next step.
4. Turn ignition off. Raise and support vehicle. Disconnect HO2S-2 Bank-2 harness connector. Turn ignition on. Connect test light between ground and ignition feed circuit at HO2S-2 Bank-2 harness connector (PCM side). If test light comes on, go to next step. If test light does not come on, go to step 7 .
5. Connect test light between ignition feed circuit and ground circuit at HO2S-2 harness connector (PCM side). If test light comes on, go to next step. If test light does not come on, go to step 8 .
6. Turn ignition off. Ensure HO2S-2 is cool. Measure resistance between ignition feed circuit and heater ground circuit at HO2S-2 harness connector (sensor side). If resistance is 3-6 ohms, go to step 9 . If resistance is not 3-6 ohms, go to step 10 .
7. Repair open in HO2S-2 Bank-2 ignition feed circuit. Retest system.
8. Repair open in HO2S-2 Bank-2 ground circuit. Retest system.
9. Check for poor connection at HO2S-2 Bank-2 harness terminals. Repair as necessary. Retest system. If harness is okay, go to next step.
10. Check for poor connection at HO2S-2 Bank-2 high or low signal circuit terminal connections at harness connector. Repair as necessary. Retest system. If connections are okay, go to next step.
11. Turn ignition off. Disconnect PCM harness connector terminals. Measure resistance of HO2S-2 Bank-2 high and low signal circuits between HO2S-2 Bank-2 and PCM harness connectors. If either circuit resistance is greater than 5 ohms, check for an open or poor connection. Repair as necessary. If wires are okay, go to next step.
12. Check for poor HO2S-2 Bank-2 high and low signal circuit terminal connections at PCM. Repair as necessary. If connections are okay, replace HO2S-2 Bank-2. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any DTCs other than P0171 and P0174 are set, diagnose them first before proceeding. If no other DTCs are set, go to next step.
3. Operate vehicle in closed loop mode while using scan tool to read BANK 1 L.T. FUEL TRIM values. If L.T. FUEL TRIM value is more than 20 percent, go to step 5 . If value is 20 percent or less, go to next step.
4. Using scan tool, read and record FAIL RECORDS data. Clear DTCs and operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0171 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S13510341102001050100000) .
5. If DTC P0174 is also set, go to next step. If DTC P0174 is not set, go to step 15 .
6. Check vacuum hoses for splits, kinks and proper routing. Repair as necessary. Retest system. If no problem is found, go to next step.
7. Check PCV valve for proper installation. Repair as necessary. Retest system. If no problem is found, go to next step.
8. Check MAF inlet screen for blockage or foreign objects which may partially block airflow sample through MAF sensor. Repair as necessary. Retest system. If no problem is found, go to next step.
9. Start engine. If a high or unsteady idle condition is present, go to next step. If idle is okay, go to step 11 .
10. Check throttle body, intake manifold, and EGR valve system for vacuum leaks. Repair as necessary. Retest system. If no problem is found, go to next step.
11. Check for fuel contamination. Repair as necessary. Retest system. If fuel is okay, go to next step.
12. Check PCM injector, power and sensor ground circuits for clean and tight connections. Repair as necessary. Retest system. If no problem is found, go to next step.
13. Disconnect MAF sensor harness connector. Operate vehicle in closed loop mode while monitoring scan tool BANK 1 S.T. FUEL TRIM. If S.T. FUEL TRIM does not decrease to about zero percent, go to next step. If S.T. FUEL TRIM decreases to about zero percent, go to step 19 .
14. Perform FUEL SYSTEM PRESSURE TEST under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
15. Check intake manifold, injector "O" rings, EGR adapter, EGR valve and EGR feed pipes for vacuum leaks. Repair as necessary. Retest system. If no problem is found, go to next step.
16. Check exhaust system for corrosion, loose or missing hardware. Repair as necessary. Retest system. If no problem is found, go to next step.
17. Perform FUEL INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. Repair as necessary. Retest system. If no problem is found, go to next step.
18. Ensure HO2S is installed securely, and connector and harness are not contacting exhaust manifold or ignition wires. Repair as necessary. Retest system. If no problem is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S13510341102001050100000) .
19. Replace MAF sensor. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any other DTCs other than P0172 or P0175 are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Operate vehicle in closed loop mode while using scan tool to read BANK 1 L.T. FUEL TRIM values. If L.T. FUEL TRIM value is less than -15 percent for auto trans and is less than -12 percent for manual trans, go to step 5 . If values are not as specified, go to next step.
4. Using scan tool, read and record FAIL RECORDS data. Clear DTCs and operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0172 FAILED THIS IGNITION, go to next step. If scan tool indication is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S01580582862001050100000) .
5. If DTC P0175 is also set, go to next step. If DTC P0175 is not set, go to step 15 .
6. Check air filter element condition. Replace air filter element if necessary. Retest system. If air filter element is okay, go to next step.
7. Check for collapsed or restricted air intake duct. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
8. Check MAF inlet screen for blockage or foreign objects which may partially block airflow sample through MAF sensor. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
9. Start engine. If a high or unsteady idle condition is present, go to next step. If Idle is okay, go to step 11 .
10. Turn ignition off. Check throttle body bore and throttle plate for restriction or foreign objects. Check for clogged Idle Air Control (IAC) passages. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
11. Disconnect vacuum hose from fuel pressure regulator and check hose for presence of fuel. If fuel is present, replace fuel pressure regulator. Retest system. If no fuel is present, go to next step.
12. Turn ignition on. On VehiCROSS, Use scan tool to read TP ANGLE while slowly depressing accelerator pedal. If TP ANGLE increases steadily from zero percent at closed throttle to 100 percent at wide open throttle, go to next step. On all other models, use scan tool to read TP1 ANGLE while slowly depressing accelerator pedal. If TP1 ANGLE increases steadily from a minimum of 8 percent at closed throttle to a maximum of 92 percent at wide open throttle, go to next step. On all models, if TP ANGLE or TP1 ANGLE does not increase as specified, go to step 19 .
13. Disconnect MAF sensor connector. Operate vehicle in closed loop mode while monitoring scan tool BANK 1 L.T. and BANK 1 S.T. FUEL TRIM. If both FUEL TRIM values change to about zero percent, go to step 20 . If FUEL TRIM values do change to about zero percent, go to next step.
14. Perform FUEL SYSTEM PRESSURE TEST. See BASIC DIAGNOSTIC PROCEDURES article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
15. Turn ignition on. Connect test light between canister purge solenoid harness connector terminals. If test light comes on, go to next step. If test light does not come on, go to step 17 .
16. Using an ohmmeter, check for short circuit to ground on canister purge solenoid control circuit between PCM and canister purge solenoid. See WIRING DIAGRAMS article. Repair as necessary. Retest system. If short circuit to ground is not present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
17. Perform FUEL INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
18. Remove HO2S-1 and check for silicone contamination (powdery white deposit). If HO2S-1 is contaminated, replace HO2S-1. Retest system. If HO2S-1 is not contaminated, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S01580582862001050100000) .
19. Check for loose TP sensor mounting screws. Tighten or replace missing screws as necessary. If mounting screws are tight, replace TP sensor. Retest system.
20. Replace MAF sensor. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any DTCs other than P0171 and P0174 are set, diagnose them first before proceeding. If no other DTCs are set, go to next step.
3. Operate vehicle in closed loop mode while using scan tool to read BANK 2 L.T. FUEL TRIM values. If L.T. FUEL TRIM value is more than 20 percent, go to step 5 . If value is not as specified, go to next step.
4. Using scan tool, read and record FAIL RECORDS data. Clear DTCs and operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0174 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S31529687522001050100000) .
5. If DTC P0171 is also set, go to next step. If DTC P0171 is not set, go to step 15 .
6. Check vacuum hoses for splits, kinks and proper routing. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
7. Check PCV valve for proper installation. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
8. Check MAF inlet screen for blockage or foreign objects which may partially block airflow sample through MAF sensor. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
9. Start engine. If a high or unsteady idle condition is present, go to next step. If idle is okay, go to step 11 .
10. Check throttle body, intake manifold, and EGR system for vacuum leaks. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
11. Check for fuel contamination. If fuel is contaminated, repair as necessary. Retest system. If fuel is okay, go to next step.
12. Check PCM injector, power and sensor ground circuits for clean and tight connections. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
13. Disconnect MAF sensor harness connector. Operate vehicle in closed loop mode while monitoring scan tool BANK 2 S.T. FUEL TRIM. If S.T. FUEL TRIM does not decrease to about zero percent, go to next step. If S.T. FUEL TRIM decreases to about zero percent, go to step 19 .
14. Perform FUEL SYSTEM PRESSURE TEST under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
15. Check intake manifold, injector "O" rings, EGR adapter, EGR valve and EGR feed pipes for vacuum leaks. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
16. Check exhaust system for corrosion, loose or missing hardware. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
17. Perform injector balance test. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
18. Ensure HO2S is installed securely, connector and harness are not contacting exhaust manifold. If a problem is found, repair as necessary. Retest system. If no problem is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S31529687522001050100000) .
19. Replace MAF sensor. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any DTCs other than P0172 and P0175 are set, diagnose them first before proceeding. If no other DTCs are set, go to next step.
3. Operate vehicle in closed loop mode while using scan tool to read BANK 2 L.T. FUEL TRIM values. If L.T. FUEL TRIM value is less than -15 percent for A/T and is less than -12 percent for M/T, go to step 5 . If values are not as specified, go to next step.
4. Using scan tool, read and record FAIL RECORDS data. Clear DTCs and operate vehicle within FAILURE RECORDS conditions. If scan tool indicates DTC P0175 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S40570038992001050100000) .
5. If DTC P0172 is also set, go to next step. If DTC P0172 is not set, go to step 15 .
6. Check air filter element condition. Replace air filter element if necessary. Retest system. If air filter element is okay, go to next step.
7. Check for collapsed or restricted air intake duct. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
8. Check MAF inlet screen for blockage or foreign objects which may partially block airflow sample through MAF sensor. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
9. Start engine. If a low or unsteady idle condition is present, go to next step. If idle is okay, go to step 11 .
10. Turn ignition off. Check throttle body bore and throttle plate for restriction or foreign objects. Check for clogged Idle Air Control (IAC) passages. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
11. Disconnect vacuum hose from fuel pressure regulator and check it for presence of fuel. If fuel is present, replace fuel pressure regulator. Retest system. If no fuel is present, go to next step.
12. Turn ignition on. On VehiCROSS, Use scan tool to read TP ANGLE while slowly depressing accelerator pedal. If TP ANGLE increases steadily from zero percent at closed throttle to 100 percent at wide open throttle, go to next step. On all other models, use scan tool to read TP1 ANGLE while slowly depressing accelerator pedal. If TP1 ANGLE increases steadily from a minimum of 8 percent at closed throttle to a maximum of 92 percent at wide open throttle, go to next step. On all models, if TP ANGLE or TP1 ANGLE does not increase as specified, go to step 20 .
13. Disconnect MAF sensor harness connector. Operate vehicle in closed loop mode while monitoring scan tool BANK 2 L.T. and BANK 2 S.T. FUEL TRIM. If both FUEL TRIM values decrease to about zero percent, go to step 21 . If FUEL TRIM values do not decrease to about zero percent, go to next step.
14. Perform FUEL SYSTEM PRESSURE TEST. See BASIC DIAGNOSTIC PROCEDURES article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
15. Turn ignition on. Connect test light between canister purge solenoid connector terminals. If test light comes on, go to next step. If test light does not come on, go to step 18 . Retest system.
16. Using an ohmmeter, check for short circuit to ground on canister purge solenoid control circuit between PCM and canister purge solenoid. See WIRING DIAGRAMS article. Repair as necessary. Retest system. If short circuit to ground is not present, go to next step.
17. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.
18. Perform INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
19. Remove HO2S-1 and check for silicone contamination (powdery white deposit). If HO2S-1 is contaminated, replace HO2S-1. Retest system. If HO2S-1 is not contaminated, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S40570038992001050100000) .
20. Check for loose TP sensor mounting screws. Tighten or replace missing screws as necessary. If mounting screws are tight, replace TP sensor. Retest system.
21. Replace MAF sensor. Retest system.

PCM has six individual injector driver circuits. Each controls an injector. When a driver circuit is ground by PCM, injector is activated. PCM monitors current in each driver circuit. Voltage on each driver is monitored to detect a fault. If voltage is not what PCM expects to read, appropriate injector DTC is set. DTC is also set if an injector driver circuit is open or shorted to voltage. Condition for setting DTC

1. Battery voltage is more than 9.0 volts.
2. Engine is running, determined by 58X crankshaft position input signal.
3. Injector voltage does not equal ignition voltage when injector is commanded "OFF" or injector voltage does not equal zero volts when injector is commanded "ON".
4. Above conditions are met for 15 seconds.

An open or short in injector circuit will set DTC. The open or short will also cause a misfire and inoperative injector. A misfire DTC will be set indicating which cylinder is malfunctioning. Excessively high or low long and short term fuel trim indicate the possibility of a bad injector. See INJECTOR COIL TEST in SYSTEM & COMPONENT TESTING article to check injector.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Attempt to start engine. If engine starts, go to next step. If engine does not start, see ENGINE CRANKS BUT WONT RUN under NO START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES article.
3. Using scan tool, clear DTCs. Start and run engine for one minute and observe scan tool display. If any DTC from P0201 to P0206 resets, go to step 5 . If no DTC resets, go to next step.
4. With ignition on and engine off, use scan tool to read FREEZE FRAME DATA and note parameters. Start engine and operate vehicle within FREEZE FRAME conditions as noted. If any DTC from P0201 to P0206 resets, go to next step. If no DTC resets, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S07181261442001050100000) .
5. Turn engine off. Disconnect appropriate injector harness connector related to DTC. Connect an injector tester (noid-light) to injector harness connector. Disable secondary ignition system to prevent engine from starting and crank engine. If noid-light blinks, see INJECTOR COIL TEST in SYSTEM & COMPONENT TESTING article. If noid-light does not blink, go to next step.
6. If noid-light was on steady in previous step, go to next step. If noid-light did not come on in previous step, go to step 8 .
7. Disconnect PCM connector containing affected injector circuit. Connect test light between battery positive terminal and affected injector driver circuit at PCM harness connector. If test light comes on, repair short to ground in injector driver circuit. If test light does not come on, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
8. Disconnect injector test connector. Using an ohmmeter connected to ignition feed wire of injector test connector, probe wire for affected cylinder. If continuity is present, go to next step. If continuity is not present, repair open circuit in injector harness wire or replace faulty fuel injector. Retest system.
9. At PCM side of injector harness connector, check for short to voltage in affected cylinder wire. If short to voltage is present, repair short in affected cylinder injector wire. Retest system. If short to voltage is not present, go to next step.
10. Check for open circuit in affected cylinder wire between PCM and injector test connector. Repair as necessary. If wires are okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Misfire is monitored as a function of Combustion Quality (CQ) signals generated from ION Sensing Module system. Combustion signals represent degree of combustion in each cylinder. Misfire is detected when combustion signal is below a predetermined value. DTC P0300 will determine if a multiple cylinder misfire is occurring by monitoring Combustion Quality (CQ). Condition for setting DTC

1. Following DTCs are not present: Throttle Position (TP) sensor. Mass Air Flow (MAF) sensor. Vehicle Speed Sensor (VSS). Engine Coolant Temperature (ECT) sensor.
2. Engine speed is between 600 and 6250 RPM.
3. System voltage is between 11.0 and 16.0 volts.
4. ECT sensor indicates an engine temperature between 19°F (-7°C) and 248°F (120°C).
5. Throttle angle is steady and throttle changes less than 15 percent per 125 milliseconds.

Scan tool message MISFIRE CUR. #1-6 is helpful for determining if only a single cylinder is affected by misfire. Check ignition coil for cracks or damage. If problem is present, substitute a known-good ignition coil. Numerous short trip drives (under 3 miles), may fuel foul spark plugs and set DTC. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

If misfire is random, inspect all system grounds. Check for low fuel pressure or lean injector(s). Perform fuel pressure test and injector balance test. See SYSTEM & COMPONENT TESTING article. Check for fuel contamination, vacuum leaks at air inductions system or EGR system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and run at idle. Using scan tool, read and record FREEZE FRAME data. Operate vehicle within FAILURE RECORDS conditions. Read MISFIRE CUR. # display for each cylinder. If MISFIRE CUR. # increases (indicating an occurring misfire) for any cylinder, go to next step. If MISFIRE CUR. # does not increase, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S18979253082001050100000) .
3. Check vacuum hoses for splits, kinks or improper connections. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
4. Check intake manifold, injector "O" rings, EGR valve and EGR feed pipes for vacuum leaks. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
5. Check PCV valve for improper installation, damaged hose or grommet. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
6. Inspect MAF inlet screen for foreign objects or damage that may block airflow to MAF sensor. Repair as necessary. Retest system. If inlet screen is okay, go to next step.
7. Remove EGR valve and inspect valve, seat and passages for carbon deposits or damage. Inspect valve pintle to ensure it is not sticking partially open. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
8. Install a spark tester on spark plug end of ignition coil for cylinder indicating a misfire. Crank engine and check for a strong Blue spark. Repeat procedure for each affected cylinder. If spark is okay on all cylinders, go to step 13 . If spark is not okay at all cylinders, go to next step.
9. Remove ignition coil related to misfiring cylinder. Check ignition coil for cracks or carbon tracking. If a problem is found, replace damaged ignition coil. Retest system. If no problem is found, go to next step.
10. Remove spark plug(s) associated with misfiring cylinder(s). Check spark plugs for excessive fouling. If spark plugs are excessively fouled, diagnose and repair mechanical engine problem. If spark plugs are not excessively fouled, go to next step.
11. Check spark plug insulators for cracks, carbon tracking or other damage. If a problem is found, replace faulty spark plug(s). Retest system. If no problem is found, go to next step.
12. Disconnect MAF sensor harness connector. Operate vehicle in closed loop. while monitoring BANK 1 L.T. FUEL TRIM and BANK 1 S.T. FUEL TRIM parameters on scan tool. If L.T. FUEL TRIM decreases to less than 20 percent and ST FUEL TRIM decreases to less than 50 percent, replace ignition coil control module. If scan tool display is not as specified, replace ignition coil control module related to affected cylinder. Retest system.
13. Ensure PCM injector ground, power ground and sensor ground connections are clean and tight. Repair as necessary. Retest system. If connections are okay, go to next step.
14. See FUEL PUMP PRESSURE TEST in BASIC DIAGNOSTIC PROCEDURES article. If a problem was found, repair as necessary. Retest system. If no problem was found, go to next step.
15. Check for fuel contamination. If fuel is contaminated, repair as necessary. Retest system. If fuel is okay, go to next step.
16. Perform FUEL INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
17. Diagnose mechanical engine problems such as faulty camshaft, leaking or sticking valves, weak valve springs, damaged piston rings, loose or worn rocker arms, incorrect valve timing, leaking head gasket or loose or broken motor mounts. If a problem is found, repair as necessary. Retest system. If no problems are found, go to next step.
18. Check for a transmission Torque Converter Clutch (TCC) problem. See HYDRA-MATIC 4L30-E article in AUTOMATIC TRANSMISSIONS. Repair as necessary. If no problem is found, replace MAF sensor. Retest system.

Misfire is monitored as a function of Combustion Quality (CQ) signals generated from ION Sensing Module system. Combustion signals represent degree of combustion in each cylinder. Misfire is detected when combustion signal is below a predetermined value. DTC will determine which cylinder misfire is occurring by monitoring Combustion Quality (CQ). If ABS rough road sensor input signal to PCM determines that a rough road condition is present, misfire diagnostic will be temporarily disabled. Condition for setting DTC

1. Following DTCs are not present: Throttle Position (TP) sensor. Mass Air Flow (MAF) sensor. Vehicle Speed Sensor (VSS). Engine Coolant Temperature (ECT) sensor.
2. Engine speed is between 600 and 6250 RPM.
3. System voltage is between 11.0 and 16.0 volts.
4. Engine Coolant Temperature (ECT) sensor indicates an engine temperature between 19°F (-7°C) and 248°F (120°C).
5. Throttle angle is steady.
6. PCM is detecting a crankshaft vibration that indicates a misfire sufficient enough to cause three-way catalytic converter damage or emission levels to exceed mandated standard.

Test system grounds. Check injector. See INJECTOR COIL TEST in SYSTEM & COMPONENT TESTING article. Check spark plugs for cracked insulator, carbon tracking, incorrect gap and wear. Check ignition coil for cracks or damage. If problem is present, substitute a known-good ignition coil.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and run at idle. Using scan tool, read and record FREEZE FRAME data. Operate vehicle within FAILURE RECORDS conditions. Read MISFIRE CUR. # display for appropriate cylinder. If MISFIRE CUR. # increases (indicating an occurring misfire) for affected cylinder, go to step 4 . If MISFIRE CUR. # does not increase, go to next step.
3. Monitor MISFIRE HIST. # while operating vehicle and attempting to duplicate conditions which caused DTC to set. If MISFIRE HIST. # increases, go to next step. If MISFIRE HIST. # does not increase, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S25548573102001050100000) .
4. Check vacuum hoses for splits, kinks or improper connections. Check intake manifold for vacuum leak. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
5. Install spark tester at affected cylinder spark plug end of ignition coil. Crank engine. If a strong Blue spark is present, go to step 8 . If no spark or weak spark is present, go to next step.
6. Remove ignition coil related to misfiring cylinder. Check ignition coil for cracks or carbon tracking. If a problem is found, replace damaged ignition coil. Retest system. If no problem is found, go to next step.
7. Measure primary coil resistance. Resistance should be 2.6-2.7 k/ohms. Replace ignition coil if resistance is not as specified. If coil is okay, replace ignition control module. Retest system.
8. Remove spark plug associated with misfiring cylinder. Check spark plug for excessive fouling. If spark plug is excessively fouled, diagnose and repair mechanical engine problem. If spark plug is not excessively fouled, go to next step.
9. Check spark plug insulator for cracks, carbon tracking or other damage. If a problem is found, replace faulty spark plug. Retest system. If no problem is found, go to next step.
10. Perform FUEL INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
11. Inspect injector "O" rings for vacuum leaks. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
12. Diagnose mechanical engine problems such as faulty camshaft, leaking or sticking valves, excessive carbon deposits, weak valve springs, damaged piston rings, loose or worn rocker arms, incorrect valve timing, leaking head gasket or loose or broken motor mounts. If a problem is found, repair as necessary. Retest system. If no problems are found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S25548573102001050100000) .

PCM checks validity of signals used in ION Sensing module. This test is performed to evaluate if Knock Intensity (KI) signal pulse width is within a predetermined range. If KI signal pulse width is out of predetermined range, fail counter will be incremented. If failure counter exceeds calibration, then test is complete and a FAILURE will be reported. If sample counter threshold is reached before failure threshold, then test is complete and a PASS will be reported. This test will detect an open/short in KI line circuit, ION Sensing module faults and analog input faults in PCM. Conditions for setting DTC

1. Ignition voltage is between 10 and 16 volts.
2. No Crank DTCs set.
3. No Electronic Spark Timing (EST) DTCs.
4. No misfire DTCs set.

Check for poor connection at PCM and Ion Sensing Module (ISM) located on top of engine. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe KNOCK PRESENT, KNOCK SENSOR NOISE CHANNEL display while moving connectors and harnesses. A change in display will indicate location of fault. If DTC can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Turn ignition on, engine off. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions noted. Monitor DTC P0325 information. If scan tool indicates DTC P0325 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, go to «DIAGNOSTIC AIDS»(ref-97343-S38388804782001050100000) .
3. Turn ignition off. Disconnect ISM and PCM harness connectors. Check electrical circuit between ISM harness connector and PCM harness connector terminal F68 (Red wire). See PIN VOLTAGE CHARTS article for PCM terminal identification. If problem was found, repair as necessary and retest system. If no problem was found, go to next step.
4. Disconnect ignition coil. Check wiring harness between ignition coil harness connector and ISM harness connector. If problem was found, repair as necessary and retest system. If no problem was found, go to next step.
5. Check ignition coil and related wiring. Check for poor ground connections. If problem was found, repair as necessary and retest system. If no problem was found, go to next step.
6. Replace ignition coil. Retest system. If problem is still present, go to next step.
7. Check ISM ground circuit for loose or poor connection. If problem was found, repair as necessary and retest system. If no problem was found, go to next step.
8. Replace ISM. Retest system. If problem is still present, go to next step.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Operate vehicle under conditions to allow DTC to set. Using scan tool, monitor SPECIFIC DTC parameter until DTC P0325 test runs. If scan tool indicates DTC P0325 FAILED THIS IGNITION, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system. If DTC P0325 is not set, go to next step.
3. With ignition on and engine off, review and record FAILURE RECORDS for DTC P0325. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC parameter until DTC P0325 test runs. If scan tool indicates DTC P0325 FAILED THIS IGNITION, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system. If DTC P0325 is not set, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S29425396172001050100000) .

