Engine Controls Self-Diagnostics - Grand Cherokee Jeep Grand Cherokee WJ

INTRODUCTION

Perform all steps in BASIC DIAGNOSTIC PROCEDURES article. If no faults are found while performing basic diagnostic procedures, proceed with self-diagnostics. If no Diagnostic Trouble Codes (DTC) or only pass codes (system functioning properly) are found during self-diagnostics, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom.

SELF-DIAGNOSTIC SYSTEM

Note. Self-diagnostic tests are written specifically for Chrysler's Diagnostic Readout Box (DRBIII(R)) scan tool. A generic scan tool may not be capable of performing all necessary test functions.

Note. Throughout this article, models with Calif. emissions may be referred to as Calif. models. Vehicles from other states may be equipped with Calif. emissions. Models with Federal emissions may be referred to as Federal models. Check underhood label for application.

Malfunction Indicator Light (MIL)

MIL may also be referred to as CHECK ENGINE light. MIL is located on right side of instrument cluster and is represented by an engine symbol. When ignition is first turned on, MIL should come on and remain on for 2 seconds to verify bulb and circuit operation, and then go off. If MIL does not come on at all, remove and inspect MIL bulb. Replace bulb as necessary. If bulb is okay, replace instrument panel circuit board. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION in INSTRUMENT PANELS - GRAND CHEROKEE article.

Powertrain Control Module (PCM) monitors several different engine control system circuits. PCM is located on firewall in right rear corner of engine compartment. If a malfunction occurs which affects vehicle emissions, a Diagnostic Trouble Code (DTC) will be stored in PCM memory and PCM will enter limp-in mode. In limp-in mode, PCM substitutes values for the failed component to continue engine operation, but a loss of good driveability may result. When DTC is stored in PCM memory, PCM will turn on MIL and MIL will remain on steady. If problem exists which does not affect vehicle emissions, a DTC will be stored in PCM but MIL will not be turned on.

PCM might not store a DTC for a monitored circuit even though a malfunction has occurred. This may happen because one of the criteria for the DTC has not been met. Criteria may be a specific engine RPM range, engine temperature and/or voltage input to PCM. For example, assume criteria for DTC requires PCM to monitor a specified sensor output circuit only when engine operates at 750-2000 RPM. If sensor output circuit becomes shorted to ground when engine is operating at 2400 RPM, DTC will not be stored, as short to ground occurred at 2400 RPM which exceeds the limit when PCM monitors the circuit.

If PCM detects an active engine misfire severe enough to cause catalytic converter damage, MIL will immediately start flashing to warn driver of possible catalytic converter damage and DTC will be stored. PCM may turn off MIL if malfunction is not detected during 3 consecutive trips, 3 consecutive engine misfire monitor tests or fuel system monitor tests. For additional information on good trips, see TRIP INDICATOR . For additional information on engine misfire monitor and fuel system monitor, see MONITORED CIRCUITS . PCM performs engine misfire and fuel system monitor tests within predetermined engine speed (RPM) and load operating conditions.

DTCs may only be retrieved for system diagnosis by using a scan tool. See RETRIEVING DIAGNOSTIC TROUBLE CODES . System malfunctions are identified as either hard failures or intermittent failures. For additional information on hard failures or intermittent failures, see HARD FAILURES or INTERMITTENT FAILURES .

Monitored Circuits

The PCM contains electronic circuit monitors that monitor fuel, vehicle emissions, engine and ignition system performance. Monitors use information from various sensor circuits for system monitoring. Monitors do not indicate a specific component failure, but indicate an implied failure within a specified system, and that problem must be diagnosed. If any monitor detects a problem affecting vehicle emissions, a Diagnostic Trouble Code (DTC) will be stored in PCM memory. The following monitors are used.

1. Engine Misfire Monitor
2. Fuel System Monitor
3. Oxygen Sensor Monitor
4. Oxygen Sensor Heater Monitor
5. Catalyst Monitor
6. EVAP System Leak Detection Pump Monitor

After 3 good trips, PCM will turn off the MIL. At that time, the PCM will automatically switch the trip counter to a warm-up cycle counter. The PCM will erase DTCs after 40 warm-up cycles if the recent malfunction does not reoccur in that time. For additional information on good trips and warm-up cycles, see TRIP INDICATOR .

Non-Monitored Circuits

The PCM does not monitor all circuits, conditions and systems that could cause a malfunction or driveability problem. However, problems with these systems may cause PCM to store DTCs for other systems or components.

For example, a fuel pressure problem will not cause a DTC directly, but could cause a rich/lean condition or misfire. This could cause PCM to store an oxygen sensor DTC. The major non-monitored circuits are identified as follows.

1. Cylinder Compression
2. Excessive Oil Consumption
3. Exhaust System
4. Fuel Injector Mechanical Faults
5. Fuel Pressure
6. PCM Connector Engagement
7. PCM System Ground
8. Secondary Ignition System
9. Throttle Body Airflow
10. Vacuum Assist

Trip Indicator

The trip is essential for running monitors and turning off the Malfunction Indicator Light (MIL). A trip is defined as a set of vehicle operating conditions that must be met for a specific monitor to run. All trips begin with an ignition key cycle. Good trip counters are, specific good trip, fuel system good trip and misfire good trip.

1. Specific Good Trip The term good trip has different meanings depending on the circumstances. If the MIL is off, a good trip is defined as when the oxygen sensor monitor and the catalyst monitor have completed in the same drive cycle. If the MIL is on and a DTC was set by the fuel system monitor or misfire monitor, vehicle must be operated in the similar conditions window for a specified amount of time. If MIL is on and a DTC was set by a PCM task manager commanded once-per-trip monitor (oxygen sensor/heater monitor, catalyst monitor, purge flow monitor, leak detection monitor or EGR monitor), a good trip is when the monitor is passed on the next engine start-up. If the MIL is on and any other emissions DTC is set (not an OBD-II monitor), a good trip is when the oxygen sensor monitor and catalyst monitor have completed, or 2 minutes of engine run time has occurred (if the oxygen sensor monitor and catalyst monitor has stopped running). NOTE: For more information on similar conditions window, see «SIMILAR CONDITIONS WINDOW»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee__similar-conditions-window) .
2. Fuel System Good Trip To count as a good trip (3 required) and turn off the MIL, the following conditions must be met. Engine must be in closed loop, must be operating in similar conditions window and short term multiplied by long term must be less than threshold value.
3. Misfire Good Trip If operating in similar conditions window and 1000 engine revolutions have occurred with no misfires, the PCM will count one good trip (3 required) in order to turn off MIL.
4. Warm-Up Cycles Once the MIL has been turned off by the good trip counter, the PCM will automatically switch to a warm-up cycle counter that can be viewed by the DRBIII(R) scan tool. Warm-up cycles are used to clear DTCs and freeze frame data from PCM memory. Forty warm-up cycles are necessary to clear DTCS and freeze frame data. A warm-up cycle is defined as the engine is started, an increase of 40°F (4°C) in engine coolant temperature exists after engine is started and engine coolant temperature reaches at least 160°F (71°C).

Similar Conditions Window

Similar conditions window data can be viewed by using the DRBIII(R) scan tool. The similar conditions window displays information about the engine operation during a monitor. Engine load (absolute manifold pressure) and engine RPM are stored in this window when a failure occurs. This information is useful in determining when a failure occurred. There are 2 different similar conditions windows, fuel system and misfire. For more information on similar conditions windows, see SELF-DIAGNOSTIC SYSTEMS in THEORY & OPERATION article.

Hard Failures

Hard failures cause Malfunction Indicator Light (MIL) to illuminate and remain on until problem is repaired. If MIL comes on and remains on during vehicle operation, cause of malfunction must be determined by retrieving Diagnostic Trouble Codes (DTC). See RETRIEVING DIAGNOSTIC TROUBLE CODES . If a sensor fails, PCM will use substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, vehicle runs but driveability will not be optimum.

Intermittent Failures

Intermittent failures may cause Malfunction Indicator Light (MIL) to flicker or illuminate and go out after intermittent failure goes away. However, the corresponding Diagnostic Trouble Code (DTC) will be retained in Powertrain Control Module (PCM) memory. If related failure does not reoccur within 40 warm-up cycles, related DTC will be erased from PCM memory. Most intermittent failures are caused by a sensor, electrical connector or wiring related problems. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.

SERVICE PRECAUTIONS

Before proceeding with system diagnosis, following precautions must be followed

1. Ensure fuel pressure is released before disconnecting any fuel line or fuel fitting, as fuel system is under pressure and may cause personal injury. See «FUEL SYSTEM PRESSURE RELEASE»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee__fuel-system-pressure-release) .
2. When using diagnostic tests for diagnosis, DO NOT skip any steps or incorrect diagnosis may result. When instructed to disconnect any connector, check that the connector is clean and in good condition after disconnecting the connector. Repair or clean connector as necessary. Always perform indicated verification procedure after repairs are made. Verification tests are listed at the end of the diagnostic tests.
3. When using a jumper wire, ensure either jumper wire or circuit is fuse-protected.
4. Ensure ignition is off before disconnecting connector from any control module.
5. When checking voltage or continuity at any control module, probe connector for control module from pin side. DO NOT probe wire through insulation or backprobe connector (unless instructed to do otherwise in test procedure).
6. DO NOT cause short circuits when performing electrical tests. This will set additional Diagnostic Trouble Codes (DTC), making diagnosis of original problem more difficult.
7. DO NOT prolong testing of fuel injectors or engine may hydrostatically lock.
8. If replacing Powertrain Control Module (PCM), correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent DTCs from being set in Anti-Lock Brake System (ABS) module, Air Bag Control Module (ACM) and Sentry Key Immobilizer Module (SKIM), if equipped. See «PROGRAMMING»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) .
9. If replacing PCM on models with a SKIM, secret key data must be updated to enable engine starting. To update secret key data, see «PROGRAMMING»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) .

DIAGNOSTIC PROCEDURE

If no faults were found while performing procedures in BASIC DIAGNOSTICS PROCEDURES article, proceed with self-diagnostics. Always perform a visual inspection before attempting to diagnose engine control system problems. See VISUAL INSPECTION .

VISUAL INSPECTION

Most engine control system driveability problems result from faulty wiring, poor electrical connections, improper wire routing, or leaking air and vacuum hose connections. Inspect all engine control system components, hoses, connectors and wiring for damage before proceeding with self-diagnostics. Diagnostic Trouble Codes (DTC) can only be retrieved by using a scan tool. See RETRIEVING DIAGNOSTIC TROUBLE CODES .

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. Ensure battery is fully charged before proceeding with Diagnostic Trouble Code (DTC) retrieval.

Scheme 26

Scheme 27

1. Turn ignition off. DTCs can only be retrieved using a scan tool. Connect scan tool to Data Link Connector (DLC), located under left side of instrument panel. (Scheme 26) Turn ignition on. Using scan tool manufacturer's instructions, read and record DTC (generic scan tool) or DTC message (DRBIII(R) scan tool), and freeze frame data.
2. If scan tool will not power up, check for loose cable connections or bad cable. If cable connections and cable are okay, measure voltage at DLC power terminal No. 16 (Pink/Red wire). (Scheme 27) Voltage should be at least 11 volts. If voltage is not as specified, check wiring circuit and fuse No. 17 (10-amp) in junction block. Junction block is located under left side of instrument panel. (Scheme 26) Repair wiring or replace fuse as necessary.
3. If scan tool displays USER-REQUESTED COLD BOOT error or USER-REQUESTED WARM BOOT error, or any other error message, record entire displayed error message and follow scan tool manufacturer's instructions.
4. If scan tool displays a bus failure error message, this indicates a scan tool failure or a bus circuit failure. To diagnose and repair bus circuit failure, see COMMUNICATIONS under SYSTEM TESTS in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.
5. If any DTCs are displayed, perform appropriate diagnostic test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. After repair is complete, clear DTCs from PCM memory and perform appropriate verification test. Verification tests are located at the end of the diagnostic tests. If no DTCs are displayed, go to one of the following: For starting or driveability problems, go to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom. For speed control problems and servicing information, refer to appropriate CRUISE CONTROL SYSTEMS article in ACCESSORIES & EQUIPMENT. For charging system problems, refer to appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. For transmission electronic controls system problems, refer to appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS.

Using Scan Tool

Note. Clearing Diagnostic Trouble Codes (DTC) with a scan tool will also erase all OBD-II monitor data. This includes all counter information for warm-up cycles, trips and freeze frame data.

Connect scan tool to Data Link Connector (DLC), located under left side of instrument panel. (Scheme 26) Turn ignition on. Using screen prompts on scan tool, clear codes from Powertrain Control Module (PCM).

Self-Erasure

After 3 good trips, Powertrain Control Module (PCM) will turn off the MIL. At that time, the PCM will automatically switch the trip counter to a warm-up cycle counter. The PCM will erase DTCs after 40 warm-up cycles if the recent malfunction does not reoccur in that time. For additional information on good trips and warm-up cycles, see TRIP INDICATOR .

POWERTRAIN CONTROL MODULE LOCATION

Powertrain Control Module (PCM) is located under left side of instrument. (Scheme 26) PCM has three 32-pin connectors. Connector C1 is Black, connector C2 is White and connector C3 is Gray colored.

FUEL SYSTEM PRESSURE RELEASE

1. Remove fuel pump relay from Power Distribution Center (PDC). PDC is located in right side of engine compartment, next to battery. (Scheme 28) Start and run engine until it stalls. Attempt to start engine. Continue restarting engine until it will no longer run. Turn ignition off.
2. Disconnect any fuel injector connector. Connect a jumper wire between either fuel injector terminal and positive battery terminal. Connect another jumper wire to other fuel injector terminal. Momentarily touch other end of jumper wire to negative battery terminal. CAUTION: DO NOT supply power to fuel injector for more than 4 seconds, or fuel injector may be damaged.
3. Place a shop towel under fuel line quick-connector at fuel rail. Use care when disconnecting fuel lines, as some fuel pressure may still exist in fuel lines. Disconnect fuel line quick-connector. Reinstall fuel pump relay in PDC. NOTE: One or more Diagnostic Trouble Codes (DTC) may set when fuel pump relay is removed.
4. Erase any DTCs that may have set after fuel pressure release procedure. See «CLEARING DIAGNOSTIC TROUBLE CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee).

Scheme 28

POWERTRAIN CONTROL MODULE

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM on models equipped with a Sentry Key Immobilizer Module (SKIM), the secret key data must also be updated to enable engine starting.

Programming Powertrain Control Module

Connect scan tool to Data Link Connector (DLC), located under left side of instrument panel. (Scheme 26) Using scan tool, enter correct VIN and mileage into PCM. Using scan tool manufacturer's instructions, clear DTCs from ABS module and ACM.

Updating Secret Key Data

1. Connect scan tool to Data Link Connector (DLC), located under left side of instrument panel. (Scheme 26)
2. Ensure transmission is in Park. Turn ignition on. Using scan tool, select THEFT ALARM, SKIM and then MISCELLANEOUS. Select PCM REPLACED. Place the SKIM in SECURED ACCESS MODE by entering the appropriate Personal Identification Number (PIN) for this vehicle. PIN may be obtained from the owner, vehicle's invoice, or from the manufacturer. Press ENTER to transfer secret key data from Sentry Key Immobilizer Module (SKIM) to the PCM. This will enable the vehicle to start.
3. If 3 attempts are made to enter the SECURED ACCESS MODE by using an incorrect PIN, the SECURED ACCESS MODE will be locked out for one hour. To exit lock out mode, leave ignition on with all accessories turned off. After one hour, enter correct PIN. It may be necessary to monitor battery voltage and connect a battery charger.

SUMMARY

If no hard failure DTCs are present, driveability symptoms exist or intermittent DTCs exist, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DTC MESSAGES & CODES

DIAGNOSTIC TESTS

Note. Self-diagnostic tests are written specifically for Chrysler's Diagnostic Readout Box (DRBIII(R)) scan tool. A generic scan tool may not be capable of performing all necessary test functions.

DTC P0031: O2 SENSOR HEATER CIRCUIT LOW 1/1 DTC P0032: O2 SENSOR HEATER CIRCUIT HIGH 1/1

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Description

Heater circuit for 1/1 Heated Oxygen Sensor (HO2S) is monitored when battery voltage is more than 10.6 volts and engine coolant temperature is less than a specified temperature, but within a set temperature difference of battery temperature sensor. DTC will set in Powertrain Control Module (PCM) memory when PCM senses HO2S heater circuit is less than a predetermined value.

Testing

Note. 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 4.0L, 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, actuate HO2S HEATER TEST and monitor 1/1 HO2S voltage for 5 minutes. If voltage changes to about zero volts, go to next step. If voltage does not change to about zero volts, go to step 3.
2. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Check for any contaminates that may have damaged the 1/1 HO2S such as contaminated fuel, unapproved silicone, oil and coolant. Repair any problems that are found. If no problems are found, start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/1 HO2S voltage while wiggling connectors and wiring harness from 1/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
3. Disconnect 1/1 HO2S connector. Measure resistance between Orange/Dark Green and Gray/White wires at 1/1 HO2S connector (component side). If resistance is not 4-5 ohms with HO2S at 70°F (21°C), replace 1/1 HO2S. If resistance is 4-5 ohms, 1/1 HO2S heater element is okay. Go to next step.
4. Measure voltage between ground and Orange/Dark Green wire at 1/1 HO2S harness connector. If voltage is more than 12 volts, go to next step. If voltage is 12 volts or less, repair open power circuit to 1/1 HO2S heater. See WIRING DIAGRAMS.
5. Disconnect Powertrain Control Module (PCM) connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Gray/White wire between 1/1 HO2S harness connector and terminal No. 8 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Gray/White wire.
6. Measure voltage between ground and terminal No. 8 (Gray/White wire) at PCM C3 harness connector. If no voltage is present, go to next step. If any voltage is present, repair short to voltage in Brown/White wire between 1/2 HO2S and PCM.
7. At this time, PCM is assumed to be defective. Replace PCM.

Scheme 29

DTC P0051: O2 SENSOR HEATER CIRCUIT LOW 2/1 DTC P0052: O2 SENSOR HEATER CIRCUIT HIGH 2/1

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Heater circuit for 2/1 Heated Oxygen Sensor (HO2S) is monitored when battery voltage is more than 10.6 volts and engine coolant temperature is less than a specified temperature, but within a set temperature difference of battery temperature sensor. DTC will set in Powertrain Control Module (PCM) memory when PCM senses HO2S heater circuit is less than a predetermined value.

Note. 2/1 HO2S may also be referred to as a upstream oxygen sensor. On 4.0L, 2/1 HO2S is located on rear exhaust manifold. On 4.7L, 2/1 HO2S is located in right (passenger's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, actuate HO2S HEATER TEST and monitor 2/1 HO2S voltage for 5 minutes. If voltage changes to about zero volts, go to next step. If voltage does not change to about zero volts, go to step 3.
2. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Check for any contaminates that may have damaged the 2/1 HO2S such as contaminated fuel, unapproved silicone, oil and coolant. Repair any problems that are found. If no problems are found, start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 2/1 HO2S voltage while wiggling connectors and wiring harness from 2/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 2/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
3. Disconnect 2/1 HO2S connector. Measure resistance between Orange/Dark Green and Dark Blue/White wires at 2/1 HO2S connector (component side). If resistance is not 4-5 ohms with HO2S at 70°F (21°C), replace 2/1 HO2S. If resistance is 4-5 ohms, 2/1 HO2S heater element is okay. Go to next step.
4. Measure voltage between ground and Orange/Dark Green wire at 2/1 HO2S harness connector. If voltage is more than 12 volts, go to next step. If voltage is 12 volts or less, repair open power circuit to 2/1 HO2S heater. See WIRING DIAGRAMS.
5. Disconnect Powertrain Control Module (PCM) connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/White wire between 2/1 HO2S harness connector and terminal No. 16 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/White wire.
6. Measure voltage between ground and terminal No. 16 (Dark Blue/White wire) at PCM C3 harness connector. If no voltage is present, go to next step. If any voltage is present, repair short to voltage in Dark Blue/White wire between 2/1 HO2S and PCM.
7. At this time, PCM is assumed to be defective. Replace PCM.

DTC P0071: AMBIENT TEMP SENSOR PERFORMANCE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Note. Ambient temperature sensor is also referred to as Battery Temperature Sensor (BTS).

BTS performance is monitored with ignition on, coolant temperature more than 160°F (71°C) and no intake air temperature sensor faults present. DTC will set in Powertrain Control Module (PCM) memory after engine has completed 5 warm-up cycles, odometer mileage has increased 197 miles and inlet air temperature has increased less than 5°F (-15°C). Two trips are required to set this DTC. Possible causes for DTC to set are: defective BTS, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0071 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0071 or displayed count is not "0", go to step 6.
2. Turn ignition off. Disconnect BTS connector. BTS is located under battery and has a Black 2-pin connector. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, connect a jumper wire between BTS harness connector terminals. Turn ignition on. Using scan tool, read BTS voltage. If voltage is less than one volt, replace BTS. If voltage is one volt or more, go to next step.
3. Turn ignition off. Reconnect BTS connector. Using a voltmeter, backprobe Black/Light Blue wire between BTS harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) PCM is located on firewall in right rear corner of engine compartment. Start engine and note voltage reading. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance in Black/Light Blue wire.
4. Turn ignition off. Using a voltmeter, backprobe Violet/Light Green wire between BTS harness connector and terminal No. 15 at PCM C3 harness connector. (Scheme 29) Start engine and note voltage reading. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance in Violet/Light Green wire.
5. At this time, PCM is assumed to be defective. Replace PCM.
6. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0107: MAP SENSOR VOLTAGE TOO LOW

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Manifold Absolute Pressure (MAP) sensor voltage is monitored when engine speed is more than 416 RPM but less than 1500 RPM, Throttle Position (TP) sensor voltage is less than 1.13 volts and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses MAP sensor voltage is less than 0.1 volt for 2 seconds with engine running.

1. Turn ignition on. Using scan tool, read Manifold Absolute Pressure (MAP) sensor voltage. If voltage is less than 1.2 volts, go to step 4. If voltage is 1.2 volts or more, go to next step.
2. Start engine and allow it to idle. Using scan tool, read MAP sensor voltage. If voltage is 0.04 volt or more, go to next step. If voltage is less than 0.04 volt, go to step 4.
3. At this time, conditions for MAP sensor low voltage do not exist or fault is an intermittent problem. Ensure engine is idling and at normal operating temperature. Using scan tool, monitor MAP sensor voltage while wiggling connectors and wiring harness from MAP sensor to Powertrain Control Module (PCM). (Scheme 30)or (Scheme 31). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which MAP sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
4. Turn ignition off. Disconnect MAP sensor connector. (Scheme 30)or (Scheme 31). Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector terminals are okay, turn ignition on. Measure voltage between ground and Orange wire at MAP sensor harness connector. If voltage is 4.5-5.2 volts, go to next step. If voltage is not 4.5-5.2 volts, go to step 8.
5. Using scan tool, read MAP sensor voltage. If voltage is 1.2 volts or less, go to next step. If voltage is more than 1.2 volts, replace MAP sensor.
6. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Dark Green/Red wire at MAP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Green/Red wire between PCM and MAP sensor connector.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. Turn ignition off. Ensure MAP sensor is disconnected. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Orange wire at MAP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Orange wire.
9. Measure resistance of Orange wire between MAP sensor harness connector and terminal No. 17 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire.
10. At this time, PCM is assumed to be defective. Replace PCM.

Scheme 30

Scheme 31

DTC P0108: MAP SENSOR VOLTAGE TOO HIGH

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Manifold Absolute Pressure (MAP) sensor voltage is monitored when engine speed is more than 400 RPM, Throttle Position (TP) sensor voltage is less than 1.13 volts and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses MAP sensor voltage is more than 4.88 volts for 2.2 seconds with engine running. Possible causes for DTC to set are: defective MAP sensor, defective PCM, or defective connectors or wiring.

1. Start engine and allow it to idle. Using scan tool, read MAP sensor voltage. If voltage is more than 4.6 volts, go to next step. If voltage is 4.6 volts or less, go to step 8.
2. Turn ignition off. Disconnect MAP sensor connector. (Scheme 30)or (Scheme 31). Disconnect Powertrain Control Module (PCM) connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between Orange and Dark Green/Red wires at MAP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Orange and Dark Green/Red wires are shorted together. Repair wiring as necessary.
3. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. Measure voltage between ground and Dark Green/Red wire at MAP sensor harness connector. If voltage is 5.2 volts or less, go to next step. If voltage is more than 5.2 volts, repair short to voltage in Dark Green/Red wire.
4. Turn ignition off. Connect a jumper wire between Black/Light Blue and Dark Green/Red wires at MAP sensor harness connector. Turn ignition on. Using scan tool, read MAP sensor voltage. If voltage is one volt or more, disconnect jumper wire and go to next step. If voltage is less than one volt, replace MAP sensor.
5. Turn ignition off. Disconnect PCM connectors. Measure resistance of Dark Green/Red wire between MAP sensor harness connector and terminal No. 27 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Green/Red wire.
6. Measure resistance of Black/Light Blue wire between MAP sensor harness connector and terminal No. 4 at PCM C1 harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Black/Light Blue wire.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for MAP sensor high voltage do not exist or fault is an intermittent problem. Ensure engine is idling and at normal operating temperature. Using scan tool, monitor MAP sensor voltage while wiggling connectors and wiring harness from MAP sensor to Powertrain Control Module (PCM). (Scheme 30)or (Scheme 31). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which MAP sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0111: INTAKE AIR TEMP PERFORMANCE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Intake air temperature performance is monitored with ignition on, coolant temperature more than 160°F (71°C) and no intake air temperature sensor faults present. DTC will set in Powertrain Control Module (PCM) memory after engine has completed 5 warm-up cycles, odometer mileage has increased 197 miles and inlet air temperature has increased less than 5°F (-15°C). Possible causes for DTC to set are: defective Intake Air Temperature (IAT) sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0111 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0111 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect IAT sensor connector. (Scheme 30)or (Scheme 32). Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Using scan tool, read IAT sensor voltage. If voltage is more than 4.6 volts, go to next step. If voltage is 4.6 volts or less, go to step 4.
3. Turn ignition off. Connect a jumper wire between IAT sensor harness connector terminals. Turn ignition on. Using scan tool, read IAT sensor voltage. If voltage is one volt or more, go to next step. If voltage is less than one volt, replace IAT sensor.
4. Turn ignition off. Reconnect all connectors. Using a voltmeter, backprobe Black/Light Blue wire between IAT harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) PCM is located on firewall in right rear corner of engine compartment. Start engine and note voltage reading. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance in Black/Light Blue wire.
5. Turn ignition off. Using a voltmeter, backprobe Black/Red wire between IAT harness connector and terminal No. 15 at PCM C1 harness connector. (Scheme 29) Start engine and note voltage reading. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance in Black/Red wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor IAT sensor voltage while wiggling connectors and wiring harness from IAT sensor to Powertrain Control Module (PCM). (Scheme 30)or (Scheme 32). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which IAT sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, go to next step.