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start and run, see ENGINE CRANKS BUT WILL NOT RUN under NO START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES article.
3. Using scan tool, review and record FAILURE RECORDS information. Clear DTC P0336. Start engine and allow it to idle for one minute. Read DTCs. If DTC P0336 resets, go to next step. If DTC does not reset, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S25798701222001050100000) .
4. Disconnect PCM and CKP sensor harness connectors. Check for an open or short to ground in 58X reference circuit between CKP sensor connector and PCM harness connector. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
5. Reconnect PCM and CKP sensor harness connectors. Measure voltage at 58X reference circuit at PCM harness connector while cranking engine. If reading is about 2.5 volts, go to step 7 . If voltage is not about 2.5 volts, go to next step.
6. Check for faulty connection at CKP sensor. If a faulty connection is found, repair as necessary. If connection is okay, replace CKP sensor. Retest system.
7. Check for faulty connection at PCM. If a faulty connection is found, repair as necessary. If connection is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

58X reference signal is produced by Crankshaft Position (CKP) sensor. During one crankshaft revolution, 58 crankshaft reference pulses will be produced. PCM uses 58X reference signal to calculate engine RPM and crankshaft position. PCM constantly monitors number of pulses on 58X reference circuit and compares them to number of Camshaft Position (CMP) sensor signal pulses being received. If PCM receives an incorrect number of pulses on 58X reference circuit, DTC P0337 is set. Conditions for setting DTC

1. No CMP sensor DTCs are set.
2. Engine cranking.
3. CKP sensor signal is not present between 2 CMP sensor pulses.
4. CKP reference pulse is not detected within 8 CMP pulses.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe 58X reference circuit readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start and run, see ENGINE CRANKS BUT WILL NOT RUN under NO START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES article.
3. Using scan tool, review and record FAILURE RECORDS information. Clear DTC P0337. Start engine and allow it to idle for one minute. Read DTCs. If DTC P0337 resets, go to next step. If DTC P0337 does not reset, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S21762912242001050100000) .
4. Turn ignition off and disconnect CKP sensor. Turn ignition on. Connect DVOM between 5-volt reference and sensor ground terminals at CKP harness connector. If reading is 4-6 volts, go to step 7 . If reading is not 4-6 volts, go to next step.
5. Use DVOM to backprobe between PCM harness connector 5-volt reference circuit and ground terminals. If reading is 4-6 volts and ground is available at PCM harness connector, go to next step. If reading is not as specified, go to step 10 .
6. Check CKP sensor 5-volt reference circuit and ground circuit between CKP sensor and PCM for an open, short to ground or short to power. Repair as necessary. Retest system.
7. Turn ignition off and disconnect PCM and CKP sensor harness connectors. Check for an open or short to ground in 58X reference circuit between CKP sensor connector and PCM harness connector. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
8. Reconnect PCM and CKP sensor harness connectors. Using voltmeter, measure voltage of 58X reference circuit at PCM harness connector while cranking engine. If reading is about 2.5 volts, go to step 10 . If reading is not about 2.5 volts, go to next step.
9. Inspect connections at CKP sensor. Repair connections as necessary. If connections are okay, replace CKP sensor. Retest system.
10. Inspect connections at PCM. Repair connections as necessary. If connections are okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Camshaft position signal is produced by Camshaft Position (CMP) sensor pulses when engine is running and Crankshaft Position (CKP) sync pulses are being received. PCM uses CMP signal pulses to initiate sequential fuel injection. PCM constantly monitors number of pulses on CMP signal circuit and compares number CMP pulses to 58X reference pulses received. If PCM receives an incorrect number of pulses on CMP reference circuit, DTC P0341 is set and PCM will initiate injector sequence without CMP signal with a one in six chance that injector sequence is correct. Engine will continue to start and run normally, although misfire diagnostic will be affected if a misfiring condition occurs. Condition for setting DTC

1. Engine is running (1X CMP reference pulses are being received).
2. CMP sensor signal is not detected at correct interval for all 6 cylinders.
3. Above condition fails for 100 occurrences within 200 test samples.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Disconnect PCM connector. Connect voltmeter to Camshaft Position (CMP) signal circuit and wiggle harness and connectors. A change in voltage will indicate area of problem. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read and record FAIL RECORDS data for DTC P0341. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0341 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S32084531542001050100000) .
3. Disconnect CMP sensor. Measure voltage between sensor ground circuit and sensor 5-volt reference circuit at CMP sensor harness connector. If reading is about 4-6 volts, go to next step. If reading is not about 4-6 volts, go to step 5 .
4. Measure voltage between CMP sensor signal circuit and sensor ground circuit at CMP sensor harness connector. If reading is about 4-6 volts, go to step 11 . If reading is not about 4-6 volts, go to step 8 .
5. If voltage measured in step 3 was less than 4-6 volts, go to next step. If voltage in step 3 was more than 4-6 volts, repair short to power in CMP sensor 5-volt reference circuit. Retest system.
6. Inspect CMP sensor for poor connection. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
7. Turn ignition off. Disconnect PCM and CMP sensor harness connectors. Inspect sensor 5-volt reference circuit for an open between ignition control module and CMP sensor. If a problem is found, repair as necessary. Retest system. If no problem is found, go to step 9 .
8. Turn ignition off. Disconnect PCM harness connectors and leave CMP sensor disconnected. Turn ignition on. Using a DVOM, check CMP sensor signal circuit for an open or short to power. Check CMP sensor input circuit for a short to ground. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
9. Check for an open or short in CMP sensor ground circuit. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
10. Check for poor connections at PCM. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
11. Reconnect PCM and CMP sensor harness connectors. Using a voltmeter, backprobe CMP sensor connector at CMP signal circuit. Crank engine and monitor voltage. If voltage toggles between zero and 4 volts, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system. If voltage does not toggle between zero and 4 volts, leave voltmeter connected and go to next step.
12. Leaving sensor wiring harness connected, remove CMP sensor. Place a magnet on CMP sensor large enough to cover face of sensor. If voltmeter reads about zero volts, replace faulty or missing sensor magnet. If voltmeter does not read about zero volts, replace CMP sensor. Retest system.

Camshaft position signal is produced by Camshaft Position (CMP) sensor pulses when engine is running and Crankshaft Position (CKP) sync pulses are being received. A hall type CMP sensor and CKP sensor share 5 volt and ground connections at PCM. Third wire at sensor is a signal circuit to PCM. PCM uses CMP signal pulses to initiate sequential fuel injection. PCM constantly monitors number of pulses on CMP signal circuit and compares them to number of 58X pulses received. If PCM receives an incorrect number of pulses on CMP reference circuit, DTC P0342 is set and PCM will initiate injector sequence without CMP signal with a one in six chance that injector sequence is correct. Engine will continue to start and run normally, although misfire diagnostic will be affected if a misfiring condition occurs. Condition for setting DTC

1. Engine is running.
2. CMP sensor signal is not received by PCM once for every 6 cylinders.
3. Above condition occurs for 10 seconds.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Disconnect PCM connector. Connect voltmeter to CMP signal circuit and wiggle harness and connectors. A change in voltage will indicate area of problem. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read and record FAIL RECORDS data for DTC P0342. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0342 FAILED THIS IGNITION, go to next step. If DTC P0342 is not stored, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S16798410492001050100000) .
3. Disconnect CMP sensor. Turn ignition on. Measure voltage between CMP sensor ground circuit and CMP sensor harness connector 5-volt reference circuit. If reading is 4-6 volts, go to step 7 . If reading is not 4-6 volts, go to next step.
4. Turn ignition off. Disconnect PCM and CMP sensor harness connectors. Check for poor connections at CMP sensor. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
5. Check for poor connection at PCM. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
6. Inspect CMP sensor 5-volt reference circuit for an open or short to ground. Inspect CMP sensor ground circuit for an open or short to power. Repair as necessary. Retest system.
7. With ignition on and engine off, measure voltage between CMP sensor signal circuit and sensor ground circuit at CMP sensor harness connector. If reading is not about 4-6 volts, go to step 9 . If reading is about 4-6 volts, got to next step.
8. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Connect a voltmeter between ground and CMP sensor signal circuit at PCM harness connector. Monitor voltage while repeatedly touching CMP sensor signal circuit at CMP sensor connection with a test light to ground. If voltmeter displays voltage toggling between zero and 5 volts when test light is touched to CMP sensor signal circuit, leave voltmeter connected and go to step 12 . If voltage is not as specified, go to next step.
9. Ensure PCM is still disconnected. Turn ignition on. Connect test light between battery voltage and CMP sensor signal circuit at PCM harness connector. If test light comes on, locate and repair short to ground in CMP signal circuit. Retest system. If test light does not come on, go to next step.
10. Probe CMP sensor signal circuit with a test light connected to ground. If test light comes on, locate and repair short to voltage in CMP sensor signal circuit. Retest system. If test light does not come on, go to next step.
11. Turn ignition off. Disconnect CMP sensor harness connector. Using an ohmmeter, check CMP sensor signal circuit for an open. If problem is found, repair as necessary. Retest system.
12. Remove CMP sensor and reconnect harness connector. Place a magnet on CMP sensor large enough to cover face of sensor. Observe voltmeter. If reading is about zero volts, go to next step. If reading is not about zero volts, replace CMP sensor. Retest system.
13. Reinstall CMP sensor, leaving voltmeter connected. Crank engine and observe voltmeter. If voltage toggles between zero and 4 volts, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. If voltage does not toggle between zero and 4 volts, replace faulty or missing CMP sensor magnet. Retest system.

ION Sensing module has function to energize and de-energize primary ignition coil in response to signals from PCM. PCM controls ignition timing and dwell. This diagnosis detects open or short circuit(s) in ignition Electronic Spark Timing (EST) line by monitoring EST signals. A failure determination is made when signal voltage remains more or less than threshold value for corresponding fault code beyond a predetermined time period. When PCM detects a problem on an EST control circuit it will set a corresponding DTC (P0351-P0356). Conditions for setting DTC

1. Ignition is on.
2. Engine is running, determined by 58X crankshaft position input signal.
3. Output voltage is not equal to 5 volts when output is ON.
4. Output voltage us not equal to zero voltage when output is OFF.
5. Test failures occur within 10 samples of continuous spark events.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor DTC P0351-P0356 and wiggle harness and connectors. A change in voltage will indicate area of problem. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, read and record FAIL RECORDS data for DTCs P0351-P0356. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, read SPECIFIC DTC. If scan tool indicates DTC P0351-P0356 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S38954193252001050100000) .
3. Check ignition coil for poor connection or damaged terminals. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
4. Check PCM harness connector for poor connection or damaged terminals. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
5. Turn ignition on. Backprobe with voltmeter between ground and affected ignition control circuit at PCM harness connector on VehiCROSS, or at Ion Sensing Module (ISM) on Passport, Rodeo and Trooper. If reading is 25-55 millivolts, go to next step. If reading is not 25-55 millivolts, go to step 8 .
6. Start engine and let idle. Backprobe with voltmeter between ground and ignition control circuit at PCM harness connector on VehiCROSS, or at ISM on Passport, Rodeo and Trooper for cylinder being tested. If reading is between 100 and 180 millivolts, rapidly toggling back and forth to a reading 20-50 millivolts higher, go to next step. If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
7. Turn ignition off. Disconnect ignition coil 3-pin harness connectors. Measure voltage of affected ignition control circuit at ignition coil harness connector while cranking engine. If reading is 200-1200 millivolts, replace ignition coil. If reading is not 200-1200 millivolts, repair open in affected ignition control circuit. Retest system.
8. Turn ignition off. Disconnect PCM and ignition coil. Using ohmmeter, check affected ignition control circuit for a short to ground, voltage, or open circuit. Repair as necessary. If circuit is okay, go to next step.
9. Turn ignition on. Using voltmeter, check affected ignition control circuit for a short to voltage. Repair as necessary. If circuit is okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM tests EGR system during deceleration by momentarily commanding EGR valve to open while monitoring Manifold Absolute Pressure (MAP) sensor signal. when EGR valve is opened, PCM monitors change in MAP sensor input signal. PCM compares MAP change to a RPM vs. BARO table. When PCM interprets change in MAP sensor to be out of limits, PCM will set DTC P0401. Number test samples required to accomplish this may vary according to severity of detected flow error. Normally, PCM will only allow one EGR flow test sample to be taken during an ignition cycle. To aid in verifying a repair, PCM allows 12 test samples during first ignition cycle following a scan tool CLEAR INFO or a battery disconnect. Between 9 and 12 samples should be sufficient for PCM to determine adequate EGR flow and to pass EGR test. Conditions for setting DTC

1. Following DTCs are not set: Throttle Position (TP) sensor. Vehicle Speed Sensor (VSS). MAP sensor. EGR pintle position sensor. Engine Coolant Temperature (ECT) sensor. Misfire codes. Automatic transmission codes.
2. Engine coolant temperature is less than 140°F (60°C).
3. Ignition voltage between 11.5 and 16.0 volts.
4. Vehicle speed is more than 15 MPH.
5. A/C clutch status is unchanged.
6. Torque Converter Clutch (TCC) status is unchanged.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor ACTUAL EGR POSITION and wiggle harness and connectors. A change in voltage will indicate area of fault. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If DTC P1404 is also set, go to «DTC P1404: EGR STUCK CLOSED»(ref-97343-S19788868302001050100000) . If DTC P1404 is not set, go to next step.
3. Start engine and allow to idle. Using scan tool, monitor MAP signal. Quickly press throttle half way down and release. If scan tool value made an immediate large change, go to next step. If scan tool value does not make an immediate large change, replace MAP sensor.
4. Inspect exhaust system for modifications or leaks. If a problem is found, repair as necessary and go to step 7 . If a problem is not found, go to next step.
5. Remove EGR valve and check pintle, valve and passages and adapter for excessive deposits or restriction. Check EGR valve gasket and pipes for leaks. If a problem is found, repair as necessary and go to step 7 . If no problem is found, go to next step.
6. Remove EGR inlet and outlet pipes from exhaust and intake manifolds. Inspect manifold EGR ports and pipes for blockage. If a problem is found, repair as necessary, then go to next step. If no problem is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S00214580152001050100000) .
7. Read and record FAIL RECORDS data for DTC P0401. Clear DTCs. Start engine and monitor system information screen while moving connectors and wiring harnesses related to EGR valve. If scan tool displays DTC P0401 FAILED THIS IGNITION, go to last step completed in this DTC test. If scan tool does not display DTC P0401, repair is complete.

PCM monitors EGR pintle position input to ensure that valve responds properly to PCM commands and to detect a fault if pintle position is stuck open. If PCM detects a pintle position signal indicates more than 21.5 percent and for more than 625 milliseconds during cranking, PCM will set DTC P0402. Condition for setting DTC

1. Ignition voltage is between 11 and 16 volts.
2. Intake Air Temperature is more than 37°F (3°C).
3. At engine revolution less than 600 RPM, EGR pintle position indicates more than 21 percent for more than 625 milliseconds.

Check for foreign material stuck between EGR valve pintle and seat. Inspect EGR valve for excessive carbon deposits on valve shaft, which may cause unsmooth valve operation.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor ACTUAL EGR POSITION and wiggle harness and connectors. A change in voltage will indicate area of fault. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P0402 until DTC P0402 test runs. Note result. If scan tool indicates DTC P0402 FAILED THIS IGNITION, go to next step. If scan tool does not indicate DTC P0402 FAILED THIS IGNITION, see «DIAGNOSTIC AIDS»(ref-97343-S11294847402001050100000) .
3. Disconnect EGR valve harness connector. Check EGR valve and connector for damaged pins or terminals. Repair as necessary. If connector pins and terminals are okay, go to next step.
4. Remove EGR valve. Check if foreign material is present between seat and pintle. If foreign material is present, go to next step. If foreign material is not present, go to step 6 .
5. Remove EGR valve foreign material. Check pintle and seat for damage. If damage was present that would affect operation of EGR valve, go to step 7 . If no damage was present that would affect operation of EGR valve, go to next step.
6. Reinstall EGR valve. Ensure ignition is off. Install scan tool. Start and run engine at idle. Using scan tool, check EGR operation. If EGR operates correctly, system is okay. If EGR does not operate correctly, go to next step.
7. Replace EGR valve. If DTC P0402 still fails SPECIFIC DTC test on scan tool, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

PCM monitors EGR valve pintle position input to ensure that valve responds properly to PCM commands and to detect a fault if pintle position is different from commanded position. If PCM detects a pintle position signal indicates more than 15 points different between current and commanded and for more than 15 seconds, PCM will set DTC P0404. Conditions for setting DTC

1. Engine is running.
2. Ignition voltage is between 11 and 16 volts.
3. Intake air temperature is more than 37°F (3°C).
4. Desired EGR position is more than zero.
5. Difference between desired EGR and current EGR is less than 3 percent.
6. Difference between EGR pintle current position and command position becomes more than 15 percent for more than 15 seconds, and this condition exists for three times in a trip cycle, PCM turns on MIL.

Check for foreign material stuck between EGR valve pintle and seat. Inspect EGR valve for excessive carbon deposits on valve shaft, which may cause sticking or unsmooth valve operation.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor ACTUAL EGR POSITION and wiggle harness and connectors. A change in voltage will indicate area of problem. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P0404 until DTC P0404 test runs. Note result. If scan tool indicates DTC P0404 FAILED THIS IGNITION, go to next step. If scan tool does not indicate DTC P0404, see «DIAGNOSTIC AIDS»(ref-97343-S21113150702001050100000) .
3. Disconnect EGR valve harness connector. Check EGR valve and connector for damaged pins or terminals. Repair as necessary. If connector pins and terminals are okay, go to next step.
4. Remove EGR valve. Check if carbon deposits are present on EGR shaft. If carbon is present, go to next step. If carbon is not present, go to step 6 .
5. Clean EGR valve shaft and inside of EGR valve. Check pintle and seat for damage. If damage was present that would effect operation of EGR valve, go to step 7 . If no damage was present that would effect operation of EGR valve, go to next step.
6. Reinstall EGR valve. Ensure ignition is off. Install scan tool. Start and run engine at idle. Using scan tool, check EGR operation. If EGR operates correctly, system is okay. If EGR does not operate correctly, go to next step.
7. Replace EGR valve. If DTC P0404 still fails SPECIFIC DTC test on scan tool, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

PCM monitors EGR valve pintle position input to ensure that valve responds properly to PCM commands. If current pintle position voltage is less than 0.1 volt and lasts for more than 10 seconds, Then PCM will set DTC P0405. Conditions for setting DTC

1. Ignition voltage is between 11 and 16 volts.
2. EGR pintle position is less than 2 percent and last more than 10 seconds. PCM turns on MIL.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor ACTUAL EGR POSITION and wiggle harness and connectors. A change in voltage will indicate area of problem. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P0405 until DTC P0405 test runs. Note result. If scan tool indicates DTC P0405 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, see «DIAGNOSTIC AIDS»(ref-97343-S06410512662001050100000) .
3. Disconnect EGR valve harness connector. Check EGR valve and connector for damaged pins or terminals. Repair as necessary. If connector pins and terminals are okay, go to next step.
4. Disconnect EGR valve harness connector. Turn ignition on. Connect voltmeter between EGR valve harness connector 5-volt reference terminal and ground terminal. If about 4-6 volts are present, go to next step. If about 4-6 volts are not present, go to step 6 .
5. Turn ignition off. Use DVOM to measure EGR valve resistance between terminals "B" (Yellow/Black wire on Passport, Rodeo and Rodeo Sport, Green wire on all other models) and "D" (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Red/Yellow wire on Trooper, and Red wire on VehiCROSS). If 5-5.5 k/ohms are present, go to step 7 . If 5-5.5 k/ohms are not present, go to step 12 .
6. Turn ignition on. Backprobe with voltmeter between ground and EGR 5-volt reference circuit at PCM harness connector terminal. If 4-6 volts are present, repair open 5-volt reference circuit between EGR valve and PCM. If 4-6 volts are not present, go to step 13 .
7. Connect ohmmeter between EGR connector pintle position pin connector terminal "C" (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Yellow/Red wire on Trooper and VehiCROSS) and ground terminal "B" (Yellow/Black wire on Passport, Rodeo and Rodeo Sport, Green wire on all other models). If resistance is 1-1.25 k/ohms, go to step 10 . If resistance is not 1-1.25 k/ohms, go to step 12 .
8. Turn ignition on. Backprobe with voltmeter between EGR connector pintle position pin terminal "C" (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Yellow/Red wire on Trooper and VehiCROSS) and ground terminal "B" (Yellow/Black wire on Passport, Rodeo and Rodeo Sport, Green wire on all other models). If voltage is less than .1 volt, go to step 12 . If voltage is .1 volt or more, go to next step.
9. Backprobe with voltmeter at PCM harness connector between EGR pintle position circuit (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Yellow/Red wire on Trooper and VehiCROSS) and sensor ground circuit (Yellow/Black wire on Passport, Rodeo and Rodeo Sport, Green wire on all other models). If voltage is less than .1 volt, go to next step. If voltage is .1 volt or more, go to step 13 .
10. Turn ignition off. Disconnect EGR harness connector. Check for short between EGR pintle position pin and ground circuits. Repair wiring as necessary. If wiring is okay, go to step 13 .
11. Disconnect PCM connector. Turn ignition on. Measure voltage between EGR pintle position connector terminal "C" (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Yellow/Red wire on Trooper and VehiCROSS) and ground. If less than .1 volt is present, go to next step. If more than .1 volt is present, check circuit for a short to voltage from other wires. Repair wiring as necessary. If wiring is okay, go to next step.
12. Replace EGR valve. If DTC P0405 still fails scan tool test, check PCM connectors for poor terminal contact. Repair as necessary. If terminal contact is okay, go to next step.
13. Examine PCM pin and terminal connection. Repair as necessary. If no problem was found, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

PCM monitors EGR valve pintle position input to ensure that valve responds properly to PCM commands. If current pintle position voltage is more than 4.8 volts and lasts for more than 10 seconds, Then PCM will set DTC P0406. Conditions for setting DTC

1. Ignition voltage is between 11 and 16 volts.
2. EGR pintle position is more than 99 percent and last more than 10 seconds.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor ACTUAL EGR POSITION and wiggle harness and connectors. A change in voltage will indicate area of problem. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P0406 until DTC P0406 test runs. Note result. If scan tool indicates DTC P0406 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, see «DIAGNOSTIC AIDS»(ref-97343-S07982753352001050100000) .
3. Disconnect EGR valve harness connector. Check EGR valve and connector for damaged pins or terminals. If any problem was found, go to next step. If no problems were found, go to step 5 .
4. Repair any damaged pins or terminals as necessary. Retest system.
5. Turn ignition on. Connect voltmeter between EGR valve harness connector 5-volt reference terminal "D" (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Red/Yellow wire on Trooper, and Red wire on VehiCROSS) and ground. If about 4-6 volts are present, go to step 8 . If about 4-6 volts are not present, go to next step.
6. Turn ignition on. Backprobe with voltmeter between ground and EGR 5-volt reference circuit at PCM harness connector terminal. If 4-6 volts are present, go to next step. If 4-6 volts are not present, go to step 16 .
7. Repair open in 5-volt reference circuit between EGR valve and PCM. Retest system.
8. Turn ignition off. Use DVOM to measure EGR valve resistance between terminals "B" (Yellow/Black wire on Passport, Rodeo and Rodeo Sport, Green wire on all other models) and "D" (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Red/Yellow wire on Trooper, and Red wire on VehiCROSS). If 5-5.5 k/ohms are present, go to next step. If 5-5.5 k/ohms are not present, go to step 15 .
9. Measure resistance between EGR connector terminals "C" (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Yellow/Red wire on Trooper and VehiCROSS) and sensor ground terminal "B" (Yellow/Black wire on Passport, Rodeo and Rodeo Sport, Green wire on all other models). If continuity is present, go to next step. If continuity is not present, go to step 15 .
10. Disconnect PCM harness connector. Check for continuity between PCM harness connector terminal No. F-53 sensor ground circuit (Yellow/Black wire on Passport, Rodeo and Rodeo Sport, Green wire on all other models) and terminal No. S-37 5-volt reference circuit (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Red/Yellow wire on Trooper, and Red wire on VehiCROSS). If continuity is present, go to step 14 . If continuity is not present, go to next step.
11. Reconnect PCM harness connector. Turn ignition on. Backprobe with voltmeter between ground and EGR valve harness connector terminal "D" (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Red/Yellow wire on Trooper, and Red wire on VehiCROSS). If more than 4.8 volts are present, go to next step. Retest system. If 4.8 volts or less are present, go to step 15 .
12. Reconnect PCM and EGR harness connectors. Measure voltage at 5-volt reference circuit by backprobing at PCM harness connector terminal No. S-37 (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Red/Yellow wire on Trooper, and Red wire on VehiCROSS). If more than 4.8 volts are present, go to step 16 . If 4.8 volts or less are present, go to next step.
13. Locate and repair short circuit in EGR wiring harness between EGR valve and PCM. Recheck voltage at 5-volt reference circuit by backprobing at PCM harness connector (Gray/Red wire on Passport, Rodeo and Rodeo Sport, Red/Yellow wire on Trooper, and Red wire on VehiCROSS). If 4.8 volts or less are present, go to next step.
14. Repair or replace EGR wiring harness. Retest system.
15. Replace EGR valve. Retest system. If DTC P0406 resets, go to next step.
16. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Diagnose any other DTCs before proceeding. If no other DTCs are set, go to next step.
3. Ensure Three Way Catalytic Converter (TWC) is an original equipment part. Check TWC for dents, holes or discoloration caused by excessive heat. Ensure rattle caused by internal catalyst damage is not present. If a problem is found, repair as necessary and go to step 6 . If no problems are found, go to next step.
4. Check exhaust system for leaks, damage, loose or missing hardware. If a problem is found, repair as necessary and go to step 7 . If no problems are found, go to next step.
5. Ensure HO2S-2 Bank-1 or Bank-2 is securely installed and that harness is not damaged or contacting exhaust system. If a problem is found, repair as necessary and go to step 7 . If no problems are found, go to next step.
6. Replace affected TWC. Check for possible engine misfire DTC or engine mechanical problem, and go to next step.
7. Read and record FAIL RECORDS data for DTC P0420 or DTC P0430. Clear DTCs. Start engine and allow coolant temperature to reach 140°F (60°C). Run engine while monitoring scan tool IAC RPM control function to maintain MAF sensor range at 8-50 grams/sec. for at least 2 minutes. Go to next step.
8. Using scan tool, monitor TWC MONITOR TEST COUNTER while operating vehicle within conditions required to set DTC. Read SPECIFIC DTC. If scan tool displays DTC P0420 or DTC P0430 PASSED THIS IGNITION, repair is complete. If scan tool does not display DTC P0420 or DTC P0430 PASSED THIS IGNITION, go to «DIAGNOSTIC AIDS»(ref-97343-S02559025392001050100000) .