DTC P0112: INTAKE AIR TEMP SENSOR VOLTAGE LOW

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Intake Air Temperature (IAT) sensor voltage is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses IAT sensor voltage is less than 0.8 volt. Possible causes for DTC to set are: defective IAT sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P0112 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P0112 is not displayed or displayed count is not "0", go to step 8.
2. Ensure ignition is on. Using scan tool, read IAT sensor voltage. If voltage is less than one volt, go to step 4. If voltage is one volt or more, go to next step.
3. At this time, conditions for IAT sensor low voltage do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor IAT sensor voltage while wiggling connectors and wiring harness from IAT sensor to Powertrain Control Module (PCM). (Scheme 30)or (Scheme 32). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which IAT sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, go to next step.
4. Turn ignition off. Disconnect IAT sensor connector. (Scheme 30)or (Scheme 32). Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Using scan tool, read IAT sensor voltage. If voltage is one volt or less, go to next step. If voltage is more than one volt, replace IAT sensor.
5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Black/Red wire at IAT sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Black/Red wire between PCM and IAT sensor.
6. Measure resistance between Black/Red and Black/Light Blue wires at IAT sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Black/Red and Black/Light Blue wires are shorted together. Repair wiring as necessary.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for IAT sensor low voltage do not exist or fault is an intermittent problem. Ensure engine is idling and at normal operating temperature. Using scan tool, monitor IAT sensor voltage while wiggling connectors and wiring harness from IAT sensor to Powertrain Control Module (PCM). (Scheme 30)or (Scheme 32). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to be set by paying special attention to the conditions during which IAT sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

Scheme 32

DTC P0113: INTAKE AIR TEMPERATURE SENSOR VOLTAGE HIGH

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Intake Air Temperature (IAT) sensor voltage is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses IAT sensor voltage is more than 4.9 volts. Possible causes for DTC to set are: defective IAT sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P0113 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P0113 is not displayed or displayed count is not "0", go to step 8.
2. Using scan tool, read IAT sensor voltage. If voltage is more than 4.6 volts, go to next step. If voltage is 4.6 volts or less, go to step 8.
3. Turn ignition off. Disconnect IAT sensor connector. (Scheme 30)or (Scheme 32). Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, start engine and allow it to idle. Measure voltage between ground and Black/Red wire at IAT sensor harness connector. If voltage is more than 5.5 volts, repair short to voltage in Black/Red wire between IAT sensor and PCM. If voltage is 5.5 volts or less, go to next step.
4. Turn ignition off. Connect a jumper wire between IAT sensor harness connector terminals. Turn ignition on. Using scan tool, read IAT sensor voltage. If voltage is one volt or more, go to next step. If voltage is less than one volt, IAT sensor circuits are okay. Replace IAT sensor.
5. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Black/Red wire between IAT sensor harness connector and terminal No. 15 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Red wire.
6. Measure resistance of Black/Light Blue wire between IAT sensor harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for IAT sensor high voltage do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor IAT sensor voltage while wiggling connectors and wiring harness from IAT sensor to Powertrain Control Module (PCM). (Scheme 30)or (Scheme 32). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which IAT sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0117: ECT SENSOR VOLTAGE TOO LOW

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Engine Coolant Temperature (ECT) sensor voltage is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses ECT sensor voltage is less than 0.8 volt for more than 3 seconds. Possible causes for DTC to set are: defective ECT sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P0117 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P0117 is not displayed or displayed count is not "0", go to step 6.
2. Turn ignition off. Disconnect ECT sensor connector. On 4.0L, ECT sensor is mounted in thermostat housing. On 4.7L, ECT is located near front of intake manifold. (Scheme 31) On all models, inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Using scan tool, read ECT sensor voltage. If voltage is one volt or less, go to next step. If voltage is more than one volt, replace ECT sensor.
3. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Tan/Black wire at ECT sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Black wire between PCM and ECT sensor.
4. Measure resistance between Tan/Black and Black/Light Blue wires at ECT sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Tan/Black and Black/Light Blue wires are shorted together. Repair wiring as necessary.
5. At this time, PCM is assumed to be defective. Replace PCM.
6. At this time, conditions for ECT sensor low voltage do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor ECT sensor voltage while wiggling connectors and wiring harness from ECT sensor to Powertrain Control Module (PCM). On 4.0L, ECT sensor is mounted in thermostat housing. On 4.7L, ECT is located near front of intake manifold. (Scheme 31) On all models, PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which ECT sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0118: ECT SENSOR VOLTAGE TOO HIGH

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Engine Coolant Temperature (ECT) sensor voltage is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses Engine Coolant Temperature (ECT) sensor voltage is more than 4.98 volts for more than 3 seconds. Possible causes for DTC to set are: defective ECT sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P0118 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P0118 is not displayed or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect ECT sensor connector. On 4.0L, ECT sensor is mounted in thermostat housing. On 4.7L, ECT is located near front of intake manifold. (Scheme 31) On all models, inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Measure voltage between ground and Tan/Black wire at ECT sensor harness connector. If voltage is 5.2 volts or less, go to next step. If voltage is more than 5.2 volts, repair short to voltage in Tan/Black wire between ECT sensor and PCM.
3. Turn ignition off. Connect a jumper wire between Tan/Black and Black/Light Blue wires at ECT harness sensor connector. Turn ignition on. Using scan tool, read ECT sensor voltage. If voltage is one volt or more, disconnect jumper wire and go to next step. If voltage is less than one volt, replace ECT sensor.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Black wire between ECT sensor harness connector and terminal No. 16 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Tan/Black wire.
5. Measure resistance of Black/Light Blue wire between ECT sensor harness connector and terminal No 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for ECT sensor high voltage do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor ECT sensor voltage while wiggling connectors and wiring harness from ECT sensor to Powertrain Control Module (PCM). On 4.0L, ECT sensor is mounted in thermostat housing. On 4.7L, ECT is located near front of intake manifold. (Scheme 31) On all models, PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which ECT sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0121: TPS VOLTAGE DOES NOT AGREE WITH MAP

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Throttle Position (TP) sensor voltage is monitored with engine running and no Manifold Absolute Pressure (MAP) or TP sensor DTCs present. Engine speed must be more than 1600 RPM for all TP sensor testing. Possible causes for DTC to set are: MAP sensor DTC present, erratic TP sensor voltage change, or defective connectors or wiring.

Note. If TP sensor connector Orange wire (5-volt supply circuit) and Black/Light Blue wire (sensor ground circuit) are switched at TP sensor connector, DTC P0121: TPS VOLTAGE DOES NOT AGREE WITH MAP DTC will set.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P0121 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P0121 is not displayed or displayed count is not "0", go to step 22.
2. Start engine and allow it to idle. Using scan tool, read MAP sensor voltage. Snap throttle open and closed. If voltage is less than 2 volts at idle and more than 3.5 volts at open throttle, turn ignition off and go to next step. If voltage is not less than 2 volts at idle and more than 3.5 volts at open throttle, go to step 13.
3. Turn ignition on. Using scan tool, monitor TP sensor voltage while slowly depressing throttle pedal from idle position to wide open throttle position. If voltage changes smoothly from about 0.8 volt to more than 3.5 volts, go to step 22. If voltage does not change smoothly from about 0.8 volt to more than 3.5 volts, go to next step.
4. Turn ignition off. Disconnect TP sensor connector. (Scheme 30)or (Scheme 32). Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Orange wire between TP sensor harness connector and terminal No. 17 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire.
5. Measure resistance between ground and Orange wire at TP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Orange wire between TP sensor and PCM.
6. Disconnect MAP sensor connector. (Scheme 30)or (Scheme 32). Measure resistance between ground and Dark Green/Red wire at MAP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Green/Red wire between PCM and MAP sensor.
7. Measure resistance of Black/Light Blue wire between MAP sensor harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
8. Reconnect MAP sensor and PCM connectors. Ensure TP sensor is disconnected. Turn ignition on. Using scan tool, read TP sensor voltage. Connect a jumper wire between Orange/Red and Black/Light Blue wires at TP sensor harness connector. Note TP sensor voltage reading. If TP sensor voltage changes from about 4.9 volts to less than 0.5 volt, replace TP sensor. If TP sensor voltage does not change from about 4.9 volts to less than 0.5 volt, go to next step.
9. Turn ignition off. Disconnect PCM connectors. On 4.7L, disconnect Transmission Control Module (TCM) 60-pin connector. TCM is located next to PCM in right rear corner of engine compartment. On all models, measure resistance of Orange/Red wire between TP sensor harness connector and terminal No. 23 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange/Red wire.
10. Measure resistance between ground and Orange/Red wire at TP sensor harness connector. If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, repair short to ground in Orange/Red wire.
11. Measure resistance of Black/Light Blue wire between TP sensor harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Black/Light Blue wire.
12. At this time, PCM is assumed to be defective. Replace PCM.
13. Turn ignition off. Disconnect MAP sensor connector. (Scheme 30)or (Scheme 32). Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Orange wire between MAP sensor harness connector and terminal No. 17 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire.
14. Measure resistance between ground and Orange wire at MAP sensor harness connector. If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, repair short to ground in Orange wire between MAP sensor and PCM.
15. Turn ignition off. Disconnect TP sensor connector. (Scheme 30)or (Scheme 32). Measure resistance of Orange wire between TP sensor harness connector and terminal No. 17 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire.
16. Measure resistance between ground and Orange wire at TP sensor harness connector. If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, repair short to ground in Orange wire between TP sensor and PCM.
17. Reconnect TP sensor and PCM connectors. Ensure MAP sensor is disconnected. Turn ignition on. Using scan tool, read MAP sensor voltage. Connect a jumper wire between Dark Green/Red and Black/Light Blue wires at MAP sensor harness connector. Note MAP sensor voltage reading. If MAP sensor voltage changes from about 4.9 volts to less than 0.5 volt, replace MAP sensor. If MAP sensor voltage does not change from about 4.9 volts to less than 0.5 volt, go to next step.
18. Turn ignition off. Disconnect PCM connectors. Measure resistance of Dark Green/Red wire between MAP sensor harness connector and terminal No. 27 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Green/Red wire.
19. Measure resistance between ground and Dark Green/Red wire at MAP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Green/Red wire between PCM and MAP sensor.
20. Measure resistance of Black/Light Blue wire between MAP sensor harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
21. At this time, PCM is assumed to be defective. Replace PCM.
22. At this time, fault does not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor TP sensor voltage while wiggling connectors and wiring harness from TP sensor to Powertrain Control Module (PCM). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, repeat wiggle test for MAP sensor. Repair connectors and wiring harness as necessary. If no problem is indicated, use scan tool and review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which TP sensor and MAP sensor are monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0122: THROTTLE POSITION SENSOR VOLTAGE LOW

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Throttle Position (TP) sensor voltage is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses TP sensor voltage is 0.1 volt for 1.3 seconds. Possible causes for DTC to set are: defective TP sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read TP sensor voltage. If voltage is less than 0.2 volt, go to next step. If voltage is 0.2 volt or more, go to step 11.
2. Turn ignition off. Disconnect TP sensor connector. (Scheme 30)or (Scheme 32). Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Measure voltage between ground and Orange wire at TP sensor harness connector. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, go to step 8.
3. Using scan tool, read TP sensor voltage. If voltage is 4.5 volts or less, go to next step. If voltage is more than 4.5 volts, replace TP sensor.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. On 4.7L, disconnect Transmission Control Module (TCM) 60-pin connector. TCM is located next to PCM in right rear corner of engine compartment. On all models, inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Orange/Red wire at TP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Orange/Red wire between TP sensor, PCM and TCM (4.7L).
5. Measure resistance between Black/Light Blue and Orange/Red wires at TP sensor harness connector. If resistance is 5 ohms or more, go to next step (4.7L) or go to step 7 (4.0L). If resistance is less than 5 ohms, Black/Light Blue and Orange/Red wires are shorted together. Repair wiring as necessary. See WIRING DIAGRAMS article.
6. Ensure ignition is off and TCM is disconnected. Reconnect PCM connectors. Turn ignition on. Using scan tool, read TP sensor voltage. If voltage is 4.5 volts or less, go to next step. If voltage is more than 4.5 volts, replace TCM. Reprogram pinion factor and perform shift quality quick learn procedure. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. Turn ignition off. Ensure TP sensor is disconnected. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Orange wire at TP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Orange wire between TP sensor and PCM.
9. Measure resistance of Orange wire between TP sensor harness connector and terminal No. 17 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire.
10. At this time, PCM is assumed to be defective. Replace PCM.
11. Turn ignition on. Using scan tool, monitor TP sensor voltage while slowly depressing throttle pedal from idle position to wide open throttle position. If voltage changes smoothly from about 0.8 volt to more than 3.5 volts, go to next step. If voltage does not change smoothly from about 0.8 volt to more than 3.5 volts, replace TP sensor.
12. At this time, conditions for TP sensor low voltage do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor TP sensor voltage while wiggling connectors and wiring harness from TP sensor to Powertrain Control Module (PCM). (Scheme 30)or (Scheme 32). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which TP sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0123: THROTTLE POSITION SENSOR VOLTAGE HIGH

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Throttle Position (TP) sensor voltage is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses TP sensor voltage is 4.9 volts for 3.2 seconds. Possible causes for DTC to set are: defective TP sensor, defective PCM, or defective connectors or wiring.

1. Start engine and allow it to idle. Turn ignition on. Using scan tool, read TP sensor voltage. If voltage is more than 4.5 volts, go to next step. If voltage is 4.5 volts or less, go to step 8.
2. Turn ignition off. Disconnect TP sensor connector. (Scheme 30)or (Scheme 32). Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. On 4.7L, disconnect Transmission Control Module (TCM) 60-pin connector. TCM is located next to PCM in right rear corner of engine compartment. On all models, inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between Orange and Orange/Red wires at TP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Orange and Orange/Red wires are shorted together. Repair wiring as necessary.
3. Reconnect PCM and TCM (4.7L) connectors. Turn ignition on. Measure voltage between ground and Orange/Red wire at TP sensor harness connector. If voltage is 5.2 volts or less, go to next step. If voltage is more than 5.2 volts, repair short to voltage in Orange/Red wire between TP sensor, PCM and TCM (4.7L).
4. Turn ignition off. Connect a jumper wire between Black/Light Blue and Orange/Red wires at TP sensor harness connector. Turn ignition on. Using scan tool, read TP sensor voltage. If voltage is 0.5 volt or more, go to next step. If voltage is less than 0.5 volt, replace TP sensor.
5. Turn ignition off. Disconnect PCM connectors. Measure resistance of Black/Light Blue wire between TP sensor harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
6. On 4.7L, disconnect TCM 60-pin connector. On all models, measure resistance of Orange/Red wire between TP sensor harness connector and terminal No. 23 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange/Red wire.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for TP sensor high voltage do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor TP sensor voltage while wiggling connectors and wiring harness from TP sensor to Powertrain Control Module (PCM). (Scheme 30)or (Scheme 32). PCM is located on firewall in right rear corner of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which TP sensor is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0125: CLOSED LOOP TEMP NOT REACHED

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Closed loop operation is monitored for 10 minutes after engine is started. DTC will set in Powertrain Control Module (PCM) memory when PCM senses that engine coolant temperature does not go to more than 18°F (-7.8°C) within 10 minutes after engine is started. Two trips are required to set this DTC. Possible causes for DTC to set are: defective Engine Coolant Temperature (ECT) sensor, defective thermostat or low coolant level.

Note. To diagnose this DTC, manufacturer recommends allowing vehicle to sit overnight in order to have a totally cold engine. If any ECT sensor DTCs are present, repair those DTCs before continuing with this test. Extremely cold outside ambient temperatures may have caused this DTC to set.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P0125 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P0125 is not displayed or displayed count is not "0", go to step 6.
2. Ensure coolant level is in good condition and at proper level. Replace or top off coolant as necessary. If coolant is okay, go to next step.
3. Turn ignition on. Using scan tool, read ENG COOLANT TPM DEG value. If engine was allowed to sit overnight, scan tool temperature value should be near ambient air temperature. If engine coolant temperature is more than 180°F (82°C), allow engine coolant temperature to cool down to 150°F (66°C) before proceeding. If engine coolant temperature is 150°F (65°C) or less, start engine. Using scan tool, monitor ENG COOLANT TPM DEG until engine coolant temperature reaches 180°F (82°C). Temperature value should increase smoothly from start-up to normal operating temperature. Also monitor actual coolant temperature with a thermometer. As engine warms up to normal operating temperature, actual coolant temperature should be relatively close to temperature reading on scan tool. Monitor coolant temperature and note when thermostat opens. Thermostat should open at about 195°F (90°C). Replace thermostat as necessary. If thermostat opens as specified, go to next step.
4. If coolant temperature increased smoothly, no problem is indicated at this time. Test is complete. If temperature did not increase smoothly, turn ignition off. Disconnect PCM connectors. PCM on firewall in right rear of engine compartment. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, go to next step.
5. Disconnect ECT sensor connector. On 4.0L, ECT sensor is mounted in thermostat housing. On 4.7L, ECT is located near front of intake manifold. (Scheme 32) On all models, visually inspect connector for corroded, damaged, pushed-out or miswired terminals. Repair connector as necessary. If connector is okay, replace ECT sensor.
6. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine. Wiggle ECT sensor connector and wiring harness while monitoring scan tool display. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.

DTC P0131: 1/1 O2 SENSOR SHORTED TO GROUND

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

1/1 Heated Oxygen Sensor (HO2S) voltage is monitored after ignition is turned off and 1/1 HO2S cools down, and after the next time ignition is turned on, provided engine coolant temperature is less than 98°F (37°C) and ambient/battery temperature is within plus or minus 27°F (-3°C) of engine coolant temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 1/1 HO2S voltage is less than 0.156 volt for 28 seconds after engine is started. Possible causes for DTC to set are: defective 1/1 HO2S, defective PCM, or defective connectors or wiring.

Note. 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 4.0L, 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0131 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0131 or displayed count is not "0", go to step 8 .
2. Start engine and allow it to idle. Using scan tool, read 1/1 HO2S voltage. If voltage is less than 0.16 volt, turn ignition off and go to next step. If voltage is 0.16 volt or more, go to step 8 .
3. Disconnect 1/1 HO2S connector. Start engine and allow it to idle. Using scan tool, read 1/1 HO2S voltage. If voltage is 0.16 volt or less, go to next step. If voltage is more than 0.16 volt, replace 1/1 HO2S.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance between ground and Light Green/Red wire at 1/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Light Green/Red wire between 1/1 HO2S and PCM.
5. Measure resistance between Light Green/Red and Black/Light Blue wires at 1/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Light Green/Red and Black/Light Blue wires are shorted together. Repair wiring as necessary.
6. Measure resistance between Light Green/Red and Gray/White wires at 1/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Light Green/Red and Gray/White wires are shorted together. Repair wiring as necessary.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/1 HO2S voltage while wiggling connectors and wiring harness from 1/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall on right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0132: 1/1 O2 SENSOR SHORTED TO VOLTAGE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

1/1 Heated Oxygen Sensor (HO2S) voltage is monitored with engine running for more than 4 minutes and engine coolant temperature reaches more than 180°F (82°C). DTC will set in Powertrain Control Module (PCM) memory when PCM senses 1/1 HO2S voltage is more than 1.5 volts. Possible causes for DTC to set are: defective 1/1 HO2S, defective PCM, or defective connectors or wiring.

Note. 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 4.0L, 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0132 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0132 or displayed count is not "0", go to step 9.
2. Start engine and allow it to idle. Using scan tool, read 1/1 HO2S voltage. If voltage is more than 1.2 volts, go to next step. If voltage is 1.2 volts or less, go to step 9.
3. Turn ignition off. Disconnect 1/1 HO2S connector. Start engine. Using scan tool, read 1/1 HO2S voltage. If voltage is 1.2 volts or more, turn ignition off and go to next step. If voltage is less than 1.2 volts, replace 1/1 HO2S.
4. Turn ignition on. Measure voltage between ground and Light Green/Red wire at 1/1 HO2S harness connector. If voltage is 1.2 volts or less, go to next step. If voltage is more than 1.2 volts, repair short to voltage in Light Green/Red wire between 1/1 HO2S and PCM.
5. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance between Light Green/Red and Orange/Dark Green wires at 1/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Light Green/Red and Orange/Dark Green wires are shorted together. Repair wiring as necessary.
6. Measure resistance of Light Green/Red wire between 1/1 HO2S harness connector and terminal No. 24 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Light Green/Red wire.
7. Measure resistance of Black/Light Blue wire between 1/1 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
8. At this time, PCM is assumed to be defective. Replace PCM.
9. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/1 HO2S voltage while wiggling connectors and wiring harness from 1/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0133: 1/1 O2 SENSOR SLOW RESPONSE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Note. 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 4.0L, 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.

1/1 Heated Oxygen Sensor (HO2S) voltage is monitored with engine coolant temperature more than 147°F (64°C), after reaching a vehicle speed of 10 MPH, and throttle remains open (off idle) for 2 minutes and subsequently bringing vehicle to a stop and allowing engine to idle in Drive. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 1/1 HO2S voltage is switching from less than 0.27 volt to more than 0.62 volt and back less times than required. Possible causes for DTC to set are: engine mechanical problem, exhaust leak, defective 1/1 HO2S, or defective connectors or wiring.

1. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0133 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0133 or displayed count is not "0", go to step 6.
2. Start engine and allow it to idle. Check exhaust system for leaks between engine and 1/1 HO2S. Repair exhaust system leaks as necessary. If exhaust system is okay, go to next step.
3. Using voltmeter, backprobe Light Green/Red wire between 1/1 HO2S harness connector and terminal No. 24 at PCM C1 harness connector. (Scheme 29) PCM is located on firewall in right rear of engine compartment. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 1/1 HO2S signal circuit (Light Green/Red wire) between 1/1 HO2S and PCM.
4. Using voltmeter, backprobe Black/Light Blue wire between 1/1 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 1/1 HO2S ground circuit (Black/Light Blue wire) between 1/1 HO2S and PCM.
5. At this time, 1/1 HO2S is assumed to be defective. Replace 1/1 HO2S.
6. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/1 HO2S voltage while wiggling connectors and wiring harness from 1/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0135: 1/1 O2 SENSOR HEATER FAILURE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

1/1 Heated Oxygen Sensor (HO2S) heater circuit is monitored with engine at idle immediately after a cold start, with engine coolant temperature less than 147°F (64°C) and ambient/battery temperature is within plus or minus 27°F (-3°C) of engine coolant temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 1/1 Heated Oxygen Sensor (HO2S) voltage is more than 3 volts for 30-90 seconds. Possible causes for DTC to set are: defective 1/1 HO2S, or defective connectors or wiring.

Note. 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 4.0L, 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0135 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0135 or displayed count is not "0", go to step 3.
2. Turn ignition off. Allow HO2S to cool down for about 8 minutes. Turn ignition on. Using scan tool in SENSOR mode, monitor 1/1 HO2S voltage until voltage stabilizes at 0.4-0.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 1/1 HO2S voltage for 3 minutes. If voltage stays at 0.4-0.6 volt, go to next step. If voltage does not stay at 0.4-0.6 volt, go to step 7.
3. Turn ignition off. Allow HO2S to cool down to room temperature. Disconnect 1/1 HO2S connector. Measure resistance between Orange/Dark Green and Gray/White wires at 1/1 HO2S connector (component side). If resistance is not 4-7 ohms, replace 1/1 HO2S. If resistance is 4-7 ohms, 1/1 HO2S heater element is okay. Go to next step.
4. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance of Gray/White wire between 1/1 HO2S harness connector and terminal No. 8 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Gray/White wire.
5. Ensure ignition is off and 1/1 HO2S is still disconnected. Reconnect PCM connectors. Turn ignition on. Using scan tool, actuate HO2S HEATER TEST. Measure voltage between ground and Orange/Dark Green wire at 1/1 HO2S harness connector. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in power circuit to 1/1 HO2S heater (Orange/Dark Green wire).
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/1 HO2S voltage while wiggling connectors and wiring harness from 1/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0136: 1/2 O2 SENSOR HEATER CIRCUIT MALFUNCTION

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

1/2 Heated Oxygen Sensor (HO2S) heater voltage is monitored after ignition is turned on and voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) when PCM senses relay control circuit between PCM and relay coil does not match desired state. Possible causes for DTC to set are: blown fuse, defective HO2S downstream heater relay, defective PCM, or defective connectors or wiring.

Note. 1/2 HO2S may also be referred to as a downstream oxygen sensor. On 4.0L, 1/2 HO2S is located in front exhaust pipe below front mini-catalytic converter. On 4.7L, 1/2 HO2S is located in exhaust pipe behind left catalytic converter.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0136 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0136 or displayed count is not "0", go to step 9.
2. Turn ignition off. Remove and inspect fuse No. 16 (15-amp) from Power Distribution Center (PDC) located in right side of engine compartment, next to battery. (Scheme 28) If fuse is okay, go to step 4. If fuse is blown, go to next step.
3. Remove HO2S downstream heater relay from PDC. (Scheme 28) Measure resistance between ground and terminal No. 30 (Orange/Dark Green wire) at HO2S downstream heater relay socket in PDC. (Scheme 28) If resistance is 5 ohms or more, circuit is okay. Replace fuse. If resistance is less than 5 ohms, repair short to ground in Orange/Dark Green wire. Replace fuse.
4. Remove HO2S downstream heater relay from PDC. (Scheme 28) Measure resistance between terminals No. 85 and 86 at downstream heater relay. (Scheme 33) If resistance is 100 ohms or less, go to next step. If resistance is more than 100 ohms, replace relay.
5. Measure resistance of Orange/Dark Green wire between terminal No. 30 at HO2S downstream heater relay socket in PDC and terminal No. 17 (output side) at fuse holder for fuse No. 16 in PDC. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange/Dark Green wire.
6. Ensure ignition is off. Disconnect Powertrain Control Module (PCM) connectors. PCM is located on firewall in right rear corner of engine compartment. Measure resistance of Light Blue wire between terminal No. 86 at HO2S downstream heater relay socket in PDC and terminal No. 9 at PCM C3 connector. (Scheme 28)and (Scheme 29). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Light Blue wire.
7. Measure resistance between ground and terminal No. 86 (Light Blue wire) at HO2S downstream heater relay socket in PDC. (Scheme 28) If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Light Blue wire. See WIRING DIAGRAMS article.
8. At this time, PCM is assumed to be defective. Replace PCM.
9. It is assumed that there is an intermittent problem with wiring harness and/or connectors. Visually inspect all related connectors and wiring harness for any possible problems. Also, check for any related technical service bulletins.