Following components are included in Evaporative (EVAP) system

1. Fuel tank.
2. EVAP canister duty solenoid valve.
3. Fuel Tank Pressure (FTP) sensor.
4. Fuel pipes and hoses.
5. Vapor lines.
6. Fuel filler cap.
7. EVAP emissions canister.
8. Purge lines.
9. EVAP canister cut valve (purge solenoid).

EVAP leak detection diagnostic strategy is based on applying vacuum to EVAP system and monitoring decay. PCM monitors vacuum level via Fuel Tank Pressure (FTP) sensor input. At an appropriate time, EVAP canister purge solenoid and EVAP canister vent solenoid are turned ON, allowing engine vacuum to draw a small vacuum on entire EVAP system. IF a sufficient vacuum level cannot be achieved, a large leak or faulty EVAP canister purge solenoid is indicated. This can be caused by following

1. Disconnected or faulty fuel tank pressure sensor.
2. Missing or faulty fuel filler cap.
3. Disconnected, damaged, pinched or blocked EVAP purge line.
4. Disconnected or damaged EVAP vent hose.
5. Disconnected, damaged, pinched or blocked fuel tank vapor line.
6. Disconnected or faulty EVAP canister cut valve.
7. Disconnected or faulty EVAP canister duty solenoid valve.
8. Open ignition feed circuit to EVAP canister vent solenoid or EVAP canister cut valve.
9. Damaged EVAP canister.
10. Leaking fuel sender assembly "O" ring.
11. Leaking fuel tank or fuel filler neck.

Any of above conditions can set DTC P0440. Conditions for setting DTC

1. No Throttle Position (TP) sensor, Intake Air Temperature (IAT) sensor or Manifold Absolute Pressure (MAP) sensor DTCs set.
2. Start-up engine coolant temperature is less than 90°F (32°C).
3. Start-up engine coolant temperature is not more than 13°F (7°C) more than start-up intake air temperature.
4. Start-up intake air temperature is more than 39°F (4°C).
5. Start-up intake air temperature is not more than 4°F (2°C) more than start-up engine coolant temperature.
6. Vehicle speed is less than 5 MPH.
7. Throttle position is more than 3 percent.
8. Minimal fuel slosh.
9. Barometer (BARO) is more than 70 kPa.
10. EVAP system is unable to achieve or maintain vacuum during diagnostic test.
11. Above conditions are present for 60-180 seconds.

An intermittent may be caused by a cracked or punctured EVAP canister, damaged or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Check for DTC P0452 or P0453. If present, diagnose other DTCs before proceeding. If no other DTCs are set, go to next step.
3. Turn ignition off. Remove fuel cap. Turn ignition on. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 1.51 volts, go to next step. If scan tool display is not as specified, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000) .
4. Reinstall fuel cap. Start engine and use scan tool to read FUEL TANK PRESSURE. If scan tool does not display 1.47-1.51 volts, go to step 6 . If scan tool display is as specified, go to step 7 .
5. Disconnect fuel tank vapor and EVAP purge lines from EVAP canister. Plug fuel tank vapor line fitting at EVAP canister. Connect a hand vacuum pump to EVAP purge line fitting at EVAP canister. Ensure EVAP vent solenoid is still commanded ON (closed). Attempt to apply vacuum to EVAP canister until FUEL TANK PRESSURE reads 1.47-1.51 volts. If FUEL TANK PRESSURE reading is maintained as specified, go to step 8 . If FUEL TANK PRESSURE reading can not be maintained as specified, go to step 7 .
6. Check fuel tank vapor line and EVAP purge line for restriction. If restriction is found, repair as necessary and retest system. If no restriction is found, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000) .
7. Check if vent hose is disconnected or damaged. Check EVAP canister for damage. If a problem is found, repair as necessary retest system. If no problem is found, go to step 11 .
8. Check for missing or faulty fuel cap. Check for disconnected or leaking fuel tank vapor line. Check for disconnected or damaged EVAP purge line. If a problem is found, repair as necessary and retest system. If no problem is found, go to next step.
9. Replace EVAP canister purge solenoid. Retest system.
10. Locate and repair cause of no source vacuum to EVAP canister purge solenoid. Retest system.
11. Replace EVAP canister vent solenoid. Retest system.

Following components are included in Evaporative (EVAP) system

1. Fuel tank
2. EVAP canister duty solenoid valve.
3. Fuel Tank Pressure (FTP) sensor.
4. Fuel pipes and hoses.
5. Vapor lines.
6. Fuel filler cap.
7. EVAP emissions canister.
8. Purge lines.
9. EVAP canister cut valve (purge solenoid).

EVAP leak detection diagnostic strategy is based on applying vacuum to EVAP system and monitoring decay. PCM monitors vacuum level via Fuel Tank Pressure (FTP) sensor input. At an appropriate time , EVAP canister purge solenoid and EVAP canister vent solenoid are turned ON, allowing engine vacuum to draw a small vacuum on entire EVAP system. If a sufficient vacuum level cannot be achieved, a large leak or faulty EVAP canister purge solenoid is indicated. This can be caused by following

1. Disconnected or faulty fuel tank pressure sensor.
2. Missing or faulty fuel filler cap.
3. Disconnected, damaged, pinched or blocked EVAP purge line.
4. Disconnected or damaged EVAP vent hose.
5. Disconnected, damaged, pinched or blocked fuel tank vapor line.
6. Disconnected or faulty EVAP canister cut valve.
7. Disconnected or faulty EVAP canister duty solenoid valve.
8. Open ignition feed circuit to EVAP canister vent solenoid or EVAP canister cut valve.
9. Damaged EVAP canister.
10. Leaking fuel sender assembly "O" ring.
11. Leaking fuel tank or fuel filler neck.

Any of above conditions can set DTC P0440. Conditions for setting DTC

1. No Throttle Position (TP) sensor, Intake Air Temperature (IAT) sensor or Manifold Absolute Pressure (MAP) sensor DTCs set.
2. Start-up engine coolant temperature is less than 90°F (32°C).
3. Start-up engine coolant temperature is not more than 13°F (7°C) more than start-up intake air temperature.
4. Start-up intake air temperature is more than 39°F (4°C).
5. Start-up intake air temperature is not more than 4°F (2°C) more than start-up engine coolant temperature.
6. Vehicle speed is less than 75 MPH.
7. Throttle position is more than 7 percent but less than 30 percent.
8. Minimal fuel slosh.
9. Fuel tank level is between 15 and 85 percent.
10. Barometer (BARO) is more than 75 kPa.
11. EVAP system is unable to achieve or maintain vacuum during diagnostic test.
12. Above conditions are present for 60-180 seconds.

An intermittent may be caused by a cracked or punctured EVAP canister, damaged or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Check for DTC P0452 or P0453. If present, diagnose other DTCs before proceeding. If no other DTCs are set, go to next step.
3. Turn ignition off. Remove fuel cap. Turn ignition on. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 1.51 volts, go to next step. If scan tool display is not as specified, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000) .
4. Zero pressure and vacuum gauges on EVAP Pressure/Purge Cart (J41413). Reinstall fuel cap. Read and record FAIL RECORDS data for DTC P0440. Clear DTCs. Using scan tool, command EVAP canister vent solenoid ON (closed). Connect EVAP pressure/purge cart to EVAP service port. Using EVAP pressure/purge cart, attempt to pressurize EVAP system to 5 in. H 2 O. If specified pressure is not achieved, go to step 6 . If specified pressure is achieved, go to next step.
5. Maintain EVAP system pressure at 5 in. H 2 O. Using scan tool, read FUEL TANK PRESSURE. If scan tool does not display 1.47-1.51 volts, go to step 7 . If scan tool display is as specified, go to step 8 .
6. Disconnect fuel tank vapor and EVAP purge lines from EVAP canister. Plug fuel tank vapor line fitting at EVAP canister. Connect a hand vacuum pump to EVAP purge line fitting at EVAP canister. Ensure EVAP vent solenoid is still commanded ON (closed). Attempt to apply 5 in. Hg vacuum to EVAP canister. If vacuum is maintained as specified, go to step 11 . If vacuum can not be maintained as specified, go to step 10 .
7. Check fuel tank vapor line and EVAP purge line for restriction. If restriction is found, repair as necessary and go to step 16 . If no restriction is found, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000) .
8. Disconnect vacuum source line and plug vacuum source fitting at EVAP canister purge solenoid. Using scan tool, select and activate SYSTEM PERF. Using EVAP pressure/purge cart, pressurize EVAP system to 5 in. H 2 O. Observe pressure gauge on EVAP pressure/purge cart while removing plug from vacuum source fitting at EVAP canister purge solenoid. If FUEL TANK PRESSURE reading decreases to 1.51 volts within 15 seconds, go to next step. If FUEL TANK PRESSURE does not decrease as specified, go to step 13 .
9. Connect EVAP pressure/purge cart vacuum gauge to vacuum source line. Start engine. Run engine speed to more than 2000 RPM while observing vacuum gauge. If vacuum is more than 15 in. Hg, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S05385388222001050100000) . If vacuum is 15 in. Hg or less, go to step 14 .
10. Check if vent hose is disconnected or damaged. Check EVAP canister for damage. If a problem is found, repair as necessary and go to step 16 . If no problem is found, go to step 15 .
11. Check for missing or faulty fuel cap. Check for disconnected or leaking fuel tank vapor line. Check for disconnected or damaged EVAP purge line. If a problem is found, repair as necessary and go to step 16 . If no problem is found, go to next step.
12. Using scan tool, command EVAP canister vent solenoid ON (closed). With EVAP pressure/purge cart connected to EVAP service port, continuously attempt to pressurize EVAP system by leaving EVAP pressure/purge cart control knob in PRESSURIZE position. Using Ultrasonic Leak Detector (J41416), locate and repair EVAP system leak. It may be necessary to lower fuel tank to check connections at top of tank. Go to step 16 .
13. Replace EVAP canister purge solenoid and go to step 16 .
14. Locate and repair cause of no source vacuum to EVAP canister purge solenoid and go to step 16 .
15. Replace EVAP canister vent solenoid and go to next step.
16. Turn ignition on, engine off. Using scan tool, command EVAP canister vent solenoid ON (closed). Using EVAP pressure/purge cart, pressurize EVAP system to 15 in. H 2 O. Monitor EVAP pressure/purge cart pressure gauge. Turn EVAP pressure/purge cart rotary switch to HOLD position. If FUEL TANK PRESSURE reading decreases to less than 2.14 volts within 2 minutes, return to step 4 . If pressure does not decrease as specified, repair is complete.

Following components are included in Evaporative (EVAP) system

1. Fuel tank.
2. EVAP canister duty solenoid valve.
3. Fuel Tank Pressure (FTP) sensor.
4. Fuel pipes and hoses.
5. Vapor lines.
6. Fuel filler cap.
7. EVAP emissions canister.
8. Purge lines.
9. EVAP canister cut valve (purge solenoid). EVAP leak detection diagnostic strategy is based on applying vacuum to EVAP system and monitoring decay. PCM monitors vacuum level via Fuel Tank Pressure (FTP) sensor input. At an appropriate time, EVAP canister purge solenoid and EVAP canister vent solenoid are turned ON, allowing engine vacuum to draw a small vacuum on entire EVAP system. After a desired vacuum level has been reached, EVAP canister purge solenoid is turned OFF, sealing system. A leak is detected by monitoring for a decrease in vacuum level over a given period of time, all other variables remaining constant. A small leak in system will cause DTC P0442 to set. Conditions for setting DTC: No Throttle Position (TP) sensor, Intake Air Temperature (IAT) sensor or Manifold Absolute Pressure (MAP) sensor DTCs set. DTC P0440 diagnostic test has passed. A vacuum decay condition, indicating a small leak, is detected during diagnostic test.

An intermittent may be caused by a cracked or punctured EVAP canister, damaged or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition off. Remove fuel cap. Turn ignition on. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 1.51 volts, go to next step. If scan tool display is not as specified, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000) .
3. Zero pressure and vacuum gauges on EVAP Pressure/Purge Cart (J41413). Reinstall fuel cap. Read and record FAIL RECORDS data for DTC P0442. Clear DTCs. Connect EVAP pressure/purge cart to EVAP service port. Using scan tool, command EVAP canister vent solenoid ON (closed). Using EVAP pressure/purge cart, pressurize EVAP system until FUEL TANK PRESSURE reading is 1.47 volts (1.52-1.69 volts on VehiCROSS). If specified FUEL TANK PRESSURE reading is achieved, go to next step. If specified pressure is not achieved, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000) .
4. Start engine and allow to idle. Using scan tool, command EVAP canister vent solenoid ON (closed). Using EVAP pressure/purge cart pressurize EVAP system to 15 in. H 2 O. Monitor EVAP pressure/purge cart pressure gauge. Turn EVAP pressure/purge cart rotary switch to HOLD position. If FUEL TANK PRESSURE reading drops to less than 1.47-1.51 volts within 2 minutes, go to next step. If FUEL TANK PRESSURE reading does not decrease as specified, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S26572890192001050100000) .
5. Disconnect fuel tank vapor and EVAP purge lines from EVAP canister. Plug fuel tank vapor line fitting at EVAP canister. Connect a hand vacuum pump to EVAP canister purge line fitting at EVAP canister. Ensure EVAP vent solenoid is still commanded ON (closed). Attempt to apply vacuum to EVAP canister until FUEL TANK PRESSURE reading reaches 1.46 volts (or vacuum gauge reads 5.0 in. Hg on VehiCROSS). If vacuum is maintained at specified level, go to step 8 . If vacuum can not be maintained as specified, go to next step.
6. Check if vent hose is disconnected or damaged. Check EVAP canister for damage. If a problem is found, repair as necessary and go to step 10 . If no problem is found, go to next step.
7. Replace EVAP canister vent solenoid and go to step 10 .
8. Check for missing or faulty fuel cap. Check for disconnected or leaking fuel tank vapor line. Check for disconnected or damaged EVAP purge line. If a problem is found, repair as necessary and go to step 10 . If no problem is found, go to next step.
9. Using scan tool, command EVAP canister vent solenoid ON (closed). With EVAP pressure/purge cart connected to EVAP service port, attempt to pressurize EVAP system by leaving EVAP pressure/purge cart control knob in PRESSURIZE position. Using Ultrasonic Leak Detector (J41416), locate and repair EVAP system leak. It may be necessary to lower fuel tank to check connections at top of tank. Go to next step.
10. Turn ignition on, engine off. Using scan tool, command EVAP canister vent solenoid ON (closed). Using EVAP pressure/purge cart, pressurize EVAP system to 15 in. H 2 O. Monitor EVAP pressure/purge cart pressure gauge. Turn EVAP pressure/purge cart rotary switch to HOLD position. If FUEL TANK PRESSURE reading drops to less than 2.14 volts within 2 minutes, return to step 2 . If pressure does not decrease as specified, repair is complete.

Canister purge solenoid valve is controlled by PCM. PCM monitors vacuum level via Fuel Tank Pressure (FTP) sensor input. At an appropriate time, Evaporative (EVAP) canister purge solenoid is ON, allowing engine vacuum to draw a small vacuum on entire EVAP emission system. Conditions for setting DTC P0444

1. Ignition is on.
2. Engine is running.
3. System voltage is between 11.5 and 16.0 volts.

An intermittent may be caused by a damaged, restricted or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC P0444 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and rev engine 3 or 4 times. Using scan tool, observe EVAP canister purge solenoid. If EVAP canister purge solenoid reading is about one percent or more, problem is intermittent. See «DIAGNOSTIC AIDS»(ref-97343-S35217019072001082900000) . If scan tool reading is less than specified, go to next step.
3. Turn ignition off. Disconnect EVAP canister purge solenoid valve. Turn ignition on. Using DVOM, measure voltage between ground and EVAP canister purge solenoid valve harness connector power supply terminal. If battery voltage is present, go to next step. If battery voltage is not present, go to step 5 .
4. Turn ignition off. Disconnect PCM. Check signal circuit between EVAP canister purge solenoid valve harness connector and PCM harness connector. If problem is found, go to next step. If problem is not found, go to step 6 .
5. Repair circuit as necessary and retest system.
6. Using DVOM, measure EVAP canister purge solenoid valve resistance. If resistance reading is within 25-30 ohms at 68°F (20°C), replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. If resistance reading is not as specified, replace EVAP canister purge solenoid valve. Retest system.

Canister purge solenoid valve is controlled by PCM. PCM monitors vacuum level via Fuel Tank Pressure (FTP) sensor input. At an appropriate time, Evaporative (EVAP) canister purge solenoid is ON, allowing engine vacuum to draw a small vacuum on entire EVAP emission system. Conditions for setting DTC P0445

1. Ignition is on.
2. Engine is running.
3. System voltage is between 11.5 and 16.0 volts.

An intermittent may be caused by a damaged, restricted or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC P0445 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, observe EVAP canister purge solenoid. If EVAP canister purge solenoid reading is about zero percent or more, problem is intermittent. See «DIAGNOSTIC AIDS»(ref-97343-S42393961462001082900000) . If scan tool reading is less than specified, go to next step.
3. Turn ignition off. Disconnect EVAP canister purge solenoid valve and PCM harness connectors. Using DVOM, check signal circuit between EVAP canister purge solenoid valve and PCM. If problem is found, repair as necessary. Retest system. If problem is not found, go to next step.
4. Using DVOM, measure resistance of EVAP canister purge solenoid valve. If resistance reading is within 25-30 ohms at 68°F (20°C), replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. If resistance reading is not within specification, replace EVAP canister purge solenoid valve. Retest system.

Evaporative (EVAP) system includes following components

1. Fuel tank.
2. EVAP canister duty solenoid valve.
3. Fuel Tank Pressure (FTP) sensor.
4. Fuel pipes and hoses.
5. Vapor lines.
6. Fuel filler cap.
7. EVAP emissions canister.
8. Purge lines.
9. EVAP canister purge solenoid. Incorrect fuel tank pressure sensor signal is detected by monitoring fuel tank pressure when ignition is first turned on during cold start. If fuel tank pressure signal is out of range, DTC P0446 will set. A restricted or blocked EVAP vent path is detected by monitoring fuel tank pressure during normal operation (EVAP canister vent solenoid open, EVAP canister purge solenoid normal). With EVAP canister vent solenoid open, Vacuum level in system should be very low unless vent path is blocked. A blockage can be cause by following conditions: Faulty EVAP canister vent solenoid (closed). Plugged, kinked or pinched vent hose. Shorted EVAP canister vent solenoid driver circuit. Plugged EVAP canister. If any of the above conditions are present, DTC P0446 will set. Other conditions for setting DTC P0446: No Throttle Position (TP) sensor, Fuel Tank Pressure (FTP) sensor, Intake Air Temperature (IAT) sensor or Manifold Absolute Pressure (MAP) sensor DTCs set. Start-up engine coolant temperature and start-up intake air temperature are more than 39°F (4°C) but less than 93°F (34°C). Start-up engine coolant temperature is not more than 13°F (7°C) greater than start-up intake air temperature. Fuel tank level is between 15 and 85 percent. Barometer (BARO) is more than 70 kPa.

An intermittent may be caused by a damaged, restricted or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Read and record FAIL RECORDS data for DTC P0446. Clear DTCs. Turn ignition off. Remove fuel cap. Turn ignition on. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 1.51 volts, go to next step. If scan tool display is not as specified, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000) .
3. Zero pressure and vacuum gauges on EVAP Pressure/Purge Cart (J41413). Reinstall fuel cap. Using scan tool, command EVAP canister vent solenoid ON (closed). Connect EVAP pressure/purge cart to EVAP service port. Using EVAP pressure/purge cart, pressurize EVAP system to 5 in. H 2 O. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 1.52-1.69 volts, go to next step. If scan tool display is not as specified, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000) .
4. Maintain EVAP system pressure at 5 in. H 2 O. Using scan tool, command EVAP canister vent solenoid OFF (open). Monitor EVAP pressure/purge cart pressure gauge. If pressure decreases to zero in. H 2 O within 5 seconds, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S38161675032001050100000) . If pressure does not decrease as specified, go to next step.
5. Disconnect large vent hose, marked "AIR", from EVAP canister. Switch EVAP pressure/purge cart rotary switch to PURGE. Start engine and allow it to reach operating temperature. Monitor vacuum gauge for 5 seconds while holding engine speed at 2500 RPM. If vacuum remains at less than 30 in. H 2 O, go to next step. If vacuum reading is not as specified, go to step 8 .
6. Check if vent hose between EVAP canister and EVAP canister vent solenoid valve is kinked, pinched or blocked. If a problem is found, repair as necessary and go to step 9 . If no problem is found, go to next step.
7. Replace EVAP vent solenoid and go to step 9 .
8. Replace EVAP canister and go to next step.
9. Using scan tool, command EVAP canister vent solenoid ON (closed). With EVAP pressure/purge cart connected to EVAP service port, pressurize EVAP system to 15 in. H 2 O. Switch EVAP pressure/purge cart rotary switch to HOLD. Using scan tool, command EVAP canister vent solenoid OFF (open). If pressure decreases to zero in. H 2 O within 5 seconds, repair is complete. If pressure does not decrease as specified, return to step 2 .

Canister purge solenoid valve is controlled by PCM. PCM monitors vacuum level via Fuel Tank Pressure (FTP) sensor input. At an appropriate time, Evaporative (EVAP) canister purge solenoid is ON, allowing engine vacuum to draw a small vacuum on entire EVAP emission system. Conditions for setting DTC P0447

1. Ignition is on.
2. Engine is running.
3. System voltage is between 11.5 and 16.0 volts.

An intermittent may be caused by a damaged, restricted or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC P0447 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Start engine and rev engine 3 or 4 times. Using scan tool, observe EVAP canister vent solenoid. If EVAP canister vent solenoid is on, problem is intermittent. See «Diagnostic Aids»(ref-97343-S32780690652001083000000) . If scan tool reading is not ON, go to next step.
3. Turn ignition off. Disconnect EVAP canister vent solenoid valve harness connector. Turn ignition on. Using DVOM, measure voltage between ground and EVAP canister vent solenoid connector voltage supply terminal. If battery voltage is present, go to next step. If battery voltage is not present, go to step 5 .
4. Turn ignition off. Disconnect PCM. Check signal circuit between EVAP canister vent solenoid valve harness connector and PCM harness connector. If problem is found, go to next step. If problem is not found, go to step 6
5. Repair circuit as necessary. Retest system.
6. Using DVOM, measure EVAP canister vent solenoid valve resistance. If resistance reading is within 21.8-28.5 ohms at 68°F (20°C), replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. If resistance reading is not as specified, replace EVAP canister vent solenoid valve. Retest system.

Canister vent solenoid valve is controlled by PCM. PCM monitors vacuum level via fuel tank pressure (FTP) sensor input. At an appropriate time, EVAP canister vent solenoid is ON, allowing engine vacuum to draw a small vacuum on entire Evaporative (EVAP) emission system. Conditions for setting DTC P0448

1. Ignition is on.
2. Engine is running.
3. System voltage is between 11.5 and 16.0 volts.

An intermittent may be caused by a damaged, restricted or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC P0448 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Using scan tool, observe EVAP canister vent solenoid. If EVAP canister vent solenoid reading is about zero percent or more, problem is intermittent. See «DIAGNOSTIC AIDS»(ref-97343-S05725323472001083000000) . If scan tool reading is less than specified, go to next step.
3. Turn ignition off. Disconnect EVAP canister vent solenoid valve and PCM harness connectors. Using DVOM, check signal circuit between EVAP canister vent solenoid valve and PCM. If problem is found, repair as necessary. Retest system. If problem is not found, go to next step.
4. Using DVOM, measure resistance of EVAP canister vent solenoid valve. If resistance reading is within 21.8-28.5 ohms at 68°F (20°C), replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. If resistance reading is not within specification, replace EVAP canister vent solenoid valve. Retest system.

PCM monitors Fuel Tank Pressure (FTP) sensor (Vapor pressure sensor) of enhanced evaporative system. When FTP sensor output indicates low voltage, PCM will set DTC P0452. Conditions for setting DTC

1. FTP sensor output is less than 0.2 volts for 12.5 seconds.
2. 100 test failures within 200 tests.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor fuel level display while moving connectors and harness related to fuel sensor. Change in display will indicate problem area.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Read and record FAIL RECORDS data for DTC P0452. Clear DTCs. Using scan tool, monitor SPECIFIC DTC information for DTC P0452 until DTC P0452 runs. Note result. If scan tool indicates DTC P0452 FAILED THIS IGNITION, go to step 6 . If scan tool indicates DTC P0452/P0107 FAILED THIS IGNITION, go to next step. If neither DTC is present, see «DIAGNOSTIC AIDS»(ref-97343-S08908428512001050100000) .
3. Turn ignition on. Measure voltage by backprobing between Fuel Tank Pressure (FTP) sensor 5-volt reference circuit and sensor ground circuit at PCM connector. If about 4-6 volts are present, go to next step. If about 4-6 volts are not present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.
4. Measure voltage by backprobing between FTP sensor 5-volt reference circuit and sensor ground circuit at FTP sensor connector. If DVOM display reads between 4-6 volts and DTC P0452 is present, go to next step. If 4-6 volts are displayed and DTC P0107 is present, go to «DTC P0107: MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR CIRCUIT, LOW VOLTAGE»(ref-97343-S26471712482001050100000) test.
5. Locate and repair open circuit on 5-volt reference circuit between FTP sensor and PCM. Retest system.
6. Turn ignition on. Backprobe with voltmeter between ground and FTP sensor output circuit at PCM harness connector. If less than .2 volt is present, go to next step. If .2 volt or more are present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.
7. Backprobe with voltmeter at FTP sensor between FTP sensor output and ground. If less than .2 volt is present, replace fuel tank pressure sensor. If .2 volt or more are present, locate open or short circuit in sensor ground circuit. Repair wiring as necessary.