Scheme 33

DTC P0137: 1/2 O2 SENSOR SHORTED TO GROUND

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

1/2 Heated Oxygen Sensor (HO2S) voltage is monitored after ignition is turned off and 1/2 HO2S cools down, and after the next time ignition is turned on, provided engine coolant temperature is less than 98°F (37°C) and ambient/battery temperature is within plus or minus 27°F (-3°C) of engine coolant temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 1/2 HO2S voltage is less than 0.156 volt for 28 seconds after engine is started. Possible causes for DTC to set are: defective 1/2 HO2S, defective PCM, or defective connectors or wiring.

Note. 1/2 HO2S may also be referred to as a downstream oxygen sensor. On 4.0L, 1/2 HO2S is located in front exhaust pipe below front mini-catalytic converter. On 4.7L, 1/2 HO2S is located in exhaust pipe behind left catalytic converter.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0137 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0137 or displayed count is not "0", go to step 8 .
2. Start engine and allow it to idle. Using scan tool, read 1/2 HO2S voltage. If voltage is less than 0.16 volt, turn ignition off and go to next step. If voltage is 0.16 volt or more, go to step 8 .
3. Disconnect 1/2 HO2S connector. Start engine and allow it to idle. Using scan tool, read 1/2 HO2S voltage. If voltage is 0.16 volt or less, go to next step. If voltage is more than 0.16 volt, replace 1/2 HO2S.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance between ground and Black/Dark Green wire at 1/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Black/Dark Green wire between 1/2 HO2S and PCM.
5. Measure resistance between Black/Dark Green and Black/Light Blue wires at 1/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Black/Dark Green and Black/Light Blue wires are shorted together. Repair wiring as necessary.
6. Measure resistance between Black/Dark Green and Black wires at 1/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Black/Dark Green and Black wires are shorted together. Repair wiring as necessary.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/2 HO2S voltage while wiggling connectors and wiring harness from 1/2 HO2S to Powertrain Control Module (PCM). PCM is located on firewall on right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/2 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0138: 1/2 O2 SENSOR SHORTED TO VOLTAGE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

1/2 Heated Oxygen Sensor (HO2S) voltage is monitored with engine running for more than 4 minutes and engine coolant temperature at more than 180°F (82°C). DTC will set in Powertrain Control Module (PCM) memory when PCM senses 1/2 HO2S voltage is more than 1.5 volts. Possible causes for DTC to set are: defective 1/2 HO2S, defective PCM, or defective connectors or wiring.

Note. 1/2 HO2S may also be referred to as a downstream oxygen sensor. On 4.0L, 1/2 HO2S is located in front exhaust pipe below front mini-catalytic converter. On 4.7L, 1/2 HO2S is located in exhaust pipe behind left catalytic converter.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0138 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0138 or displayed count is not "0", go to step 9.
2. Start engine and allow it to idle. Using scan tool, read 1/2 HO2S voltage. If voltage is more than 1.2 volts, go to next step. If voltage is 1.2 volts or less, go to step 9.
3. Turn ignition off. Disconnect 1/2 HO2S connector. Start engine. Using scan tool, read 1/2 HO2S voltage. If voltage is 1.2 volts or more, turn ignition off and go to next step. If voltage is less than 1.2 volts, replace 1/2 HO2S.
4. Turn ignition on. Measure voltage between ground and Black/Dark Green wire at 1/2 HO2S harness connector. If voltage is 1.2 volts or less, go to next step. If voltage is more than 1.2 volts, repair short to voltage in Black/Dark Green wire between 1/2 HO2S and PCM.
5. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance between Black/Dark Green and Violet/Orange wires at 1/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Black/Dark Green and Violet/Orange wires are shorted together. Repair wiring as necessary.
6. Measure resistance of Black/Dark Green wire between 1/2 HO2S harness connector and terminal No. 25 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Dark Green wire.
7. Measure resistance of Black/Light Blue wire between 1/2 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
8. At this time, PCM is assumed to be defective. Replace PCM.
9. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/2 HO2S voltage while wiggling connectors and wiring harness from 1/2 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/2 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0139: 1/2 O2 SENSOR SLOW RESPONSE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

1/2 Heated Oxygen Sensor (HO2S) voltage is monitored with engine coolant temperature more than 147°F (64°C), after reaching a vehicle speed of 10 MPH, and throttle remains open (off idle) for 2 minutes and subsequently bringing vehicle to a stop and allowing engine to idle in Drive. DTC will be set in Powertrain Control Module (PCM) memory when PCM senses that 1/2 HO2S voltage is switching from less than 0.27 volt to more than 0.62 volt and back less times than required. Possible causes for DTC to set are: engine mechanical problem, exhaust leak, defective 1/2 HO2S, or defective connectors or wiring.

Note. 1/2 HO2S may also be referred to as a downstream oxygen sensor. On 4.0L, 1/2 HO2S is located in front exhaust pipe below front mini-catalytic converter. On 4.7L, 1/2 HO2S is located in exhaust pipe behind left catalytic converter.

1. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0139 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0139 or displayed count is not "0", go to step 6.
2. Start engine and allow it to idle. Check exhaust system for leaks between engine and 1/2 HO2S. Repair exhaust system leaks as necessary. If exhaust system is okay, go to next step.
3. Using voltmeter, backprobe Black/Dark Green wire between 1/2 HO2S harness connector and terminal No. 25 at PCM C1 harness connector. (Scheme 29) PCM is located on firewall in right rear of engine compartment. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 1/2 HO2S signal circuit (Black/Dark Green wire) between 1/2 HO2S and PCM.
4. Using voltmeter, backprobe Black/Light Blue wire between 1/2 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 1/2 HO2S ground circuit (Black/Light Blue wire) between 1/2 HO2S and PCM.
5. At this time, 1/2 HO2S is assumed to be defective. Replace 1/2 HO2S.
6. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/2 HO2S voltage while wiggling connectors and wiring harness from 1/2 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/2 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0141: 1/2 O2 SENSOR HEATER FAILURE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

1/2 Heated Oxygen Sensor (HO2S) heater circuit is monitored with engine at idle immediately after a cold start, with engine coolant temperature less than 147°F (64°C) and ambient/battery temperature within plus or minus 27°F (-3°C) of engine coolant temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 1/2 HO2S voltage is more than 3 volts for 30-90 seconds. Possible causes for DTC to set are: defective 1/2 HO2S, or defective connectors or wiring.

Note. 1/2 HO2S may also be referred to as a downstream oxygen sensor. On 4.0L, 1/2 HO2S is located in front exhaust pipe below front mini-catalytic converter. On 4.7L, 1/2 HO2S is located in exhaust pipe behind left catalytic converter.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0141 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0141 or displayed count is not "0", go to step 3 .
2. Turn ignition off. Allow HO2S to cool down for about 8 minutes. Turn ignition on. Using scan tool in SENSOR mode, monitor 1/2 HO2S voltage until voltage stabilizes at 0.4-0.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 1/2 HO2S voltage for 3 minutes. If voltage stays at 0.4-0.6 volt, go to next step. If voltage does not stay at 0.4-0.6 volt, go to step 7 .
3. Turn ignition off. Allow HO2S to cool down to room temperature. Disconnect 1/2 HO2S connector. Measure resistance between Violet/Orange and Black wires at 1/2 HO2S connector (component side). If resistance is not 4-7 ohms, replace 1/2 HO2S. If resistance is 4-7 ohms, 1/2 HO2S heater element is okay. Go to next step.
4. Measure resistance between ground and Black wire at 1/2 HO2S harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire.
5. Ensure 1/2 HO2S is still disconnected. Turn ignition on. Using scan tool, actuate HO2S HEATER TEST. Measure voltage between ground and Violet/Orange wire at 1/2 HO2S harness connector. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in power circuit to 1/2 HO2S heater (Violet/Orange wire).
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 1/2 HO2S voltage while wiggling connectors and wiring harness from 1/2 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 1/2 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0151: 2/1 O2 SENSOR SHORTED TO GROUND

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

2/1 Heated Oxygen Sensor (HO2S) voltage is monitored after engine coolant temperature reaches 170°F (77°C), ignition is turned off, 2/1 HO2S cools down, and after the next time ignition is turned on, engine coolant temperature is less than 98°F (37°C) and ambient/battery temperature is within 27°F (-3°C) plus or minus of engine coolant temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 2/1 HO2S voltage is less than 0.156 volt for 28 seconds after engine is started. Possible causes for DTC to set are: defective 2/1 HO2S, defective PCM, or defective connectors or wiring.

Note. 2/1 HO2S may also be referred to as a upstream oxygen sensor. On 4.0L, 2/1 HO2S is located on rear exhaust manifold. On 4.7L, 2/1 HO2S is located in right (passenger's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0151 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0151 or displayed count is not "0", go to step 8 .
2. Start engine and allow it to idle. Using scan tool, read 2/1 HO2S voltage. If voltage is less than 0.16 volt, turn ignition off and go to next step. If voltage is 0.16 volt or more, go to step 8 .
3. Disconnect 2/1 HO2S connector. Start engine and allow it to idle. Using scan tool, read 2/1 HO2S voltage. If voltage is 0.16 volt or less, go to next step. If voltage is more than 0.16 volt, replace 2/1 HO2S.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance between ground and Tan/White wire at 2/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/White wire between 1/2 HO2S and PCM.
5. Measure resistance between Tan/White and Black/Light Blue wires at 2/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Tan/White and Black/Light Blue wires are shorted together. Repair wiring as necessary.
6. Measure resistance between Tan/White and Dark Blue/White wires at 2/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Tan/White and Dark Blue/White wires are shorted together. Repair wiring as necessary.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 2/1 HO2S voltage while wiggling connectors and wiring harness from 2/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall on right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 2/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0152: 2/1 O2 SENSOR SHORTED TO VOLTAGE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

2/1 Heated Oxygen Sensor (HO2S) voltage is monitored with engine running for more than 4 minutes and engine coolant temperature at more than 180°F (82°C). DTC will set in Powertrain Control Module (PCM) memory when PCM senses 2/1 HO2S voltage is more than 1.5 volts. Possible causes for DTC to set are: defective 2/1 HO2S, defective PCM, or defective connectors or wiring.

Note. 2/1 HO2S may also be referred to as a upstream oxygen sensor. On 4.0L, 2/1 HO2S is located on rear exhaust manifold. On 4.7L, 2/1 HO2S is located in right (passenger's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0152 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0152 or displayed count is not "0", go to step 9.
2. Start engine and allow it to idle. Using scan tool, read 2/1 HO2S voltage. If voltage is more than 1.2 volts, go to next step. If voltage is 1.2 volts or less, go to step 9.
3. Turn ignition off. Disconnect 2/1 HO2S connector. Start engine. Using scan tool, read 2/1 HO2S voltage. If voltage is 1.2 volts or more, turn ignition off and go to next step. If voltage is less than 1.2 volts, replace 2/1 HO2S.
4. Turn ignition on. Measure voltage between ground and Tan/White wire at 2/1 HO2S harness connector. If voltage is 1.2 volts or less, go to next step. If voltage is more than 1.2 volts, repair short to voltage in Tan/White wire between 2/1 HO2S and PCM.
5. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance between Tan/White and Orange/Dark Green wires at 2/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Tan/White and Orange/Dark Green wires are shorted together. Repair wiring as necessary.
6. Measure resistance of Tan/White wire between 2/1 HO2S harness connector and terminal No. 26 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Tan/White wire.
7. Measure resistance of Black/Light Blue wire between 2/1 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
8. At this time, PCM is assumed to be defective. Replace PCM.
9. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 2/1 HO2S voltage while wiggling connectors and wiring harness from 2/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 2/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0153: 2/1 O2 SENSOR SLOW RESPONSE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Note. 2/1 HO2S may also be referred to as a upstream oxygen sensor. On 4.0L, 2/1 HO2S is located on rear exhaust manifold. On 4.7L, 2/1 HO2S is located in right (passenger's side) exhaust downpipe in front of catalytic converter.

2/1 Heated Oxygen Sensor (HO2S) voltage is monitored with engine coolant temperature more than 147°F (64°C), after reaching a vehicle speed of 10 MPH, and throttle remains open (off idle) for 2 minutes and subsequently bringing vehicle to a stop and allowing engine to idle in Drive. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 2/1 HO2S voltage is switching from less than 0.27 volt to more than 0.62 volt and back less times than required. Possible causes for DTC to set are: engine mechanical problem, exhaust leak, defective 2/1 HO2S, or defective connectors or wiring.

1. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0153 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0153 or displayed count is not "0", go to step 6.
2. Start engine and allow it to idle. Check exhaust system for leaks between engine and 2/1 HO2S. Repair exhaust system leaks as necessary. If exhaust system is okay, go to next step.
3. Using voltmeter, backprobe Tan/White wire between 2/1 HO2S harness connector and terminal No. 26 at PCM C1 harness connector. (Scheme 29) PCM is located on firewall in right rear of engine compartment. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 2/1 HO2S signal circuit (Tan/White wire) between 2/1 HO2S and PCM.
4. Using voltmeter, backprobe Black/Light Blue wire between 2/1 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 2/1 HO2S ground circuit (Black/Light Blue wire) between 2/1 HO2S and PCM.
5. At this time, 2/1 HO2S is assumed to be defective. Replace 2/1 HO2S.
6. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 2/1 HO2S voltage while wiggling connectors and wiring harness from 2/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right side of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 2/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0155: 2/1 O2 SENSOR HEATER FAILURE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

2/1 Heated Oxygen Sensor (HO2S) heater circuit is monitored with engine at idle for at least 12 seconds after a cold start, battery voltage is more than 9 volts, engine coolant temperature is less than 147°F (64°C) and ambient/battery temperature is within 27°F (-3°C) plus or minus of engine coolant temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 2/1 HO2S voltage is more than 3 volts for 30-90 seconds. Possible causes for DTC to set are: defective 2/1 HO2S, or defective connectors or wiring.

Note. 2/1 HO2S may also be referred to as a upstream oxygen sensor. On 4.0L, 2/1 HO2S is located on rear exhaust manifold. On 4.7L, 2/1 HO2S is located in right (passenger's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0155 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0155 or displayed count is not "0", go to step 3.
2. Turn ignition off. Allow HO2S to cool down for about 8 minutes. Turn ignition on. Using scan tool in SENSOR mode, monitor 2/1 HO2S voltage until voltage stabilizes at 0.4-0.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 2/1 HO2S voltage for 3 minutes. If voltage stays at 0.4-0.6 volt, go to next step. If voltage does not stay at 0.4-0.6 volt, go to step 7.
3. Turn ignition off. Allow HO2S to cool down to room temperature. Disconnect 2/1 HO2S connector. Measure resistance between Orange/Dark Green and Dark Blue/White wires at 2/1 HO2S connector (component side). If resistance is not 4-7 ohms, replace 2/1 HO2S. If resistance is 4-7 ohms, 2/1 HO2S heater element is okay. Go to next step.
4. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance of Dark Blue/White wire between 2/1 HO2S harness connector and terminal No. 16 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/White wire.
5. Ensure ignition is off and 2/1 HO2S is still disconnected. Reconnect PCM connectors. Turn ignition on. Using scan tool, actuate HO2S HEATER TEST. Measure voltage between ground and Orange/Dark Green wire at 2/1 HO2S harness connector. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in power circuit to 2/1 HO2S heater (Orange/Dark Green wire).
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 2/1 HO2S voltage while wiggling connectors and wiring harness from 2/1 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 2/1 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0157: 2/2 O2 SENSOR SHORTED TO GROUND

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

2/2 Heated Oxygen Sensor (HO2S) voltage is monitored after engine coolant temperature reaches 170°F (77°C), ignition is turned off, 2/2 HO2S cools down, and after the next time ignition is turned on, engine coolant temperature is less than 98°F (36°C) and ambient/battery temperature is within 27°F (-3°C) plus or minus of engine coolant temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 2/2 HO2S voltage is less than 0.156 volt for 28 seconds after engine is started. Possible causes for DTC to set are: defective 2/2 HO2S, defective PCM, or defective connectors or wiring.

Note. 2/2 HO2S may also be referred to as a downstream oxygen sensor. On 4.0L, 2/2 HO2S is located on rear exhaust pipe below front mini-catalytic converter. On 4.7L, 2/2 HO2S is located in exhaust pipe behind right (passenger's side) catalytic converter.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0157 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0157 or displayed count is not "0", go to step 8 .
2. Start engine and allow it to idle. Using scan tool, read 2/2 HO2S voltage. If voltage is less than 0.16 volt, turn ignition off and go to next step. If voltage is 0.16 volt or more, go to step 8 .
3. Disconnect 2/2 HO2S connector. Start engine and allow it to idle. Using scan tool, read 2/2 HO2S voltage. If voltage is 0.16 volt or less, go to next step. If voltage is more than 0.16 volt, replace 2/2 HO2S.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance between ground and Pink/White wire at 2/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Pink/White wire between 2/2 HO2S and PCM.
5. Measure resistance between Pink/White and Black/Light Blue wires at 2/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Pink/White and Black/Light Blue wires are shorted together. Repair wiring as necessary.
6. Measure resistance between Pink/White and Black wires at 2/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Pink/White and Black wires are shorted together. Repair wiring as necessary.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 2/2 HO2S voltage while wiggling connectors and wiring harness from 2/2 HO2S to Powertrain Control Module (PCM). PCM is located on firewall on right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 2/2 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0158: 2/2 O2 SENSOR SHORTED TO VOLTAGE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

2/2 Heated Oxygen Sensor (HO2S) voltage is monitored with engine running for more than 4 minutes and engine coolant temperature at more than 180°F (82°C). DTC will set in Powertrain Control Module (PCM) memory when PCM senses 2/2 HO2S voltage is more than 1.5 volts. Possible causes for DTC to set are: defective 2/2 HO2S, defective PCM, or defective connectors or wiring.

Note. 2/2 HO2S may also be referred to as a downstream oxygen sensor. On 4.0L, 2/2 HO2S is located on rear exhaust pipe below front mini-catalytic converter. On 4.7L, 2/2 HO2S is located in exhaust pipe behind right (passenger's side) catalytic converter.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0158 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0158 or displayed count is not "0", go to step 9.
2. Start engine and allow it to idle. Using scan tool, read 2/2 HO2S voltage. If voltage is more than 1.2 volts, go to next step. If voltage is 1.2 volts or less, go to step 9.
3. Turn ignition off. Disconnect 2/2 HO2S connector. Start engine. Using scan tool, read 2/2 HO2S voltage. If voltage is 1.2 volts or more, turn ignition off and go to next step. If voltage is less than 1.2 volts, replace 2/2 HO2S.
4. Turn ignition on. Measure voltage between ground and Pink/White wire at 2/2 HO2S harness connector. If voltage is 1.2 volts or less, go to next step. If voltage is more than 1.2 volts, repair short to voltage in Pink/White wire between 2/2 HO2S and PCM.
5. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear of engine compartment. Measure resistance between Pink/White and Violet/Orange wires at 2/2 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Pink/White and Violet/Orange wires are shorted together. Repair wiring as necessary.
6. Measure resistance of Pink/White wire between 2/2 HO2S harness connector and terminal No. 29 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Pink/White wire.
7. Measure resistance of Black/Light Blue wire between 2/2 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
8. At this time, PCM is assumed to be defective. Replace PCM.
9. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 2/2 HO2S voltage while wiggling connectors and wiring harness from 2/2 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 2/2 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0159: 2/2 O2 SENSOR SLOW RESPONSE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

2/2 Heated Oxygen Sensor (HO2S) voltage is monitored with engine coolant temperature more than 147°F (64°C), after reaching a vehicle speed of 10 MPH, and throttle remains open (off idle) for 2 minutes and subsequently bringing vehicle to a stop and allowing engine to idle in Drive. DTC will be set in Powertrain Control Module (PCM) memory when PCM senses that 2/2 HO2S voltage is switching from less than 0.27 volt to more than 0.62 volt and back less times than required. Possible causes for DTC to set are: engine mechanical problem, exhaust leak, defective 2/2 HO2S, or defective connectors or wiring.

Note. 2/2 HO2S may also be referred to as a downstream oxygen sensor. On 4.0L, 2/2 HO2S is located on rear exhaust pipe below front mini-catalytic converter. On 4.7L, 2/2 HO2S is located in exhaust pipe behind right (passenger's side) catalytic converter.

1. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0159 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0159 or displayed count is not "0", go to step 6.
2. Start engine and allow it to idle. Check exhaust system for leaks between engine and 2/2 HO2S. Repair exhaust system leaks as necessary. If exhaust system is okay, go to next step.
3. Using voltmeter, backprobe Pink/White wire between 2/2 HO2S harness connector and terminal No. 29 at PCM C1 harness connector. (Scheme 29) PCM is located on firewall in right rear of engine compartment. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 2/2 HO2S signal circuit (Pink/White wire) between 2/2 HO2S and PCM.
4. Using voltmeter, backprobe Black/Light Blue wire between 2/2 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 2/2 HO2S ground circuit (Black/Light Blue wire) between 2/2 HO2S and PCM.
5. At this time, 2/2 HO2S is assumed to be defective. Replace 2/2 HO2S.
6. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 2/2 HO2S voltage while wiggling connectors and wiring harness from 2/2 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 2/2 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0161: 2/2 O2 SENSOR HEATER FAILURE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

2/2 Heated Oxygen Sensor (HO2S) heater circuit is monitored with engine at idle for at least 12 seconds after a cold start, battery voltage is more than 9 volts, engine coolant temperature is less than 147°F (64°C) and ambient/battery temperature is within 27°F (-3°C) plus or minus of engine coolant temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 2/2 HO2S voltage is more than 3 volts for 30-90 seconds. Possible causes for DTC to set are: blown fuse, defective HO2S downstream heater relay, defective PCM, or defective connectors or wiring.

Note. 2/2 HO2S may also be referred to as a downstream oxygen sensor. On 4.0L, 2/2 HO2S is located on rear exhaust pipe below front mini-catalytic converter. On 4.7L, 2/2 HO2S is located in exhaust pipe behind right (passenger's side) catalytic converter.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0161 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0161 or displayed count is not "0", go to step 3 .
2. Turn ignition off. Allow HO2S to cool down for about 8 minutes. Turn ignition on. Using scan tool in SENSOR mode, monitor 2/2 HO2S voltage until voltage stabilizes at 0.4-0.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 2/2 HO2S voltage for 3 minutes. If voltage stays at 0.4-0.6 volt, go to next step. If voltage does not stay at 0.4-0.6 volt, go to step 7 .
3. Turn ignition off. Allow HO2S to cool down to room temperature. Disconnect 2/2 HO2S connector. Measure resistance between Violet/Orange and Black wires at 2/2 HO2S connector (component side). If resistance is not 4-7 ohms, replace 1/1 HO2S. If resistance is 4-7 ohms, 2/2 HO2S heater element is okay. Go to next step.
4. Measure resistance between ground and Black wire at 2/2 HO2S harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire.
5. Ensure 2/2 HO2S is still disconnected. Turn ignition on. Using scan tool, actuate HO2S HEATER TEST. Measure voltage between ground and Violet/Orange wire at 2/2 HO2S harness connector. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in power circuit to 2/2 HO2S heater (Violet/Orange wire).
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor 2/2 HO2S voltage while wiggling connectors and wiring harness from 2/2 HO2S to Powertrain Control Module (PCM). PCM is located on firewall in right rear of engine compartment. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set by paying special attention to the conditions during which 2/2 HO2S is monitored. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0171: 1/1 FUEL SYSTEM LEAN

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel system lean condition is monitored with engine running in closed loop mode, ambient/battery temperature at more than 20°F (-7°C), and at altitude less than 8000 feet. DTC will set in Powertrain Control Module (PCM) memory when PCM senses fuel system is running too lean on 2 sequential trips. Possible causes for DTC to set are: defective Throttle Position (TP) sensor, binding throttle linkage, defective Engine Coolant Temperature (ECT) sensor, engine mechanical problem, fuel pressure out of specification or defective Manifold Absolute Pressure (MAP) sensor.

Note. 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 4.0L, 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.

Scheme 34

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P0171 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P0171 is not displayed or displayed count is not "0", go to step 16.
2. Turn ignition off. Release fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee__fuel-system-pressure-release). Remove test port cap from fuel rail. Install a 0-60 psi (0-4.2 kg/cm 2 ) fuel pressure gauge to test port on fuel rail. Turn ignition on. Using scan tool, actuate ASD fuel system test. Allow fuel pressure gauge to stabilize. Stop ASD fuel system activation. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is less than specified, go to next step. If fuel pressure is more than specified, check fuel return line for kinks or restrictions. (Scheme 34) Repair fuel return line as necessary. If fuel return line is okay, replace fuel filter/pressure regulator. See FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel pressure is as specified, go to step 6.
3. If engine runs but fuel pressure is less than specified, check for kinked or damaged fuel supply line between fuel pump module and fuel rail. Repair fuel line as necessary and retest. If fuel line is okay, release fuel pressure. Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator. (Scheme 34) Connect Fuel Line Pressure Test Adapter Hose (6539) between disconnected fuel line and fuel filter/pressure regulator. Connect fuel pressure gauge to fuel line adapter hose. Turn ignition on, with engine off. Using scan tool, actuate ASD fuel system test and note fuel pressure. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is within specification, stop ASD fuel system activation, release fuel pressure and replace fuel filter/pressure regulator. If fuel pressure is not within specification, stop ASD fuel system activation and go to next step.
4. Release fuel pressure. Remove fuel pump module and inspect fuel inlet strainer. See FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel inlet strainer is plugged, replace fuel pump inlet strainer. If fuel inlet strainer is not plugged, go to next step.
5. At this time, fuel pump module is assumed to be defective. Replace fuel pump module.
6. Turn ignition on. Using scan tool, read 1/1 HO2S voltage. If voltage is 0.4-0.6 volt, go to next step. If voltage is not 0.4-0.6 volt, go to step 13.
7. Turn ignition off. Wait at least 10 minutes to allow HO2S to cool. Turn ignition on. Using scan tool in SENSOR mode, monitor 1/1 HO2S voltage until voltage stabilizes at 0.4-0.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 1/1 HO2S voltage for 3 minutes. If voltage does not stay at 0.4-0.6 volt, go to next step. If voltage stays at 0.4-0.6 volt, replace 1/1 HO2S.
8. Ensure ignition is on. Ensure throttle plate is fully closed against stop. Using scan tool, read TP sensor voltage. If voltage is less than 0.92 volt, go to next step. If voltage is 0.92 volt or more, check throttle plate and linkage for binding. Repair throttle plate and linkage as necessary. If throttle plate and linkage are okay, replace TP sensor.
9. Ensure ignition is on. Using scan tool, read TP sensor voltage. Slowly open and close throttle plate while monitoring TP sensor voltage. If voltage change is smooth, go to next step. If voltage change is erratic, replace TP sensor.
10. Turn ignition off. Connect a vacuum gauge to manifold vacuum source. Start engine and allow it to idle. If engine will not idle, maintain a constant RPM above idle. Using scan tool in SENSOR mode, monitor Manifold Absolute Pressure (MAP) vacuum value. Compare scan tool reading with vacuum gauge reading. If scan tool reading is within one in. Hg of vacuum gauge, turn ignition off and go to next step. If scan tool reading is not within one in. Hg of vacuum gauge reading, replace MAP sensor.
11. Turn ignition on. Using scan tool, read ECT sensor value. If engine coolant temperature is more than 180°F (82°C), allow engine coolant temperature to cool down to 150°F (66°C) before proceeding. If engine coolant temperature is 150°F (66°C) or less, start engine and monitor scan tool until engine coolant temperature reaches 180°F (82°C). If ECT sensor value increases smoothly and reaches at least 180°F (82°C), go to next step. If ECT sensor value increase is erratic or does not reach at least 180°F (82°C), check for cooling system problems. Repair cooling system as necessary. If cooling system is okay, replace ECT sensor.
12. Check the following additional items as possible mechanical problems: Engine vacuum must be at least 13 in. Hg with shift selector in Neutral. Engine valve timing must be within specification. Engine compression must be within specification. Engine exhaust system must be free of restrictions. Engine Closed Crankcase Ventilation (CCV) system (4.0L) or Positive Crankcase Ventilation (PCV) system (4.7L) must flow freely. Torque converter stall speed must be within specification. Power brake booster must have no internal leaks. Fuel must be free of contamination. Fuel injectors must be free of restrictions. Fuel injector control wires must be installed on correct injector. Repair any mechanical problems as necessary. If no mechanical problems exist, test is complete.
13. Turn ignition on. Disconnect 1/1 HO2S connector. Using scan tool, read 1/1 HO2S voltage. If voltage is not 0.4-0.6 volt, go to next step. If voltage is 0.4-0.6 volt, replace 1/1 HO2S.
14. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Measure resistance between ground and Light Green/Red wire at 1/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Light Green/Red wire between PCM and 1/1 HO2S.
15. At this time, PCM is assumed to be defective. Replace PCM.
16. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0172: 1/1 FUEL SYSTEM RICH

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel system rich condition is monitored with engine running in closed loop mode, ambient/battery temperature at more than 20°F (-7°C), and at altitude less than 8000 feet. DTC will set in Powertrain Control Module (PCM) memory when PCM senses fuel system is running too rich on 2 sequential trips. Possible causes for DTC to set are: defective Engine Coolant Temperature (ECT) sensor, engine mechanical problem or fuel pressure out of specification.

Note. 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 4.0L, 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0172 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0172 or displayed count is not "0", go to step 18.
2. Turn ignition off. Release fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee__fuel-system-pressure-release). Remove test port cap from fuel rail. Install a 0-60 psi (0-4.2 kg/cm 2 ) fuel pressure gauge to test port on fuel rail. Turn ignition on. Using scan tool, actuate ASD fuel system test. Allow fuel pressure gauge to stabilize. Stop ASD fuel system activation. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is less than specified, go to next step. If fuel pressure is more than specified, check fuel return line for kinks or restrictions. (Scheme 34) Repair fuel return line as necessary. If fuel return line is okay, replace fuel filter/pressure regulator. See FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel pressure is as specified, go to step 6.
3. If engine runs but fuel pressure is less than specified, check for kinked or damaged fuel supply line between fuel pump module and fuel rail. Repair fuel line as necessary and retest. If fuel line is okay, release fuel pressure. Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator. (Scheme 34) Connect Fuel Line Pressure Test Adapter Hose (6539) between disconnected fuel line and fuel filter/pressure regulator. Connect fuel pressure gauge to fuel line adapter hose. Turn ignition on, with engine off. Using scan tool, actuate ASD fuel system test and note fuel pressure. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is within specification, stop ASD fuel system activation, release fuel pressure and replace fuel filter/pressure regulator. If fuel pressure is not within specification, stop ASD fuel system activation and go to next step.
4. Release fuel pressure. Remove fuel pump module and inspect fuel inlet strainer. See FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel inlet strainer is plugged, replace fuel pump inlet strainer. If fuel inlet strainer is not plugged, go to next step.
5. At this time, fuel pump module is assumed to be defective. Replace fuel pump module.
6. Turn ignition on. Using scan tool, read 1/1 HO2S voltage. If voltage is 0.4-0.6 volt, go to next step. If voltage is not 0.4-0.6 volt, go to step 14.
7. Turn ignition off. Wait at least 10 minutes to allow HO2S to cool. Turn ignition on. Using scan tool in SENSOR mode, monitor 1/1 HO2S voltage until voltage stabilizes at 0.4-0.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 1/1 HO2S voltage for 3 minutes. If voltage does not stay at 0.4-0.6 volt, go to next step. If voltage stays at 0.4-0.6 volt, replace 1/1 HO2S.
8. Start engine and allow it to idle. Ensure engine is at normal operating temperature and in closed loop mode. Using scan tool, select SYSTEM TESTS, then PURGE VAPORS TEST. Monitor short term adaptive value on scan tool and press "3" to flow. Short term adaptive value should change. If value changes, go to next step. If value does not change, go to CHECKING EVAPORATIVE EMISSION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article.
9. Ensure ignition is on. Ensure throttle plate is fully closed against stop. Using scan tool, read TP sensor voltage. If voltage is less than 0.92 volt, go to next step. If voltage is 0.92 volt or more, check throttle plate and linkage for binding. Repair throttle plate and linkage as necessary. If throttle plate and linkage are okay, replace TP sensor.
10. Ensure ignition is on. Using scan tool, read TP sensor voltage. Slowly open and close throttle plate while monitoring TP sensor voltage. If voltage change is smooth, go to next step. If voltage change is erratic, replace TP sensor.
11. Turn ignition off. Connect a vacuum gauge to manifold vacuum source. Start engine and allow it to idle. If engine will not idle, maintain a constant RPM above idle. Using scan tool in SENSOR mode, monitor Manifold Absolute Pressure (MAP) vacuum value. Compare scan tool reading with vacuum gauge reading. If scan tool reading is within one in. Hg of vacuum gauge, turn ignition off and go to next step. If scan tool reading is not within one in. Hg of vacuum gauge reading, replace MAP sensor.
12. Turn ignition on. Using scan tool, read ECT sensor value. If engine coolant temperature is more than 180°F (82°C), allow engine coolant temperature to cool down to 150°F (66°C) before proceeding. If engine coolant temperature is 150°F (66°C) or less, start engine and monitor scan tool until engine coolant temperature reaches 180°F (82°C). If ECT sensor value increases smoothly and reaches at least 180°F (82°C), go to next step. If ECT sensor value increase is erratic or does not reach at least 180°F (82°C), check for cooling system problems. Repair cooling system as necessary. If cooling system is okay, replace ECT sensor.
13. Check the following additional items as possible mechanical problems: Engine vacuum must be at least 13 in. Hg with shift selector in Neutral. Engine valve timing must be within specification. Engine compression must be within specification. Engine exhaust system must be free of restrictions. Engine Closed Crankcase Ventilation (CCV) system (4.0L) or Positive Crankcase Ventilation (PCV) system (4.7L) must flow freely. Torque converter stall speed must be within specification. Power brake booster must have no internal leaks. Fuel must be free of contamination. Fuel injectors must be free of restrictions. Fuel injector control wires must be installed on correct injector. Repair any mechanical problems as necessary. If no mechanical problems exist, test is complete.
14. Turn ignition on. Disconnect 1/1 HO2S connector. Using scan tool, read 1/1 HO2S voltage. If voltage is not 0.4-0.6 volt, go to next step. If voltage is 0.4-0.6 volt, replace 1/1 HO2S.
15. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Light Green/Red wire between 1/1 HO2S harness connector and terminal No. 24 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Light Green/Red wire between PCM and 1/1 HO2S.
16. Ensure ignition is off. Reconnect PCM connectors. Start engine and allow it to idle. Measure voltage between ground and Light Green/Red wire at 1/1 HO2S harness connector. If voltage is 0.6 volt or less, go to next step. If voltage is more than 0.6 volt, repair short to voltage in Light Green/Red wire between 1/1 HO2S and PCM.
17. At this time, PCM is assumed to be defective. Replace PCM.
18. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0174: 2/1 FUEL SYSTEM LEAN

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel system lean condition is monitored with engine running in closed loop mode, ambient/battery temperature at more than 20°F (-7°C), and at altitude less than 8000 feet. DTC will set in Powertrain Control Module (PCM) memory when PCM senses fuel system is running too lean on 2 sequential trips. Possible causes for DTC to set are: defective Throttle Position (TP) sensor, binding throttle linkage, defective Engine Coolant Temperature (ECT) sensor, engine mechanical problem, fuel pressure out of specification or defective Manifold Absolute Pressure (MAP) sensor.

Note. 2/1 HO2S may also be referred to as a upstream oxygen sensor. On 4.0L, 2/1 HO2S is located on rear exhaust manifold. On 4.7L, 2/1 HO2S is located in right (passenger's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P0174 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P0174 is not displayed or displayed count is not "0", go to step 16.
2. Turn ignition off. Release fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee__fuel-system-pressure-release). Remove test port cap from fuel rail. Install a 0-60 psi (0-4.2 kg/cm 2 ) fuel pressure gauge to test port on fuel rail. Turn ignition on. Using scan tool, actuate ASD fuel system test. Allow fuel pressure gauge to stabilize. Stop ASD fuel system activation. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is less than specified, go to next step. If fuel pressure is more than specified, check fuel return line for kinks or restrictions. (Scheme 34) Repair fuel return line as necessary. If fuel return line is okay, replace fuel filter/pressure regulator. See FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel pressure is as specified, go to step 6.
3. If engine runs but fuel pressure is less than specified, check for kinked or damaged fuel supply line between fuel pump module and fuel rail. Repair fuel line as necessary and retest. If fuel line is okay, release fuel pressure. Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator. (Scheme 34) Connect Fuel Line Pressure Test Adapter Hose (6539) between disconnected fuel line and fuel filter/pressure regulator. Connect fuel pressure gauge to fuel line adapter hose. Turn ignition on, with engine off. Using scan tool, actuate ASD fuel system test and note fuel pressure. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is within specification, stop ASD fuel system activation, release fuel pressure and replace fuel filter/pressure regulator. If fuel pressure is not within specification, stop ASD fuel system activation and go to next step.
4. Release fuel pressure. Remove fuel pump module and inspect fuel inlet strainer. See FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel inlet strainer is plugged, replace fuel pump inlet strainer. If fuel inlet strainer is not plugged, go to next step.
5. At this time, fuel pump module is assumed to be defective. Replace fuel pump module.
6. Turn ignition on. Using scan tool, read 2/1 HO2S voltage. If voltage is 0.4-0.6 volt, go to next step. If voltage is not 0.4-0.6 volt, go to step 13.
7. Turn ignition off. Wait at least 10 minutes to allow HO2S to cool. Turn ignition on. Using scan tool in SENSOR mode, monitor 2/1 HO2S voltage until voltage stabilizes at 0.4-0.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 2/1 HO2S voltage for 3 minutes. If voltage does not stay at 0.4-0.6 volt, go to next step. If voltage stays at 0.4-0.6 volt, replace 2/1 HO2S.
8. Ensure ignition is on. Ensure throttle plate is fully closed against stop. Using scan tool, read TP sensor voltage. If voltage is less than 0.92 volt, go to next step. If voltage is 0.92 volt or more, check throttle plate and linkage for binding. Repair throttle plate and linkage as necessary. If throttle plate and linkage are okay, replace TP sensor.
9. Ensure ignition is on. Using scan tool, read TP sensor voltage. Slowly open and close throttle plate while monitoring TP sensor voltage. If voltage change is smooth, go to next step. If voltage change is erratic, replace TP sensor.
10. Turn ignition off. Connect a vacuum gauge to manifold vacuum source. Start engine and allow it to idle. If engine will not idle, maintain a constant RPM above idle. Using scan tool in SENSOR mode, monitor Manifold Absolute Pressure (MAP) vacuum value. Compare scan tool reading with vacuum gauge reading. If scan tool reading is within one in. Hg of vacuum gauge, turn ignition off and go to next step. If scan tool reading is not within one in. Hg of vacuum gauge reading, replace MAP sensor.
11. Turn ignition on. Using scan tool, read ECT sensor value. If engine coolant temperature is more than 180°F (82°C), allow engine coolant temperature to cool down to 150°F (66°C) before proceeding. If engine coolant temperature is 150°F (66°C) or less, start engine and monitor scan tool until engine coolant temperature reaches 180°F (82°C). If ECT sensor value increases smoothly and reaches at least 180°F (82°C), go to next step. If ECT sensor value increase is erratic or does not reach at least 180°F (82°C), check for cooling system problems. Repair cooling system as necessary. If cooling system is okay, replace ECT sensor.
12. Check the following additional items as possible mechanical problems: Engine vacuum must be at least 13 in. Hg with shift selector in Neutral. Engine valve timing must be within specification. Engine compression must be within specification. Engine exhaust system must be free of restrictions. Engine Closed Crankcase Ventilation (CCV) system (4.0L) or Positive Crankcase Ventilation (PCV) system (4.7L) must flow freely. Torque converter stall speed must be within specification. Power brake booster must have no internal leaks. Fuel must be free of contamination. Fuel injectors must be free of restrictions. Fuel injector control wires must be installed on correct injector. Repair any mechanical problems as necessary. If no mechanical problems exist, test is complete.
13. Turn ignition on. Disconnect 2/1 HO2S connector. Using scan tool, read 2/1 HO2S voltage. If voltage is not 0.4-0.6 volt, go to next step. If voltage is 0.4-0.6 volt, replace 2/1 HO2S.
14. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Measure resistance between ground and Tan/White wire at 2/1 HO2S harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/White wire between PCM and 2/1 HO2S.
15. At this time, PCM is assumed to be defective. Replace PCM.
16. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0175: 2/1 FUEL SYSTEM RICH

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel system rich condition is monitored with engine running in closed loop mode, ambient/battery temperature at more than 20°F (-7°C), and at altitude less than 8000 feet. DTC will set in Powertrain Control Module (PCM) memory when PCM senses fuel system is running too rich on 2 sequential trips. Possible causes for DTC to set are: defective Engine Coolant Temperature (ECT) sensor, engine mechanical problem or fuel pressure out of specification.

Note. 2/1 HO2S may also be referred to as a upstream oxygen sensor. On 4.0L, 2/1 HO2S is located on rear exhaust manifold. On 4.7L, 2/1 HO2S is located in right (passenger's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0175 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0175 or displayed count is not "0", go to step 18.
2. Turn ignition off. Release fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee__fuel-system-pressure-release). Remove test port cap from fuel rail. Install a 0-60 psi (0-4.2 kg/cm 2 ) fuel pressure gauge to test port on fuel rail. Turn ignition on. Using scan tool, actuate ASD fuel system test. Allow fuel pressure gauge to stabilize. Stop ASD fuel system activation. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is less than specified, go to next step. If fuel pressure is more than specified, check fuel return line for kinks or restrictions. (Scheme 34) Repair fuel return line as necessary. If fuel return line is okay, replace fuel filter/pressure regulator. See FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel pressure is as specified, go to step 6.
3. If engine runs but fuel pressure is less than specified, check for kinked or damaged fuel supply line between fuel pump module and fuel rail. Repair fuel line as necessary and retest. If fuel line is okay, release fuel pressure. Raise and support vehicle. Disconnect fuel pressure line from fuel filter/pressure regulator. (Scheme 34) Connect Fuel Line Pressure Test Adapter Hose (6539) between disconnected fuel line and fuel filter/pressure regulator. Connect fuel pressure gauge to fuel line adapter hose. Turn ignition on, with engine off. Using scan tool, actuate ASD fuel system test and note fuel pressure. Fuel pressure should be 44.2-54.2 psi (3.23-3.96 kg/cm 2 ). If fuel pressure is within specification, stop ASD fuel system activation, release fuel pressure and replace fuel filter/pressure regulator. If fuel pressure is not within specification, stop ASD fuel system activation and go to next step.
4. Release fuel pressure. Remove fuel pump module and inspect fuel inlet strainer. See FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. If fuel inlet strainer is plugged, replace fuel pump inlet strainer. If fuel inlet strainer is not plugged, go to next step.
5. At this time, fuel pump module is assumed to be defective. Replace fuel pump module.
6. Turn ignition on. Using scan tool, read 2/1 HO2S voltage. If voltage is 0.4-0.6 volt, go to next step. If voltage is not 0.4-0.6 volt, go to step 14.
7. Turn ignition off. Wait at least 10 minutes to allow HO2S to cool. Turn ignition on. Using scan tool in SENSOR mode, monitor 2/1 HO2S voltage until voltage stabilizes at 0.4-0.6 volt. Using scan tool, actuate HO2S HEATER TEST and monitor 2/1 HO2S voltage for 3 minutes. If voltage does not stay at 0.4-0.6 volt, go to next step. If voltage stays at 0.4-0.6 volt, replace 2/1 HO2S.
8. Start engine and allow it to idle. Ensure engine is at normal operating temperature and in closed loop mode. Using scan tool, select SYSTEM TESTS, then PURGE VAPORS TEST. Monitor short term adaptive value on scan tool and press "3" to flow. Short term adaptive value should change. If value changes, go to next step. If value does not change, go to CHECKING EVAPORATIVE EMISSION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article.
9. Ensure ignition is on. Ensure throttle plate is fully closed against stop. Using scan tool, read TP sensor voltage. If voltage is less than 0.92 volt, go to next step. If voltage is 0.92 volt or more, check throttle plate and linkage for binding. Repair throttle plate and linkage as necessary. If throttle plate and linkage are okay, replace TP sensor.
10. Ensure ignition is on. Using scan tool, read TP sensor voltage. Slowly open and close throttle plate while monitoring TP sensor voltage. If voltage change is smooth, go to next step. If voltage change is erratic, replace TP sensor.
11. Turn ignition off. Connect a vacuum gauge to manifold vacuum source. Start engine and allow it to idle. If engine will not idle, maintain a constant RPM above idle. Using scan tool in SENSOR mode, monitor Manifold Absolute Pressure (MAP) vacuum value. Compare scan tool reading with vacuum gauge reading. If scan tool reading is within one in. Hg of vacuum gauge, turn ignition off and go to next step. If scan tool reading is not within one in. Hg of vacuum gauge reading, replace MAP sensor.
12. Turn ignition on. Using scan tool, read ECT sensor value. If engine coolant temperature is more than 180°F (82°C), allow engine coolant temperature to cool down to 150°F (66°C) before proceeding. If engine coolant temperature is 150°F (66°C) or less, start engine and monitor scan tool until engine coolant temperature reaches 180°F (82°C). If ECT sensor value increases smoothly and reaches at least 180°F (82°C), go to next step. If ECT sensor value increase is erratic or does not reach at least 180°F (82°C), check for cooling system problems. Repair cooling system as necessary. If cooling system is okay, replace ECT sensor.
13. Check the following additional items as possible mechanical problems: Engine vacuum must be at least 13 in. Hg with shift selector in Neutral. Engine valve timing must be within specification. Engine compression must be within specification. Engine exhaust system must be free of restrictions. Engine Closed Crankcase Ventilation (CCV) system (4.0L) or Positive Crankcase Ventilation (PCV) system (4.7L) must flow freely. Torque converter stall speed must be within specification. Power brake booster must have no internal leaks. Fuel must be free of contamination. Fuel injectors must be free of restrictions. Fuel injector control wires must be installed on correct injector. Repair any mechanical problems as necessary. If no mechanical problems exist, test is complete.
14. Turn ignition on. Disconnect 2/1 HO2S connector. Using scan tool, read 2/1 HO2S voltage. If voltage is not 0.4-0.6 volt, go to next step. If voltage is 0.4-0.6 volt, replace 2/1 HO2S.
15. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/White wire between 2/1 HO2S harness connector and terminal No. 26 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Tan/White wire between PCM and 2/1 HO2S.
16. Ensure ignition is off. Reconnect PCM connectors. Start engine and allow it to idle. Measure voltage between ground and Tan/White wire at 2/1 HO2S harness connector. If voltage is 0.6 volt or less, go to next step. If voltage is more than 0.6 volt, repair short to voltage in Tan/White wire between 2/1 HO2S and PCM.
17. At this time, PCM is assumed to be defective. Replace PCM.
18. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

DTC P0201: INJECTOR #1 CONTROL CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel injector operation is monitored when battery voltage is more than 10.4 volts, ASD relay energized, injector pulse width less than 10 milliseconds, and engine speed less than 3000 RPM. DTC will set in Powertrain Control Module (PCM) memory .64-10.00 seconds after PCM does not sense any inductive kick 18 milliseconds after injector is turned off, and no other injectors are turned on. Possible causes for DTC to set are: defective injector, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0201 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0201 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect fuel injector No. 1 connector. Turn ignition on. Using a test light connected to ground, backprobe Dark Green/Light Green wire at fuel injector No. 1 harness connector. Using scan tool, actuate Auto Shutdown (ASD) relay. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair power circuit to fuel injector No. 1. See WIRING DIAGRAMS article.
3. Using a test light connected to positive battery voltage, backprobe White/Dark Blue wire at fuel injector No. 1 harness connector. Using scan tool, actuate fuel injector No. 1 while observing test light. If test light does not blink/flicker, go to next step. If test light blinks/flickers, replace fuel injector.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of White/Dark Blue wire between fuel injector No. 1 harness connector and terminal No. 4 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in White/Dark Blue wire.
5. Using ohmmeter, measure resistance between ground and White/Dark Blue wire at fuel injector No. 1 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in White/Dark Blue wire between PCM and fuel injector No. 1.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Start engine and allow it to idle. Wiggle wiring harness from fuel injector No. 1 to PCM. PCM is located on firewall in right rear corner of engine compartment. If engine misses or stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to misfire or stall. If engine does not misfire or stall while wiggling wiring harness, go to next step.
8. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, turn ignition on. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0201: INJECTOR #1 CONTROL CIRCUIT returns, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If DTC P0201: INJECTOR #1 CONTROL CIRCUIT does not return, no problem is indicated at this time. Test is complete.

DTC P0202: INJECTOR #2 CONTROL CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel injector operation is monitored when battery voltage is more than 10.4 volts, ASD relay energized, injector pulse width less than 10 milliseconds, and engine speed less than 3000 RPM. DTC will set in Powertrain Control Module (PCM) memory .64-10.00 seconds after PCM does not sense any inductive kick 18 milliseconds after injector is turned off, and no other injectors are turned on. Possible causes for DTC to set are: defective injector, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0202 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0202 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect fuel injector No. 2 connector. Turn ignition on. Using a test light connected to ground, backprobe Dark Green/Light Green wire at fuel injector No. 2 harness connector. Using scan tool, actuate Auto Shutdown (ASD) relay. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair power circuit to fuel injector No. 2. See WIRING DIAGRAMS article.
3. Using a test light connected to positive battery voltage, backprobe Tan wire at fuel injector No. 2 harness connector. Using scan tool, actuate fuel injector No. 2 while observing test light. If test light does not blink/flicker, go to next step. If test light blinks/flickers, replace fuel injector.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan wire between fuel injector No. 2 harness connector and terminal No. 15 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Tan wire.
5. Using ohmmeter, measure resistance between ground and Tan wire at fuel injector No. 2 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan wire between PCM and fuel injector No. 2.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Start engine and allow it to idle. Wiggle wiring harness from fuel injector No. 2 to PCM. PCM is located on firewall in right rear corner of engine compartment. If engine misses or stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to misfire or stall. If engine does not misfire or stall while wiggling wiring harness, go to next step.
8. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, turn ignition on. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0202: INJECTOR #2 CONTROL CIRCUIT returns, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If DTC P0202: INJECTOR #2 CONTROL CIRCUIT does not return, no problem is indicated at this time. Test is complete.

DTC P0203: INJECTOR #3 CONTROL CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel injector operation is monitored when battery voltage is more than 10.4 volts, ASD relay energized, injector pulse width less than 10 milliseconds, and engine speed less than 3000 RPM. DTC will set in Powertrain Control Module (PCM) memory .64-10.00 seconds after PCM does not sense any inductive kick 18 milliseconds after injector is turned off, and no other injectors are turned on. Possible causes for DTC to set are: defective injector, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0203 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0203 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect fuel injector No. 3 connector. Turn ignition on. Using a test light connected to ground, backprobe Dark Green/Light Green wire at fuel injector No. 3 harness connector. Using scan tool, actuate Auto Shutdown (ASD) relay. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair power circuit to fuel injector No. 3. See WIRING DIAGRAMS article.
3. Using a test light connected to positive battery voltage, backprobe Yellow/White wire at fuel injector No. 3 harness connector. Using scan tool, actuate fuel injector No. 3 while observing test light. If test light does not blink/flicker, go to next step. If test light blinks/flickers, replace fuel injector.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Yellow/White wire between fuel injector No. 3 harness connector and terminal No. 5 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Yellow/White wire.
5. Using ohmmeter, measure resistance between ground and Yellow/White wire at fuel injector No. 3 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Yellow/White wire between PCM and fuel injector No. 3.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Start engine and allow it to idle. Wiggle wiring harness from fuel injector No. 3 to PCM. PCM is located on firewall in right rear corner of engine compartment. If engine misses or stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to misfire or stall. If engine does not misfire or stall while wiggling wiring harness, go to next step.
8. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, turn ignition on. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0203: INJECTOR #3 CONTROL CIRCUIT returns, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If DTC P0203: INJECTOR #3 CONTROL CIRCUIT does not return, no problem is indicated at this time. Test is complete.