PCM monitors Fuel Tank Pressure (FTP) sensor (Vapor pressure sensor) of enhanced evaporative system. When FTP sensor output indicates high voltage, PCM will set DTC P0453. Conditions for setting DTC

1. FTP sensor output is more than 4.9 volts for 12.5 seconds.
2. 100 test failures within 200 tests.

Check for an open circuit in Fuel Tank Pressure (FTP) sensor ground. Inspect wiring harness between FTP sensor and PCM. Reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Read and record FAIL RECORDS data for DTC P0453. Clear DTCs. Using scan tool, monitor SPECIFIC DTC information for DTC P0453 until DTC P0453 runs. Note result. If scan tool indicates DTC P0453 FAILED THIS IGNITION, go to step 6 . If scan tool indicates DTC P0453/P0108 FAILED THIS IGNITION, go to next step. If neither DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-97343-S25218028262001050100000) .
3. Turn ignition on. Measure voltage by backprobing between FTP sensor 5-volt reference circuit and sensor ground circuit at PCM connector. If about 4-6 volts are present, go to next step. If about 4-6 volts are not present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.
4. Measure voltage by backprobing between FTP sensor 5-volt reference circuit and sensor ground circuit at FTP sensor connector. If DVOM display reads between 4 and 6 volts and DTC P0453 is present, go to step 6 . If 4-6 volts are displayed and DTC P0108 is present, go to «DTC P0108: MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT, HIGH VOLTAGE»(ref-97343-S28670158232001050100000) test. If DVOM display does not read between 4 and 6 volts, go to next step.
5. Locate and repair open circuit on FTP sensor ground between FTP sensor and PCM. Retest system.
6. Turn ignition on. Backprobe with DVOM between ground and FTP sensor output circuit at PCM harness connector. If more than 4.9 volts are present, go to next step. If 4.9 volts or less are present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.
7. Backprobe with DVOM between ground and FTP sensor output circuit at FTP harness connector. If more than 4.9 volts are present, replace fuel tank pressure sensor. If 4.9 volts or less are present, locate open or short circuit in FTP sensor ground circuit.

Following components are included in Evaporative (EVAP) system

1. Fuel tank.
2. EVAP canister duty solenoid valve.
3. Fuel Tank Pressure (FTP) sensor.
4. Fuel pipes and hoses.
5. Vapor lines.
6. Fuel filler cap.
7. EVAP emissions canister.
8. Purge lines.
9. EVAP canister cut valve (purge solenoid). EVAP leak detection diagnostic strategy is based on applying vacuum to EVAP system and monitoring decay. PCM monitors vacuum level via Fuel Tank Pressure (FTP) sensor input. At an appropriate time, EVAP canister purge solenoid and EVAP canister vent solenoid are turned ON, allowing engine vacuum to draw a small vacuum on entire EVAP system. After a desired vacuum level has been reached, EVAP canister purge solenoid is turned OFF, sealing system. A leak is detected by monitoring for a decrease in vacuum level over a given period of time, all other variables remaining constant. A small leak in system will cause DTC P0456 to set. Conditions for setting DTC: No Throttle Position (TP) sensor, Intake Air Temperature (IAT) sensor or Manifold Absolute Pressure (MAP) sensor DTCs set. No Fuel Tank Pressure (FTP) sensor DTCs set. Barometer (BARO) is more than 70 kPa. A vacuum decay condition, indicating a very small leak, is detected during diagnostic test.

An intermittent may be caused by a cracked or punctured EVAP canister, damaged or disconnected vacuum, vent or purge line. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition off. Remove fuel cap. Turn ignition on. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 1.51 volts, go to next step. If scan tool display is not as specified, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000)
3. Check EVAP canister vent hose for damage or if disconnected. Check EVAP canister and fuel cap for damage. If problem is found, repair as necessary. Retest system. If problem is not found, go to next step.
4. Turn ignition on. Install fuel cap. Read and record scan tool FAIL RECORDS data. Operate vehicle within FAIL RECORDS conditions as recorded. Using scan tool, monitor DTC information for DTC P0456. If scan tool displays P0456, go to next step. If scan tool does not display DTC, see «DIAGNOSTIC AIDS»(ref-97343-S18615234872001050100000) .
5. Start engine and allow to idle. Using scan tool, command EVAP canister vent solenoid ON (closed). Using EVAP pressure/purge cart pressurize EVAP system to 15 in. H 2 O. Monitor EVAP pressure/purge cart pressure gauge. Turn EVAP pressure/purge cart rotary switch to HOLD position. If FUEL TANK PRESSURE reading drops more than 1.47-1.51 volts within 2 minutes, go to next step. If FUEL TANK PRESSURE reading drops within specification, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S26572890192001050100000) .
6. Using Ultrasonic Leak Detector (J41416), locate and repair EVAP system leak. It may be necessary to lower fuel tank to check connections at top of tank.

Fuel level sensor is an important input to PCM for enhanced evaporative system diagnostic. Fuel level information is needed for PCM to know volume of fuel in tank. Fuel level affects rate of change in air pressure in Evaporative (EVAP) system. Sending unit is a float in fuel tank which moves a wiper arm across a variable resister. Low fuel level causes high resistance in sending unit and this is recognized by PCM because circuit operates at a corresponding low voltage. When circuit is continuously open or has a high resistance connection, DTC P0461 is set. Conditions for setting DTC

1. Sensor output is changing more than 2 percent within 124 miles.
2. Intake air temperature is more than 32°F (0°C).
3. Manifold absolute pressure changing less than 10 kPa. in 3 seconds.
4. Engine speed changing less than 50 RPM in 3 seconds.

When there are 12 test failures within 80 test samples, DTC is stored.

Check for damaged wire harness. If wire harness appears okay, check for poor connections or loose terminals. Using scan tool, read FUEL LEVEL display while moving wire harness and connectors. Display will change when a fault is detected.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition off. Install scan tool. Turn ignition on and check for stored codes. If DTCs P0462, P0463 or P0464 are stored, go to «DTC P0462: FUEL LEVEL SENSOR CIRCUIT LOW VOLTAGE»(ref-97343-S04404426062001050100000) , «DTC P0463: FUEL LEVEL SENSOR CIRCUIT HIGH VOLTAGE»(ref-97343-S15520150462001050100000) or «DTC P0464: FUEL LEVEL SENSOR NOISY SIGNAL»(ref-97343-S10415939862001082000000) . If DTCs P0462, P0463 or P0464 are not stored, go to next step.
3. Turn ignition off. Replace fuel level sensor. Retest system.

Fuel level sensor is an important input to PCM for enhanced Evaporative EVAP system diagnostic. Fuel level information is needed for PCM to know volume of fuel in tank. Fuel level affects rate of change in air pressure in EVAP system. Several enhanced EVAP system diagnostic sub-tests are dependent upon correct fuel level information. Diagnostics will not run when fuel tank level is more than 85 percent, or less than 15 percent full. Fuel level DTCs should be diagnosed before other EVAP system DTCs because they can cause other DTCs to set. Sending unit is a float in fuel tank that moves a wiper arm across a variable resister. Low fuel level causes high resistance in sending unit. PCM recognizes this because circuit operates at a corresponding low voltage. When circuit is continuously open or has a high resistance connection, DTC is set. Conditions for setting code

1. Fuel tank level SLOSH TEST is completed.
2. Fuel tank level MAIN TEST is completed.
3. Fuel tank level data is valid.
4. Fuel tank level signal is less than specified value.
5. There are 100 test failures within a 200-test sample.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor fuel level display while moving connectors and harness related to fuel sensor. Change in display will indicate problem area.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. If any ECT or MAP sensor DTCs are set, diagnose them first. If no other DTCs are set, go to next step.
3. Disconnect fuel level sensor harness connector. Turn ignition on. Using a voltmeter, measure voltage at fuel level sensor harness connector between sensor harness positive and sensor ground terminals. See WIRING DIAGRAMS article. If reading is 5 volts, go to step 7 . If reading is not as specified, go to next step.
4. Using a voltmeter, backprobe between ground and fuel level sensor 5-volt reference circuit at PCM harness connector. If reading is 5 volts, go to next step. If reading is not as specified, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
5. Backprobe between ground and fuel level sensor 5-volt reference circuit at sensor. If reading is 5 volts, go to next step. If reading is not as specified, Check for open or short to ground on 5-volt reference circuit between fuel level sensor and PCM.
6. Check for an open or high resistance in sensor ground circuit between PCM and fuel level sensor. Repair as necessary. Retest system.
7. Remove fuel level sensor from fuel tank. Ensure sensor arm moves freely. Check wiring for an intermittent open circuit. Replace as necessary. If fuel level sensor tests okay, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Fuel level sensor is an important input to PCM for enhanced Evaporative EVAP system diagnostic. Fuel level information is needed for PCM to know volume of fuel in tank. Fuel level affects rate of change in air pressure in EVAP system. Several enhanced EVAP system diagnostic sub-tests are dependent upon correct fuel level information. Diagnostics will not run when fuel tank level is more than 85 percent, or less than 15 percent full. Fuel level DTCs should be diagnosed before other EVAP system DTCs because they can cause other DTCs to set. Sending unit is a float in fuel tank that moves a wiper arm across a variable resister. High fuel level causes low resistance in sending unit. PCM recognizes this because circuit operates at a corresponding high voltage. When circuit is continuously shorted to a voltage source more than a specified value, or when 5-volt signal is shorted to ground, DTC P0463 is set. Conditions for setting code

1. Fuel tank level SLOSH TEST is completed.
2. Fuel tank level MAIN TEST is completed.
3. Fuel tank level data is valid.
4. Fuel tank level signal is more than specified value.
5. There are 100 test failures within a 200-test sample.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor fuel level display while moving connectors and harness related to fuel sensor. Change in display will indicate problem area.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Disconnect fuel level sensor harness connector. Turn ignition on. Using a DVOM, measure voltage at fuel level sensor harness connector between sensor harness 5-volt reference and sensor ground terminals. See WIRING DIAGRAMS article. If reading is about 5 volts, go to step 7 . If reading is not as specified, go to next step.
3. Connect DVOM between ground and sensor ground circuit at fuel level sensor harness connector. If DVOM indicates a short to voltage, go to next step. If no short is detected, go to step 5 .
4. Repair short to voltage between fuel level sensor harness connector and PCM harness connector. Retest system.
5. With DVOM negative lead still connected to ground, connect DVOM positive lead to fuel level sensor harness connector 5-volt reference circuit. If reading is more than 5 volts, go back to step 4 . If reading is not as specified, go to next step.
6. Check 5-volt reference circuit for open circuit between fuel level sensor harness connector and PCM harness connector. Repair as necessary. If no problem was found, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.
7. Turn ignition off. Remove fuel level sensor from fuel tank. Ensure sensor arm moves freely. Check wiring for an intermittent open circuit. Replace fuel level sensor if operation is not as specified. If no problem was found, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Fuel level sensor is an important input to PCM for enhanced evaporative (EVAP) system diagnostic. Fuel level information is needed for PCM to know volume of fuel in tank. Fuel level affects rate of change in air pressure in Evaporative (EVAP) system. Sending unit is a float in fuel tank which moves a wiper arm across a variable resister. Low fuel level causes high resistance in sending unit and this is recognized by PCM because circuit operates at a corresponding low voltage. When circuit is continuously open or has a high resistance connection, DTC P0464 is set. Conditions for setting DTC

1. No fuel level DTCs set.
2. Fuel volume level is more than 3 percent.
3. Intake air temperature is more than 14°F (-10°C).
4. Engine is running.

When there are 40 test failures within 60 test samples, DTC is stored.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Using scan tool, monitor fuel level display while moving connectors and harness related to fuel sensor. Change in display will indicate problem area.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition off. Check for loose wire harness, cracked connector, poor wire condition, fuel tank condition and level sensor condition.
3. Turn ignition off. Remove fuel level sensor from fuel tank. Ensure sensor arm moves freely. Check wiring for an intermittent open circuit. Replace fuel level sensor if operation is not as specified. Retest system. If fuel sender is okay, Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Vehicle Speed Sensor (VSS) has a magnet rotated by transmission output shaft. Attached to sensor is a hall effect circuit that interacts with magnetic field created by a rotating magnet. METER fuse supplies 12 volts to VSS hall circuit. VSS pulses a 9-volt signal sent on reference circuit from PCM to ground. PCM interprets vehicle speed by monitoring number of pulses to ground on reference circuit. Conditions for setting DTC

1. Engine is running.
2. Engine speed is between 1800 and 2500 RPM.
3. Throttle angle is between 10 and 40 percent.
4. Engine load in more than 50 kPa.
5. PCM detects no VSS signal for 12.5 seconds over a period of 15 seconds.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Check speedometer. If speedometer works, go to step 10 . If speedometer does not work, go to next step.
3. Disconnect Vehicle Speed Sensor (VSS) harness connector and turn ignition on (with engine off). Connect test light to positive battery terminal. Probe VSS connector ground terminal. If test light illuminates, go to step 5 . If test light does not illuminate, go to next step.
4. Repair sensor ground. Retest system.
5. With VSS disconnected, turn ignition on. Using DVOM, probe VSS connector ground circuit and voltage supply circuit. If battery voltage is not displayed on DVOM, go to next step. If battery voltage is displayed, go to step 7 .
6. Repair open or short to ground. After repair ensure METER (15-amp) fuse is not blown. Retest system.
7. With sensor disconnected, turn ignition on. Using DVOM, measure voltage between VSS connector ground circuit and speedometer circuit. If DVOM reads about 7.5-8.0 volts, go to step 9 . If reading is not as specified, go to next step.
8. Repair open or short circuit between speedometer and VSS. Retest system.
9. Replace speedometer. Retest system.
10. Turn ignition off. Disconnect MAF sensor harness connector. Remove air cleaner assembly. Disconnect Black 16-pin connector located behind left headlight assembly. Connect fused jumper wire between battery voltage and Blue/Yellow wire on transmission side of 16-pin connector. Measure voltage between ground and Black 16-pin connector Light Green/White wire. Disconnect Blue connector located next to Black 16-pin connector. Connect jumper wire between VSS ground at Blue connector Black/Red wire and ground. Raise and support rear of vehicle. Place transmission in Neutral. Rotating rear wheels by hand, observe DVOM readings. If reading toggles between .6 and 10.0 volts, go to step 12 . If readings are not as specified, go to next step.
11. Replace VSS. Retest system.
12. Repair open or short between PCM harness connector and speedometer harness connector. Retest system. If problem was not found, go to next step.
13. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Information not available from manufacturer.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation at PCM and IAC motor. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Ensure air intake system is not restricted. Check throttle body for blockage and carbon build up. Clean as necessary. Inspect for a large vacuum leak at brake booster or PCV. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

Diagnostic testing procedure for DTC P0506 is not available from manufacturer.

PCM controls engine idle speed by adjusting position of Idle Air Control (IAC) motor pintle. IAC is a bi-directional stepper motor driven by 2 coils. PCM applies current to IAC coils in steps (counts) to extend IAC pintle into a throttle body passage to decrease air flow. To increase air flow PCM reverses current and retracts pintle. This method allows highly accurate control of idle speed and quick response to changes in engine load. If PCM detects a condition where too low an idle speed is present and PCM is unable to compensate for idle speed by increasing IAC counts, DTC P0506 is set. Conditions for setting DTC

1. No scan tool test is being run.
2. No Throttle Position (TP) sensor, Vehicle Speed Sensor (VSS), Engine Coolant Temperature (ECT) sensor, EGR, Mass Air Flow (MAF) sensor, Manifold Absolute Pressure (MAP) sensor, Intake Air Temperature (IAT) sensor, misfire, low voltage, fuel system, canister purge, injector control or ignition control DTCs are present.
3. Barometric (BARO) pressure is more than 75 kPa.
4. Canister purge duty cycle is more than 10 percent.
5. Engine running time is more than 125 seconds.
6. Vehicle speed is less than one MPH.
7. Engine coolant temperature is more than 122 °F (50°C).
8. Ignition voltage is between 9.5 and 16.7 volts.
9. Throttle is closed.
10. EVAP purge duty cycle is more than 10 percent.
11. Engine speed is more than 100-200 RPM less than desired idle, based upon engine coolant temperature.
12. All conditions are present for 10 seconds.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation at PCM and IAC motor. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Ensure air intake system is not restricted. Check throttle body for blockage and carbon build up. Clean as necessary. Inspect for a large vacuum leak at brake booster or PCV. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose them first before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, then back up to 1500 RPM. If ENGINE SPEED remains within 50 RPM of desired RPM for each command, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S36347327222001050100000) . If operation is not as specified, go to next step.
4. Disconnect Idle Air Control (IAC) harness connector. Install IAC Noid-Light (J37027A) in IAC harness connector. With engine running, monitor IAC noid-lights while commanding engine speed up to 1500 RPM, down to 500 RPM, then back up to 1500 RPM. Both noid-lights should cycle Green and Red, but not OFF as RPM changes from 500 to 1500 RPM. If IAC noid-lights cycle as specified, go to step 6 . If IAC noid-lights do not cycle as specified, go to next step.
5. Check IAC "A" high and low and "B" high and low circuits for an open, short to voltage, short to ground or poor connection at PCM. If a problem is found, repair as necessary. Retest system. If no problem is found, go to step 9 .
6. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Check for restrictions, collapse or blockage in air intake system. Check throttle body bore and IAC valve for excessive deposits. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
7. Check for faulty connection at IAC valve harness connector. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to next step.
8. Replace IAC valve. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Information not available from manufacturer.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation at PCM and IAC motor. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Check for sticking throttle valve. Check IAC passage for deposits that would prevent IAC pintle from seating. Check for vacuum leak. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

Diagnostic testing procedure for DTC P0507 is not available from manufacturer.

PCM controls engine idle speed by adjusting position of Idle Air Control (IAC) motor pintle. IAC is a bi-directional stepper motor driven by 2 coils. PCM applies current to IAC coils in steps (counts) to extend IAC pintle into a throttle body passage to decrease air flow. To increase air flow PCM reverses current and retracts pintle. This method allows highly accurate control of idle speed and quick response to changes in engine load. If PCM detects a condition where too high an idle speed is present and PCM is unable to compensate for idle speed by decreasing IAC counts, DTC P0507 is set. Conditions for setting DTC

1. No intrusive scan tool tests are being run.
2. Engine run time is more than 125 seconds.
3. No Engine Coolant Temperature (ECT) sensor, EGR, canister purge, Ignition control, Injector control, Intake Air Temperature (IAT) sensor, Mass Air Flow (MAF) sensor, Manifold Absolute Pressure (MAP) sensor, Throttle Position (TP) sensor, Vehicle Speed Sensor (VSS), misfire, low voltage or fuel system DTCs are present.
4. Barometric (BARO) pressure is more than 72.7 kPa.
5. Canister purge duty cycle is above 10 percent.
6. Vehicle speed is less than one MPH.
7. Engine coolant temperature (ECT) is more than 122°F (50°C).
8. Ignition voltage is between 9.5 and 16.0 volts.
9. Throttle is closed.
10. EVAP purge duty cycle is more than 10 percent.
11. All conditions are met for 10 seconds.
12. Engine speed is more than 100-200 RPM more than desired idle based upon coolant temperature.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation at PCM and IAC motor. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Check for sticking throttle valve. Check IAC passage for deposits that would prevent IAC pintle from seating. Check for vacuum leak. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose them first before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, then back up to 1500 RPM. If ENGINE SPEED remains within 50 RPM of desired RPM for each command, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S35067338792001050100000) . If operation is not as specified, go to next step.
4. Disconnect IAC harness connector. Install IAC Noid-Light (J37027A) in IAC harness connector. With engine running, monitor noid-lights while commanding engine speed up to 1500 RPM, down to 500 RPM, then back up to 1500 RPM. Both IAC noid-lights should cycle Green and Red, but not OFF as RPM changes from 500 to 1500 RPM. If IAC noid-lights flash as specified, go to step 6 . If noid-lights do not flash as specified, go to next step.
5. Check IAC "A" high and low and "B" high and low circuits for an open, short to voltage or short to ground. If a problem is found, repair as necessary. Retest system. If no problem is found, go to step 9 .
6. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Ensure no vacuum leaks are present. Check for binding throttle shaft or cruise control cables. Check for incorrectly installed PCV valve. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
7. Check for faulty connection at IAC valve harness connector. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to next step.
8. Replace IAC valve. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM monitors system voltage on ignition feed terminal to PCM. A system voltage DTC will set any time voltage is less than calibrated value. Conditions for setting DTC

1. Ignition on.
2. System voltage is less than 11.5 volts for 15 minutes.

If DTC sets when an accessory is operated, check component for poor connection or excessive current draw.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Using DVOM, measure voltage at battery. If reading is more than 11.5 volts, go to next step. If reading is 11.5 volts or less, charge battery before proceeding to next step.
3. Install scan tool and select IGNITION VOLTS. Place vehicle in Neutral or Park. Start engine, raise engine speed to 2000 RPM and load electrical system (turn on headlights, high blower, etc.). If scan tool reads 12.8-14.1 volts, go to next step. If reading is not as specified, see appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.
4. Turn ignition off. Disconnect PCM harness connector. Using a DVOM, check for battery voltage at PCM harness connector ignition feed circuit (White wires on Trooper and VehiCROSS, Red/White wire on Passport, Rodeo and Rodeo Sport). If output is equal to battery voltage, check for excessive current draw with ignition off. If voltage is not equal to battery voltage, go to next step.
5. Check for poor connections at PCM harness terminals. Repair as necessary. Retest system. If no problem is found, go to next step.
6. Check for an open battery feed circuit to PCM. Repair as necessary. Retest system. If no problem is found, go to next step.
7. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM monitors system voltage on ignition feed terminal to PCM. A system voltage DTC will set any time voltage is more than calibrated value. Conditions for setting DTC

1. Ignition on.
2. System voltage is more than 16.0 volts for 15 minutes.

If DTC sets when an accessory is operated, check component for poor connection or excessive draw.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Using DVOM, measure voltage at battery. If reading is less than 11.5 volts, go to next step. If reading is 11.5 volts or more, go to step 4 .
3. Charge battery and clean terminals and cable connections. If voltage is less than 11.5 volts, replace battery. If voltage is 11.5 volts or more, go next step.
4. Turn all accessories off. Install scan tool and select ignition voltage parameter. Place vehicle in Park or Neutral. Start engine and increase engine speed to 2000 RPM. If scan tool reading is more than 2.5 volts more than voltage measured in step 2 or 3 , see appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If voltage is not as specified, go to next step.
5. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. After repair is completed, repeat OBD system check.

PCM detects inconsistencies between multiple CPU systems located inside the PCM. Conditions for setting DTC

1. Inconsistencies between individual CPUs will set DTC P0602.
2. Inconsistencies between individual CPU RAMs will set DTC P0604.
3. Inconsistencies between individual CPU A/D converters will set DTC P0606.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. After repair is completed, repeat OBD system check.

Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). MAP sensor signal voltage to PCM varies from less than 2 volts at idle (high vacuum) to more than 4 volts with ignition on, engine not running or at wide open throttle (low vacuum). MAP sensor is used to determine manifold pressure changes while liner EGR flow test diagnostic is being performed, to determine engine vacuum level for some other diagnostics and to determine barometric (BARO) pressure. See DTC P0401: EGR FLOW INSUFFICIENT diagnostic procedure. PCM compares MAP sensor signal to a calculated MAP based on throttle position and various engine load factors. If PCM detects a MAP signal that is intermittently more than calculated value, DTC P1106 is set. Conditions for setting DTC

1. No Throttle Position (TP) sensor DTCs are present.
2. Engine is running for at least 10 seconds.
3. Throttle angle is less than 3 percent if engine speed is less than 1000 RPM.
4. Throttle angle is less than 10 percent if engine speed is more than 1000 RPM.
5. MAP sensor indicates an intermittent manifold absolute pressure of more than 80 kPa for a total of about 5 seconds over a 16-second period of time.

Inspect Manifold Absolute Pressure (MAP) sensor line for leakage or being plugged. Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe MAP sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. Check for vacuum leak. If DTC P1106 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TEST FAIL. Record any other failed DTCs. If DTC P0108 is also set, diagnose DTC P0108 before proceeding. If DTC is not set, go to next step.
3. If DTC P1111, P1115, or P1121 is also set, go to step 6 . If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal at MAP sensor harness connector. If problem is found, go to step 9 . If no problem is found, go to next step.
5. Check MAP sensor signal circuit between MAP sensor harness connector and PCM for intermittent short to voltage. If a problem is found, go to step 10 . If no problem is found, go to step 8 .
6. Check for intermittent short to voltage on 5-volt reference circuit between PCM and MAP, EGR and TP sensors. If a problem is found, go to step 10 . If no problem is found, go to next step.
7. Check for faulty ground circuit terminal connection at PCM harness connector. If problem is found, go to step 9 . If no problem is found, go to next step.
8. Check for intermittent open or faulty splice in sensor ground circuit. If a problem is found, go to step 10 . If no problem is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S11990959492001050100000) .
9. Replace faulty PCM harness connector terminal for sensor ground circuit. See WIRING DIAGRAMS article. Retest system.
10. Locate and repair intermittent open/short circuit in wire harness. Retest system.

Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). MAP sensor signal voltage to PCM varies from less than 2 volts at idle (high vacuum) to more than 4 volts with ignition on, engine not running or at wide open throttle (low vacuum). MAP sensor is used to determine manifold pressure changes while liner EGR flow test diagnostic is being performed, to determine engine vacuum level for some other diagnostics and to determine barometric (BARO) pressure. For description, see DTC P0401: EGR FLOW INSUFFICIENT diagnostic procedure. PCM compares MAP sensor signal to a calculated MAP based on throttle position and various engine load factors. If PCM detects a MAP signal that is intermittently more than calculated value, DTC P1106 is set. Conditions for setting DTC

1. No Throttle Position (TP) sensor DTCs are present.
2. Engine is running.
3. Ignition voltage is more than 11 volts.
4. Throttle angle is more than one percent if engine speed is less than 1000 RPM.
5. Throttle angle is more than 2 percent if engine speed is more than 1000 RPM.
6. MAP sensor indicates an intermittent manifold absolute pressure of more than 11 kPa for a total of about 5 seconds over a 16-second period of time.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe MAP sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC P1107 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TEST FAIL. Record any other failed DTCs. If DTC P0107 is also set, diagnose DTC P0107 before proceeding. See «DTC P0107: MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT, LOW VOLTAGE»(ref-97343-S26471712482001050100000) . If DTC is not set, go to next step.
3. Check for faulty 5-volt reference or signal circuit terminal connection at MAP sensor harness connector. If a problem is found, go to step 8 . If no problem is found, go to next step.
4. Check MAP signal circuit between MAP sensor harness connector and PCM harness connector for intermittent open or short to ground. If problem is found, go to step 9 . If no problem is found, go to step 7 .
5. Check for intermittent short to ground on 5-volt reference circuit between PCM and EGR valve, MAP and TP sensors. If a problem is found, go to step 9 . If no problem is found, go to next step.
6. Check for faulty 5-volt reference circuit connection at PCM. If faulty connection is found, go to step 8 . If connection is okay, go to next step.
7. Check for intermittent open or faulty splice in 5-volt reference circuit. If a problem is found, go to step 9 . If no problem is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S21690770902001050100000) .
8. Replace faulty harness connector terminal(s) for 5-volt reference circuit and/or MAP signal circuit as necessary. Retest system.
9. Repair open or short circuit in wire harness as necessary. Retest system.

Intake Air Temperature (IAT) sensor is a thermistor which measures temperature of air entering engine. PCM applies 5 volts through pull-up resister to IAT sensor. When intake air is cold, IAT sensor resistance is high causing high signal circuit voltage. When intake air is warm, IAT sensor resistance is low causing low signal circuit voltage. PCM monitors IAT sensor signal circuit. If PCM intermittently detects an excessively high IAT signal circuit voltage, DTC P1111 will set. Conditions for setting DTC

1. Engine has been running for over 4 minutes.
2. Vehicle speed is less than 32 MPH.
3. Engine coolant temperature is more than 140°F (60°C).
4. Mass air flow is less than 20 grams/sec.
5. IAT signal voltage indicates intake air temperature intermittently less than -38°F (-39°C), about 5 volts, for about 2.5 seconds over a 25-second period of time.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe IAT sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC P1111 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Using scan tool, select LAST TEST FAIL. Record any other failed DTCs. If DTC P0113 is also set, diagnose DTC P0113 before proceeding. See «DTC P0113: INTAKE AIR TEMPERATURE CIRCUIT, HIGH VOLTAGE»(ref-97343-S17708061502001050100000) . If DTC is not set, go to next step.
3. If DTC P1106, P1115, and/or P1121 is also set, go to step 6 . If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal at Intake Air Temperature (IAT) sensor. If problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
5. Check for faulty signal circuit connection at IAT sensor. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to next step.
6. Check IAT signal circuit between IAT sensor harness connector and PCM harness connector for intermittent open. If open is found, repair as necessary. Retest system. If no open is found, go to next step.
7. Check IAT signal circuit between IAT sensor harness connector and PCM harness connector for intermittent short to voltage. If short to voltage is found, repair as necessary. Retest system. If no short to voltage is found, go to next step.
8. Check for faulty ground circuit terminal connection at PCM harness connector. If problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
9. Check for intermittent open or faulty splice in IAT sensor ground circuit. If a problem is found, repair as necessary. Retest system. If no problem is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S02754306742001050100000) .

Intake Air Temperature (IAT) sensor is a thermistor which measures temperature of air entering engine. PCM applies 5 volts through pull-up resister to IAT sensor. When intake air is cold, IAT sensor resistance is high causing high signal circuit voltage. When intake air is warm, IAT sensor resistance is low causing low signal circuit voltage. PCM monitors IAT sensor signal circuit. If PCM intermittently detects an excessively low IAT signal circuit voltage, DTC P1112 will set. Conditions for setting DTC

1. Engine has been running for more than 2 minutes.
2. Vehicle speed is more than 30 MPH.
3. IAT signal voltage is more than 298°F (148°C), about 0.10 volts, for a total of 2.5 seconds over a 25-second period of time.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe IAT sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC P1112 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If DTC P0112 is also set, diagnose DTC P0112 before proceeding. See «DTC P0112: INTAKE AIR TEMPERATURE CIRCUIT, LOW VOLTAGE»(ref-97343-S23506199112001050100000) . If DTC is not set, go to next step.
3. Check Intake Air Temperature (IAT) sensor signal circuit between IAT sensor harness connector and PCM harness connector for intermittent short to ground. If short to ground is found, repair as necessary. Retest system. If no short to ground is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S41777031522001050100000) .

Engine Coolant Temperature (ECT) sensor is a thermistor mounted in engine coolant stream. PCM applies about 5 volts through a pull-up resister to ECT signal circuit. When engine coolant is cold, ECT sensor resistance and voltage signal are high. As engine coolant warms, ECT sensor resistance and voltage signal are low. With engine fully warmed up, ECT signal voltage should measure about 1.5-2.0 volts. If PCM detects an ECT signal that is intermittently less than specified, DTC P1114 will set. Condition for setting DTC

1. Engine running for more than 60 seconds.
2. ECT sensor signal is intermittently more than 302°F (150°C), 0.10 volts for a total of 10 seconds over a 100-second period of time.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation at PCM and IAC motor. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. If DTC P0117 is also set, diagnose DTC P0117 before proceeding. See «DTC P0117: ENGINE COOLANT TEMPERATURE CIRCUIT, LOW VOLTAGE»(ref-97343-S16135797792001050100000) . If DTC is not set, go to next step.
3. Check ECT sensor signal circuit between ECT sensor harness connector and PCM harness connector for intermittent short to ground. If short to ground is found, repair as necessary. Retest system. If no short to ground is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S34588018712001050100000) .

Engine Coolant Temperature (ECT) sensor is a thermistor mounted in engine coolant stream. PCM applies about 5 volts through a pull-up resister to ECT signal circuit. When engine coolant is cold, ECT sensor resistance and voltage signal are high. As engine coolant warms, ECT sensor resistance and voltage signal are low. With engine fully warmed up, ECT signal voltage should measure about 1.5-2.0 volts. If PCM detects an ECT signal that is intermittently less than specified, DTC P1115 will set. Condition for setting DTC

1. Engine running for more than 60 seconds.
2. ECT sensor signal is intermittently more than -38°F (-39°C), 5 volts for a total of 10 seconds over a 100-second period of time.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation . Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC P1115 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If DTC P0118 is also set, diagnose DTC P0118 before proceeding. See «DTC P0118: ENGINE COOLANT TEMPERATURE CIRCUIT, HIGH VOLTAGE»(ref-97343-S08452785862001050100000) . If DTC is not set, go to next step.
3. If DTC P1106, P1111, or P1121 is also set, go to step 8 . If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal connection at ECT sensor harness connector. If problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
5. Check for faulty signal circuit connection at ECT sensor harness connector. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to next step.
6. Check ECT signal circuit between ECT sensor harness connector and PCM harness connector for intermittent open. If open circuit is found, repair as necessary. Retest system. If no open is found, go to next step.
7. Check ECT signal circuit between ECT sensor harness connector and PCM harness connector for intermittent short to voltage. If short to voltage is found, repair as necessary. Retest system. If no short to voltage is found, go to next step.
8. Check for faulty ground circuit terminal connection at PCM. If problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
9. Check for intermittent open or faulty splice in sensor ground circuit. If a problem is found, repair as necessary. Retest system. If no problem is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S19638206282001050100000) .

Throttle Position Sensor 1 (TPS1) circuit provides a voltage signal relative to throttle valve position. Throttle valve angle will vary from about 8 percent at closed throttle to about 92 percent at Wide Open Throttle (WOT). PCM detects a continuous short to ground or high resistance in either circuit or sensor. Condition for setting DTC

1. Ignition is on.
2. Throttle blade angle is less than 2.5 percent or more than 97.5 percent for 18 failures within 500 test samples.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation . Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe TPS1 display while moving connectors and harnesses. A change in display will indicate location of fault. If DTC P1120 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Turn ignition on. Observe MAP reading on scan tool. If MAP reading is less than 65 kPa, go to next step. If MAP reading is not as specified, go to step 6 .
3. Disconnect MAP sensor harness connector. Using fused jumper wire, connect harness connector 5-volt reference circuit to MAP signal circuit at MAP sensor harness connector. See WIRING DIAGRAMS article. Observe MAP reading on scan tool. If 5 volts is not present, check other sensors on reference circuit for 5 volts. Repair as necessary. If MAP sensor reading is less than 5 volts, go to step 5 . If MAP sensor reading is not as specified, go to next step.
4. Check MAP sensor signal circuit between PCM harness connector and MAP sensor harness connector. If MAP signal circuit is shorted or open, repair as necessary. If MAP signal wire is not shorted to ground or open, go to step 12 .
5. Replace MAP sensor. Retest system.
6. Using scan tool, observe TPS1 angle while slowly opening throttle. TPS1 angle should increase steadily and smoothly from closed value (8 percent) to WOT value (92 percent). If TPS1 operates as specified, see «DIAGNOSTIC AIDS»(ref-97343-S19638206282001050100000) . If TPS1 operates as specified, go to next step.
7. Disconnect TPS1 harness connector. Using scan tool, observe TPS1 reading. If TPS1 reading is zero percent, go to next step. If TPS1 reading is not as specified, go to step 9 .
8. Connect test light between 5-volt reference circuit and TPS1 signal circuit at TPS1 harness connector. See WIRING DIAGRAMS article. Using scan tool, observe TPS1 reading. If TPS1 reading is 5 volts, go to step 11 . If TPS1 reading is not as specified, go to step 10 .
9. Check TPS1 signal circuit for a short to voltage. Check TPS1 sensor ground circuit for high resistance or faulty connection between PCM harness connector and TPS1 sensor harness connector. If problem is present, repair as necessary. Retest system. If problem is not present, go to step 12 .
10. Check TPS1 signal circuit or 5-volt reference circuit for faulty connection or high resistance between PCM harness connector and TPS1 sensor harness connector. If problem is present, repair as necessary. Retest system. If problem is not present, go to step 12 .
11. Replace TP sensor. Retest system.
12. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Throttle Position (TP) sensor circuit provides voltage signal that changes relative to throttle blade angle. Signal voltage will vary from about 0.6 volts at closed throttle to about 4.5 volts at wide open throttle (WOT). TP signal is the most important inputs used by PCM for fuel control and for most PCM controlled outputs. If PCM detects a TP signal that is intermittently more than TP sensor range, DTC P1121 will set. Conditions for setting code

1. Ignition is on.
2. TP sensor indicates throttle position voltage intermittently more than 4.9 volts for a total of 0.15 seconds over a 1.5-second period.

Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe TP sensor display while moving connectors and harnesses. A change in display will indicate location of fault. If DTC 1121 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. If DTC P0123 is also set, diagnose DTC P0123 before proceeding. See «DTC P0123: THROTTLE POSITION SENSOR CIRCUIT, LOW VOLTAGE»(ref-97343-S07314898212001050100000) . If DTC is not set, go to next step.
3. If DTC P1106, P1111, or P1115 is also set, go to step 6 . If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal connection at Throttle Position (TP) sensor harness connector. If problem is found, go to step 9 . If no problem is found, go to next step.
5. Check TP signal circuit between TP sensor harness connector and PCM harness connector for intermittent short to voltage. If a problem is found, go to step 10 . If no problem is found, go to step 8 .
6. Check for intermittent short to voltage on 5-volt reference circuit between PCM and MAP, EGR and TP sensors. If a problem is found, go to step 10 . If no problem is found, go to next step.
7. Check for faulty sensor ground circuit terminal connection at PCM. If problem is found, go to step 9 . If no problem is found, go to next step.
8. Check for intermittent open or faulty splice in sensor ground circuit. If a problem is found, go to step 10 . If no problem is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S26239005982001050100000) .
9. Replace faulty harness connector terminal for sensor ground circuit. Retest system.
10. Locate and repair intermittent open or short circuit in wiring harness. Retest system.

Throttle Position (TP) sensor circuit provides voltage signal that changes relative to throttle blade angle. Signal voltage will vary from about 0.6 volts at closed throttle to about 4.5 volts at wide open throttle (WOT). TP signal is the most important inputs used by PCM for fuel control and for most PCM controlled outputs. If PCM detects a TP signal that is intermittently less than TP sensor range, DTC P1122 will set. Conditions for setting code

1. Ignition is on.
2. TP sensor indicates throttle position voltage intermittently less than 0.22 volts for a total of 0.15 seconds over a 1.5-second period.

Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC P1122 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. If DTC P0122 is also set, diagnose DTC P0122 before proceeding. See «DTC P0122: THROTTLE POSITION SENSOR CIRCUIT, LOW VOLTAGE»(ref-97343-S29228762202001050100000) . If DTC is not set, go to next step.
3. If DTC P1107 is also set, go to step 6 . If DTC is not set, go to next step.
4. Check for faulty 5-volt reference or signal circuit connections at Throttle Position (TP) sensor harness connector. If a problem is found, go to step 9 . If no problem is found, go to next step.
5. Check TP sensor signal circuit between TP sensor and PCM for intermittent open or short to ground. If problem is found, go to step 10 . If no problem is found, go to step 8 .
6. Check for intermittent short to ground on 5-volt reference circuit between PCM and EGR, MAP and TP sensors. See WIRING DIAGRAMS article. If a problem is found, go to step 10 . If no problem is found, go to next step.
7. Check for faulty 5-volt reference circuit connection at PCM. If faulty connection is found, go to step 9 . If connection is okay, go to next step.
8. Check for intermittent open or faulty splice in 5-volt reference circuit. If a problem is found, go to step 10 . If no problem is found, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S09248211022001050100000) .
9. Replace faulty connector terminal(s) for 5-volt reference or signal circuit. Retest system.
10. Repair intermittent open or short circuit in wiring harness as necessary. Retest system.

Acceleration Position Sensor (APS 1) circuit provides a voltage signal relative to acceleration pedal angle. Acceleration position angle will vary about 13 percent at idle position to about 87 percent at Wide Open Throttle (WOT). PCM detects if acceleration position system is in Limited Performance Mode (Fail Safe Mode). Conditions for setting DTC

1. Ignition is on.
2. Limited Performance Mode (Fail Safe Mode) is active.

Intermittent problem may be caused by poor connections, misrouted harness, rubbed through wire insulation, broken wire inside insulation. Check for faulty connection PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connection. Check for wire harness damage. Using scan tool, observe display for AP sensors 1, 2 and 3 while moving wire harness connectors and wire harnesses related to AP sensors. A change in display will indicate location of fault. If DTC P1125 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) . Go to next step.
3. Using scan tool, observe AP angle values. At idle position, APS1 value equals 13 percent, APS2 and 3 equal 85-89 percent. Slowly move acceleration pedal to WOT. APS angle values should increase steadily and smoothly. At WOT APS 1 value should be 85-89 percent, APS2 value should be 11-15 percent, AP sensor 3 value should be 32-36 percent. If AP sensor values are as specified, see «DIAGNOSTIC AIDS»(ref-97343-S23347967202001091300000) . If AP sensor values are not as specified, go to next step.
4. Disconnect faulty AP sensor. Using scan tool, observe AP sensor value. If AP sensor value is about zero percent, got to next step. If AP sensor value is not a specified, go to step 6 .
5. Connect test light between APS 5-volt supply circuit and signal circuit at individual APS harness connectors. Using scan tool, observe AP sensor display. If APS values each read about 5 volts, go to step 7 . If AP sensor readings are not as specified, go to step 8 .
6. Check individual APS signal circuits for a short to voltage. Check individual AP sensor ground circuits for faulty connection or high resistance between PCM harness connector and APS connectors. See WIRING DIAGRAMS article. If problem is present, repair wiring as necessary and retest system. If problem are not present, go to step 9 .
7. Check individual AP signal or 5-volt supply circuits for faulty connections or high resistance between PCM harness connector and AP sensor harness connectors. If problem is present, repair wiring as necessary and retest system. If problem is not present, go to step 9 .
8. Replace Faulty AP sensor. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. If any DTC other than P1153 or P1154 sets, diagnose affected DTC before proceeding. If no other DTCs are set, start engine and allow it to idle. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1133 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1133 FAILED THIS IGN, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S06509434492001050100000) .
3. If DTC P1153 or P1154 is also set, go to step 11 . If DTC is not set, go to next step.
4. Check exhaust system for leaks. If any exhaust leaks are found, repair as necessary and go to step 2 . If no exhaust leak is found, go to next step.
5. Tighten bolts or nuts at leaking joints. Retest system.
6. Disconnect HO2S-1 Bank-1 connector. Connect a DVOM to PCM side of HO2S-1 Bank-1 connector between high signal circuit and ground, and low signal circuit and ground. Turn ignition on and read DVOM at each connection. If reading is 3-4 millivolts, go to step 9 . If voltage is not as specified, go to next step.
7. Turn ignition off and check for damage to PCM pins or terminals. If a problem was found, repair as necessary. Retest system. If no problem was found, go to next step.
8. Inspect signal circuit for a short to voltage, ground or an open. If problem was found repair as necessary. Retest system. If no problem was found, go to next step.
9. With ignition off, disconnect PCM connector. Disconnect HO2S-1 Bank-1 and check for continuity between high and low signal circuits between PCM and HO2S-1 Bank-1. If continuity is present between high and low signal circuits, repair short as necessary. Retest system. If no problem was found, go to next step.
10. Connect PCM and disconnect HO2S-1 Bank-1. Using scan tool, check HO2S-1 Bank-1 voltage. If reading is 425-475 millivolts, go to step 12 . If voltage is not as specified, go to step 13 .
11. Check for fuel contamination, use of improper RTV sealant or engine oil and coolant consumption. Replace affected HO2S. Retest system.
12. Replace HO2S-1 Bank-1. Retest system.
13. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any DTC other than P1153 or P1154 sets, diagnose affected DTC before proceeding. If no other DTC sets, start engine and allow it to idle. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1134 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1134 FAILED THIS IGN, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S07957069722001050100000) .
3. If DTC P1153 or P1154 is also set, go to step 11 . If DTC is not set, go to next step.
4. Check exhaust system for leaks. If exhaust leak is found, repair as necessary. Retest system. If no exhaust leak is found, go to next step.
5. Visually inspect HO2S-1 Bank-1 for secure installation or corrosion on terminals. Check terminal tension at HO2S-1 Bank-1 and PCM. Check for damaged wiring. If a problem is found, go to step 8 . If no problem is found, go to next step.
6. Disconnect HO2S-1 Bank-1 connector. Turn ignition on. Using DVOM, probe connector, measure voltage between high and low signal circuits and ground. If DVOM reads 3-4 volts, go to next step. If voltage is not as specified, go to step 9 .
7. Turn ignition off. With HO2S-1 Bank-1 disconnected, connect jumper wires between HO2S-1 Bank-1 harness connector high and low signal circuits and ground. Turn ignition on. If scan tool reading increases from less than 10 millivolts to about 450 millivolts when jumper is removed, replace HO2S-1 Bank-1. Retest system. If voltage does not change as specified, go to step 12 .
8. Repair condition as necessary. Retest system.
9. Check for faulty PCM connections or terminal damage. Repair as necessary. Retest system. If no problem is found, go to next step.
10. Repair open, grounded or shorted signal circuit. Retest system. If no problem is found, go to step 7 .
11. Remove HO2S-1 Bank-1 and check it for fuel contamination, improper RTV sealant (white powdery coating on sensor) and engine oil or coolant contamination. Replace HO2S-1 Bank-1 if contaminated. Retest system.
12. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any DTC other than P1133 or P1134 sets, diagnose affected DTC before proceeding. If no other DTC sets, start engine and allow it to idle. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1153 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1153 FAILED THIS IGN, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S03477250562001050100000) .
3. If DTC P1133 or P1134 is also set, go to step 11 . If DTC is not set, go to next step.
4. Check exhaust system for leaks. If exhaust leak is found, repair as necessary and go to step 2 . If no exhaust leak is found, go to next step.
5. Visually inspect HO2S-1 Bank-2 for secure installation or corrosion on terminals. Check terminal tension at HO2S-1 Bank-2 and PCM. Check for damaged wiring. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
6. Disconnect HO2S-1 Bank-2 connector. Connect a DVOM to PCM side of HO2S-1 Bank-2 connector between high and low signal circuits and ground. Turn ignition on and read DVOM at each connection. If reading is 3-4 volts, go to step 9 . If voltage is not as specified, go to next step.
7. Turn ignition off and check for damage to PCM pins or terminals. If a problem was found repair as necessary. Retest system. If no problem was found, go to next step.
8. Inspect signal circuit for a short to voltage, ground or an open. If problem was found repair as necessary. Retest system. If no problem was found, go to next step.
9. With ignition off, disconnect PCM connector. Disconnect HO2S-1 Bank-2 and check high and low signal circuits between PCM and HO2S-1 Bank-2 for shorting together. If a problem was found, repair as necessary. Retest system. If no problem was found, go to next step.
10. Connect PCM and disconnect HO2S-1 Bank 2. Using scan tool, check HO2S-1 Bank-2 voltage. If reading is 425-475 millivolts, go to step 12 . If voltage is not as specified, go to step 13 .
11. Check for fuel contamination, use of improper RTV sealant or engine oil and coolant contamination. Replace HO2S-1 Bank-2 if contaminated. Retest system.
12. Replace HO2S 1 Bank-2. Retest system.
13. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any DTC other than P1133 or P1134 sets, diagnose affected DTC before proceeding. If no other DTC sets, start engine and allow it to idle. Operate vehicle within conditions required to set DTC. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P1154 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1154 FAILED THIS IGN, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S00908904232001050100000) .
3. If DTC P1133 or P1134 is also set, go to step 11 . If DTC is not set, go to next step.
4. Check exhaust system for leaks. If exhaust leak is found, repair as necessary. Retest system. If no exhaust leak is found, go to next step.
5. Visually inspect HO2S-1 Bank-2 for secure installation or corrosion on terminals. Check terminal tension at HO2S-1 Bank-2 and PCM. Check for damaged wiring. If a problem is found, go to step 8 . If no problem is found, go to next step.
6. Disconnect HO2S-1 Bank-2 connector. Turn ignition on. Using DVOM, measure voltage at PCM side of connector between high and low signal circuit and ground. If DVOM reads 3-4 volts, go to next step. If voltage is not as specified, go to step 9 .
7. Turn ignition off. With HO2S-1 Bank-2 disconnected, connect jumper wires between HO2S-1 Bank-2 harness connector high signal and ground, and between low signal and ground. Turn ignition on. If scan tool reading jumps from less than 10 millivolts to about 450 millivolts when jumper wire is removed, go to step 11 . If voltage does not change as specified, go to step 12 .
8. Repair condition as necessary. Retest system.
9. Check for poor PCM harness connections or terminal damage. Repair as necessary. Retest system. If no problem is found, go to next step.
10. Repair open, grounded or shorted signal circuit. Retest system. If no problem is found, go to step 7 .
11. Remove HO2S-1 Bank-2 and check it for fuel contamination, improper RTV sealant (white powdery coating on sensor) and engine oil or coolant contamination. Repair as necessary. Replace HO2S-1 Bank-2 if contaminated. Retest system.
12. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM continuously monitors Heated Oxygen Sensor (HO2S) activity for 90 seconds after closed loop has been enabled. During this test period, PCM counts number of times HO2S signal voltage crosses rich-to-lean and lean-to-rich threshold and how long it took to complete all transitions. PCM detects if HO2S-1 Bank-1 indicated a rich exhaust condition while in Decel Fuel Cut Off (DFCO) for fuel control sensors. Condition for setting DTC

1. No related DTCs set.
2. Engine coolant temperature is more than 140°F (60°C).
3. Engine is in closed loop power enrichment mode for 3 seconds.
4. While in power enrichment mode oxygen sensor voltage remains more than 600 millivolts in DFCO.

A restricted fuel system may provide adequate fuel supply at idle, but not during acceleration. Water or alcohol in fuel may cause low HO2S voltage during acceleration. Check for defective or plugged fuel injectors or fuel pump. Check for low fuel.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any other component-related DTCs are set, diagnose them first. If no other DTC is present, go to next step.
3. Start vehicle and bring engine to normal operating temperature 167-203°F (75-95°C). Increase engine speed to 1200 RPM. Using scan tool, observe HO2S-1 Bank-2 voltage. If scan tool reading varies between 100 and 600 millivolts and voltage increases suddenly when throttle is quickly opened to WOT a few times, see OBD II SYSTEM CHECK in BASIC DIAGNOSTICS PROCEDURE article. If voltage reading is not as specified, go to next step.
4. Remove fuel pump relay and crank engine to relieve fuel pressure. Install fuel pressure gauge. Replace fuel pump relay and start engine, bring engine to normal operating temperature and allow it to idle. Disconnect vacuum line to fuel pressure regulator and read pressure gauge. If pressure is 41-46 psi (2.9-3.2 kg/cm 2 ), see OBD II SYSTEM CHECK in BASIC DIAGNOSTICS PROCEDURE article. If pressure reading is not as specified, go to next step.
5. Turn ignition off. Remove fuel pump relay. Connect fused jumper wire between fuel pump relay battery feed terminal and fuel pump fuse terminal. With fuel pressure gauge still connected, pinch off fuel return line. Do not allow fuel pressure to exceed 60 psi (4.2 kg/cm 2 ). Manipulate fuel line to raise pressure to more than 46 psi (3.2 kg/cm 2 ). If pressure increases to more than 46 psi (3.2 kg/cm 2 ), check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S27508068832001091400000) . If pressure does not increase to 46 psi (3.2 kg/cm 2 ), go to next step.
6. Check for faulty fuel pump, incorrect fuel pump, incorrect fuel grade or cold fuel. If any problem is found, repair as necessary. Retest system.