DTC P0204: INJECTOR #4 CONTROL CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel injector operation is monitored when battery voltage is more than 10.4 volts, ASD relay energized, injector pulse width less than 10 milliseconds, and engine speed less than 3000 RPM. DTC will set in Powertrain Control Module (PCM) memory .64-10.00 seconds after PCM does not sense any inductive kick 18 milliseconds after injector is turned off, and no other injectors are turned on. Possible causes for DTC to set are: defective injector, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0204 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0204 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect fuel injector No. 4 connector. Turn ignition on. Using a test light connected to ground, backprobe Dark Green/Light Green wire at fuel injector No. 4 harness connector. Using scan tool, actuate Auto Shutdown (ASD) relay. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair power circuit to fuel injector No. 4. See WIRING DIAGRAMS article.
3. Using a test light connected to positive battery voltage, backprobe Light Blue/Brown wire at fuel injector No. 4 harness connector. Using scan tool, actuate fuel injector No. 4 while observing test light. If test light does not blink/flicker, go to next step. If test light blinks/flickers, replace fuel injector.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Light Blue/Brown wire between fuel injector No. 4 harness connector and terminal No. 16 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Light Blue/Brown wire.
5. Using ohmmeter, measure resistance between ground and Light Blue/Brown wire at fuel injector No. 4 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Light Blue/Brown wire between PCM and fuel injector No. 4.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Start engine and allow it to idle. Wiggle wiring harness from fuel injector No. 4 to PCM. PCM is located on firewall in right rear corner of engine compartment. If engine misses or stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to misfire or stall. If engine does not misfire or stall while wiggling wiring harness, go to next step.
8. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, turn ignition on. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0204: INJECTOR #4 CONTROL CIRCUIT returns, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If DTC P0204: INJECTOR #4 CONTROL CIRCUIT does not return, no problem is indicated at this time. Test is complete.

DTC P0205: INJECTOR #5 CONTROL CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel injector operation is monitored when battery voltage is more than 10.4 volts, ASD relay energized, injector pulse width less than 10 milliseconds, and engine speed less than 3000 RPM. DTC will set in Powertrain Control Module (PCM) memory .64-10.00 seconds after PCM does not sense any inductive kick 18 milliseconds after injector is turned off, and no other injectors are turned on. Possible causes for DTC to set are: defective injector, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0205 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0205 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect fuel injector No. 5 connector. Turn ignition on. Using a test light connected to ground, backprobe Dark Green/Light Green wire at fuel injector No. 5 harness connector. Using scan tool, actuate Auto Shutdown (ASD) relay. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair power circuit to fuel injector No. 5. See WIRING DIAGRAMS article.
3. Using a test light connected to positive battery voltage, backprobe Gray wire at fuel injector No. 5 harness connector. Using scan tool, actuate fuel injector No. 5 while observing test light. If test light does not blink/flicker, go to next step. If test light blinks/flickers, replace fuel injector.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Gray wire between fuel injector No. 5 harness connector and terminal No. 6 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Gray wire.
5. Using ohmmeter, measure resistance between ground and Gray wire at fuel injector No. 5 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Gray wire between PCM and fuel injector No. 5
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Start engine and allow it to idle. Wiggle wiring harness from fuel injector No. 5 to PCM. PCM is located on firewall in right rear corner of engine compartment. If engine misses or stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to misfire or stall. If engine does not misfire or stall while wiggling wiring harness, go to next step.
8. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, turn ignition on. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0205: INJECTOR #5 CONTROL CIRCUIT returns, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If DTC P0205: INJECTOR #5 CONTROL CIRCUIT does not return, no problem is indicated at this time. Test is complete.

DTC P0206: INJECTOR #6 CONTROL CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel injector operation is monitored when battery voltage is more than 10.4 volts, ASD relay energized, injector pulse width less than 10 milliseconds, and engine speed less than 3000 RPM. DTC will set in Powertrain Control Module (PCM) memory .64-10.00 seconds after PCM does not sense any inductive kick 18 milliseconds after injector is turned off, and no other injectors are turned on. Possible causes for DTC to set are: defective injector, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0206 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0206 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect fuel injector No. 6 connector. Turn ignition on. Using a test light connected to ground, backprobe Dark Green/Light Green wire at fuel injector No. 6 harness connector. Using scan tool, actuate Auto Shutdown (ASD) relay. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair power circuit to fuel injector No. 6. See WIRING DIAGRAMS article.
3. Using a test light connected to positive battery voltage, backprobe Brown/Dark Blue wire at fuel injector No. 6 harness connector. Using scan tool, actuate fuel injector No. 6 while observing test light. If test light does not blink/flicker, go to next step. If test light blinks/flickers, replace fuel injector.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Brown/Dark Blue wire between fuel injector No. 6 harness connector and terminal No. 12 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Brown/Dark Blue wire.
5. Using ohmmeter, measure resistance between ground and Brown/Dark Blue wire at fuel injector No. 6 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Brown/Dark Blue wire between PCM and fuel injector No. 6
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Start engine and allow it to idle. Wiggle wiring harness from fuel injector No. 6 to PCM. PCM is located on firewall in right rear corner of engine compartment. If engine misses or stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to misfire or stall. If engine does not misfire or stall while wiggling wiring harness, go to next step.
8. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, turn ignition on. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0206: INJECTOR #6 CONTROL CIRCUIT returns, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If DTC P0206: INJECTOR #6 CONTROL CIRCUIT does not return, no problem is indicated at this time. Test is complete.

DTC P0207: INJECTOR #7 CONTROL CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel injector operation is monitored when battery voltage is more than 10.4 volts, ASD relay energized, injector pulse width less than 10 milliseconds, and engine speed less than 3000 RPM. DTC will set in Powertrain Control Module (PCM) memory .64-10.00 seconds after PCM does not sense any inductive kick 18 milliseconds after injector is turned off, and no other injectors are turned on. Possible causes for DTC to set are: defective injector, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0207 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0207 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect fuel injector No. 7 connector. Turn ignition on. Using a test light connected to ground, backprobe Dark Green/Light Green wire at fuel injector No. 7 harness connector. Using scan tool, actuate Auto Shutdown (ASD) relay. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair power circuit to fuel injector No. 7. See WIRING DIAGRAMS article.
3. Using a test light connected to positive battery voltage, backprobe Dark Blue/Tan wire at fuel injector No. 7 harness connector. Using scan tool, actuate fuel injector No. 7 while observing test light. If test light does not blink/flicker, go to next step. If test light blinks/flickers, replace fuel injector.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/Tan wire between fuel injector No. 7 harness connector and terminal No. 2 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Tan wire.
5. Using ohmmeter, measure resistance between ground and Dark Blue/Tan wire at fuel injector No. 7 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Tan wire between PCM and fuel injector No. 7.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Start engine and allow it to idle. Wiggle wiring harness from fuel injector No. 7 to PCM. PCM is located on firewall in right rear corner of engine compartment. If engine misses or stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to misfire or stall. If engine does not misfire or stall while wiggling wiring harness, go to next step.
8. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, turn ignition on. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0207: INJECTOR #7 CONTROL CIRCUIT returns, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If DTC P0207: INJECTOR #7 CONTROL CIRCUIT does not return, no problem is indicated at this time. Test is complete.

DTC P0208: INJECTOR #8 CONTROL CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel injector operation is monitored when battery voltage is more than 10.4 volts, ASD relay energized, injector pulse width less than 10 milliseconds, and engine speed less than 3000 RPM. DTC will set in Powertrain Control Module (PCM) memory .64-10.00 seconds after PCM does not sense any inductive kick 18 milliseconds after injector is turned off, and no other injectors are turned on. Possible causes for DTC to set are: defective injector, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0208 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0208 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect fuel injector No. 8 connector. Turn ignition on. Using a test light connected to ground, backprobe Dark Green/Light Green wire at fuel injector No. 8 harness connector. Using scan tool, actuate Auto Shutdown (ASD) relay. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair power circuit to fuel injector No. 8. See WIRING DIAGRAMS article.
3. Using a test light connected to positive battery voltage, backprobe Dark Blue/Gray wire at fuel injector No. 8 harness connector. Using scan tool, actuate fuel injector No. 8 while observing test light. If test light does not blink/flicker, go to next step. If test light blinks/flickers, replace fuel injector.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/Gray wire between fuel injector No. 8 harness connector and terminal No. 13 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Gray wire.
5. Using ohmmeter, measure resistance between ground and Dark Blue/Gray wire at fuel injector No. 8 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Gray wire between PCM and fuel injector No. 8.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Start engine and allow it to idle. Wiggle wiring harness from fuel injector No. 8 to PCM. PCM is located on firewall in right rear corner of engine compartment. If engine misses or stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to misfire or stall. If engine does not misfire or stall while wiggling wiring harness, go to next step.
8. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, turn ignition on. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0208: INJECTOR #8 CONTROL CIRCUIT returns, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If DTC P0208: INJECTOR #8 CONTROL CIRCUIT does not return, no problem is indicated at this time. Test is complete.

DTC P0300: MULTIPLE CYLINDER MISFIRE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform FUEL SYSTEM/MISFIRE MONITOR VERIFICATION TEST under VERIFICATION TESTS to ensure system is functioning properly.

Cylinder misfire is monitored with engine running, after successfully performing Crankshaft Position (CKP) sensor learn procedure. DTC will set in Powertrain Control Module (PCM) memory when PCM senses more than 2 percent misfire rate during 2 trips or with a 10-30 percent misfire rate during one trip. Possible causes for DTC to set are: defective Camshaft Position (CMP) or CKP sensor, improper valve timing, vacuum leak, defective ignition system, engine mechanical problem, fuel contamination, improper fuel pressure or capacity, or defective fuel pump.

1. Turn ignition on. Using scan tool, read DTCs. If MISFIRE GOOD TRIP counter is displayed and displayed count is "0", go to next step. If MISFIRE GOOD TRIP counter is not displayed or displayed count is not "0", go to step 4 .
2. At this time, conditions required to set DTC are present. Using scan tool, read and record FREEZE FRAME and SIMILAR CONDITIONS data. Operate vehicle using data in SIMILAR CONDITIONS. While in SIMILAR CONDITIONS screen, go to WHICH CYLINDER IS MISFIRING monitor. If scan tool is counting misfires at this time, go to next step. If scan tool is not counting misfires at this time, no problem is indicated. Test is complete.
3. Using scan tool, read and record FREEZE FRAME data. Using freeze frame data, attempt to determine cause of misfire. If adaptive fuel percentages are not more than plus or minus 15 percent, go to next step. If adaptive fuel percentages are more than plus or minus 15 percent, check fuel delivery. See FUEL SYSTEMS under SYSTEM & COMPONENT TESTING article.
4. At this time, engine misfire does not exist or is an intermittent problem. Using scan tool, read and record FREEZE FRAME and SIMILAR CONDITIONS data. Road test vehicle under conditions in FREEZE FRAME and SIMILAR CONDITIONS data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC returns, go to next step. If DTC does not return, no problem is indicated at this time. Test is complete.
5. Using scan tool, read and record FREEZE FRAME data. Using freeze frame data, attempt to determine cause of misfire. If adaptive fuel percentages are more than plus or minus 15 percent, check fuel delivery. See FUEL SYSTEMS under SYSTEM & COMPONENT TESTING article. If adaptive fuel percentages are not more than plus or minus 15 percent, go to next step.
6. Using scan tool, read and record FREEZE FRAME and ENGINE RPM data. Using freeze frame data, attempt to determine cause of misfire. If engine speed is less than 3000 RPM and/or engine coolant temperature is not within normal range, go to next step. If engine speed is more than 3000 RPM and engine coolant temperature is within normal operating range, use lab scope to test CMP and CKP sensors, and check valve timing and engine vacuum.
7. Check the following additional items as possible mechanical problems: Engine vacuum must be at least 13 in. Hg with shift selector in Neutral. Engine valve timing must be within specification. Engine compression must be within specification. Engine exhaust system must be free of restrictions. Engine Closed Crankcase Ventilation (CCV) system (4.0L) or Positive Crankcase Ventilation (PCV) system (4.7L) must flow freely. Torque converter stall speed must be within specification. Power brake booster must have no internal leaks. Fuel must be free of contamination. Fuel injectors must be free of restrictions. Fuel injector control wires must be installed on correct injector. Repair mechanical problems as necessary. If no mechanical problems exist, go to next step.
8. Using scan tool, read and record FREEZE FRAME and LOAD VALUE data. Using freeze frame data, attempt to determine cause of misfire. If load value is 50 percent or less and/or engine coolant temperature is not within normal operating range, go to next step. If load value is more than 50 percent and engine coolant temperature is within normal operating range, check secondary ignition, compression and cylinder leakage.
9. Check following items for possible causes of cylinder misfire. Ignition Coil Circuit Spark Plugs Engine Mechanical Problem PCM Power Or Grounds Irregular CMP Sensor Signal Irregular CKP Sensor Signal Intake Restriction Damaged Trigger Wheel Accessory Drive Belt If any problems are found, repair as necessary. If no problems are found, test is complete. Check for any related technical service bulletins that may apply.

Cylinder misfire is monitored with engine running after successfully performing Crankshaft Position (CKP) sensor learn procedure. DTC will set in Powertrain Control Module (PCM) memory when more than a 2 percent misfire rate during 2 trips or with a 10-30 percent misfire rate during one trip. For misfire DTC identification, see CYLINDER MISFIRE DTC IDENTIFICATION table. Possible causes for DTC to set are: defective Camshaft Position (CMP) or CKP sensor, improper valve timing, vacuum leak, defective ignition system, engine mechanical problem, fuel contamination, improper fuel pressure or capacity, or defective fuel pump.

For diagnosis and repair procedure, see DTC P0300: MULTIPLE CYLINDER MISFIRE .

CYLINDER MISFIRE DTC IDENTIFICATION

DTC P0320: NO CRANK REFERENCE SIGNAL AT PCM

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Crank reference signal is monitored during engine cranking. DTC will set in Powertrain Control Module (PCM) memory when PCM senses no Crankshaft Position (CKP) sensor signal during engine cranking, and at least 3 Camshaft Position (CMP) sensor signals have occurred. Possible causes for DTC to set are: defective tone wheel/flexplate, defective PCM, defective CKP sensor, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read current CKP state while cranking engine. If scan tool displays current CKP state PRESENT, go to next step. If scan tool does not display current CKP state PRESENT, go to step 6. NOTE: The following step checks for any pulses generated on lab scope by the CKP sensor. With ignition on, no CKP sensor pulses should be generated.
2. Backprobe lab scope lead to terminal No. 8 (Gray/Black wire) at PCM C1 harness connector. (Scheme 29) PCM is located on firewall in right rear corner of engine compartment. Observe lab scope screen and turn ignition on. If any pulses were generated when ignition was turned on, replace CKP sensor. If no pulses were generated, go to next step. NOTE: The following step checks for any pulses generated on lab scope by the CMP sensor. With ignition on, no CMP sensor pulses should be generated.
3. Turn ignition off. Disconnect lab scope. Backprobe lab scope lead to terminal No. 18 (Tan/Yellow wire) at PCM C1 harness connector. (Scheme 29) Observe lab scope screen and turn ignition on. If any pulses were generated when ignition was turned on, replace CMP sensor. If no pulses were generated, go to next step.
4. Turn ignition off. Backprobe lab scope lead to terminal No. 8 (Gray/Black wire) at PCM C1 harness connector. (Scheme 29) Observe lab scope screen and start engine. Wiggle wiring harness from CKP sensor to PCM while observing lab scope pattern. On 4.0L, CKP sensor is mounted to left side of transmission bellhousing. CKP sensor connector is located on top of intake manifold, near firewall. On 4.7L, CKP sensor is bolted to side of engine cylinder block, above starter motor. (Scheme 35) On all models, if any irregularities in lab scope pattern occurs while wiggling wiring harness, check wiring harness where wiggling caused irregularity in lab scope pattern. Repair wiring as necessary. If wiring harness is okay, replace CKP sensor. If there are no irregularities in lab scope pattern while wiggling wiring harness, go to next step.
5. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
6. Turn ignition off. On 4.0L, CKP sensor is mounted to left side of transmission bellhousing. CKP sensor connector is located on top of intake manifold, near firewall. On 4.7L, CKP sensor is bolted to side of engine cylinder block, above starter motor. (Scheme 35)On all models, turn ignition on. Measure voltage between ground and Orange wire at CKP sensor harness connector. If voltage is 4.5-5.0 volts, go to next step. If voltage is not 4.5-5.0 volts, go to step 15.
7. Measure voltage between ground and Gray/Black wire at CKP sensor harness connector. If voltage is 4.5-5.0 volts, go to next step. If voltage is not 4.5-5.0 volts, go to step 10.
8. Turn ignition off. Measure resistance between ground and Black/Light Blue wire at CKP sensor harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
9. Turn ignition off. Remove CKP sensor. Inspect tone wheel/flexplate for damage. Check slotted areas on tone wheel/flexplate for damage or any foreign debris. Ensure tone wheel/flexplate turns when engine is cranked. Repair or replace tone wheel/flexplate as necessary. If slotted areas on flywheel/drive plate are okay and no debris exists, replace CKP sensor.
10. Turn ignition off. Ensure CKP sensor connector is still disconnected. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Gray/Black wire at CKP harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Gray/Black wire between CKP sensor and PCM.
11. Measure resistance of Gray/Black wire between CKP harness connector and terminal No. 8 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Gray/Black wire.
12. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. Measure voltage between ground and Gray/Black wire at CKP sensor harness connector. If voltage is 5 volts or less, go to next step. If voltage is more than 5 volts, repair short to voltage in Gray/Black wire between CKP sensor and PCM.
13. Turn ignition off. Disconnect PCM connectors. Ensure CKP sensor is still disconnected. Measure resistance between Orange and Gray/Black wires at CKP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Orange and Gray/Black wires are shorted together. Repair wiring as necessary.
14. At this time, PCM is assumed to be defective. Replace PCM.
15. Turn ignition off. Disconnect PCM connectors. Measure resistance between ground and Orange wire at CKP harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Orange wire between PCM and CKP sensor.
16. Measure resistance of Orange wire between CKP sensor harness connector and terminal No. 17 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire.
17. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. Measure voltage between ground and Orange wire at CKP sensor harness connector. If voltage is 5.5 volts or less, go to next step. If voltage is more than 5.5 volts, repair short to voltage in Orange wire between CKP sensor and PCM.
18. At this time, PCM is assumed to be defective. Replace PCM.

Scheme 35

DTC P0340: NO CAM SIGNAL AT PCM

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Cam signal is monitored with engine cranking or running and battery voltage is more than 10 volts. DTC will set in Powertrain Control Module (PCM) memory after 5 seconds and PCM senses Crankshaft Position (CKP) sensor signals but no signal from Camshaft Position (CMP) sensor. Possible causes for DTC to set are: no-start condition present, defective tone wheel/pulse ring, defective CMP sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read current CMP state while cranking engine. If scan tool displays current CMP state PRESENT, go to next step. If scan tool does not display current CMP state PRESENT, go to step 6. NOTE: The following step checks for any pulses generated on lab scope by the CKP sensor. With ignition on, no CKP sensor pulses should be generated.
2. Turn ignition off. Backprobe lab scope lead to terminal No. 8 (Gray/Black wire) at PCM C1 harness connector. (Scheme 29) PCM is located on firewall in right rear corner of engine compartment. Observe lab scope screen and turn ignition on. If any pulses were generated when ignition was turned on, replace CKP sensor. If no pulses were generated, go to next step. NOTE: The following step checks for any pulses generated on lab scope by the CMP sensor. With ignition on, no CMP sensor pulses should be generated.
3. Turn ignition off. Disconnect lab scope. Backprobe lab scope lead to terminal No. 18 (Tan/Yellow wire) at PCM C1 harness connector. (Scheme 29) Observe lab scope screen and turn ignition on. If any pulses were generated when ignition was turned on, replace CMP sensor. If no pulses were generated, go to next step.
4. Turn ignition off. Ensure lab scope lead is still connected to terminal No. 18 (Tan/Yellow wire) at PCM C1 harness connector. Observe lab scope screen and start engine. Wiggle wiring harness from CMP sensor to PCM while observing lab scope pattern. On 4.0L, CMP sensor is mounted on top of oil pump drive shaft assembly and is located on right side of engine, near oil filter. On 4.7L, CMP sensor is mounted on right front corner of right cylinder head. On all models, if any irregularities in lab scope pattern occurs while wiggling wiring harness, check wiring harness where wiggling caused irregularity in lab scope pattern. Repair wiring as necessary. If wiring harness is okay, replace CMP sensor. If there are no irregularities in lab scope pattern while wiggling wiring harness, go to next step.
5. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
6. Turn ignition off. Disconnect CMP sensor connector. On 4.0L, CMP sensor is mounted on top of oil pump drive shaft assembly and is located on right side of engine, near oil filter. On 4.7L, CMP sensor is mounted on right front corner of right cylinder head. On all models, turn ignition on. Measure voltage between ground and Orange wire at CMP sensor harness connector. If voltage is 4.5-5.0 volts, go to next step. If voltage is not 4.5-5.0 volts, go to step 15.
7. Measure voltage between ground and Tan/Yellow wire at CMP sensor harness connector. If voltage is 4.5-5.0 volts, go to next step. If voltage is not 4.5-5.0 volts, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Black/Light Blue wire between CMP sensor harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
9. Turn ignition off. On 4.0L, remove CMP sensor and oil pump drive shaft. See IGNITION SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. Inspect oil pump drive shaft. Replace oil pump drive shaft as necessary. If oil pump drive shaft is okay, replace CMP sensor. On 4.7L, remove CMP sensor from right front corner of right cylinder head. Inspect tone wheel for damage. Ensure tone wheel turns when engine is cranked. Replace tone wheel as necessary. If tone wheel is okay, replace CMP sensor.
10. Turn ignition off. Ensure CMP sensor connector is still disconnected. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Tan/Yellow wire at CMP harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Yellow wire between CMP sensor and PCM.
11. Measure resistance of Tan/Yellow wire between CMP harness connector and terminal No. 18 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Tan/Yellow wire.
12. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. Measure voltage between ground and Tan/Yellow wire at CMP sensor harness connector. If voltage is 5 volts or less, go to next step. If voltage is more than 5 volts, repair short to voltage in Tan/Yellow wire between CMP sensor and PCM.
13. Turn ignition off. Disconnect PCM connectors. Ensure CMP sensor is still disconnected. Measure resistance between Orange and Tan/Yellow wires at CMP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Orange and Tan/Yellow wires are shorted together. Repair wiring as necessary.
14. At this time, PCM is assumed to be defective. Replace PCM.
15. Turn ignition off. Disconnect PCM connectors. Measure resistance between ground and Orange wire at CMP harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Orange wire between PCM and CMP sensor.
16. Measure resistance of Orange wire between CMP sensor harness connector and terminal No. 17 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire.
17. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. Measure voltage between ground and Orange wire at CMP sensor harness connector. If voltage is 5.5 volts or less, go to next step. If voltage is more than 5.5 volts, repair short to voltage in Orange wire between CMP sensor and PCM.
18. At this time, PCM is assumed to be defective. Replace PCM.

DTC P0351: IGNITION COIL #1 PRIMARY CIRCUIT (4.0L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0351 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective ignition coil No. 1, defective PCM, or defective connectors or wiring.

Note. A one-piece coil rail assembly containing 3 individual coils is used. Coil rail assembly is located on top of engine, right of valve cover. Individual coils cannot be replaced separately. If any coils are defective, coils and coil rail assembly must be replaced as an assembly.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0351 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0351 or displayed count is not "0", go to step 8.
2. Turn ignition off. Disconnect ignition coil rail connector. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Measure resistance between Dark Green/Orange and Tan/Red wires at ignition coil rail connector (component side). If resistance is 0.6-0.9 ohm, go to next step. If resistance is not 0.6-0.9 ohm, replace ignition coil rail. NOTE: In the following step, when checking for power at the coil connector, Auto Shutdown (ASD) relay must be activated. When PCM receives a command to activate the ASD relay, the PCM toggles the ASD relay control circuit (2 seconds on and 2 seconds off) and voltage is supplied via the ASD relay to the coils. ASD relay can be activated by using a scan tool and activating generator field or ASD relay.
3. Turn ignition on. Using a test light connected to ground, probe Dark Green/Orange wire at ignition coil rail harness connector. Using scan tool, actuate generator field or ASD relay and observe test light. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open or high resistance in ASD relay output circuit to ignition coil rail. See WIRING DIAGRAMS article.
4. Turn ignition off. Ensure ignition coil rail connector is still disconnected. Using a test light connected to positive battery voltage, probe Tan/Red wire at ignition coil rail harness connector while cranking engine. If test light does not blink/flicker, go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Red wire between ignition coil rail harness connector and terminal No. 7 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Tan/Red wire.
6. Measure resistance between ground and Tan/Red wire at ignition coil rail harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Red wire.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0351: IGNITION COIL #1 PRIMARY CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0351 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective coil on plug No. 1, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0351 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0351 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect coil on plug No. 1 connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Red wire between coil on plug No. 1 harness connector and terminal No. 7 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Tan/Red wire between PCM and coil on plug No. 1.
3. Measure resistance between coil on plug No. 1 terminals. Resistance should be 0.6-0.9 ohm with coil on plug temperature at 70-80°F (21-27°C). If resistance is as specified, go to next step. If resistance is not as specified, replace coil on plug No. 1.
4. Ensure ignition is off. Reconnect all connectors. Using a test light connected to positive battery voltage, backprobe Tan/Red wire at coil on plug harness connector. Start engine and observe test light. If test light does not blink/flicker, turn ignition off and go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Turn ignition off. Disconnect coil on plug No. 1 connector. Disconnect PCM connectors. Measure resistance between ground and Tan/Red wire at coil on plug No. 1 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Red wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0352: IGNITION COIL #2 PRIMARY CIRCUIT (4.0L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0352 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective ignition coil No. 2, defective PCM, or defective connectors or wiring.