PCM continuously monitors HO2S activity for 90 seconds after closed loop has been enabled. During this test period, PCM counts number of times HO2S signal voltage crosses rich-to-lean and lean-to-rich threshold and how long it took to complete all transitions. PCM detects if HO2S-1 Bank-2 indicated a rich exhaust condition while in Decel Fuel Cut Off (DFCO) for fuel control sensors. Condition for setting DTC

1. No related DTCs set.
2. Engine coolant temperature is more than 140°F (60°C).
3. Engine is in closed loop power enrichment mode for 3 seconds.
4. While in power enrichment mode oxygen sensor voltage remains more than 600 millivolts in DFCO.

A restricted fuel system may provide adequate fuel supply at idle, but not during acceleration. Water or alcohol in fuel may cause low HO2S voltage during acceleration. Check for defective or plugged fuel injectors or fuel pump. Check for low fuel.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any other component-related DTCs are set, diagnose them first. If no other DTC is present, go to next step.
3. Turn ignition on, engine running. Allow engine to reach normal operating temperature, 167-203°F (75-95°C). Using scan to, monitor HO2S-1 Bank-2 voltage at 1200 RPM. Voltage should vary between 100 and 900 millivolts. Quickly open throttle to Wide Open Throttle (WOT) a few times. If voltage increased quickly with throttle to low end of specified range (100-600 millivolts), see OBD II SYSTEM CHECK in BASIC DIAGNOSTICS PROCEDURE article. If voltage did not increased as specified, go to next step.
4. Disconnect fuel pump relay and crank engine to relieve fuel pressure. Install fuel pressure gauge. Start engine and allow to idle at normal operating temperature. Disconnect vacuum line to fuel pressure regulator. If fuel pressure is between 41 and 46 PSI (2.9 and 3.2 kg/cm 2 ), see OBD II SYSTEM CHECK in BASIC DIAGNOSTICS PROCEDURE article. If fuel pressure is not as specified, go to next step.
5. Turn ignition off. Remove fuel pump relay. Connect fused jumper wire between fuel pump relay battery feed terminal and fuel pump fuse terminal. With fuel pressure gauge still connected, pinch off fuel return line. Do not allow fuel pressure to exceed 60 psi (4.2 kg/cm 2 ). Manipulate fuel line to raise pressure to more than 46 psi (3.2 kg/cm 2 ). If pressure increases to more than 46 psi (3.2 kg/cm 2 ), check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S27508068832001091400000) . If pressure does not increase as specified, go to next step.
6. Check for faulty fuel pump, incorrect fuel pump, incorrect fuel grade or cold fuel. If any problem is found, repair as necessary. Retest system.

PCM internal circuitry can identify if vehicle fuel system is capable of supplying enough fuel during heavy acceleration (power enrichment). PCM monitors voltage from HO2S during power enrichment. During closed loop, when power enrichment mode is requested (by heavy acceleration), PCM will provide more fuel to engine. Under these conditions, PCM should detect a rich condition (high HO2S voltage). If high HO2S voltage is not recognized at this time, DTC P1171 will set. A plugged fuel filter restricted fuel line, restricted in-tank fuel filter or faulty fuel pump can prevent enough fuel from being supplied during power enrichment mode. Condition for setting DTC

1. No related DTCs set.
2. Engine coolant temperature is more than 140°F (60°C).
3. Engine is in closed loop power enrichment mode for 3 seconds.
4. While in power enrichment mode oxygen sensor voltage remains more than 400 millivolts for 3 seconds.

A restricted fuel system may provide adequate fuel supply at idle, but not during acceleration. Water or alcohol in fuel may cause low HO2S voltage during acceleration. Check for faulty or plugged fuel injectors or fuel pump. Check for low fuel level.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. If any other component-related DTCs are set, diagnose them first. If no other DTC is present, go to next step.
3. Check fuel level. Add fuel if tank is almost empty. If fuel was added, go to next step. If no additional fuel was required, go to step 6 .
4. Start vehicle and bring engine to normal operating temperature 167-203°F (75-95°C). Increase engine speed to 1200 RPM. Using scan tool, observe HO2S-1 Bank-2 voltage. If scan tool reading varies between 100 and 900 millivolts and voltage increases suddenly when throttle is quickly opened to WOT a few times, see FUEL SYSTEM ELECTRICAL TEST in BASIC DIAGNOSTIC PROCEDURES article. If voltage reading is not as specified, go to next step.
5. Replace HO2S-1 Bank-2. Using scan tool observe HO2S-1 Bank-2 voltage. Increase engine speed to 1200 RPM for 15 seconds. HO2S voltage should vary within 100-900 millivolts. Quickly open throttle halfway for a few seconds. Voltage should increase suddenly to high end of specified range. If voltage increased as specified, verify repair. If voltage did not increase as specified, go to next step.
6. Turn ignition off. Remove fuel pump relay and crank engine to relieve fuel pressure. Install fuel pressure gauge. Replace fuel pump relay and start engine, bring engine to normal operating temperature and allow it to idle. Disconnect vacuum line to fuel pressure regulator and read pressure gauge. If pressure is 41-46 psi (2.9-3.2 kg/cm 2 ), see OBD II SYSTEM CHECK in BASIC DIAGNOSTICS PROCEDURE article. If pressure reading is not as specified, go to next step.
7. Check for restricted fuel lines or filter. If problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
8. Turn ignition off. Remove fuel pump relay. Connect fused jumper wire between fuel pump relay battery feed terminal and fuel pump fuse terminal. With fuel pressure gauge still connected, pinch off fuel return line. Do not allow fuel pressure to exceed 60 psi (4.2 kg/cm 2 ). Manipulate fuel line to raise pressure to more than 46 psi (3.2 kg/cm 2 ). If pressure increases to more than 46 psi (3.2 kg/cm 2 ), check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S38279320372001050100000) . If pressure does not increase as specified, go to next step.
9. Check for faulty fuel pump, restricted fuel pump strainer, incorrect fuel pump, incorrect fuel grade or cold fuel. If any problem is found, repair as necessary. Retest system.

Throttle Position Sensor 2 (TPS2) circuit provides a voltage signal relative to throttle valve position. Throttle valve angle will vary from about 92 percent at closed throttle to about 8 percent at wide open throttle. PCM detects a continuous short to ground or high resistance in either circuit or sensor. Condition for setting DTC

1. Ignition is on.
2. Throttle blade angle is less than 2.5 percent or more than 97.5 percent for 18 failures within 500 test samples.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe TPS2 display while moving connectors and harnesses. A change in display will indicate location of fault. If DTC P1220 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. If no problems are present, go to next step.
3. Turn ignition on. Observe Manifold Absolute Pressure (MAP) sensor reading on scan tool. If MAP sensor reading is less than 65 kPa, go to next step. If MAP sensor reading is not as specified, go to step 7 .
4. Disconnect MAP sensor harness connector. Using fused jumper wire, connect harness connector 5-volt reference circuit to MAP sensor signal circuit at MAP sensor harness connector. See WIRING DIAGRAMS article. Observe MAP sensor reading on scan tool. If 5 volts is not present, check other sensors on reference circuit for 5 volts. Repair as necessary. If MAP sensor reading is less than 5 volts, go to step 6 . If MAP reading is not as specified, go to next step.
5. Check MAP sensor signal circuit between PCM harness connector and MAP sensor harness connector. If MAP sensor signal circuit is shorted or open, repair as necessary. If MAP sensor signal wire is not shorted to ground or open, go to step 13 .
6. Replace MAP sensor. Retest system.
7. Using scan tool, observe TPS2 angle while slowly opening throttle. TPS2 angle should increase steadily and smoothly from closed value (8-10 percent) to wide open throttle value (90-92 percent). If TPS2 does not operate as specified, see «DIAGNOSTIC AIDS»(ref-97343-S19638206282001050100000) . If TPS2 operates as specified, go to next step.
8. Disconnect TPS2 harness connector. Using scan tool, observe TPS2 reading. If TPS2 reading is zero percent, go to next step. If TP sensor reading is not as specified, go to step 10 .
9. Connect test light between 5-volt reference circuit and TPS2 signal circuit at TPS2 harness connector. See WIRING DIAGRAMS article. Using scan tool, observe TPS2 sensor reading. If TPS2 reading is 5 volts, go to step 12 . If TPS2 reading is not as specified, go to step 11 .
10. Check TPS2 signal circuit for a short to voltage. Check TPS2 sensor ground circuit for high resistance or faulty connection between PCM harness connector and TPS2 sensor harness connector. If problem is present, repair as necessary. Retest system. If problem is not present, go to step 13 .
11. Check TPS2 signal circuit or 5-volt reference circuit for faulty connection or high resistance between PCM harness connector and TPS2 sensor harness connector. If problem is present, repair as necessary. Retest system. If problem is not present, go to step 13 .
12. Replace TP sensor. Retest system.
13. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM controls engine speed by adjusting position of throttle control valve. Throttle valve motor is a DC motor driven by one coil. PCM applies voltage to DC motor in steps (percentages) adjusting air flow through the throttle body. This method allows accurate control of engine speed and quick response to changes in engine load.

Accelerator Position Sensor (APS) circuit provides a voltage signal relative to accelerator pedal angle. APS1 angle varies from 13 percent at idle to 87 percent at wide open throttle. APS signal is used to determine throttle valve adjustment position. APS signal is processed by PCM, PCM then commands throttle valve motor to move throttle angle position.

When DTC sets, PCM will not illuminate MIL. PCM will store conditions present when DTC was set as FAILURE RECORDS data only.

A history DTC will clear after 40 consecutive trip cycles during which diagnostic runs and fault is no longer recognized. DTC can be cleared with scan tool, or by disconnecting battery voltage feed to PCM.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use scan tool to observe TPS1 and 2 parameter while moving connectors and harnesses. A change in display will indicate location of fault. Check accelerator pedal assembly for objects which might block movement. Ensure that accelerator pedal moves smoothly over entire range. Check throttle body for foreign objects or excessive deposits. Ensure that throttle valve moves smoothly over entire range. If problem is found, repair as necessary.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing electronic throttle control system check, go to next step.
3. Check for visual evidence of throttle body tampering, a restricted intake system (collapsed intake tube, clogged air filter foreign objects), excessive deposits on throttle body or plate. Ensure that throttle does not bind, moves smoothly and that return spring is not binding. Ensure that throttle valve closes fully. If problem is found with any area, repair as necessary. If no problem is found, go to next step.
4. Check for visual evidence of tampering with accelerator pedal, foreign objects blocking accelerator pedal or return spring. Ensure that accelerator pedal does not bind, that pedal moves smoothly and does not have excessive play. If problem is found with any area, repair as necessary. If no problem is found, go to next step.
5. Check for poor, loose or corroded connections in TPS and APS harness connector terminals. If problem is found, repair or replace as necessary. If no problem is found, go to next step.
6. Use DVOM to check for open, short to ground, short to voltage, or high resistance in circuits between Throttle Position Sensor 1 (TPS1), Throttle Position Sensor 2 (TPS2), throttle valve motor and PCM. See WIRING DIAGRAMS article. Measure resistance of TPS1 and 2 and throttle valve motor. See instructions in «TEST DESCRIPTION»(ref-97343-S38877201682009090800000) . If faulty circuit or high resistance in throttle valve motor is present, repair or replace as necessary. If no problems were found, go to next step.
7. Disconnect APS 10-pin harness connector. Check for open circuit, short to voltage and/or ground or poor connection in circuits between APS1, APS2, APS3 and PCM. See WIRING DIAGRAMS article. Measure resistance of APS1, 2 and 3. See instructions in «TEST DESCRIPTION»(ref-97343-S38877201682009090800000) . If faulty circuit or high resistance is found, repair or replace as necessary. If no problem is found, go to next step.
8. Replace APS. See ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION article.
9. Using scan tool, retrieve DTCs. If DTCs P1225, P1290, P1295 or P1299 were stored, perform appropriate test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-97343-S30450709862001050100000) . If none of these DTCs were stored, go to next step.
10. Using scan tool, retrieve DTCs. If DTCs P1514, P1515, P1516, P1523, P1271, P1272 or P1273 were stored, perform appropriate test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-97343-S30450709862001050100000) . If none of these DTCs were stored, go to next step.
11. Replace and reprogram PCM. See «PCM PROGRAMMING PROCEDURE»(ref-97343-S21922797332001050100000) . Use scan tool to clear DTC and verify repair.

Acceleration Position Sensor (APS) circuit provides a voltage signal relative to acceleration pedal angle. APS1 angle will vary about 13 percent at idle position to about 87 percent at Wide Open Throttle (WOT). Code detects a correlation error between APS1 and APS2. Condition for setting DTC

1. Ignition is on.
2. Acceleration pedal angle difference is less than 4.5 percent between APS1 and 2 for 50 counts within 50 test samples.

An intermittent may be caused by poor connections, misrouted harness, rubbed through wire insulation or broken wire inside insulation. Check for poor connection at PCM, backed out terminals, improper mating, broken lock, improperly formed or damaged terminals and poor terminal to wire connection. Using scan tool, monitor APS1 and 2. While moving wire harnesses and connectors, a change in display will indicate location of fault. If DTC P1271 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. If no problems are present, go to next step.
3. Using scan tool, observe APS angle reading while slowly opening throttle valve. APS1 angle increases from 13 percent at idle to 85-89 percent at WOT. APS2 angle decreases from 85-89 percent at idle to 11-15 percent at WOT. Readings should change steadily and evenly. If APS do not operate as specified, go to next step. If APS operate as specified, see «DIAGNOSTIC AIDS»(ref-97343-S15005071402001091700000) .
4. Disconnect APS and observe reading on scan tool. If APS reading is zero volts, go to next step. If APS reading is not as specified, go to step 6 .
5. Connect test light between 5-volt supply circuit and APS signal circuit at APS1 and 2 harness connectors. See WIRING DIAGRAMS article. If APS reading is about 5 volts, go to step 7 . If APS reading is not about 5 volts, go to step 8 .
6. Check APS1 and 2 signal circuits for short to voltage. Check APS1 and 2 ground circuits for high resistance between PCM and AP sensors. Check APS1 and 2 ground circuits for poor connections. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
7. Check APS1 and 2 signal circuits or 5-volt supply circuits for poor connections. Check APS1 and 2 signal circuits or 5-volt supply circuits for high resistance between PCM and AP sensors. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
8. Replace faulty AP sensor. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Acceleration Position Sensor (APS) circuit provides a voltage signal relative to acceleration pedal angle. AP2 angle will vary about 87 percent at idle position to about 13 percent at Wide Open Throttle (WOT). Code detects a correlation error between APS2 and 3. Condition for setting DTC

1. Ignition is on.
2. Acceleration pedal angle difference is less than 4.5 percent between AP2 and 3 for 50 counts within 50 test samples.

An intermittent may be caused by poor connections, misrouted harness, rubbed through wire insulation or broken wire inside insulation. Check for poor connection at PCM, backed out terminals, improper mating, broken lock, improperly formed or damaged terminals and poor terminal to wire connection. Using scan tool, monitor APS2 and APS3. While moving wire harnesses and connectors, a change in display will indicate location of fault. If DTC P1272 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. If no problems are present, go to next step.
3. Using scan tool, observe APS angle reading while slowly opening throttle valve. APS2 angle decreases from 85-89 percent at idle to 12-14 percent at WOT. APS3 angle decreases from 85-89 percent at idle to 32-36 percent at WOT. Readings should change steadily and evenly. If APS do not operate as specified, go to next step. If APS operate as specified, see «DIAGNOSTIC AIDS»(ref-97343-S25744200152001091700000) .
4. Disconnect APS and observe reading on scan tool. If APS reading is zero volts, go to next step. If APS reading is not as specified, go to step 6 .
5. Connect test light between 5-volt supply circuit and APS signal circuit at APS2 and 3 harness connectors. See WIRING DIAGRAMS article. If APS reading is about 5 volts, go to step 7 . If APS reading is not about 5 volts, go to step 8 .
6. Check APS1 and APS2 signal circuits for short to voltage. Check APS2 and 3 ground circuits for high resistance between PCM and AP sensors. Check APS2 and 3 ground circuits for poor connections. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
7. Check APS2 and 3 signal circuits or 5-volt supply circuits for poor connections. Check APS2 and 3 signal circuits or 5-volt supply circuits for high resistance between PCM and AP sensors. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
8. Replace faulty AP sensor. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Acceleration Position Sensor (APS) circuit provides a voltage signal relative to acceleration pedal angle. AP1 angle will vary about 13 percent at idle position to about 87 percent at Wide Open Throttle (WOT). Code detects a correlation error between APS1 and APS3. Condition for setting DTC

1. Ignition is on.
2. Acceleration pedal angle difference is less than 4.5 percent between APS1 and APS2 for 50 counts within 50 test samples.

An intermittent may be caused by poor connections, misrouted harness, rubbed through wire insulation or broken wire inside insulation. Check for poor connection at PCM, backed out terminals, improper mating, broken lock, improperly formed or damaged terminals and poor terminal to wire connection. Using scan tool, monitor APS1 and APS3. While moving wire harnesses and connectors, a change in display will indicate location of fault. If DTC P1273 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. If no problems are present, go to next step.
3. Using scan tool, observe APS angle reading while slowly opening throttle valve. APS1 angle increases from 13 percent at idle to 85-89 percent at WOT. APS3 angle decreases from 85-89 percent at idle to 32-36 percent at WOT. Readings should change steadily and evenly. If APS do not operate as specified, go to next step. If APS operate as specified, see «DIAGNOSTIC AIDS»(ref-97343-S00785457242001091700000) .
4. Disconnect APS and observe reading on scan tool. If APS reading is zero volts, go to next step. If APS reading is not as specified, go to step 6 .
5. Connect test light between 5-volt supply circuit and APS signal circuit at APS1 and 3 harness connectors. See WIRING DIAGRAMS article. If APS reading is about 5 volts, go to step 7 . If APS reading is not about 5 volts, go to step 8 .
6. Check APS1 and 2 signal circuits for short to voltage. Check APS1 and 2 ground circuits for high resistance between PCM and AP sensors. Check APS1 and 2 ground circuits for poor connections. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
7. Check APS1 and 3 signal circuits or 5-volt supply circuits for poor connections. Check APS1 and 3 signal circuits or 5-volt supply circuits for high resistance between PCM and AP sensors. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
8. Replace faulty AP sensor. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Acceleration Position Sensor (APS) circuit provides a voltage signal relative to acceleration pedal angle. AP1 angle will vary about 13 percent at idle position to about 87 percent at Wide Open Throttle (WOT). Code detects a continuous short to ground or high resistance in either circuit or sensor. Condition for setting DTC

1. Ignition is on.
2. Acceleration pedal angle is less than 2.5 percent or more than 97 percent for 12 counts within 500 test samples.

An intermittent may be caused by poor connections, misrouted harness, rubbed through wire insulation or broken wire inside insulation. Check for poor connection at PCM, backed out terminals, improper mating, broken lock, improperly formed or damaged terminals and poor terminal to wire connection. Using scan tool, monitor APS1. While moving wire harnesses and connectors, a change in display will indicate location of fault. If DTC P1275 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. If no problems are present, go to next step.
3. Using scan tool, observe APS1 angle reading while slowly opening throttle valve. APS1 angle increases from 12-14 percent at idle to 85-89 percent at WOT. Readings should change steadily and evenly. If APS1 does not operate as specified, go to next step. If APS1 operates as specified, see «DIAGNOSTIC AIDS»(ref-97343-S00954538852001091800000) .
4. Disconnect APS1 and observe reading on scan tool. If APS1 reading is zero volts, go to next step. If APS1 reading is not as specified, go to step 6 .
5. Connect test light between 5-volt supply circuit and APS signal circuit at APS1 harness connector. See WIRING DIAGRAMS article. If APS reading is about 5 volts, go to step 7 . If APS reading is not about 5 volts, go to step 8 .
6. Check APS1 signal circuit for short to voltage. Check APS1 ground circuit for high resistance between PCM and AP sensor. Check APS1 ground circuit for poor connections. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
7. Check APS1 signal circuit or 5-volt supply circuit for poor connections. Check APS1 signal circuit or 5-volt supply circuit for high resistance between PCM and AP sensor. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
8. Replace faulty AP sensor. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Acceleration Position Sensor (APS) circuit provides a voltage signal relative to acceleration pedal angle. AP2 angle will vary about 87 percent at idle position to about 13 percent at Wide Open Throttle (WOT). Code detects a continuous short to ground or high resistance in either circuit or sensor. Condition for setting DTC

1. Ignition is on.
2. Acceleration pedal angle is less than 2.5 percent or more than 97 percent for 12 counts within 500 test samples.

An intermittent may be caused by poor connections, misrouted harness, rubbed through wire insulation or broken wire inside insulation. Check for poor connection at PCM, backed out terminals, improper mating, broken lock, improperly formed or damaged terminals and poor terminal to wire connection. Using scan tool, monitor APS2. While moving wire harnesses and connectors, a change in display will indicate location of fault. If DTC P1280 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. If no problems are present, go to next step.
3. Using scan tool, observe APS2 angle reading while slowly opening throttle valve. APS2 angle decreases from 85-89 percent at idle to 12-14 percent at WOT. Readings should change steadily and evenly. If APS do not operate as specified, go to next step. If APS operate as specified, see «DIAGNOSTIC AIDS»(ref-97343-S35285900532001091800000) .
4. Disconnect APS2 and observe reading on scan tool. If APS2 reading is zero volts, go to next step. If APS2 reading is not as specified, go to step 6 .
5. Connect test light between 5-volt supply circuit and APS signal circuit at APS2 harness connector. See WIRING DIAGRAMS article. If APS reading is about 5 volts, go to step 7 . If APS reading is not about 5 volts, go to step 8 .
6. Check APS2 signal circuit for short to voltage. Check APS2 ground circuit for high resistance between PCM and AP sensor. Check APS2 ground circuit for poor connections. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
7. Check APS2 signal circuit or 5-volt supply circuit for poor connections. Check APS2 signal circuit or 5-volt supply circuit for high resistance between PCM and AP sensor. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
8. Replace faulty AP sensor. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Acceleration Position Sensor (APS) circuit provides a voltage signal relative to acceleration pedal angle. AP3 angle will vary about 87 percent at idle position to about 34 percent at Wide Open Throttle (WOT). Code detects a continuous short to ground or high resistance in either circuit or sensor. Condition for setting DTC

1. Ignition is on.
2. Acceleration pedal angle is less than 2.5 percent or more than 97 percent for 12 counts within 500 test samples.