Note. A one-piece coil rail assembly containing 3 individual coils is used. Coil rail assembly is located on top of engine, right of valve cover. Individual coils cannot be replaced separately. If any coils are defective, coils and coil rail assembly must be replaced as an assembly.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0352 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0352 or displayed count is not "0", go to step 8.
2. Turn ignition off. Disconnect ignition coil rail connector. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Measure resistance between Dark Green/Orange and Tan/Pink wires at ignition coil rail connector (component side). If resistance is 0.6-0.9 ohm, go to next step. If resistance is not 0.6-0.9 ohm, replace ignition coil rail. NOTE: In the following step, when checking for power at the coil connector, Auto Shutdown (ASD) relay must be activated. When PCM receives a command to activate the ASD relay, the PCM toggles the ASD relay control circuit (2 seconds on and 2 seconds off) and voltage is supplied via the ASD relay to the coils. ASD relay can be activated by using a scan tool and activating generator field or ASD relay.
3. Turn ignition on. Using a test light connected to ground, probe Dark Green/Orange wire at ignition coil rail harness connector. Using scan tool, actuate generator field or ASD relay and observe test light. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open or high resistance in ASD relay output circuit to ignition coil rail. See WIRING DIAGRAMS article.
4. Turn ignition off. Ensure ignition coil rail connector is still disconnected. Using a test light connected to positive battery voltage, probe Tan/Pink wire at ignition coil rail harness connector while cranking engine. If test light does not blink/flicker, go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Pink wire between ignition coil rail harness connector and terminal No. 9 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Tan/Pink wire.
6. Measure resistance between ground and Tan/Pink wire at ignition coil rail harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Pink wire.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0352: IGNITION COIL #2 PRIMARY CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0352 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective coil on plug No. 2, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0352 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0352 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect coil on plug No. 2 connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Pink wire between coil on plug No. 2 harness connector and terminal No. 9 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Tan/Pink wire between PCM and coil on plug No. 2.
3. Measure resistance between coil on plug No. 2 terminals. Resistance should be 0.6-0.9 ohm with coil on plug temperature at 70-80°F (21-27°C). If resistance is as specified, go to next step. If resistance is not as specified, replace coil on plug No. 2.
4. Ensure ignition is off. Reconnect all connectors. Using a test light connected to positive battery voltage, backprobe Tan/Pink wire at coil on plug harness connector. Start engine and observe test light. If test light does not blink/flicker, turn ignition off and go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Turn ignition off. Disconnect coil on plug No. 2 connector. Disconnect PCM connectors. Measure resistance between ground and Tan/Pink wire at coil on plug No. 2 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Pink wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0353 IGNITION COIL #3 PRIMARY CIRCUIT (4.0L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0353 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective ignition coil No. 3, defective PCM, or defective connectors or wiring.

Note. A one-piece coil rail assembly containing 3 individual coils is used. Coil rail assembly is located on top of engine, right of valve cover. Individual coils cannot be replaced separately. If any coils are defective, coils and coil rail assembly must be replaced as an assembly.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0353 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0353 or displayed count is not "0", go to step 8.
2. Turn ignition off. Disconnect ignition coil rail connector. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Measure resistance between Dark Green/Orange and Tan/Orange wires at ignition coil rail connector (component side). If resistance is 0.6-0.9 ohm, go to next step. If resistance is not 0.6-0.9 ohm, replace ignition coil rail. NOTE: In the following step, when checking for power at the coil connector, Auto Shutdown (ASD) relay must be activated. When PCM receives a command to activate the ASD relay, the PCM toggles the ASD relay control circuit (2 seconds on and 2 seconds off) and voltage is supplied via the ASD relay to the coils. ASD relay can be activated by using a scan tool and activating generator field or ASD relay.
3. Turn ignition on. Using a test light connected to ground, probe Dark Green/Orange wire at ignition coil rail harness connector. Using scan tool, actuate generator field or ASD relay and observe test light. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open or high resistance in ASD relay output circuit to ignition coil rail. See WIRING DIAGRAMS article.
4. Turn ignition off. Ensure ignition coil rail connector is still disconnected. Using a test light connected to positive battery voltage, probe Tan/Orange wire at ignition coil rail harness connector while cranking engine. If test light does not blink/flicker, go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Orange wire between ignition coil rail harness connector and terminal No. 1 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Tan/Orange wire.
6. Measure resistance between ground and Tan/Orange wire at ignition coil rail harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Orange wire.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0353: IGNITION COIL #3 PRIMARY CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0353 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective coil on plug No. 3, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0353 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0353 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect coil on plug No. 3 connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Orange wire between coil on plug No. 3 harness connector and terminal No. 1 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Tan/Orange wire between PCM and coil on plug No. 3.
3. Measure resistance between coil on plug No. 3 terminals. Resistance should be 0.6-0.9 ohm with coil on plug temperature at 70-80°F (21-27°C). If resistance is as specified, go to next step. If resistance is not as specified, replace coil on plug No. 3.
4. Ensure ignition is off. Reconnect all connectors. Using a test light connected to positive battery voltage, backprobe Tan/Orange wire at coil on plug harness connector. Start engine and observe test light. If test light does not blink/flicker, turn ignition off and go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Turn ignition off. Disconnect coil on plug No. 3 connector. Disconnect PCM connectors. Measure resistance between ground and Tan/Orange wire at coil on plug No. 3 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Orange wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0354: IGNITION COIL #4 PRIMARY CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0354 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective coil on plug No. 4, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0354 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0354 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect coil on plug No. 4 connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Light Green wire between coil on plug No. 4 harness connector and terminal No. 3 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Tan/Light Green wire between PCM and coil on plug No. 4.
3. Measure resistance between coil on plug No. 4 terminals. Resistance should be 0.6-0.9 ohm with coil on plug temperature at 70-80°F (21-27°C). If resistance is as specified, go to next step. If resistance is not as specified, replace coil on plug No. 4.
4. Ensure ignition is off. Reconnect all connectors. Using a test light connected to positive battery voltage, backprobe Tan/Light Green wire at coil on plug harness connector. Start engine and observe test light. If test light does not blink/flicker, turn ignition off and go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Turn ignition off. Disconnect coil on plug No. 4 connector. Disconnect PCM connectors. Measure resistance between ground and Tan/Light Green wire at coil on plug No. 4 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Light Green wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0355: IGNITION COIL #5 PRIMARY CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0355 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective coil on plug No. 5, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0355 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0355 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect coil on plug No. 5 connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Dark Green wire between coil on plug No. 5 harness connector and terminal No. 21 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Tan/Dark Green wire between PCM and coil on plug No. 5.
3. Measure resistance between coil on plug No. 5 terminals. Resistance should be 0.6-0.9 ohm with coil on plug temperature at 70-80°F (21-27°C). If resistance is as specified, go to next step. If resistance is not as specified, replace coil on plug No. 5.
4. Ensure ignition is off. Reconnect all connectors. Using a test light connected to positive battery voltage, backprobe Tan/Dark Green wire at coil on plug harness connector. Start engine and observe test light. If test light does not blink/flicker, turn ignition off and go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Turn ignition off. Disconnect coil on plug No. 5 connector. Disconnect PCM connectors. Measure resistance between ground and Tan/Dark Green wire at coil on plug No. 5 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Dark Green wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0356: IGNITION COIL #6 PRIMARY CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0356 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective coil on plug No. 6, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0356 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0356 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect coil on plug No. 6 connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Tan/Light Blue wire between coil on plug No. 6 harness connector and terminal No. 5 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Tan/Light Blue wire between PCM and coil on plug No. 6.
3. Measure resistance between coil on plug No. 6 terminals. Resistance should be 0.6-0.9 ohm with coil on plug temperature at 70-80°F (21-27°C). If resistance is as specified, go to next step. If resistance is not as specified, replace coil on plug No. 6.
4. Ensure ignition is off. Reconnect all connectors. Using a test light connected to positive battery voltage, backprobe Tan/Light Blue wire at coil on plug harness connector. Start engine and observe test light. If test light does not blink/flicker, turn ignition off and go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Turn ignition off. Disconnect coil on plug No. 6 connector. Disconnect PCM connectors. Measure resistance between ground and Tan/Light Blue wire at coil on plug No. 6 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Tan/Light Blue wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0357: IGNITION COIL #7 PRIMARY CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0357 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective coil on plug No. 7, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0357 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0357 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect coil on plug No. 7 connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Brown wire between coil on plug No. 7 harness connector and terminal No. 7 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Brown wire between PCM and coil on plug No. 7.
3. Measure resistance between coil on plug No. 7 terminals. Resistance should be 0.6-0.9 ohm with coil on plug temperature at 70-80°F (21-27°C). If resistance is as specified, go to next step. If resistance is not as specified, replace coil on plug No. 7.
4. Ensure ignition is off. Reconnect all connectors. Using a test light connected to positive battery voltage, backprobe Brown wire at coil on plug harness connector. Start engine and observe test light. If test light does not blink/flicker, turn ignition off and go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Turn ignition off. Disconnect coil on plug No. 7 connector. Disconnect PCM connectors. Measure resistance between ground and Brown wire at coil on plug No. 7 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Brown wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0358: IGNITION COIL #8 PRIMARY CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Ignition coil primary circuit is monitored when battery voltage is more than 8 volts during engine cranking or more than 12 volts with engine running at less than 2016 RPM, and no coils in dwell when checked. DTC will set in Powertrain Control Module (PCM) memory when PCM senses peak current is not achieved with battery based dwell plus 1.5 milliseconds of diagnostic offset. DTC P0358 takes less than 3 seconds to set with engine cranking, or up to 6 seconds with engine running. Possible causes for DTC to set are: defective coil on plug No. 8, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0357 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0357 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect coil on plug No. 8 connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Light Blue/Red wire between coil on plug No. 8 harness connector and terminal No. 8 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Brown wire between PCM and coil on plug No. 8.
3. Measure resistance between coil on plug No. 8 terminals. Resistance should be 0.6-0.9 ohm with coil on plug temperature at 70-80°F (21-27°C). If resistance is as specified, go to next step. If resistance is not as specified, replace coil on plug No. 8.
4. Ensure ignition is off. Reconnect all connectors. Using a test light connected to positive battery voltage, backprobe Light Blue/Red wire at coil on plug harness connector. Start engine and observe test light. If test light does not blink/flicker, turn ignition off and go to next step. If test light blinks/flickers, no problem is indicated at this time. Test is complete.
5. Turn ignition off. Disconnect coil on plug No. 8 connector. Disconnect PCM connectors. Measure resistance between ground and Light Blue/Red wire at coil on plug No. 8 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Light Blue/Red wire.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or engine misses, repair wiring where wiggling caused engine to miss. If engine does not miss and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

DTC P0420: 1/1 CATALYTIC CONVERTER EFFICIENCY

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Note. 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 4.0L, 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.

Catalytic converter efficiency is monitored after engine warms up to 147°F (64°C), throttle has been open for 180 seconds at vehicle speed more than 20 MPH, with engine speed at 1200-1700 RPM and MAP vacuum 15-21 in. Hg. DTC will set in Powertrain Control Module (PCM) memory when PCM senses catalyst efficiency deteriorated to a predetermined value. Possible causes for DTC to set are: exhaust leak, engine mechanical problem, defective catalytic converter or upstream Heated Oxygen Sensor (HO2S) is older than downstream HO2S.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0420 and displayed count is "0", go to step 3 . If GOOD TRIP counter is not displayed for DTC P0420 or displayed count is not "0", go to next step.
2. At this time, conditions for catalyst efficiency failure do not exist or is an intermittent problem. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0420: 1/1 CATALYTIC CONVERTER EFFICIENCY returns, go to next step. If DTC P0420: 1/1 CATALYTIC CONVERTER EFFICIENCY does not return, no problem is indicated at this time. Test is complete.
3. Start engine and allow it to idle. Check for exhaust leaks between engine and downstream HO2S. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
4. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace catalytic converter. If engine mechanical condition is okay, go to next step.
5. If downstream HO2S has been replaced without replacing upstream HO2S, replace upstream HO2S. If downstream HO2S has not been replaced recently or downstream HO2S has been replaced along with upstream HO2S, replace catalytic converter.

DTC P0432: 2/1 CATALYTIC CONVERTER EFFICIENCY

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Note. 2/1 Heated Oxygen Sensor (HO2S) may also be referred to as a upstream oxygen sensor. On 4.0L, 2/1 HO2S is located on rear exhaust manifold. On 4.7L, 2/1 HO2S is located in right (passenger's side) exhaust downpipe in front of catalytic converter.

Catalytic converter efficiency is monitored after engine warms up to 147°F (64°C), throttle has been open for 180 seconds at vehicle speed more than 20 MPH, with engine speed at 1200-1700 RPM and MAP vacuum 15-21 in. Hg. DTC will set in Powertrain Control Module (PCM) memory when PCM senses catalyst efficiency deteriorated to a predetermined value. Possible causes for DTC to set are: exhaust leak, engine mechanical problem, defective catalytic converter or upstream HO2S is older than downstream HO2S.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0432 and displayed count is "0", go to step 3 . If GOOD TRIP counter is not displayed for DTC P0432 or displayed count is not "0", go to next step.
2. At this time, conditions for catalyst efficiency failure do not exist or is an intermittent problem. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0432: 2/1 CATALYTIC CONVERTER EFFICIENCY returns, go to next step. If DTC P0432: 2/1 CATALYTIC CONVERTER EFFICIENCY does not return, no problem is indicated at this time. Test is complete.
3. Start engine and allow it to idle. Check for exhaust leaks between engine and downstream HO2S. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
4. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace catalytic converter. If engine mechanical condition is okay, go to next step.
5. If downstream HO2S has been replaced without replacing upstream HO2S, replace upstream HO2S. If downstream HO2S has not been replaced recently or downstream HO2S has been replaced along with upstream HO2S, replace catalytic converter.

DTC P0441: EVAP PURGE FLOW MONITOR FAILURE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

EVAP purge flow is monitored after engine warms up to more than 170°F (77°C) in closed loop mode, at idle for 2 minutes, Manifold Absolute Pressure (MAP) at less than 15.7 in. Hg, and altitude at less than 8000 feet. DTC will set in Powertrain Control Module (PCM) memory when PCM senses no airflow through Evaporative Emission (EVAP) system. Possible causes for DTC to set are: EVAP purge solenoid contaminated, defective EVAP purge solenoid, or damaged or plugged vacuum hoses.

Note. EVAP purge solenoid may also be referred to as EVAP canister purge solenoid or duty cycle EVAP purge solenoid.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is displayed for DTC P0441 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0441 or displayed count is not "0", go to step 8.
2. EVAP canister is located in engine compartment, left of brake booster. (Scheme 36) Visually inspect EVAP canister for damage or signs that fuel has entered canister. Any sign of fuel in EVAP canister may indicate a defective rollover valve. Rollover valve is located on top of fuel tank and is not serviceable. If rollover valve is defective, fuel tank must be replaced. Replace EVAP canister and/or fuel tank as necessary. If EVAP canister is okay, go to next step.
3. Visually inspect EVAP purge hose between EVAP canister and fuel tank. Check for plugged, pinched, ripped or dry-rotted hose. Replace EVAP purge hose as necessary. If EVAP purge hose is okay, go to next step.
4. Visually inspect EVAP purge hose between EVAP canister and EVAP purge solenoid. EVAP purge solenoid is located in engine compartment, left of brake booster. (Scheme 36) Check for plugged, pinched, ripped or dry-rotted hose. Replace EVAP purge hose as necessary. If EVAP purge hose is okay, go to next step.
5. Visually inspect vacuum hose between EVAP purge solenoid and throttle body. Check for plugged, pinched, ripped or dry-rotted hose. Replace vacuum hose as necessary. If vacuum hose is okay, check for plugged throttle body vacuum nipple. Repair vacuum nipple as necessary. If vacuum nipple is okay, go to next step.
6. Disconnect EVAP purge solenoid vacuum hoses. Using a vacuum pump, apply 10 in. Hg to EVAP purge solenoid vacuum source port. If vacuum holds, go to next step. If vacuum does not hold, replace EVAP canister purge valve.
7. Using a vacuum pump, apply 10 in. Hg to EVAP purge solenoid vacuum source port. Turn ignition on. Using scan tool, actuate EVAP purge solenoid and observe vacuum gauge. If vacuum holds, replace EVAP purge solenoid. If vacuum releases, no problem is indicated at this time. Test is complete.
8. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Turn ignition on. Using scan tool, actuate EVAP purge solenoid. Wiggle EVAP purge solenoid wiring harness and listen for EVAP purge solenoid to quit actuating. Using scan tool, read DTCs. If GOOD TRIP counter is displayed and displayed count changes to "0", or EVAP purge solenoid quits actuating, repair wiring where wiggling caused EVAP purge solenoid to quit actuating. If EVAP purge solenoid does not stop actuating and GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Test is complete.

Scheme 36

DTC P0442: EVAP LEAK MONITOR MEDIUM (.040") LEAK DETECTED DTC P0455: EVAP LEAK MONITOR LARGE LEAK DETECTED DTC P0456: EVAP LEAK MONITOR SMALL (.020") LEAK DETECTED

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-6 under VERIFICATION TESTS to ensure system is functioning properly.

Note. EVAP purge solenoid may also be referred to as EVAP canister purge solenoid or duty cycle EVAP purge solenoid.

EVAP leak monitor is monitored immediately after a cold start, with ambient temperature 40-90°F (4-32°C) and engine coolant temperature within 10°F of ambient temperature. DTC P0442 will set in Powertrain Control Module (PCM) memory when PCM senses a leak of .040-.080" (.01-.02 mm) in Evaporative Emission (EVAP) system. DTC P0455 will set when PCM senses a leak bigger than .080" (.02 mm) in EVAP system. DTC P0456 will set when PCM senses a leak of .020-.040" (.005-.010 mm) in EVAP system. Possible causes for DTC to set are: damaged EVAP hose, leaking EVAP system component, leaking Leak Detection Pump (LDP), loose fuel tank cap, defective secondary seal in fuel filler neck, or defective connectors or wiring.

Note. A loose fuel tank cap could cause this trouble code to set. Ensure fuel tank cap is tight and in good condition.

1. Turn ignition on. Using scan tool, check for DTCs. If GOOD TRIP counter is not displayed for DTC or displayed count is not "0", go to step 4. If GOOD TRIP counter is displayed for DTC and displayed count is "0", go to next step.
2. To test EVAP system properly, fuel tank should have 20-80 percent of fuel capacity. Miller Evaporative System Testing Kit (6872A) and Gas Cap Adapter (8382) are used to perform evaporative system pressure test. Connect scan tool to Data Link Connector (DLC). Connect EVAP system testing kit positive lead to positive battery terminal and negative lead to negative battery terminal. Using EVAP system testing kit, and instructions printed on EVAP system testing kit cover, perform EVAP system pressure pump self-test. Remove gas cap and install gas cap adapter to fuel tank. Install gas cap to gas cap adapter. Connect pressure supply hose from evaporative system testing kit to fitting on gas cap adapter. Disconnect vacuum supply hose at Leak Detection Pump (LDP). LDP is located at left front corner of engine compartment, below air cleaner housing. (Scheme 39) Apply a continuous vacuum supply of about 20 in. Hg to vacuum supply nipple on LDP. An A/C recovery unit works well for supplying a continuous vacuum supply. Turn ignition on. Using scan tool, select ENGINE SYSTEM TESTS, then LEAK DETECTION PUMP TEST. Read instructions on scan tool and then press ENTER. Select #3 HOLD PSI. Set EVAP system testing kit PRESSURE/HOLD valve to OPEN and set VENT valve to CLOSED. While monitoring EVAP system testing kit pressure gauge, turn EVAP system testing kit pump timer on. When pressure gauge reaches 14 in. H2O, turn PRESSURE HOLD valve to CLOSED. Turn timer off. Note time and pressure. If pressure drops more than 6 in. H2O in 2 minutes, go to next step. If pressure drops 6 in. H2O or less in 2 minutes, go to step 4.
3. EVAP system pressure pump self-test should still be running. If DRBIII(R) has timed out, restart EVAP system pressure pump self-test. Set EVAP system testing kit PRESSURE/HOLD valve to OPEN. Set VENT valve to CLOSED. Turn EVAP system testing kit pump timer on. To prevent noise from interfering with test, move EVAP system kit pressure gauge away from vehicle. Using Ultrasonic Leak Detector (6904A), check for leaks at gas cap, rollover valve, EVAP canister, LDP and EVAP purge solenoid. Rollover valve is located on top of fuel tank next to fuel pump module. Rollover valve is not serviceable. If rollover valve is defective, fuel tank must be replaced. EVAP canister is located on left front fender of engine compartment. Leak test all EVAP system hoses, tubes and connections. Repair or replace leaking component(s) as necessary. If no leaks exist, no problem is indicated at this time. Test is complete.
4. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Thoroughly perform a visual inspection of EVAP system hoses, tubes and connections. Look for any physical damage or signs of wetness at connections. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Turn ignition on. Using scan tool in SYSTEM TESTS, perform LDP monitor test. This will force the PCM to run LDP monitor. If monitor fails, further diagnosis is required to find faulty component. Go to step 2. If monitor passes, no problem is indicated at this time. Test is complete.

DTC P0443: EVAP PURGE SOLENOID CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

EVAP purge solenoid is monitored immediately after ignition is turned on and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory if actual state of EVAP purge solenoid does not match the intended state when requested to operate by PCM. Possible causes for DTC to set are: defective EVAP purge solenoid, defective PCM, or defective connectors or wiring.

Note. EVAP purge solenoid may also be referred to as EVAP canister purge solenoid or duty cycle EVAP purge solenoid.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0443 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0443 or displayed count is not "0", go to step 7.
2. Ensure ignition is off. Disconnect EVAP purge solenoid connector. EVAP purge solenoid is located in engine compartment, left of brake booster. (Scheme 36) Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, measure resistance between EVAP purge solenoid terminals. If resistance is 30-40 ohms, go to next step. If resistance is not 30-40 ohms, replace EVAP purge solenoid.
3. Turn ignition on. Using a voltmeter, measure voltage between ground and Orange wire at EVAP purge solenoid harness connector. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, check for open in Orange wire (fused ignition switch output circuit) between EVAP purge solenoid and junction block. Junction block is located under left side of instrument panel. (Scheme 26)
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Pink/Black wire between EVAP purge solenoid harness connector and terminal No. 20 at PCM C3 harness connector. (Scheme 29) If resistance is 5 ohms or more, repair open in Pink/Black wire between EVAP purge solenoid and PCM. If resistance is less than 5 ohms, go to next step.
5. Measure resistance between ground and Pink/Black wire at EVAP purge solenoid wiring harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Pink/Black wire between PCM and EVAP purge solenoid.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Ensure ignition is on, with engine off. Using scan tool, read and then clear DTCs. Using scan tool, actuate EVAP purge solenoid. Wiggle wiring harness from EVAP purge solenoid to PCM. EVAP purge solenoid is located in engine compartment, left of brake booster. (Scheme 36) PCM is located on firewall in right rear corner of engine compartment. If EVAP purge solenoid DTC returns while wiggling wiring harness, repair wiring harness where wiggling caused DTC to return. If EVAP purge solenoid DTC does not return while wiggling wiring harness, no problem is indicated at this time. Test is complete.

DTC P0460: FUEL LEVEL UNIT NO CHANGE OVER MILES DTC P0461: FUEL LEVEL UNIT NO CHANGE OVER TIME

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel level is monitored with engine running and fuel level at less than 15 percent or more than 85 percent capacity. DTC will set in Powertrain Control Module (PCM) memory when PCM senses low fuel for more than 120 miles, or fuel level does not change by at least 4 percent for more than 250 miles. Possible causes for DTC to set are: defective fuel level sensor, or defective connectors or wiring.

1. Turn ignition off. Remove fuel tank. See FUEL TANK under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article. Remove fuel pump module from fuel tank. Visually inspect inside of fuel tank for obstructions or deformities. Repair or replace fuel tank as necessary. If fuel tank is okay, go to next step.
2. At this time, fuel level sensor is assumed to be defective. Replace fuel level sensor. Fuel level sensor is located on fuel pump module and can be replaced separately. See FUEL LEVEL SENSOR under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article.

DTC P0462: FUEL LEVEL SENDING UNIT VOLTS TOO LOW

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel level sending unit may also be referred to as fuel level sensor. Fuel level sensor voltage is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses fuel level sensor signal less than 0.4 volt for 4 seconds. Possible causes for DTC to set are: defective fuel level sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read FUEL LEVEL SENSOR voltage. If voltage is less than 0.4 volt, go to next step. If voltage is 0.4 volt or more, go to step 6.
2. Turn ignition off. Disconnect fuel pump module connector. Fuel pump module is mounted in top of fuel tank. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Using scan tool, read FUEL LEVEL SENSOR voltage. If voltage does not change from less than 0.4 volt to more than 9.0 volts, go to next step. If voltage changes from less than 0.4 volt to more than 9.0 volts, replace fuel level sensor. Fuel level sensor is located on fuel pump module and can be replaced separately. See FUEL LEVEL SENSOR under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article.
3. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between terminal No. 4 (Black/Light Blue wire) at PCM C1 connector and terminal No. 26 (Light Blue/Yellow wire) at PCM C3 harness connector. (Scheme 29) If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Black/Light Blue and Light Blue/Yellow wires are shorted together. Repair wiring as necessary.
4. Measure resistance between ground and terminal No. 26 (Light Blue/Yellow wire) at PCM C3 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Light Blue/Yellow wire.
5. At this time, PCM is assumed to be defective. Replace PCM.
6. Ensure ignition is on, with engine off. Using scan tool, monitor FUEL LEVEL SENSOR voltage while wiggling fuel pump module connector and wiring harness. Fuel pump module is mounted in top of fuel tank. If voltage changes while wiggling wiring harness, repair wiring harness where wiggling caused voltage to change. If voltage does not change while wiggling wiring harness, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, no problem is indicated at this time. Test is complete.