An intermittent may be caused by poor connections, misrouted harness, rubbed through wire insulation or broken wire inside insulation. Check for poor connection at PCM, backed out terminals, improper mating, broken lock, improperly formed or damaged terminals and poor terminal to wire connection. Using scan tool, monitor APS3. While moving wire harnesses and connectors, a change in display will indicate location of fault. If DTC P1285 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. If no problems are present, go to next step.
3. Using scan tool, observe APS angle reading while slowly opening throttle valve. APS3 angle decreases from 85-89 percent at idle to 32-36 percent at WOT. Readings should change steadily and evenly. If APS do not operate as specified, go to next step. If APS operate as specified, see «DIAGNOSTIC AIDS»(ref-97343-S00785457242001091700000) .
4. Disconnect APS3 and observe reading on scan tool. If APS3 reading is zero volts, go to next step. If APS3 reading is not as specified, go to step 6 .
5. Connect test light between 5-volt supply circuit and APS signal circuit at APS3 harness connector. See WIRING DIAGRAMS article. If APS reading is about 5 volts, go to step 7 . If APS reading is not about 5 volts, go to step 8 .
6. Check APS3 signal circuit for short to voltage. Check APS3 ground circuit for high resistance between PCM and AP sensor. Check APS3 ground circuits for poor connections. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
7. Check APS3 signal circuit or 5-volt supply circuit for poor connections. Check APS3 signal circuit or 5-volt supply circuit for high resistance between PCM and AP sensor. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
8. Replace faulty AP sensor. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Acceleration Position Sensor (APS) circuit provides a voltage signal relative to acceleration pedal angle. AP1 angle will vary about 13 percent at idle position to about 87 percent at Wide Open Throttle (WOT). Code detects if system is in Electric Throttle Control (ETC) Forced Idle Mode (Fail Safe Mode). Condition for setting DTC

1. Ignition is on.
2. Forced Idle Mode is active.

An intermittent may be caused by poor connections, misrouted harness, rubbed through wire insulation or broken wire inside insulation. Check for poor connection at PCM, backed out terminals, improper mating, broken lock, improperly formed or damaged terminals and poor terminal to wire connection. Using scan tool, monitor APS1, 2 and 3. While moving wire harnesses and connectors, a change in display will indicate location of fault. If DTC P1290 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. If no problems are present, go to next step.
3. Using scan tool, observe APS angle reading while slowly opening throttle valve. APS1 angle increases from 12-14 percent at idle to 85-89 percent at WOT. Readings should change steadily and evenly. If APS do not operate as specified, go to next step. If APS operate as specified, see «DIAGNOSTIC AIDS»(ref-97343-S16079501002001091800000) .
4. Disconnect APS1, 2, and 3 and observe readings on scan tool. If APS1 reading is zero volts, go to next step. If APS1 reading is not as specified, go to step 6 .
5. Connect test light between 5-volt supply circuits and APS signal circuits at APS1, 2 and 3 harness connectors. See WIRING DIAGRAMS article. If APS readings are about 5 volts, go to step 7 . If APS readings are not about 5 volts, go to step 8 .
6. Check APS1, 2 and 3 signal circuits for shorts to voltage. Check APS1, 2 and 3 ground circuits for high resistance between PCM and AP sensors. Check APS1, 2 and 3 ground circuits for poor connections. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
7. Check APS1, 2 and 3 signal circuits or 5-volt supply circuits for poor connections. Check APS1, 2 and 3 signal circuits or 5-volt supply circuits for high resistance between PCM and AP sensors. If problem is present, repair as necessary and retest system. If problem is not present, go to step 9 .
8. Replace faulty AP sensor. Retest system.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Throttle Position Sensor 1 (TPS1) circuit provides a voltage signal relative to throttle valve position. Throttle valve angle will vary from about 8 percent at closed throttle to about 92 percent at Wide Open Throttle (WOT). PCM detects a continuous short to ground or high resistance in either circuit or sensor. Mass Air Flow (MAF) sensor measures amount of air which passes through it into the engine during a given time. PCM uses MAF information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle. MAF sensor produces a frequency signal which can be monitored using a scan tool. Frequency will vary within about 4-7 grams/sec. at idle to about 25-40 grams/sec. at maximum engine load. DTC detects if system is in Power Management Mode (Fail Safe Mode). Condition for setting DTC

1. Ignition is on.
2. Power Management Mode is active.

Intermittent problem may be caused by poor connections, misrouted harness, rubbed through wire insulation, broken wire inside insulation. Check for faulty connection PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connection. Check for wire harness damage. Using scan tool, observe display for TP sensors 1 and 2 while moving wire harness connectors and wire harnesses related to TP sensors. A change in display will indicate location of fault. If DTC P1295 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) . Go to next step.
3. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P1295 until DTC P1295 test runs. Note result. If scan tool indicates DTC P1295 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, see «DIAGNOSTIC AIDS»(ref-97343-S25820454352001091800000) .
4. Using scan tool, observe TPS1 angle while slowly opening throttle. TPS1 and 2 angle should increase steadily and smoothly from closed value (8-10 percent) to WOT value (90-92 percent). If TP sensors operate as specified, go to step 9 . If TP sensors do not operate as specified, go to next step.
5. Turn ignition off. Disconnect DC motor. If DC motor resistance is 0.3-100 ohms, go to next step. If DC motor resistance is not as specified, go to step 8 .
6. Check DC motor wire harness between PCM and DC motor at DC motor harness connector for short or open circuits. See «DIAGNOSTIC AIDS»(ref-97343-S25820454352001091800000) . If problem is present, repair as necessary and retest system. If problem is not found, go to next step.
7. Check Throttle valve assembly for sticking or binding. If problem is present, verify repair and retest system. If problem is not present, go to next step.
8. Replace throttle valve assembly (DC motor not available separately). Retest system.
9. Disconnect Throttle Position (TP) sensor harness connector. Using scan tool, observe TP sensor reading. If TP sensor reading is about zero volts, go to next step. If TP sensor reading is not as specified, go to step 11 .
10. Connect test light between 5-volt reference circuit and TPS1 and 2 signal circuit at TP sensor harness connector. See WIRING DIAGRAMS article. Using scan tool, observe TP sensor readings. If TPS1 and 2 readings are 5 volts, go to step 13 . If TPS1 and 2 readings are not as specified, go to step 12 .
11. Check TPS1 and 2 signal circuits for a short to voltage. Check TPS1 and 2 sensor ground circuits for high resistance or faulty connections between PCM harness connector and TP sensor harness connector. If problem is present, repair as necessary. Retest system. If problem is not present, go to step 14 .
12. Check TPS1 and 2 signal circuits or 5-volt reference circuits for faulty connections or high resistance between PCM harness connector and TP sensor harness connector. If problem is present, repair as necessary. Retest system. If problem is not present, go to step 14 .
13. Replace TP sensor assembly. Retest system.
14. Start engine. Allow engine to idle. Using scan tool, monitor MAF FREQUENCY display. If MAF FREQUENCY value is less than 6-10 grams/sec., go to next step. If MAF FREQUENCY is not as specified, go to step 18 .
15. Turn ignition off. Disconnect MAF sensor harness connector. Start engine and allow to idle. Using scan tool, monitor MAF FREQUENCY. If scan tool indicates MAF FREQUENCY value is zero grams/sec., go to next step. If MAF FREQUENCY value is not as specified, go to step 17 .
16. Replace MAF sensor. Retest system. Go to step 19 .
17. Check for incorrect routing of MAF sensor harness near high voltage components (solenoids, relays and motors). If problem is present, reroute harness correctly and retest system. If problem is not present, go to next step.
18. With engine at idle, monitor MAF FREQUENCY value on scan tool. Snap throttle wide open and release while under a road load, record display. If value reading was 6-10 grams/sec., go to step 16 . If value reading was not as specified, go to next step.
19. Turn ignition on. Engine off. Monitor MAP sensor reading on scan tool. If MAP sensor reading is less than 65 kPa, go to next step. If MAP sensor reading is not as specified, go to step 23 .
20. Disconnect MAP sensor harness connector. Using fused jumper wire, connect harness connector 5-volt reference circuit to MAP signal circuit at MAP sensor harness connector. See WIRING DIAGRAMS article. Observe MAP reading on scan tool. If 5 volts is not present, check other sensors on reference circuit for 5 volts. go to next step. If MAP sensor reading is less than 5 volts, go to step 22 . If MAP sensor reading is not as specified, go to next step.
21. Check MAP sensor signal circuit between PCM harness connector and MAP sensor harness connector. If MAP signal circuit is shorted or open, repair as necessary. If MAP sensor signal wire is not shorted to ground or open, go to step 23 .
22. Replace MAP sensor. Retest system.
23. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Throttle Position (TP) sensor circuit provides a voltage signal relative to throttle valve position. Throttle valve angle will vary from about 8 percent at closed throttle to about 92 percent at Wide Open Throttle (WOT). The DC motor circuit provides a voltage signal relative to throttle angle. Mass Air Flow (MAF) sensor measures amount of air which passes through it into the engine during a given time. PCM uses MAF information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle. MAF sensor produces a frequency signal which can be monitored using a scan tool. Frequency will vary within about 4-7 grams/sec. at idle to about 25-40 grams/sec. at maximum engine load. DTC detects if system is in Electric Throttle Control (ETC) Forced Engine Shutdown Mode (Fail Safe Mode). Condition for setting DTC

1. Ignition is on.
2. ETC Forced Engine Shutdown Mode is active.

Intermittent problem may be caused by poor connections, misrouted harness, rubbed through wire insulation, broken wire inside insulation. Check for faulty connection PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connection. Check for wire harness damage. Using scan tool, observe display for TP sensors 1 and 2 while moving wire harness connectors and wire harnesses related to TP sensors. A change in display will indicate location of fault. If DTC P1299 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Perform «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) . Go to next step.
3. Using scan tool, observe TP angle while slowly opening throttle. TPS1 and 2 angle should increase steadily and smoothly from closed value (8-10 percent) to WOT value (90-92 percent). If TP sensors operate as specified, go to step 8 . If TP sensors do not operate as specified, go to next step.
4. Turn ignition off. Disconnect DC motor. If DC motor resistance is 0.3-100 ohms, go to next step. If DC motor resistance is not as specified, go to step 7 .
5. Check DC motor wire harness between PCM and DC motor at DC motor harness connector for short or open circuits. See «DIAGNOSTIC AIDS»(ref-97343-S31189643152001091800000) . If problem is present, repair as necessary and retest system. If problem is not found, go to next step.
6. Check Throttle valve assembly for sticking or binding. If problem is present, verify repair and retest system. If problem is not present, go to next step.
7. Replace throttle valve assembly (DC motor not available separately). Retest system.
8. Disconnect Throttle Position (TP) sensor harness connector. Using scan tool, observe TP sensor reading. If TP sensor reading is about zero volts, go to next step. If TP sensor reading is not as specified, go to step 10 .
9. Connect test light between 5-volt reference circuit and TPS1 and 2 signal circuits at TP sensor harness connector. See WIRING DIAGRAMS article. Using scan tool, observe TP sensor readings. If TPS1 and 2 readings are 5 volts, go to step 12 . If TPS1 and 2 readings are not as specified, go to step 11 .
10. Check TPS1 and 2 signal circuits for a short to voltage. Check TPS1 and 2 sensor ground circuits for high resistance or faulty connections between PCM harness connector and TP sensor harness connector. If problem is present, repair as necessary. Retest system. If problem is not present, go to step 13 .
11. Check TPS1 and 2 signal circuits or 5-volt reference circuits for faulty connections or high resistance between PCM harness connector and TP sensor harness connector. If problem is present, repair as necessary. Retest system. If problem is not present, go to step 13 .
12. Replace TP sensor assembly. Retest system.
13. Start engine. Allow engine to idle. Using scan tool, monitor MAF FREQUENCY display. If MAF FREQUENCY value is less than 6-10 grams/sec., go to next step. If MAF FREQUENCY is not as specified, go to step 17 .
14. Turn ignition off. Disconnect MAF sensor harness connector. Start engine and allow to idle. Using scan tool, monitor MAF FREQUENCY. If scan tool indicates MAF FREQUENCY value is zero grams/sec., go to next step. If MAF FREQUENCY value is not as specified, go to step 16 .
15. Replace MAF sensor. Retest system. Go to step 18 .
16. Check for incorrect routing of MAF sensor harness near high voltage components (solenoids, relays and motors). If problem is present, reroute harness correctly and retest system. If problem is not present, go to next step.
17. With engine at idle, monitor MAF FREQUENCY value on scan tool. Snap throttle wide open and release while under a road load and record display. If value reading was 6-10 grams/sec., go to step 15 . If value reading was not as specified, go to next step.
18. Turn ignition on. Engine off. Monitor Manifold Absolute Pressure (MAP) sensor reading on scan tool. If MAP sensor reading is less than 65 kPa, go to next step. If MAP sensor reading is not as specified, go to step 22 .
19. Disconnect MAP sensor harness connector. Using fused jumper wire, connect harness connector 5-volt reference circuit to MAP sensor signal circuit at MAP sensor harness connector. See WIRING DIAGRAMS article. Observe MAP sensor reading on scan tool. If 5 volts is not present, check other sensors on reference circuit for 5 volts. Go to next step. If MAP sensor reading is less than 5 volts, go to step 21 . If MAP sensor reading is not as specified, go to next step.
20. Check MAP sensor signal circuit between PCM harness connector and MAP sensor harness connector. If MAP sensor signal circuit is shorted or open, repair as necessary. If MAP sensor signal wire is not shorted to ground or open, go to step 22 .
21. Replace MAP sensor. Retest system.
22. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM checks validity of signals used in ION Sensing Module under various conditions. Deceleration Fuel Cut Off (DFCO) test is performed to evaluate if Combustion Quality (CQ) signal pulse width is less than predetermined value, value it is expected to be during DFCO conditions. If CQ signal pulse width is more than predetermined threshold, fail counter will be incremented. If failure counter exceeds calibration, test is complete and a failure is reported. Power Enrichment (PE) test is performed to determine if CQ signal pulse width is less than predetermined value. Value it is expected to be during PE conditions. If CQ signal pulse width is more than predetermined threshold, fail counter will be incremented. If failure counter exceeds calibration, test is complete and a failure is reported. Combustion Quality (CQ) test is performed to check if inappropriate CQ signal status were detected. If CQ pulses, multiple CQ pulses or CQ pulse width calculation errors were detected, failure counter will be incremented. If failure counter exceeds calibration, test is complete and a failure will be reported. Conditions for setting DTC

1. Ignition voltage is between 10 and 16 volts.
2. MAP sensor signal is between 26 and 100 kPa.
3. Engine speed is between 650 and 6500 RPM.
4. No Crank DTCs set.
5. No System Voltage DTCs set.

Intermittent problem may be caused by poor connections, misrouted harness, rubbed through wire insulation, broken wire inside insulation. Check for faulty connection PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connection. Check for wire harness damage. Using scan tool, observe display for ION Sensing Monitor while moving related wire harness connectors and wire harnesses. A change in display will indicate location of fault. If DTC P1310 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P1310 until DTC P1310 test runs. Note result. If scan tool indicates DTC P1310 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, see «DIAGNOSTIC AIDS»(ref-97343-S27477964912001091900000) .
3. Turn ignition off. Disconnect ION Sensing Module and PCM harness connectors. Check wire harness between ION Sensing Module harness connector and PCM harness connector. See WIRING DIAGRAMS article. If problem is present, repair as necessary and retest system. If problem is not present, go to next step.
4. Disconnect ignition coil. Check ION Sensing Module wire harness between ignition coil and ION Sensing Module circuit at ION Sensing Module harness connector. If problem is present, repair as necessary and retest system. If problem is not present, go to next step.
5. Check ignition coil, ignition coil circuit and ground circuit for poor connections. If problem is present, repair wiring harness as necessary and retest system. If problem is not present, go to next step.
6. Replace ignition coil. Retest system. Go to next step.
7. Check ION Sensing Module ground circuit for poor connection. If problem is present, repair wiring harness as necessary and retest system. If problem is still present, go to next step. If problem is not present, go to step 9 .
8. Replace ION Sensing Module. Retest system. If problem is not present, go to next step.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM will compare secondary current reading to predetermined maximum and minimum thresholds. If secondary current signal pulse is out of predetermined range, fail counter will be incremented. If failure counter exceeds calibration, test is complete and failure will be reported. If sample threshold is reached before failure threshold, test is complete and pass will be reported. PCM will detect an open or short circuit in secondary current sensing input circuit, misfire on entire bank for secondary current sense input circuit, coil failure and internal ION Sensing module faults. Conditions for setting DTC

1. Ignition voltage is between 10 and 16 volts.
2. MAP sensor signal is between 26 and 100 kPa.
3. Fuel level is more than 10 percent.
4. Engine speed is between 650 and 6500 RPM.
5. ION Sensing Module circuit has open or shorted signals on SEC 1 line.

Intermittent problem may be caused by poor connections, misrouted harness, rubbed through wire insulation, broken wire inside insulation. Check for faulty connection PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connection. Check for wire harness damage. Using scan tool, observe display while moving related wire harness connectors and wire harnesses. A change in display will indicate location of fault. If DTC P1311 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P1311 until DTC P1311 test runs. Note result. If scan tool indicates DTC P1311 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, see «DIAGNOSTIC AIDS»(ref-97343-S11241462842001091900000) .
3. Turn ignition off. Disconnect ION Sensing Module and PCM harness connectors. Check wire harness between ION Sensing Module harness connector and PCM harness connector. See WIRING DIAGRAMS article. If problem is found, repair as necessary and retest system. If problem is not found, go to next step.
4. Disconnect ignition coil. Check ION Sensing Module wire harness between ignition coil and ION Sensing Module circuit at SEC line 1 harness connector. If problem is found, repair as necessary and retest system. If problem is not present, go to next step.
5. Check ignition coil, ignition coil circuit and ground circuit for poor connections. If problem is present, repair wiring harness as necessary and retest system. If problem is not present, go to next step.
6. Replace ignition coil. Retest system. Go to next step.
7. Check ION Sensing Module ground circuit for poor connection. If problem is present, repair wiring harness as necessary and retest system. If problem is still present, go to next step. If problem is not present, go to step 9 .
8. Replace ION Sensing Module. Retest system. If problem is not present, go to next step.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM will compare secondary current reading to predetermined maximum and minimum thresholds. If secondary current signal pulse is out of predetermined range, fail counter will be incremented. If failure counter exceeds calibration, test is complete and failure will be reported. If sample threshold is reached before failure threshold, test is complete and pass will be reported. PCM will detect an open or short circuit in secondary current sensing input circuit, misfire on entire bank for secondary current sense input circuit, coil failure and internal ION Sensing module faults. Conditions for setting DTC

1. Ignition voltage is between 10 and 16 volts.
2. MAP sensor signal is between 26 and 100 kPa.
3. Fuel level is more than 10 percent.
4. Engine speed is between 650 and 6500 RPM.
5. ION Sensing Module circuit has open or shorted signals.

Intermittent problem may be caused by poor connections, misrouted harness, rubbed through wire insulation, broken wire inside insulation. Check for faulty connection PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connection. Check for wire harness damage. Using scan tool, observe display while moving related wire harness connectors and wire harnesses. A change in display will indicate location of fault. If DTC P1312 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P1312 until DTC P1312 test runs. Note result. If scan tool indicates DTC P1312 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, see «DIAGNOSTIC AIDS»(ref-97343-S15342787502001091900000) .
3. Turn ignition off. Disconnect ION Sensing Module and PCM harness connectors. Check wire harness between PCM and ION Sensing Module circuit at ION Sensing Module harness connector. See WIRING DIAGRAMS article. If problem is found, repair as necessary and retest system. If problem is not found, go to next step.
4. Disconnect ignition coil. Check ION Sensing Module wire harness between ignition coil and ION Sensing Module circuit at ION Sensing Module harness connector. If problem is found, repair as necessary and retest system. If problem is not present, go to next step.
5. Check ignition coil, ignition coil circuit and ground circuit for poor connections. If problem is present, repair wiring harness as necessary and retest system. If problem is not present, go to next step.
6. Replace ignition coil. Retest system. Go to next step.
7. Check ION Sensing Module ground circuit for poor connection. If problem is present, repair wiring harness as necessary and retest system. If problem is still present, go to next step. If problem is not present, go to step 9 .
8. Replace ION Sensing Module. Retest system. If problem is not present, go to next step.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM checks validity of signals used in ION Sensing Module at various engine operating conditions. Test is performed to evaluate Combustion Quality (CQ) signal pulse width if it is within predetermined range. If CQ signal pulse width is out of predetermined range, fail counter will be incremented. If failure counter exceeds calibration, test is complete and a failure record will be reported. If same counter threshold is reached before failure threshold, then test is complete and a pass will be reported. This test will detect an open or short in CQ line circuit, ION Sensing Module faults and analog input faults in PCM. Conditions for setting DTC

1. Ignition voltage is between 11 and 16 volts.
2. No Crank DTCs set.
3. No cylinder ID DTCs set.

Intermittent problem may be caused by poor connections, misrouted harness, rubbed through wire insulation, broken wire inside insulation. Check for faulty connection PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connection. Check for wire harness damage. Using scan tool, observe display while moving related wire harness connectors and wire harnesses. A change in display will indicate location of fault. If DTC P1326 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P1326 until DTC P1326 test runs. Note result. If scan tool indicates DTC P1326 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, see «DIAGNOSTIC AIDS»(ref-97343-S22140514162001091900000) .
3. Turn ignition off. Disconnect ION Sensing Module and PCM harness connectors. Check wire harness between PCM and ION Sensing Module circuit at CQ line harness connector. See WIRING DIAGRAMS article. If problem is found, repair as necessary and retest system. If problem is no found, go to next step.
4. Disconnect ignition coil. Check ION Sensing Module wire harness between ignition coil and ION Sensing Module circuit at ION Sensing Module harness connector. If problem is found, repair as necessary and retest system. If problem is not present, go to next step.
5. Check ignition coil, ignition coil circuit and ground circuit for poor connections. If problem is present, repair wiring harness as necessary and retest system. If problem is not present, go to next step.
6. Replace ignition coil. Retest system. Go to next step.
7. Check ION Sensing Module ground circuit for poor connection. If problem is present, repair wiring harness as necessary and retest system. If problem is still present, go to next step. If problem is not present, go to step 9 .
8. Replace ION Sensing Module. Retest system. If problem is not present, go to next step.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM checks validity of signals used in ION Sensing Module at various engine operating conditions. Test will return a fault if cylinder synchronization routine has not been completed after a predetermined number of events after crank. Test will detect fault that will prevent PCM from synchronization, such as Knock Signal (KI), Combustion Quality (CQ) lines being swapped, shorted spark plugs, ION Sensing Module faults and PCM hardware faults. Conditions for setting DTC

1. Ignition voltage is between 11 and 16 volts.
2. Engine speed is between 650 and 6500 RPM.
3. No ECT DTCs set.
4. No injector DTCs set.
5. No fuel trim DTCs set.
6. No Misfire DTCs set.
7. No system voltage DTCs set.

Intermittent problem may be caused by poor connections, misrouted harness, rubbed through wire insulation, broken wire inside insulation. Check for faulty connection PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connection. Check for wire harness damage. Using scan tool, observe display while moving related wire harness connectors and wire harnesses. A change in display will indicate location of fault. If DTC P1340 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC information for DTC P1340 until DTC P1340 test runs. Note result. If scan tool indicates DTC P1340 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, see «DIAGNOSTIC AIDS»(ref-97343-S22140514162001091900000) .
3. Turn ignition off. Disconnect ION Sensing Module and PCM harness connectors. Check wire harness between PCM and ION Sensing Module circuit at CQ line harness connector. See WIRING DIAGRAMS article. If problem is found, repair as necessary and retest system. If problem is no found, go to next step.
4. Disconnect ignition coil. Check ION Sensing Module wire harness between ignition coil and ION Sensing Module circuit at ION Sensing Module harness connector. If problem is found, repair as necessary and retest system. If problem is not present, go to next step.
5. Check ignition coil, ignition coil circuit and ground circuit for poor connections. If problem is present, repair wiring harness as necessary and retest system. If problem is not present, go to next step.
6. Replace ignition coil. Retest system. Go to next step.
7. Check ION Sensing Module ground circuit for poor connection. If problem is present, repair wiring harness as necessary and retest system. If problem is still present, go to next step. If problem is not present, go to step 9 .
8. Replace ION Sensing Module. Retest system. If problem is not present, go to next step.
9. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

PCM monitors ABS fault signal. When PCM receives fault signal, PCM will set DTC P1380. Conditions for setting DTC

1. Vehicle speed is more than 5 MPH.
2. Load is less than 99 percent.
3. Engine speed is less than 6250 RPM.
4. PCM receives ABS fault signals from ABS ECU.
5. Ignition on.
6. Misfire DTCs exist.
7. 100 test failures within 120 test samples.

Check for PCM and ABS ECU communication line short circuit.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on, engine off. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS condition. Using scan tool, monitor DTC information for DTC P1380 and misfire DTCs. If scan tool shows DTC P1380 and misfire DTCs PASSED THIS IGNITION, clear DTC. If scan tool shows DTC P1380 and misfire DTCs FAILED THIS IGNITION, see appropriate ANTI-LOCK article in BRAKES. If problem is still present, repeat this step. If repeating this step does not correct problem, go to next step.
3. Check for short circuit between ABS ECU and PCM communications lines. Repair as necessary. If a short circuit is not present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

PCM is not monitoring an ABS fault signal. When PCM does not receive ABS signal, PCM will set DTC P1381. Conditions for setting DTC

1. PCM does not receive ABS signals from ABS ECU.
2. Vehicle speed is more than zero MPH.
3. Load is less than 99 percent.
4. 2.5 seconds after key on.
5. Misfire DTCs exist.
6. 100 test failures within 120 test samples.

Check for an open circuit in wiring between PCM and ABS ECU.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on, engine off. Review and record scan tool FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS condition. Using scan tool, monitor DTC information for DTC P1381 and misfire DTCs. If scan tool shows DTC P1381 and misfire DTCs PASSED THIS IGNITION, clear DTC. If scan tool shows DTC P1381 and misfire DTCs FAILED THIS IGNITION, see appropriate ANTI-LOCK article in BRAKES. If problem is still present, repeat this step. If repeating this step does not correct problem, go to next step.
3. Check for open circuit in communications lines between ABS ECU and PCM. Repair as necessary. If a short circuit is not present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

PCM monitors EGR valve pintle position input to ensure valve responds properly to commands from PCM and to detect a fault if current pintle zero position is different from learned zero position. If PCM detects a pintle position signal indicates more than 30 percent difference between current zero position and learned zero position for more than 5 seconds and condition exists 3 times during trip, PCM will set DTC P1404. Conditions for setting DTC

1. Ignition voltage is between 11 and 16 volts.
2. Intake air temperature is more than 37°F (3°C).
3. Desired EGR position is zero.
4. Difference of EGR pintle position between current and learned zero is more than 30 percent for more than 5 seconds and exists 3 times.

Excessive carbon buildup on EGR valve shaft may cause valve to hang up or fail to seat properly. An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Monitor EGR actual position display while moving EGR connections and related harnesses. Change in scan tool display will indicate area of fault. Check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
2. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORD DATA. Operate vehicle within conditions noted in FAILED RECORDS DATA. Read SPECIFIC DTC. If scan tool displays DTC P1404 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1404 FAILED THIS IGN, check for an intermittent problem. See «DIAGNOSTIC AIDS»(ref-97343-S32173049532001050100000) .
3. Turn ignition off. Disconnect EGR valve harness connector. Inspect EGR valve and connector for damaged pins or terminals. Repair as necessary. If EGR valve and connector pins or terminals are okay, go to next step.
4. Remove EGR valve. Check EGR valve for excessive carbon deposits on EGR shaft. Check for foreign material inside EGR valve. If excessive carbon is found, go to next step. If excessive carbon is not found, go to step 6 .
5. Clean EGR valve shaft and inside EGR. Remove foreign material from EGR valve. Check for damage of pintle and seat. If severe damage is present, replace EGR valve. If damage is not present, go to next step.
6. Reinstall EGR valve. Install scan tool. Start and run engine at idle. Using scan tool, check EGR operation by using UP arrow to increase EGR from zero percent to 40 percent. If EGR operates, system is okay. If EGR does not operate, go to next step.
7. Using scan tool, reset learned zero EGR valve position. Repeat test in step 6 . If EGR operates, system is okay. If EGR does not operate, replace EGR valve. If system still does not operate after replacement of EGR, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

Canister purge is controlled by a solenoid valve that allows manifold vacuum to purge canister. PCM supplies a ground to energize solenoid valve (purge ON). EVAP purge solenoid control is Pulse-Width Modulated (PWM) or turned on and off several times a second. 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 output is commanded when appropriate conditions have been met. Conditions for setting DTC

1. No active Engine Coolant Temperature (ECT), Intake Air Temperature (IAT), Manifold Absolute Pressure (MAP) or Throttle Position (TP) sensor DTCs set.
2. BARO reading is more than 85 kPa.
3. Engine Coolant Temperature is less than 158°F (70°C).
4. Start-up intake air temperature and start-up engine coolant temperature are both more than 41°F (5°C).
5. Difference between start-up ECT and start-up IAT is less than 45°F (25°C).
6. TP sensor indicates a throttle position more than 12 percent.
7. Battery voltage is between 11.5 and 16 volts.
8. Engine speed is between 800 and 6000 RPM.
9. Canister purge duty cycle is less than 3 percent.
10. All conditions are present for at least 3 seconds.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Monitor EVAP VACUUM SWITCH display while moving EVAP connections and related harnesses. Change in scan tool display will indicate area of fault. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Remove fuel cap. Turn ignition on. Using scan tool, observe FUEL TANK PRESSURE. If scan tool display reads 1.51 volts, go to next step. If scan tool display is not as specified, go to «DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE»(ref-97343-S14206540072001050100000) or «DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE»(ref-97343-S05130155482001050100000) .
3. Zero pressure and vacuum gauges on EVAP Pressure/Purge Cart (J41413). Reinstall fuel cap. Using scan tool, command EVAP vent solenoid ON (closed). Disconnect EVAP canister hose that comes from EVAP purge solenoid valve. Connect EVAP pressure/purge cart to EVAP service port. Using EVAP pressure/purge cart, attempt to pressurize EVAP system until scan tool FUEL TANK PRESSURE reads 1.52-1.60 volts. If specified pressure is not achieved, go to step 6 . If specified pressure is achieved, go to next step.
4. Disconnect EVAP pressure/purge cart from EVAP service port. Disconnect vacuum source line at engine for EVAP purge solenoid. Connect a vacuum pump to EVAP canister purge valve vacuum source fitting. Apply 15 in. H 2 O vacuum. If scan tool FUEL TANK PRESSURE display reads 1.47-1.51 volts and holds steady, go to step 6 . If scan tool reading is not as specified, go to next step.
5. Replace EVAP purge solenoid valve. Retest system.
6. Check for leaks, kinked or pinched hoses at EVAP system. Ensure that all hoses are routed correctly. Check for leak from vent solenoid valve, and also ensure that filter located near vent solenoid is not plugged. Repair as necessary and retest system. If no problem was found, go to next step.
7. Start engine. Remove fuel cap. Using scan tool, command EVAP vent solenoid ON (closed) and EVAP purge solenoid OFF (zero percent). Reinstall fuel cap. Monitor scan tool FUEL TANK VACUUM display while holding engine speed at 2500 RPM. If scan tool display reads 30-40 percent when vent solenoid valve is ON, and zero percent when purge solenoid valve is OFF, repair is complete. If scan tool display is not as specified, go to «DIAGNOSTIC AIDS»(ref-97343-S20072462622001050100000) .

PCM controls engine idle speed by adjusting position of Idle Air Control (IAC) motor pintle. IAC is a bi-directional stepper motor driven by 2 coils. PCM applies current to IAC coils in steps (counts) to extend IAC pintle into a throttle body passage to decrease air flow. To increase air flow PCM reverses current and retracts pintle. This method allows highly accurate control of idle speed and quick response to changes in engine load. If PCM detects a condition where too low an idle speed is present and PCM is unable to compensate for idle speed by increasing IAC counts, DTC P1508 is set. Conditions for setting DTC

1. No scan tool test is being run.
2. No Throttle Position (TP) sensor, Vehicle Speed Sensor (VSS), Engine Coolant Temperature (ECT) sensor, EGR, Mass Air Flow (MAF) sensor, Manifold Absolute Pressure (MAP) sensor, Intake Air Temperature (IAT) sensor, misfire, low voltage, fuel system, canister purge, injector control or ignition control DTCs are present.
3. Barometric (BARO) pressure is more than 75 kPa.
4. Canister purge duty cycle is more than 10 percent.
5. Engine running time is more than 125 seconds.
6. Vehicle speed is less than one MPH.
7. Engine coolant temperature is more than 122°F (50°C).
8. Ignition voltage is between 9.5 and 16.7 volts.
9. Throttle is closed.
10. Engine speed is more than 100-200 RPM less than desired idle, based upon engine coolant temperature.
11. Engine speed is less than desired idle.
12. All conditions are present for 10 seconds.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation at PCM and Idle Air Control (IAC) motor. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Ensure air intake system is not restricted. Check throttle body for blockage and carbon build up. Clean as necessary. Inspect for a large vacuum leak at brake booster or PCV. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start and idle engine. Turn off all accessories. Using scan tool, select MISC TEST, then select IAC SYSTEM. Command engine speed up to 1500 RPM, down to 500 RPM, then back to 1500 RPM while monitoring ENGINE SPEED display. If ENGINE SPEED display remains within 50 RPM of desired value, for each RPM command, fault is not present, see «DIAGNOSTIC AIDS»(ref-97343-S26641797962001050100000) . If engine speed is not within 50 RPM of desired value, go to next step.
3. Disconnect IAC valve. Install IAC Noid-Light (J 37027). Start engine. Command engine speed up to 1500 RPM, down to 500 RPM, then back to 1500 RPM while monitoring noid-light. If noid-light cycles Red and Green (never off), go to step 5 . If noid-light does not cycle, go to next step.
4. Check all IAC circuits for open, short to ground or short to voltage. Repair as necessary. If circuits are okay, go to step 8 .
5. Check throttle body for objects blocking IAC passage or throttle bore, excessive deposits in IAC passage, pintle, throttle bore or throttle plate. Check for restriction or vacuum leaks in air intake system. Check adjustment screw for tampering. Repair as necessary. If no problems are found, go to next step.
6. Check for poor terminal contact at IAC harness connector. Repair as necessary. If terminal contacts are okay, go to next step.
7. Replace IAC valve. Retest system.
8. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest System.

PCM controls engine idle speed by adjusting position of Idle Air Control (IAC) motor pintle. IAC is a bi-directional stepper motor driven by 2 coils. PCM applies current to IAC coils in steps (counts) to extend IAC pintle into a throttle body passage to decrease air flow. To increase air flow PCM reverses current and retracts pintle. This method allows highly accurate control of idle speed and quick response to changes in engine load. If PCM detects a condition where too high an idle speed is present and PCM is unable to compensate for idle speed by increasing IAC counts, DTC P1509 is set. Conditions for setting DTC

1. No scan tool test is being run.
2. No Throttle Position (TP) sensor, Vehicle Speed Sensor (VSS), Engine Coolant Temperature (ECT) sensor, EGR, Mass Air Flow (MAF) sensor, Manifold Absolute Pressure (MAP) sensor, Intake Air Temperature (IAT) sensor, fuel system, canister purge, injector control or ignition control DTCs are present.
3. Barometric (BARO) pressure is more than 75 kPa.
4. Canister purge duty cycle is more than 10 percent.
5. Engine running time is more than 125 seconds.
6. Vehicle speed is less than one MPH.
7. Engine coolant temperature is more than 122°F (50°C).
8. Engine speed is less than desired idle.
9. Ignition voltage is between 9.5 and 16.7 volts.
10. Engine speed is more than 100 and 200 RPM less than desired idle, based upon engine coolant temperature.
11. All conditions are present for 10 seconds.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation at PCM and Idle Air Control (IAC) motor. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Ensure air intake system is not restricted. Check throttle body for blockage and carbon build up. Clean as necessary. Check for vacuum leak. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start and idle engine. Turn off all accessories. Using scan tool, select MISC TEST, then select IAC SYSTEM. Command engine speed up to 1500 RPM, down to 500 RPM, then back to 1500 RPM while monitoring ENGINE SPEED display. If ENGINE SPEED display remains within 50 RPM of desired value, for each RPM command, fault is not present, see «DIAGNOSTIC AIDS»(ref-97343-S33073148562001050100000) . If engine speed is not within 50 RPM of desired value, go to next step.
3. Disconnect IAC valve. Install IAC Noid-Light (J 37027). Start engine. Command engine speed up to 1500 RPM, down to 500 RPM, then back to 1500 RPM while monitoring noid-light. If noid-light cycles Red and Green (never off), go to step 5 . If noid-light does not cycle, go to next step.
4. Check all IAC circuits for open, short to ground or short to voltage. Repair as necessary. If circuits are okay, go to step 8 .
5. Check throttle body for objects blocking IAC passage or throttle bore, excessive deposits in IAC passage, pintle, throttle bore or throttle plate. Check for restriction or vacuum leaks in air intake system. Check adjustment screw for tampering. Repair as necessary. If no problems are found, go to next step.
6. Check for poor terminal contact at IAC harness connector. Repair as necessary. If terminal contacts are okay, go to next step.
7. Replace IAC valve. Retest system.
8. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Throttle Position Sensor 1 (TP) sensor circuit provides a voltage signal relative to throttle valve position. Throttle valve angle will vary from about 8 percent at closed throttle to about 92 percent at Wide Open Throttle (WOT). Mass Air Flow (MAF) sensor measures amount of air which passes through it into engine during a given time. PCM uses MAF information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle. MAF sensor produces a frequency signal which can be monitored using a scan tool. Frequency will vary within about 4-7 grams/sec. at idle to about 25-40 grams/sec. at maximum engine load. Condition for setting DTC

1. Engine is running.
2. No MAF sensor DTCs are set.
3. Throttle actuation mode is not off.
4. MAF reading-ETC estimated air flow is less than 40 grams/sec. for 250 failures within 1000 test samples

Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe Mass Air Flow (MAF), Throttle Position Sensor (TPS) 1 and TPS2 sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. Check for plugged intake air duct or filter. A wide-open throttle acceleration from a stop should mass air flow displayed on scan tool to increase from about 3-6 grams/sec. at idle to 100 grams/sec. or more at time of 1-2 shift. If air flow is not as specified, check for a restriction. If DTC P1514 can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Perform Electric Throttle Control (ETC) System Check. See «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
3. Turn ignition on. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions noted. Monitor DTC information for DTC P1514. If scan tool indicates that DTC P1514 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, go to «DIAGNOSTIC AIDS»(ref-97343-S42222927542001050100000) .
4. Start engine. While engine is idling, monitor scan tool MAF FREQUENCY. If scan tool display is less than 6-10 grams/sec., go to next step. If scan tool display is 6-10 grams/sec. or more, go to step 8 .
5. Turn ignition off. Disconnect MAF sensor. Turn ignition on. If scan tool MAF FREQUENCY shows zero grams/sec., go to next step. If scan tool display is not as specified, go to step 7 .
6. Replace MAF sensor. Retest system. If problem is still present, go to step 9 .
7. Check for incorrect MAF sensor harness routing near high voltage components such as solenoids, relays or electrical motors. Repair as necessary. If no problem was found, go to next step.
8. With engine at idle, monitor scan tool MAF FREQUENCY. Under road load, snap throttle open quickly to wide open throttle and note MAF FREQUENCY. If scan tool display reads 6-10 grams/sec., go back to step 6 . If scan tool display is not as specified, go to next step.
9. Turn ignition on, engine off. Observe MAP sensor reading on scan tool. If MAP sensor value is less than 65 kPa, go to next step. If scan tool display is 65 kPa or more, go to step 13 .
10. Disconnect MAP sensor. If scan tool display is less than 104 kPa, go to step 12 . If scan tool display is not as specified, go to next step.
11. Check for an open or short on MAP sensor ground circuit between PCM and MAP sensor. Repair as necessary. If no problem was found, go to step 13 .
12. Replace MAP sensor. Retest system.
13. Use scan tool to monitor TPS1 and TPS2 throttle angles. At closed throttle, TPS1 value should be between 8 and 10 percent and TPS2 value should be between 90 and 92 percent. TPS values should change smoothly as throttle valve is opened all the way. At WOT, TPS1 value should be between 90 and 92 percent, and TPS2 value should be between 8 and 10 percent. If TPS operation is as specified, go to «DIAGNOSTIC AIDS»(ref-97343-S42222927542001050100000) . If TPS operation is not as specified, go to next step.
14. Disconnect TPS1 and TPS2. Observe scan tool values for both sensors. If both values are zero, go to next step. If scan tool display is not as specified, go to step 16 .
15. Connect test light between TPS harness connector 5-volt reference circuit and each TPS signal circuit. Scan tool display should read 5 volts as each sensor signal circuit is probed. If scan tool display is as specified, go to step 18 . If scan tool display is not as specified, go to next step.
16. Check affected TPS for short to voltage on signal circuit, high resistance on ground circuit or poor ground circuit connection between PCM and TPS. Repair as necessary. If no problem was found, go to step 19 .
17. Check affected TPS for poor connection or high resistance on 5-volt reference circuit between PCM and TPS. Repair as necessary. If no problem was found, go to next step.
18. Replace affected TPS. Retest system.
19. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

Throttle Position Sensor 1 (TP) sensor circuit provides a voltage signal relative to throttle valve position. Throttle valve angle will vary from about 8 percent at closed throttle to about 92 percent at Wide Open Throttle (WOT). DC motor circuit provides a voltage signal relative to command throttle position (blade angle). DTC detects difference between actual throttle position and command throttle position. Conditions for setting DTC

1. Ignition is on.
2. Throttle actuation mode is normal.
3. Command throttle position to actual throttle position is less than 8 percent when desired throttle position is steady within 0.5 percent for 100 counts within 1000 test samples.

Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe TPS1 and TPS2 sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Perform Electric Throttle Control (ETC) System Check. See «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
3. Turn ignition on. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions noted. Monitor DTC information for DTC P1515 or P1516. If scan tool indicates that DTC P1515 or P1516 FAILED THIS IGNITION, go to next step. If scan tool display is not as specified, go to «DIAGNOSTIC AIDS»(ref-97343-S05488210332001050100000) .
4. Use scan tool to monitor TPS1 and TPS2 throttle angles. At closed throttle, TPS1 value should be between 8 and 10 percent and TPS2 value should be between 90 and 92 percent. TPS values should change smoothly as throttle valve is opened all the way. At WOT, TPS1 value should be between 90 and 92 percent, and TPS2 value should be between 8 and 10 percent. If TPS operation is as specified, go to step 8 . If TPS operation is not as specified, go to next step.
5. Turn ignition off. Disconnect DC motor. Use DVOM, measure DC motor resistance. If resistance is between 0.3 and 100 ohms, go to next step. If resistance is not as specified, go to step 7 .
6. Check for faulty circuit between DC motor and PCM. Repair as necessary. If no problem was found, go to step 8 .
7. Replace DC motor. Retest system. If problem is still present, go back to step 6 .
8. Disconnect TPS1 and TPS2. Observe scan tool values for both sensors. If both TPS values are zero volts, go to next step. If scan tool display is not as specified, go to step 10 .
9. Connect test light between TPS harness connector 5-volt reference circuit and each TPS signal circuit. See WIRING DIAGRAMS article. Scan tool display should read 5 volts as each sensor signal circuit is probed. If scan tool display is as specified, go to step 12 . If scan tool display is not as specified, go to step 11 .
10. Check affected TPS for short to voltage on signal circuit, high resistance on ground circuit or poor ground circuit connection between PCM and TPS. Repair as necessary. If no problem was found, go to step 13 .
11. Check affected TPS for poor connection or high resistance on 5-volt reference circuit between PCM and TPS. Repair as necessary. If no problem was found, go to step 13 .
12. Replace affected TPS. Retest system.
13. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Throttle Position Sensor 1 (TP) sensor circuit provides a voltage signal relative to throttle valve position. Throttle valve angle will vary from about 8 percent at closed throttle to about 92 percent at Wide Open Throttle (WOT). DC motor circuit provides a voltage signal relative to command throttle position (blade angle). DTC detects if throttle returns to default position with key on, steady state. Conditions for setting DTC

1. Ignition is on.
2. Normalized TPS1 is less than zero percent but normalized TPS2 is more than 25 percent.

Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. If harness appears to be okay, use scan tool to observe TPS1 and TPS2 sensor readings while moving connectors and harnesses. A change in display will indicate location of fault. If DTC can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Perform Electric Throttle Control (ETC) System Check. See «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) under SELF-DIAGNOSTIC SYSTEM. Go to next step.
3. Use scan tool to monitor TPS1 and TPS2 throttle angles. At closed throttle, TPS1 value should be between 8 and 10 percent and TPS2 value should be between 90 and 92 percent. TPS values should change smoothly as throttle valve is opened all the way. At WOT, TPS1 value should be between 90 and 92 percent, and TPS2 value should be between 8 and 10 percent. If TPS operation is as specified, go to step 7 . If TPS operation is not as specified, go to next step.
4. Turn ignition off. Disconnect DC motor. Use DVOM to measure DC motor resistance. If resistance is between 0.3 and 100 ohms, go to next step. If resistance is not as specified, go to step 6 .
5. Check for faulty circuit between DC motor and PCM. Repair as necessary. If no problem was found, go to step 7 .
6. Replace DC motor. Retest system. If problem is still present, go back to step 5 .
7. Disconnect TPS1 and TPS2. Observe scan tool values for both sensors. If both scan tool values are zero volts, go to next step. If scan tool display is not as specified, go to step 9 .
8. Connect test light between TPS harness connector 5-volt reference circuit and each TPS signal circuit. Scan tool display should read 5 volts as each sensor signal circuit is probed. If scan tool display is as specified, go to step 11 . If scan tool display is not as specified, go to step 10 .
9. Check affected TPS for short to voltage on signal circuit, high resistance on ground circuit or poor ground circuit connection between PCM and TPS. Repair as necessary. If no problem was found, go to step 12 .
10. Check affected TPS for poor connection or high resistance on 5-volt reference circuit between PCM and TPS. Repair as necessary. If no problem was found, go to step 12 .
11. Replace affected TPS. Retest system.
12. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.

Serial Peripheral Interface (SPI) communication is used internally by PCM to send messages between engine processor and automatic transmission processor. Included in each message sent between both processors is a checksum value of message. Both engine processor and automatic transmission processor will compare this checksum value with calculated value. If checksums do not match, receiving processor will view new data as being corrupted and ignore values. Receiving processor will then use previous message. Receiving processor will then send a message to sending processor informing it that its last message was corrupted. Conditions for setting DTC

1. Battery voltage is more than 9.0 volts for 2 seconds.
2. PCM detects an internal program fault (checksum data communications error).
3. Checksum fault for 3 out of 6 seconds.
4. No TCM resets for 2 seconds.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. If EEPROM calibration is latest version available, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system. If EEPROM calibration is not latest version, go to next step.
3. Reprogram PCM with latest available EEPROM calibration. Clear DTCs. If DTC P1618 resets, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. If DTC P1618 does not reset, repair is complete.

PCM monitors unexpected PCM reset. DTC will not turn MIL on. Only records DTC. Condition for setting DTC is Clock or Computer Operating Properly (COP) reset.

DTC P1625 stored by itself does not require diagnosis. Clear DTC.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on. Install scan tool. Start and idle engine. Select DTC INFO on scan tool. If scan tool indicates DTC P1625 failed, go to next step. If scan tool indicates DTC P1625 did not fail, see «DIAGNOSTIC AIDS»(ref-97343-S38762135542001050100000) .
3. Using scan tool, clear DTC P1625. Start and idle engine. Select DTC INFO. If scan tool indicates DTC P1625 failed, go to next step. If scan tool indicates DTC P1625 did not fail, see «DIAGNOSTIC AIDS»(ref-97343-S38762135542001050100000) .
4. Check vehicle for aftermarket electronic devices, such as phones, alarms, etc. If an aftermarket device is incorrectly installed PCM may detect a false sensor reading. Repair as necessary.

Throttle Position Sensor (TPS) 1 shares a 5-volt reference with PCM. If PCM detects 5-volt reference for TPS1 is failure, DTC 1635 will set. Conditions for setting DTC

1. Ignition is on.
2. Five-volt reference voltage for TPS1 is less than 4 volts.
3. Five-volt reference voltage for TPS1 is more than 5 volts.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Turn ignition on. Using DVOM, measure voltage at PCM harness connector TPS1 5-volt reference circuit by backprobing terminal S38. If voltage reading is between 4.95 and 5.0 volts, go to «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) . If voltage is not as specified, go to next step.
3. Measure voltage at PCM battery feed circuits (terminals F20 and F57). If voltage reading is between 11.6 and 12.7 volts, go to step 5 . If battery voltage is not as specified, go to next step.
4. Check for opens on both battery feed circuits. Repair as necessary. If no problem was found, go to next step.
5. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

Acceleration Position Sensor (APS) 1 shares a 5-volt reference with PCM. If PCM detects 5-volt reference for APS1 is failure, DTC 1639 will set. Conditions for setting DTC

1. Ignition is on.
2. Five-volt reference voltage for TPS1 is less than 4 volts.
3. Five-volt reference voltage for TPS1 is more than 5 volts.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Turn ignition on. Using DVOM, measure voltage at PCM harness connector Acceleration Position Sensor (APS1) 5-volt reference circuit by backprobing terminal S36. If voltage reading is between 4.95-5.0 volts, go to «ELECTRIC THROTTLE CONTROL SYSTEM CHECK»(ref-97343-S18866373762001050100000) . If voltage is not as specified, go to next step.
3. Measure voltage at PCM battery feed circuits (terminals F20 and F57). If voltage reading is between 11.6 and 12.7 volts, go to step 5 . If voltage is not present, go to next step.
4. Check for opens on both battery feed circuits. Repair as necessary. If no problem was found, go to next step.
5. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING.

Output Driver Modules (ODM) are used by PCM to turn on many current driven devices that are needed to control various engine and transmission functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to device which PCM is commanding ON. Unlike ODMs used in prior years, ODMs have capability each output circuit individually. DTC P1640 set, indicates an improper voltage level has been detected on an ODM output. Since A/C is an option, no A/C will cause air conditioning clutch relay output to always fail. If a fault is seen on air conditioning clutch relay output, it will not be logged as a fault until A/C request input interrupts a high voltage, indicating A/C has been installed. Conditions for setting DTC

1. Ignition is on.
2. Engine is running.
3. No DTC P1618 set.
4. Ignition voltage is more than 13.2 volts for 4 seconds.
5. Output voltage does not equal ignition voltage when output is OFF or voltage is not less than one volt when output is ON.
6. All conditions occur for at least 1 second.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use DVOM to observe suspect circuits while moving connectors and harnesses. A change in display will indicate location of fault. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
2. Check fuse for driver circuit that was shown as faulty. If fuse is blown, check for short circuit to ground between fuse and affected component. Replace fuse after repair. If fuse is not blown, go to next step.
3. Disconnect PCM connector for affected driver circuit. Repair damaged pins or terminals as necessary. If pins or terminals are okay, go to next step.
4. Check if either lamp circuit for CHECK ENGINE or CHECK TRANS is indicated as faulty by scan tool. If no fault is indicated, go to step 8 . If a fault is indicated, leave PCM connector for lamp driver circuit disconnected. Turn ignition on. Check voltage at PCM connector for affected lamp driver circuit. If battery voltage is present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. If battery voltage is not present, go to next step.
5. Turn ignition on. Check for battery voltage at fuse for affected lamp driver circuit. If battery voltage is present, go to next step. If battery voltage is not present, repair open circuit between ignition switch and fuse.
6. Turn ignition off. Using DVOM, check for continuity between ground and affected driver terminal at PCM connector. If continuity is present, repair short to ground in affected driver circuit between affected component and PCM connector. Retest system. If continuity is not present, go to next step.
7. Repair open in affected driver circuit between fuse and PCM connector. Retest system.
8. Reconnect PCM. Start engine and allow to idle. Using DVOM, backprobe affected terminal at PCM connector for battery voltage. If battery voltage is present, replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system. If battery voltage is not present, go to next step.
9. Run engine at idle. Check for battery voltage to affected circuit fuse. If voltage is as specified, go to step 6 . If voltage is not as specified, repair open circuit between ignition switch and fuse. Retest system.

Quad Driver Modules (QDM) are used by PCM to turn ON current-driven devices that are needed to control 2 engine functions. PCM monitors open or short circuits of either Canister Control Purge (CCP) vent solenoid or Variable Intake Manifold (VIM). Conditions for setting DTC

1. Ignition ON.
2. Engine running.
3. Ignition voltage.
4. Output voltage does not equal less than 1 volt when output is ON.
5. All conditions occur for at least 0.5 seconds.

Check for poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. If harness appears to be okay, use DVOM to observe suspect circuits while moving connectors and harnesses. A change in display will indicate location of fault. If DTC P1650 cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.

1. Perform «ON-BOARD DIAGNOSTIC II SYSTEM CHECK»(ref-97343-S01178100682001050100000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Check fuse for driver circuit that is shown as faulty. If fuse is not blown, go to next step. If fuse is blown, check for short circuit to ground between fuse and affected component. Replace fuse after repair.
3. Disconnect PCM connector for affected driver circuit. Check for damaged pins or terminals. Repair as necessary. If pins or terminals are okay, go to next step.
4. If either CHECK ENGINE or CHECK TRANS light circuits are indicated as faulty by scan tool, go to next step. If either CHECK ENGINE or CHECK TRANS light circuits are not indicated as faulty by scan tool, go to step 8 .
5. Leave PCM connector for lamp driver circuit disconnected. Turn ignition on. Measure voltage at PCM connector for affected lamp driver circuit. If battery voltage is present, go to step 10 . If battery voltage is not present, go to next step.
6. Turn ignition on. Check for battery voltage at fuse for affected lamp circuit. If battery voltage is present, go to next step. If battery voltage is not present, repair open circuit between ignition switch and fuse.
7. Turn ignition off. Disconnect PCM connector for affected driver terminal. Connect DVOM between ground and PCM connector for affected driver. If continuity is present, repair short circuit to ground between affected component and PCM driver terminal. If continuity is not present, repair open circuit between fuse and PCM driver terminal.
8. Reconnect PCM. Start and idle engine. Backprobe affected terminal at PCM with DVOM. If battery voltage is present, go to step 10 . If battery voltage is not present, go to next step.
9. Start and run engine at idle. Check for battery voltage at fuse for affected circuit. If battery voltage is present, go to step 7 . If battery voltage is not present, repair open circuit between ignition switch and fuse.
10. Replace and reprogram PCM. See «EEPROM PROGRAMMING PROCEDURE»(ref-97343-S42360493802001050100000) under PROGRAMMING. Retest system.