DTC P0463: FUEL LEVEL SENDING UNIT VOLTS TOO HIGH

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Fuel level sending unit may also be referred to as fuel level sensor. Fuel level sensor is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses fuel level sensor signal is more than 9.9 volts for 2 seconds. Possible causes for DTC to set are: defective fuel level sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read FUEL LEVEL SENSOR voltage. If voltage is more than 9.9 volts, go to next step. If voltage is 9.9 volts or less, go to step 6.
2. Turn ignition off. Disconnect fuel pump module connector. Fuel pump module is mounted in top of fuel tank. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, connect a jumper wire between Light Blue/Yellow and Black/Light Blue wires at fuel pump module harness connector. Turn ignition on. Using scan tool, read FUEL LEVEL SENSOR voltage. If voltage did not change from more than 9.9 volts to less than 0.4 volt, go to next step. If voltage changed from more than 9.9 volts to less than 0.4 volt, replace fuel level sensor. Fuel level sensor is located on fuel pump module and can be replaced separately. See FUEL LEVEL SENSOR under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION article.
3. Turn ignition off. Disconnect jumper wire. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Black/Light Blue wire between fuel pump module harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
4. Turn ignition off. Measure resistance of Dark Blue/Light Green wire between fuel pump module harness connector and terminal No. 26 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Light Green wire.
5. At this time, PCM is assumed to be defective. Replace PCM.
6. Ensure ignition is on, with engine off. Using scan tool, monitor FUEL LEVEL SENSOR voltage while wiggling fuel pump module connector and wiring harness. Fuel pump module is mounted in top of fuel tank. If voltage changes while wiggling wiring harness, repair wiring harness where wiggling caused voltage to change. If voltage does not change while wiggling wiring harness, visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, no problem is indicated at this time. Test is complete.

DTC P0500: NO VEHICLE SPEED SENSOR SIGNAL

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Vehicle Speed Sensor (VSS) signal is sent through Controller Anti-Lock Brake (CAB) module by rear wheel speed sensor located on rear axle. VSS signal is monitored after engine warms up to 104°F (40°C), Manifold Absolute Pressure (MAP) vacuum is 15-16 in. Hg and engine speed is 1400-3000 RPM. DTC will set in Powertrain Control Module (PCM) memory when PCM senses output no VSS signal for more than 15 seconds for 2 consecutive trips. Possible causes for DTC to set are: inactive DTC, defective CAB module, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0500 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P0500 or displayed count is not "0", go to step 7.
2. Using scan tool, read DTCs. If any Controller Anti-Lock Brake (CAB) module DTCs are present, see appropriate ANTI-LOCK article in BRAKES. If no CAB module DTCs are present, go to next step.
3. Turn ignition off. Disconnect CAB module connector. CAB module is located on front of Hydraulic Control Unit (HCU). HCU is mounted near brake master cylinder. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of White/Orange wire between terminals No. 27 at PCM C2 connector and No. 3 at CAB module connector. (Scheme 29)and (Scheme 37). If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in White/Orange wire.
4. Reconnect PCM connectors. Ensure CAB module connector is still disconnected. Turn ignition on, with engine off. Measure voltage between ground and terminal No. 3 (White/Orange wire) at CAB module connector. (Scheme 37) If voltage is 6 volts or less, go to next step. If voltage is more than 6 volts, repair short to voltage in White/Orange wire.
5. Connect one end of a jumper wire to terminal No. 3 (White/Orange wire) at CAB module connector. Using scan tool, read VSS signal while briefly tapping other end of jumper wire to ground. If scan tool displays zero MPH, go to next step. If scan tool displays more than zero MPH, replace CAB module.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, start engine and allow it to idle. With engine running, wiggle wiring harness from CAB to PCM. CAB module is located on front of Hydraulic Control Unit (HCU). HCU is mounted near brake master cylinder. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.

Scheme 37

DTC P0505: IDLE AIR CONTROL MOTOR CIRCUITS

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Idle Air Control (IAC) motor voltage is monitored immediately after ignition is turned on and battery voltage is more than 11.5 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses a short to ground or battery voltage on any of the 4 IAC driver circuits while IAC motor is active. Possible causes for DTC to set are: defective IAC motor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P0505 and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P0505 is not displayed or displayed count is not "0", go to step 22.
2. Start engine and allow it to idle. Disconnect IAC motor connector. Measure voltage between ground and Gray/Red wire (4.0L) or Gray/Black wire (4.7L) at IAC motor harness connector. If voltage changes to more than 5 volts at any time, go to next step. If voltage does not change to more than 5 volts at any time, go to step 19.
3. With engine still idling, measure voltage between ground and Yellow/Black wire at IAC motor harness connector. If voltage changes to more than 5 volts at any time, go to next step. If voltage does not change to more than 5 volts at any time, go to step 16.
4. With engine still idling, measure voltage between ground and Brown/White wire at IAC motor harness connector. If voltage changes to more than 5 volts at any time, go to next step. If voltage does not change to more than 5 volts at any time, go to step 13.
5. With engine still idling, measure voltage between ground and Violet/Black wire at IAC motor harness connector. If voltage changes to more than 5 volts at any time, go to next step. If voltage does not change to more than 5 volts at any time, go to step 10.
6. Turn engine off. Ensure IAC motor is still disconnected. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. On 4.0L, measure resistance between Gray/Red wire and Yellow/Black, Brown/White and Violet/Black wires at IAC motor harness connector. On 4.7L, measure resistance between Gray/Black wire and Yellow/Black, Brown/White and Violet/Black wires at IAC motor harness connector. On all models, if any resistance reading is less than 5 ohms, Gray/Red wire (4.0L) or Gray/Black wire (4.7L) is shorted to wire with resistance less than 5 ohms. Repair wiring as necessary. If all resistance readings are 5 ohms or more, go to next step.
7. Measure resistance between Yellow/Black wire and Brown/White and Violet/Black wires at IAC motor harness connector. If any resistance reading is less than 5 ohms, Yellow/Black wire is shorted to wire with resistance less than 5 ohms. Repair wiring as necessary. If all resistance readings are 5 ohms or more, go to next step.
8. Measure resistance between Brown/White and Violet/Black wires at IAC motor harness connector. If resistance is less than 5 ohms, Brown/White and Violet/Black wires are shorted together. Repair wiring as necessary. If all resistance is 5 ohms or more, go to next step.
9. At this time, IAC motor is assumed to be defective. Replace IAC motor.
10. Turn ignition off. Ensure IAC motor is disconnected. Disconnect PCM connectors. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Violet/Black wire between IAC motor harness connector and terminal No. 20 at PCM C1 connector. (Scheme 29) If resistance is 5 ohms or more, repair open in Violet/Black wire. If resistance is less than 5 ohms, go to next step.
11. Measure resistance between ground and Violet/Black wire at IAC motor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Violet/Black wire between IAC motor and PCM.
12. At this time, PCM is assumed to be defective. Replace PCM.
13. Turn ignition off. Ensure IAC motor is disconnected. Disconnect PCM connectors. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Brown/White wire between IAC motor harness connector and terminal No. 11 at PCM C1 connector. (Scheme 29) If resistance is 5 ohms or more, repair open in Brown/White wire. If resistance is less than 5 ohms, go to next step.
14. Measure resistance between ground and Brown/White wire at IAC motor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Brown/White wire between IAC motor and PCM.
15. At this time, PCM is assumed to be defective. Replace PCM.
16. Turn ignition off. Ensure IAC motor is disconnected. Disconnect PCM connectors. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Yellow/Black wire between IAC motor harness connector and terminal No. 10 at PCM C1 connector. (Scheme 29) If resistance is 5 ohms or more, repair open in Yellow/Black wire. If resistance is less than 5 ohms, go to next step.
17. Measure resistance between ground and Yellow/Black wire at IAC motor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Yellow/Black wire between IAC motor and PCM.
18. At this time, PCM is assumed to be defective. Replace PCM.
19. Turn ignition off. Ensure IAC motor is disconnected. Disconnect PCM connectors. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Gray/Red wire (4.0L) or Gray/Black wire (4.7L) between IAC motor harness connector and terminal No. 19 at PCM C1 connector. (Scheme 29) If resistance is 5 ohms or more, repair open in Gray/Red wire or Gray/Black wire. If resistance is less than 5 ohms, go to next step.
20. Measure resistance between ground and Gray/Red wire (4.0L) or Gray/Black wire (4.7L) at IAC motor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Gray/Red wire or Gray/Black wire between IAC motor and PCM.
21. At this time, PCM is assumed to be defective. Replace PCM.
22. Start engine and allow it to idle. Using scan tool, go to SYSTEM TESTS and select IAC WIGGLE TEST. While monitoring IAC motor operation, wiggle wiring harness from IAC motor to PCM. PCM is located on firewall in right rear corner of engine compartment. If IAC motor stops operating at any time while wiggling wiring harness, repair wiring harness where wiggling caused IAC motor to stop operating. If IAC motor does not stop operating at any time while wiggling wiring harness, go to next step.
23. Visually inspect related connectors and wiring harness for damage. Repair wiring as necessary. If wiring is okay, no problem is indicated at this time. Test is complete.

DTC P0522: OIL PRESSURE SENSOR VOLTS LOW

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Oil pressure sensor voltage is monitored immediately after ignition is turned on and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses voltage on oil pressure sensor signal circuit is less than 0.1 volt. Possible causes for DTC to set are: defective oil pressure sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read oil pressure sensor voltage. If voltage is 0.1 volt or less, go to step 3 . If voltage is more than 0.1 volt, go to next step.
2. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. Check for any related technical service bulletins that may apply. Start engine. Using scan tool, monitor oil pressure sensor voltage while wiggling oil pressure sensor wiring harness and connector. On 4.0L, oil pressure sensor is located at right rear of engine, above starter motor. On 4.7L, oil pressure sensor is mounted on right side of engine in oil filter housing. On all models, if oil pressure sensor voltage changes while wiggling wiring harness, repair wiring harness or connector where wiggling caused voltage to change. If voltage does not change, no problem is indicated at this time. Test is complete.
3. Turn ignition off. Disconnect oil pressure sensor connector. On 4.0L, oil pressure sensor is located at right rear of engine, above starter motor. On 4.7L, oil pressure sensor is mounted on right side of engine in oil filter housing. On all models, inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. Measure voltage between ground and Violet/Black wire at oil pressure sensor harness connector. If voltage is more than 4.9 volts, go to next step. If voltage is 4.9 volts or less, repair open in Violet/Black wire between oil pressure sensor and PCM.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Gray/Yellow wire at oil pressure sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Gray/Yellow wire between oil pressure sensor and PCM.
5. Measure resistance between Gray/Yellow and Black/Light Blue wires at oil pressure sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Gray/Yellow and Black/Light Blue wires are shorted together. Repair wiring as necessary.
6. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. Using scan tool, read oil pressure sensor voltage. If voltage is more than 4.5 volts, replace oil pressure sensor. If voltage is 4.5 volts or less, replace PCM.

DTC P0523: OIL PRESSURE SENSOR VOLTS HIGH

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Oil pressure sensor voltage is monitored with ignition on. DTC will set in Powertrain Control Module (PCM) memory when PCM senses voltage on oil pressure sensor signal circuit more than 4.8 volts. Possible causes for DTC to set are: defective oil pressure sensor, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read oil pressure sensor voltage. If voltage is 4.8 volts or less, go to step 6. If voltage is more than 4.8 volts, go to next step.
2. Turn ignition off. Disconnect oil pressure sensor connector. On 4.0L, oil pressure sensor is located at right rear of engine, above starter motor. On 4.7L, oil pressure sensor is mounted on right side of engine in oil filter housing. On all models, disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Black/Light Blue wire between oil pressure sensor harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
3. Measure resistance of Gray/Yellow wire between oil pressure sensor harness connector and terminal No. 23 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Gray/Yellow wire.
4. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. Measure voltage between ground and Gray/Yellow wire at oil pressure sensor harness connector. If voltage is 5 volts or less, go to next step. If voltage is more than 5 volts, repair short to voltage in Gray/Yellow wire between oil pressure sensor and PCM.
5. Turn ignition off. Connect a jumper wire between Gray/Yellow and Black/Light Blue wires at oil pressure sensor harness connector. Turn ignition on. Using scan tool, read oil pressure sensor voltage. If voltage is one volt or more, replace PCM. If voltage is less than one volt, replace oil pressure sensor.
6. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. Check for any related technical service bulletins that may apply. Start engine. Using scan tool, monitor oil pressure sensor voltage while wiggling oil pressure sensor wiring harness and connector. On 4.0L, oil pressure sensor is located at right rear of engine, above starter motor. On 4.7L, oil pressure sensor is mounted on right side of engine in oil filter housing. On all models, if oil pressure sensor voltage changes while wiggling wiring harness, repair wiring harness or connector where wiggling caused voltage to change. If voltage does not change, no problem is indicated at this time. Test is complete.

DTC P0601: INTERNAL CONTROLLER FAILURE

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Internal controller operation is monitored with ignition on. DTC will set in Powertrain Control Module (PCM) memory when PCM senses internal checksum for software failed and does not match calculated value. Possible cause for DTC to set is: defective PCM.

Turn ignition on, with engine off. Using scan tool, read DTCs. If DTC P0601: INTERNAL CONTROLLER FAILURE is present, replace PCM. If DTC P0601: INTERNAL CONTROLLER FAILURE is not present, no problem is indicated at this time. Test is complete.

DTC P0645: A/C CLUTCH RELAY CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

A/C clutch relay voltage is monitored when ignition switch is in RUN position, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) when PCM senses an open or short in A/C clutch relay control circuit. Possible causes for DTC to set are: defective A/C clutch relay, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, actuate A/C clutch relay. A/C clutch relay is located in Power Distribution Center (PDC). PDC is located in engine compartment, next to battery. (Scheme 28) If A/C clutch relay clicks, go to next step. If A/C clutch relay does not click, go to step 4.
2. Ensure ignition is on, with engine off. Wiggle wiring harness from A/C clutch relay to PCM while actuating A/C clutch relay. PCM is located on firewall in right rear corner of engine compartment. If A/C clutch relay stops clicking at any time while wiggling wiring harness, repair wiring harness where wiggling caused A/C clutch relay to stop clicking. If A/C clutch relay does not stop clicking at any time while wiggling wiring harness, go to next step.
3. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, no problem is indicated at this time. Test is complete.
4. Turn ignition off. Remove A/C clutch relay. A/C clutch relay is located in Power Distribution Center (PDC). PDC is located in engine compartment, next to battery. (Scheme 28) Measure voltage between ground and terminal No. 85 (Orange wire) at A/C clutch relay socket in PDC. (Scheme 28) If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in fused ignition switch output circuit (Orange wire) to A/C clutch relay. See WIRING DIAGRAMS article.
5. Measure resistance between terminals No. 85 and 86 at A/C clutch relay. (Scheme 33) If resistance is 50-90 ohms, go to next step. If resistance is no 50-90 ohms, replace A/C clutch relay.
6. Ensure ignition is off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/Orange wire between terminal No. 86 at A/C clutch relay socket in PDC and terminal No. 1 at PCM C3 harness connector. (Scheme 28)and (Scheme 29). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Orange wire.
7. Measure resistance between ground and Dark Blue/Orange wire at terminal No. 1 at PCM C3 connector. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Orange wire. If resistance is 5 ohms or more, go to next step.
8. At this time, PCM is assumed to be defective. Replace PCM.

DTC P0700: TCM CONTROLLER DTC PRESENT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components.

Transmission Control Module (TCM) is monitored for DTCs when ignition is on and engine is running. DTC will set in Powertrain Control Module (PCM) memory if any DTC is set in the TCM memory. Possible cause for DTC to set is: TCM DTC is present in PCM.

Turn ignition on. Using scan tool, read DTCs. If DTC P0700: TCM CONTROLLER DTC PRESENT is set, this DTC indicates a transmission DTC has previously been set. A DTC may not currently be present in TCM if a transmission repair was performed. If after reading transmission DTCs there are no DTCs in TCM, this DTC may be erased from PCM. If a TCM DTC is present, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS. If no TCM DTCs are present, test is complete.

DTC P1195: SLOW 1/1 O2S DURING CATALYST MONITOR

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

1/1 Heated Oxygen Sensor (HO2S) catalyst monitor is monitored with engine running, coolant temperature more than 170°F (77°C), open throttle, vehicle speed steadily increased to more than 18 MPH but less than 55 MPH, and light engine load exists for at least 5 minutes. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 1/1 HO2S is switching from less than 0.39 volt to more than 0.6 volt fewer times than required. Possible causes for DTC to set are: oil or coolant consumption, defective 1/1 HO2S, or defective connectors or wiring.

Note. 1/1 HO2S may also be referred to as an upstream oxygen sensor. On 4.0L, 1/1 HO2S is located in front exhaust manifold. On 4.7L, 1/1 HO2S is located in left (driver's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1195 and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P1195 is not displayed or displayed count is not "0", go to step 14.
2. Ensure ignition is on. Using scan tool in SENSOR mode, monitor 1/1 HO2S voltage until voltage stabilizes. Using scan tool, actuate HO2S HEATER TEST and monitor 1/1 HO2S voltage for 3 minutes. If voltage changes to less than 1.5 volts, go to next step. If voltage does not change to less than 1.5 volts, go to step 7.
3. Start engine and allow it to idle. Check exhaust system for leaks between engine and catalytic converter. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
4. Ensure engine is still idling. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace 1/1 HO2S. If engine mechanical condition is okay, go to next step.
5. Turn ignition off. Using a voltmeter, backprobe Black/Light Blue wire between 1/1 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) PCM is located on firewall in right rear corner of engine compartment. Start engine and ensure engine is at normal operating temperature. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 1/1 HO2S ground circuit (Black/Light Blue wire) between 1/1 HO2S and PCM.
6. Turn ignition off. Using a voltmeter, backprobe Light Green/Red wire between 1/1 HO2S harness connector and terminal No. 24 at PCM C1 harness connector. (Scheme 29) Start engine and ensure engine is at normal operating temperature. If voltage is less than 0.1 volt, go to step 13. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 1/1 HO2S signal circuit (Light Green/Red wire) between 1/1 HO2S and PCM.
7. Turn ignition off. Disconnect 1/1 HO2S connector. Turn ignition on. Using scan tool, actuate O2 HEATER TEST. Measure voltage between ground and Orange/Dark Green wire at 1/1 HO2S harness connector. If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open in power circuit (Orange/Dark Green wire) to 1/1 HO2S heater. See WIRING DIAGRAMS.
8. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Gray/White wire between 1/1 HO2S harness connector and terminal No. 8 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Gray/White wire.
9. Ensure ignition is off. Reconnect PCM connectors. Using a voltmeter, backprobe Light Green/Red wire between 1/1 HO2S harness connector and terminal No. 24 at PCM C1 harness connector. (Scheme 29) Start engine and ensure engine is at normal operating temperature. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 1/1 HO2S signal circuit (Light Green/Red wire) between 1/1 HO2S and PCM.
10. Turn ignition off. Using a voltmeter, backprobe Black/Light Blue wire between 1/1 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) Start engine and ensure engine is at normal operating temperature. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 1/1 HO2S ground circuit (Black/Light Blue wire) between 1/1 HO2S and PCM.
11. Ensure engine is still idling. Check exhaust system for leaks between engine and catalytic converter. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
12. Ensure engine is still idling. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace 1/1 HO2S. If engine mechanical condition is okay, go to next step.
13. At this time, 1/1 HO2S is assumed to be defective. Replace 1/1 HO2S.
14. Start engine and allow it to idle. Check exhaust system for leaks between engine and catalytic converter. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
15. Ensure engine is still idling. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace 1/1 HO2S. If engine mechanical condition is okay, go to next step.
16. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine. Wiggle related connectors and wiring harness while monitoring scan tool display. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.

DTC P1196: SLOW 2/1 O2S DURING CATALYST MONITOR

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

2/1 Heated Oxygen Sensor (HO2S) catalyst monitor is monitored with engine running, coolant temperature more than 170°F (77°C), open throttle, vehicle speed steadily increased to more than 18 MPH but less than 55 MPH, and light engine load exists for at least 5 minutes. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 2/1 HO2S is switching from less than 0.39 volt to more than 0.6 volt fewer times than required. Possible causes for DTC to set are: oil or coolant consumption, defective 2/1 HO2S, or defective connectors or wiring.

Note. 2/1 HO2S may also be referred to as a upstream oxygen sensor. On 4.0L, 2/1 HO2S is located on rear exhaust manifold. On 4.7L, 2/1 HO2S is located in right (passenger's side) exhaust downpipe in front of catalytic converter.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1196 and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P1196 is not displayed or displayed count is not "0", go to step 14.
2. Ensure ignition is on. Using scan tool in SENSOR mode, monitor 2/1 HO2S voltage until voltage stabilizes. Using scan tool, actuate HO2S HEATER TEST and monitor 2/1 HO2S voltage for 3 minutes. If voltage changes to less than 1.5 volts, go to next step. If voltage does not change to less than 1.5 volts, go to step 7.
3. Start engine and allow it to idle. Check exhaust system for leaks between engine and catalytic converter. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
4. Ensure engine is idling. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace 2/1 HO2S. If engine mechanical condition is okay, go to next step.
5. Turn ignition off. Using a voltmeter, backprobe Black/Light Blue wire between 2/1 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) Start engine and ensure engine is at normal operating temperature. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 2/1 HO2S ground circuit (Black/Light Blue wire) between 2/1 HO2S and PCM.
6. Turn ignition off. Using a voltmeter, backprobe Tan/White wire between 2/1 HO2S harness connector and terminal No. 26 at PCM C1 harness connector. (Scheme 29) Start engine and ensure engine is at normal operating temperature. If voltage is less than 0.1 volt, go to step 13. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 2/1 HO2S signal circuit (Tan/White wire) between 2/1 HO2S and PCM.
7. Turn ignition off. Disconnect 2/1 HO2S connector. Turn ignition on. Using scan tool, actuate O2 HEATER TEST. Measure voltage between ground and Orange/Dark Green wire at 2/1 HO2S harness connector. If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, open in power circuit (Orange/Dark Green wire) to 1/1 HO2S heater. See WIRING DIAGRAMS.
8. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/White wire between 2/1 HO2S harness connector and terminal No. 16 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/White wire.
9. Ensure ignition is off. Reconnect PCM connectors. Using a voltmeter, backprobe Tan/White wire between 2/1 HO2S harness connector and terminal No. 26 at PCM C1 harness connector. (Scheme 29) Start engine and ensure engine is at normal operating temperature. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 2/1 HO2S signal circuit (Tan/White wire) between 2/1 HO2S and PCM.
10. Turn ignition off. Using a voltmeter, backprobe Black/Light Blue wire between 2/1 HO2S harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) Start engine and ensure engine is at normal operating temperature. If voltage is less than 0.1 volt, go to next step. If voltage is 0.1 volt or more, repair poor connection causing high resistance on 2/1 HO2S ground circuit (Black/Light Blue wire) between 2/1 HO2S and PCM.
11. Ensure engine is still idling. Check exhaust system for leaks between engine and catalytic converter. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
12. Ensure engine is still idling. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace 2/1 HO2S. If engine mechanical condition is okay, go to next step.
13. At this time, 2/1 HO2S is assumed to be defective. Replace 2/1 HO2S.
14. Start engine and allow it to idle. Check exhaust system for leaks between engine and catalytic converter. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
15. Ensure engine is still idling. Check exhaust system for excessive smoke caused by internal oil or coolant consumption. Repair engine mechanical condition as necessary and replace 2/1 HO2S. If engine mechanical condition is okay, go to next step.
16. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine. Wiggle related connectors and wiring harness while monitoring scan tool display. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.

Engine coolant temperature is monitored with engine running. DTC will set in Powertrain Control Module (PCM) memory when PCM senses engine coolant temperature does not reach 176°F (80°C) while driving for 20 minutes after start. Possible causes for DTC to set are: defective thermostat or cooling system problem.

Start engine and allow it to idle. Road test vehicle under normal operating conditions for 20 minutes. Using scan tool, read engine coolant temperature. If scan tool does not read at least 176°F (80°C), check thermostat and cooling system for probable causes. Repair cooling system as necessary. If scan tool reads at least 176°F (80°C), no problem is indicated at this time. Test is complete.

DTC P1282: FUEL PUMP RELAY CONTROL CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly. under VERIFICATION TESTS to ensure system is functioning properly.

Fuel pump relay voltage is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses an open or short condition in fuel pump relay control circuit. Possible causes for DTC to set are: defective fuel pump relay, defective PCM, or defective connectors or wiring

1. Turn ignition on. Using scan tool, actuate fuel pump relay. Fuel pump relay is located in Power Distribution Center (PDC). PDC is located in engine compartment, next to battery. (Scheme 28) If fuel pump relay clicks, go to next step. If fuel pump relay does not click, go to step 4.
2. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, go to next step.
3. Ensure ignition is on. Wiggle wiring harness from fuel pump relay to Powertrain Control Module (PCM) while actuating fuel pump relay. PCM is located on firewall in right rear corner of engine compartment. If fuel pump relay stops clicking at any time while wiggling wiring harness, repair wiring harness where wiggling caused fuel pump relay to stop clicking. If fuel pump relay does not stop clicking at any time while wiggling wiring harness, go to next step.
4. Turn ignition off. Remove fuel pump relay from PDC. Turn ignition on. Measure voltage between ground and terminal No. 85 (Orange/Dark Blue wire) at fuel pump relay socket in PDC. (Scheme 28) If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in fused ignition switch output circuit (Orange/Dark Blue wire) between fuel pump relay and junction block. Junction block is located under left side of instrument panel. (Scheme 26)
5. Using an ohmmeter, measure resistance between terminals No. 85 and 86 at fuel pump relay. (Scheme 33) If resistance is 50-90 ohms, go to next step. If resistance is not 50-90 ohms or more, replace fuel pump relay.
6. Ensure ignition is off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Brown wire between terminal No. 86 at fuel pump relay socket in PDC and terminal No. 19 at PCM C3 harness connector. (Scheme 28)and (Scheme 29). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Brown wire between fuel pump relay and PCM.
7. Measure resistance between ground and terminal No. 19 (Brown wire) at PCM C3 connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Brown wire between fuel pump relay and PCM.
8. At this time, PCM is assumed to be defective. Replace PCM.

DTC P1294: TARGET IDLE NOT REACHED

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Engine speed is monitored with engine idling, transmission in Drive, and no Manifold Absolute Pressure (MAP) or Throttle Position (TP) sensor DTCs present. DTC will set in Powertrain Control Module (PCM) memory when PCM senses engine speed at more than 200 RPM more or 100 RPM less than target idle speed for 14 seconds. Three separate failures are required to set a bad trip. Two bad trips are required to set DTC. Possible causes for DTC to set are: vacuum leak, defective throttle body, throttle plate or linkage improperly positioned, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1294 and displayed count is "0", go to step 3 . If GOOD TRIP counter for DTC P1294 is not displayed or displayed count is not "0", go to next step.
2. Check FREEZE FRAME data on scan tool to determine conditions when DTC was set. Attempt to duplicate conditions for added diagnosis. Recheck for DTCs. If DTC P1294: TARGET IDLE NOT REACHED reoccurs, go to next step. If DTC P1294: TARGET IDLE NOT REACHED does not reoccur, conditions to set DTC are not present at this time. Test is complete.
3. Turn ignition on, with engine off. Ensure throttle plate is fully closed against stop. Check throttle plate and linkage for binding. Repair throttle plate and linkage as necessary. If throttle plate and linkage are okay, go to next step.
4. Start engine and allow it to idle for 60 seconds. If vehicle is equipped with A/T, apply brakes and shift gear selector to Drive. Using scan tool, read TARGET IDLE and ENGINE RPM. If engine RPM is within 100 RPM of target idle, go to next step. If engine RPM is not within 100 RPM of target idle, go to step 8 .
5. Turn ignition off. Using scan tool, go to SYSTEM TESTS and select IAC WIGGLE TEST. If idle speed raises and lowers during wiggle test, go to next step. If idle speed does not raise and lower during wiggle test, perform «DTC P0505: IDLE AIR CONTROL MOTOR CIRCUITS»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee__dtc-p0505-idle-air-control-motor) test.
6. Start engine and allow it to idle. Using scan tool, go to SYSTEM TESTS and select IAC WIGGLE TEST. While wiggling wiring harness between IAC motor and PCM, monitor engine RPM. IAC motor is located on throttle body. PCM is located on firewall in right rear corner of engine compartment. If IAC motor stops operating at any time while wiggling wiring harness, repair wiring harness where wiggling caused IAC motor to stop operating. If IAC motor does not stop operating, no problem is indicated at this time. Test is complete.
7. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, no problem is indicated at this time. Test is complete. NOTE: The following step is invalid if engine has any vacuum leaks.
8. Start engine and allow it to idle. Check engine, brake booster and vacuum hoses for leaks. Ensure Closed Crankcase Ventilation (CCV) system (4.0L) or Positive Crankcase Ventilation (PCV) system (4.7L) is functioning properly. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. Repair vacuum leaks as necessary. If CCV system or PCV system is okay and no vacuum leaks exist, go to next step.
9. Start engine and allow it to idle for 60 seconds. Using scan tool, go to SYSTEM TESTS and select IAC WIGGLE TEST. If idle speed raises and lowers during wiggle test, go to next step. If idle speed does not raise and lower during wiggle test, perform «DTC P0505: IDLE AIR CONTROL MOTOR CIRCUITS»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee__dtc-p0505-idle-air-control-motor) test.
10. Turn ignition off. Remove throttle body. While holding throttle open, spray entire throttle body bore with appropriate cleaner. Using a soft scuff pad, clean throttle body bore and throttle plate. Using compressed air, dry throttle body. Install throttle body. Start engine and allow it to idle. Using scan tool, actuate MIN AIRFLOW. If engine speed is less than 550 RPM, replace throttle body. If engine speed is 550 RPM or more, no problem is indicated at this time. Test is complete.

DTC P1296: NO 5 VOLTS TO MAP SENSOR

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Manifold Absolute Pressure (MAP) sensor voltage is monitored when ignition is on and battery voltage is more than 10.4 volts. DTC will set in PCM memory when PCM senses MAP sensor voltage is less than 2.35 volts for 5 seconds with ignition on. Possible causes for either DTC to set are: defective MAP sensor, defective PCM, or defective connectors or wiring.

Note. If DTC P0107 is also present with DTC P1296, repair DTC P0107 before continuing with this test. See DTC P0107: MAP SENSOR VOLTAGE TOO LOW .

1. Turn ignition on. Using scan tool, read Manifold Absolute Pressure (MAP) sensor voltage. If voltage is less than 2.35 volts, go to next step. If voltage is 2.35 volts or more, go to step 6.
2. Turn ignition off. Disconnect MAP sensor connector. see scheme 13or see scheme 14. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector terminals are okay, turn ignition on. Measure voltage between ground and Orange wire at MAP sensor harness connector. If voltage is more than 4.5 volts, go to next step. If voltage is 4.5 volts or less, repair 5-volt supply circuit (Orange wire) between MAP sensor and PCM.
3. Using scan tool, read MAP sensor voltage. If voltage is 4.5 volts or less, go to next step. If voltage is more than 4.5 volts, replace MAP sensor.
4. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Orange wire at MAP sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in 5-volt supply circuit (Orange wire).
5. At this time, PCM is assumed to be defective. Replace PCM.
6. Start engine and allow it to idle. Wiggle connectors and wiring harness from MAP sensor to PCM while monitoring MAP sensor voltage. see scheme 13or see scheme 14. If voltage changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused voltage to change. If voltage does not change, no problem is indicated at this time. Test is complete.

DTC P1297: NO CHANGE IN MAP FROM START TO RUN

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Manifold Absolute Pressure (MAP) sensor operation is monitored with engine speed at 400-1500 RPM and throttle closed. DTC will set in Powertrain Control Module (PCM) when PCM senses too small a difference between barometric pressure with ignition on, and manifold vacuum with engine running for 8.8 seconds. Possible causes for DTC to set are: defective MAP sensor, defective or restricted vacuum ports, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If DTC P0107: MAP SENSOR VOLTAGE TOO LOW is present, go to «DTC P0107: MAP SENSOR VOLTAGE TOO LOW»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee__dtc-p0107-map-sensor-voltage-too). If DTC P0107: MAP SENSOR VOLTAGE TOO LOW is not present, go to next step.
2. Ensure ignition is on. Using scan tool, erase DTCs. Start engine and allow it to idle for 30 seconds. Using scan tool, read DTCs. If DTC P1297: NO CHANGE IN MAP FROM START TO RUN is present, go to next step. If DTC P1297: NO CHANGE IN MAP FROM START TO RUN is not present, go to step 6.
3. Turn ignition off. Disconnect MAP sensor connector. (Scheme 30)or (Scheme 31). Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Orange wire between MAP sensor connector and terminal No. 17 at PCM C1 connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire.
4. Turn ignition off. Remove MAP sensor and inspect sensor vacuum port for restrictions. Repair any restrictions as necessary. If no restrictions exist, go to next step.
5. At this time, MAP sensor is assumed to be defective. Replace MAP sensor.
6. Start engine. Using scan tool, set engine speed to 1500 RPM and read MAP sensor voltage. Wiggle connectors and wiring harness from MAP sensor to PCM. (Scheme 30)or (Scheme 31). PCM is located on firewall in right rear corner of engine compartment. If engine stalls or voltage becomes erratic while wiggling wiring harness, repair connectors and wiring harness as necessary where wiggling caused engine to stall or voltage to become erratic. If engine does not stall and voltage does not become erratic, go to next step.
7. Start engine and allow it to idle. Using scan tool, set engine speed to 1500 RPM. Using scan tool, monitor engine vacuum while snapping throttle open and closed. If vacuum drops rapidly to less than one in. Hg, no problem is indicated at this time. Test is complete. If vacuum does not drop rapidly to less than one in. Hg, go to next step.
8. Turn ignition off. Remove MAP sensor and inspect sensor vacuum port for restrictions. Repair any restrictions as necessary. Inspect intake manifold or throttle body vacuum port and hose for restrictions. Repair any restrictions as necessary. If no restrictions exist, go to next step.
9. At this time, MAP sensor is assumed to be defective. Replace MAP sensor.

DTC P1299: VACUUM LEAK FOUND (IAC FULLY SEATED)

Note. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

DTC will set in Powertrain Control Module (PCM) memory if Manifold Absolute Pressure (MAP) sensor does not correlate with Throttle Position (TP) sensor. Possible causes for DTC to set are: vacuum leak, defective MAP sensor or defective TP sensor.

Note. A large vacuum leak is most likely cause for DTC to set.

1. Start engine and allow it to idle. Check engine, brake booster and vacuum hoses for leaks. Ensure Closed Crankcase Ventilation (CCV) system (4.0L) or Positive Crankcase Ventilation (PCV) system (4.7L) is functioning properly. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. Repair vacuum leaks as necessary. If CCV system or PCV system is okay and no vacuum leaks exist, go to next step.
2. Turn ignition on. Using scan tool, monitor TP sensor voltage while slowly depressing throttle pedal from idle position to wide open throttle position. If voltage changes smoothly from about 0.8 volt to more than 3.5 volts, go to next step. If voltage does not change smoothly from about 0.8 volt to more than 3.5 volts, replace TP sensor.
3. Ensure ignition is on. Ensure throttle plate is fully closed against stop. Using scan tool, read TP sensor voltage. If voltage is less than 0.92 volt, go to next step. If voltage is 0.92 volt or more, check throttle plate and linkage for binding. Repair throttle plate and linkage as necessary. If throttle plate and linkage are okay, replace TP sensor.
4. Turn ignition off. Connect a vacuum gauge to manifold vacuum source. Start engine and allow it to idle. If engine will not idle, maintain a constant RPM above idle. Using scan tool in SENSOR mode, monitor Manifold Absolute Pressure (MAP) vacuum value. Compare scan tool reading with vacuum gauge reading. If scan tool reading is within one in. Hg of vacuum gauge, no problem is indicated at this time. Test is complete. If scan tool reading is not within one in. Hg of vacuum gauge reading, replace MAP sensor.

DTC P1388: AUTO SHUTDOWN RELAY CONTROL CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Auto Shutdown (ASD) relay voltage is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses an open or short condition in ASD relay circuit. Possible causes for DTC to set are: defective ASD relay, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1388 and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P1388 is not displayed or displayed count is not "0", go to step 7.
2. Turn ignition off. Remove ASD relay. ASD relay is located in Power Distribution Center (PDC). PDC is located in engine compartment, next to battery. (Scheme 28) Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Measure resistance of Dark Blue/Yellow wire between terminal No. 86 at ASD relay socket in PDC and terminal No. 3 at PCM C3 harness connector. (Scheme 28)and (Scheme 29). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Yellow wire.
3. Turn ignition on. Measure voltage between ground and terminal No. 85 (Orange/Dark Blue wire) at ASD relay socket in PDC. (Scheme 28) If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, check for repair open in Orange/Dark Blue wire between ASD relay and junction block. Also check fuse No. 12 (10-amp) in fuse block. Junction block is located under left side of instrument panel. (Scheme 26) Repair wiring or replace fuse as necessary.
4. Turn ignition off. Ensure PCM is disconnected. Measure resistance between ground and terminal No. 3 (Dark Blue/Yellow wire) at PCM C3 harness connector. (Scheme 29) If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Yellow wire between ASD relay and PCM.
5. Measure resistance between terminals No. 85 and 86 at ASD relay. (Scheme 38) If resistance is not 50-80 ohms, replace ASD relay. If resistance is 50-80 ohms, go to next step.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine. Wiggle wiring harness from ASD relay to PCM while monitoring scan tool display. PCM is located on firewall in right rear corner of engine compartment. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.

Scheme 38

DTC P1389: NO ASD RELAY OUTPUT VOLTAGE AT PCM

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Auto Shutdown (ASD) relay voltage is monitored when engine is running, battery voltage is more than 10.4 volts, and engine speed is more than 400 RPM. DTC will set in Powertrain Control Module (PCM) memory when PCM does not sense voltage when ASD relay is energized. Possible causes for DTC to set are: defective ASD relay, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1389 and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P1389 is not displayed or displayed count is not "0", go to step 8.
2. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 5.
3. Turn ignition off. Remove ASD relay from Power Distribution Center (PDC). PDC is located in engine compartment, next to battery. (Scheme 28) Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between terminal No. 87 at ASD relay socket in PDC and terminal No. 12 (Dark Green/Light Green wire) at PCM C3 connector. (Scheme 28) and (Scheme 29). If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, check for open in Dark Green/White wire between PCM and PDC. Check for open in Dark Green/Orange wire between ASD relay and PDC. Also check fuse No. 26 (15-amp) in PDC. See WIRING DIAGRAMS article. Repair wiring or replace fuse as necessary.
4. At this time, PCM is assumed to be defective. Replace PCM.
5. Turn ignition off. Remove ASD relay from Power Distribution Center (PDC). PDC is located in engine compartment, next to battery. (Scheme 28) Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between terminal No. 87 at ASD relay socket in PDC and terminal No. 12 (Dark Green/Light Green wire) at PCM C3 connector. (Scheme 28)and (Scheme 29). If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, check for open in Dark Green/White wire between PCM and PDC. Check for open in Dark Green/Orange wire between ASD relay and PDC. Also check fuse No. 26 (15-amp) in PDC. See WIRING DIAGRAMS article. Repair wiring or replace fuse as necessary.
6. Measure voltage between ground and terminal No. 30 (Red/Dark Green wire) at ASD relay socket in PDC. (Scheme 28) If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open fused B+ output circuit (Red/Dark Green wire) between ASD relay and PDC.
7. Install a known-good ASD relay and attempt to start engine. If engine does not start, go to next step. If engine starts, replace original ASD relay.
8. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine and allow it to idle. Wiggle wiring harness from ASD relay to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If DTC P1389: NO ASD RELAY OUTPUT VOLTAGE AT PCM returns or engine stalls, repair wiring harness as necessary. If DTC P1389: NO ASD RELAY OUTPUT VOLTAGE AT PCM does not return and engine does not stall, no problem is indicated at this time. Test is complete. Check for any related technical service bulletins that may apply.

DTC P1391: INTERMITTENT LOSS OF CMP OR CKP

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Camshaft Position (CMP) sensor and Crankshaft Position (CKP) sensor signals are monitored with engine running or cranking. DTC will set in Powertrain Control Module (PCM) memory when PCM senses FAILURE counter reaches 20 failures for 2 consecutive trips. Possible causes for DTC to set are: Crankshaft Position (CKP) sensor improperly installed, defective CKP sensor, defective Camshaft Position (CMP) sensor, defective PCM, defective tone wheel/flexplate, or defective connectors or wiring.

Note. CMP or CKP sensor signal loss can be detected by an RPM change, DTC or by observing oscilloscope pattern. Refer to manufacturer's operation manual for instructions in use of oscilloscope and procedure for pattern analysis.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is not displayed for DTC P1391 or displayed count is not "0", go to step 14. If GOOD TRIP counter is displayed for DTC P1391 and displayed count is "0", go to next step (4.0L) or go to step 3 (4.7L).
2. Start engine and allow it to reach normal operating temperature (closed loop). Using scan tool, select MISCELLANEOUS, then SET SYNC. Observe scan tool for ACTUAL SYNC SETTING. If display indicates IN RANGE, go to next step. If display does not indicate IN RANGE, locate CMP sensor. CMP sensor is mounted on top of oil pump drive shaft assembly and is located on right side of engine, near oil filter. Loosen oil pump drive hold-down clamp bolt and rotate oil pump drive until reading is as close to zero degrees as possible, and IN RANGE message is displayed. Tighten hold-down clamp bolt to 17 ft. lbs. (23 N.m).
3. Turn ignition off. Ensure CMP sensor connector is connected. On 4.0L, CMP sensor is mounted on top of oil pump drive shaft assembly and is located on right side of engine, near oil filter. On 4.7L, CMP sensor is mounted on right front corner of right cylinder head. On all models, using oscilloscope's voltage lead, backprobe Tan/Yellow wire at CMP sensor harness connector. Start engine and observe oscilloscope pattern. If CMP sensor signal pattern is not consistent, go to next step. If CMP sensor signal pattern is consistent, go to step 7.
4. Turn engine off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. Ensure CMP sensor and/or CKP sensor mounting bolts are tight. Check for any technical service bulletins that may apply and repair as necessary. If no problems are found, go to next step.
5. Ensure ignition is off. Remove CMP sensor. Inspect tone wheel/pulse ring for damage or looseness. Repair or replace tone wheel/pulse ring as necessary. If tone wheel/pulse ring is okay, go to next step.
6. At this time, CMP sensor is assumed to be defective. Replace CMP sensor.
7. Turn ignition off. Ensure CKP sensor connector is still connected. On 4.0L, CKP sensor is mounted to left side of transmission bellhousing. CKP sensor connector is located on top of intake manifold, near firewall. On 4.7L, CKP sensor is bolted to side of engine cylinder block, above starter motor. (Scheme 35) On all models, using oscilloscope's voltage lead, backprobe Gray/Black wire at CKP sensor harness connector. Start engine and observe oscilloscope pattern. If CKP sensor signal pattern is not consistent, go to next step. If CKP sensor signal pattern is consistent, go to step 11.
8. Turn engine off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. Ensure CKP sensor mounting bolts are tight. Check for any technical service bulletins that may apply and repair as necessary. If no problems are found, go to next step.
9. Remove CKP sensor. Inspect tone wheel/flexplate for damage. Check slotted areas on tone wheel/flexplate for damage or any foreign debris. Ensure tone wheel/flexplate turns when engine is cranked. Repair or replace tone wheel/flexplate as necessary. If slotted areas on flywheel/drive plate are okay and no debris exists, go to next step.
10. At this time, CKP sensor is assumed to be defective. Replace CKP sensor.
11. Turn engine off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. Ensure CMP sensor and/or CKP sensor mounting bolts are tight. Check for any technical service bulletins that may apply and repair as necessary. If no problems are found, go to next step.
12. Turn ignition off. Using oscilloscope's voltage lead, backprobe terminal No. 8 (Gray/Black wire) at PCM C1 connector. (Scheme 29) PCM is located in right rear corner of engine compartment. Start engine. While monitoring oscilloscope pattern, wiggle wiring harness from CKP sensor to PCM. If CKP sensor signal pattern remains consistent while wiggling wiring harness, go to next step. If CKP sensor signal pattern does not remain consistent while wiggling wiring harness, repair wiring harness where wiggling caused CKP sensor signal pattern to become inconsistent.
13. Turn ignition off. Ensure CMP sensor connector is still connected. Using oscilloscope's voltage lead, backprobe terminal No. 18 (Tan/Yellow wire) at PCM C1 connector. Start engine. While monitoring oscilloscope pattern, wiggle CMP sensor signal circuit from CMP sensor to PCM. If CMP sensor signal pattern is consistent, go to next step. If CMP sensor signal pattern is not consistent, repair wiring harness where wiggling caused oscilloscope pattern to become inconsistent.
14. Turn ignition off. Using oscilloscope's voltage lead, backprobe terminal No. 18 (Tan/Yellow wire) at PCM C1 connector. (Scheme 29) PCM is located in right rear corner of engine compartment. Start engine. While monitoring oscilloscope pattern, wiggle CMP sensor signal circuit from CMP sensor to PCM. If CMP sensor signal pattern is consistent, go to next step. If CMP sensor signal pattern is not consistent, repair wiring harness where wiggling caused oscilloscope pattern to become inconsistent. If wiring harness is okay, replace CMP sensor.
15. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Check for any technical service bulletins that may apply and repair as necessary. If no problems are found, go to next step.
16. Using oscilloscope's voltage lead, backprobe terminal No. 8 (Gray/Black wire) at PCM C1 connector. Start engine. While monitoring oscilloscope pattern, wiggle wiring harness from CKP sensor to PCM. If CKP sensor signal pattern remains consistent while wiggling wiring harness, no problem is indicated at this time. Test is complete. If CKP sensor signal pattern does not remain consistent while wiggling wiring harness, repair wiring harness where wiggling caused CKP sensor signal pattern to become inconsistent. If wiring harness is okay, replace CKP sensor.

DTC P1398: MISFIRE ADAPTIVE NUMERATOR AT LIMIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Misfire adaptive numerator is monitored under closed throttle deceleration, with A/C off, engine coolant temperature more than 75°F (24°C) and more than 50 seconds after engine start. DTC will set in Powertrain Control Module (PCM) memory when PCM senses one of Crankshaft Position (CKP) sensor target windows has more than 2.86 percent variance from CKP sensor reference window. Possible causes for DTC to set are: improperly installed CKP sensor, defective CKP sensor, defective flywheel/flexplate, or defective connectors or wiring.

1. Turn ignition on. Using scan tool in MISCELLANEOUS menu, select CLEAR PCM (battery disconnect) to reset PCM. Using scan tool, select MISFIRE PRETEST screen. Road test vehicle to allow relearn of adaptive numerator. Adaptive numerator is learned when ADAPTIVE NUMERATOR DONE LEARNING line on MISFIRE PRETEST screen changes to YES. If adaptive numerator relearned, go to next step. If adaptive numerator did not relearn, go to step 3 .
2. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
3. Turn ignition off. Disconnect CKP sensor connector. On 4.0L, CKP sensor is mounted to left side of transmission bellhousing. CKP sensor connector is located on top of intake manifold, near firewall. On 4.7L, CKP sensor is bolted to side of engine cylinder block, above starter motor. On all models, visually inspect CKP sensor wiring harness for damage. Repair wiring harness as necessary. If wiring harness is okay, visually inspect CKP sensor connector for corroded, damaged, pushed-out or miswired terminals. Repair connector as necessary. If connector is okay, ensure CKP sensor is installed properly and mounting bolts/nuts are tight. Tighten mounting bolts/nuts as necessary. See TORQUE SPECIFICATIONS in REMOVAL, OVERHAUL & INSTALLATION article. If mounting bolts/nuts are tight, go to next step.
4. Turn ignition off. Remove CKP sensor. Inspect tone wheel/flexplate for damage. Check slotted areas on tone wheel/flexplate for damage or any foreign debris. Ensure tone wheel/flexplate turns when engine is cranked. Repair or replace tone wheel/flexplate as necessary. If slotted areas on flywheel/drive plate are okay and no debris exists, go to next step.
5. At this time, CKP sensor is assumed to be defective. Replace CKP sensor.

DTC P1486: EVAP LEAK MONITOR PINCHED HOSE FOUND

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-6 under VERIFICATION TESTS to ensure system is functioning properly.

EVAP leak monitor is monitored after cold start with ambient temperature of 40-90°F (4-32°C) and coolant temperature within 10°F (-12°C) of ambient temperature. If PCM detects a pinched hose, DTC will not set until EVAP monitor performs system test. If system test fails, DTC will set. DTC will set in Powertrain Control Module (PCM) memory when EVAP monitor senses no airflow through EVAP system. Possible causes for DTC to set are: blocked fuel tank-to-EVAP canister hose, blocked Leak Detection Pump (LDP) hose, pinched EVAP purge solenoid-to-EVAP canister hose, blocked LDP or blocked EVAP canister.

Note. Replacing PCM will not correct this problem.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1486 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P1486 or displayed count is not "0", go to step 7.
2. To test EVAP system properly, fuel tank should have 20-80 percent of fuel capacity. Miller Evaporative System Testing Kit (6872A) and Gas Cap Adapter (8382) are used to perform evaporative system pressure test. Connect scan tool to Data Link Connector (DLC). Connect EVAP system testing kit positive lead to positive battery terminal and negative lead to negative battery terminal. Using EVAP system testing kit, and instructions printed on EVAP system testing kit cover, perform EVAP system pressure pump self-test. Remove gas cap and install gas cap adapter to fuel tank. Install gas cap to gas cap adapter. Connect pressure supply hose from evaporative system testing kit to fitting on gas cap adapter. Disconnect vacuum supply hose at Leak Detection Pump (LDP). LDP is located on left front corner of engine compartment, under air filter housing. (Scheme 39) Apply a continuous vacuum supply of about 20 in. Hg to vacuum supply nipple on LDP. An A/C recovery unit works well for supplying a continuous vacuum supply. Turn ignition on. Using scan tool, select ENGINE SYSTEM TESTS, then LEAK DETECTION PUMP TEST. Read instructions on scan tool and then press ENTER. Select #3 HOLD PSI. Set EVAP system testing kit PRESSURE/HOLD valve to OPEN and set VENT valve to CLOSED. While monitoring EVAP system testing kit pressure gauge, turn EVAP system testing kit pump timer on. When gauge reaches 14 in. H2O, set PRESSURE/HOLD valve to CLOSED. Turn pump timer off. Disconnect fuel tank-to-EVAP canister purge hose (at EVAP canister) while monitoring gauge on evaporative system testing kit. EVAP canister is located in engine compartment, left of brake booster. (Scheme 36) If pressure decreases when purge hose is disconnected, go to next step. If pressure does not decrease when purge hose is disconnected, repair obstruction in EVAP system between EVAP canister and fuel tank.
3. Reconnect purge hose to EVAP canister. With engine still running and pump timer turned on, allow evaporative system to repressurize. Ensure PRESSURE/HOLD valve on evaporative system testing kit is set to OPEN and VENT valve is set to CLOSED. When gauge reaches 14 in. H2O, set PRESSURE/HOLD valve to CLOSED. Turn pump timer off. Disconnect LDP pressure hose (at EVAP canister) that connects EVAP canister to LDP while monitoring gauge on evaporative system testing kit. If pressure decreases when hose is disconnected, go to next step. If pressure does not decrease when hose is disconnected, replace EVAP canister.
4. Reconnect LDP pressure hose. With engine still running and pump timer turned on, allow evaporative system testing kit to repressurize. Ensure PRESSURE/HOLD valve on evaporative system testing kit is set to OPEN and VENT valve is set to CLOSED. When gauge reaches 14 in. H2O, set PRESSURE/HOLD valve to CLOSED. Turn pump timer off. Disconnect EVAP purge solenoid hoses while monitoring gauge on evaporative system testing kit. EVAP purge solenoid is located in engine compartment, left of brake booster. (Scheme 36) If pressure does not decrease when hoses are disconnected from EVAP canister, repair or replace hose/tubes to EVAP purge solenoid as necessary. If pressure decreases when vacuum hoses are disconnected from EVAP canister, go to next step.
5. Inspect pressure hose between EVAP canister and LDP. If pressure hose is okay and is not restricted, go to next step. If pressure hose is defective or restricted, replace pressure hose.
6. At this time, LDP is assumed to be defective. Replace LDP.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, review FREEZE FRAME data. Attempt to duplicate condition that caused DTC to set. Thoroughly perform a visual inspection of EVAP system hoses, tubes and connections. Look for any physical damage or signs of wetness at connections. Visually inspect related connectors and wiring harness for damage. Check for any related technical service bulletins that may apply. Turn ignition on. Using scan tool in SYSTEM TESTS, perform LDP monitor test. This will force the PCM to run LDP monitor. If monitor fails, further diagnosis is required to find faulty component. Go to step 2. If monitor passes, no problem is indicated at this time. Test is complete.

Scheme 39

DTC P1491: RADIATOR FAN CONTROL RELAY CIRCUIT (4.0L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Radiator fan relay voltage is monitored when ignition is on, battery voltage is more than 10 volts. DTC will set in PCM memory if PCM detects an open or shorted condition in radiator fan control relay circuit. Possible causes for DTC to set are: defective radiator fan relay, defective radiator fan, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, actuate radiator fan relay. Check radiator fan operation. If radiator fan cycles on and off, go to next step. If radiator fan does not cycle on and off, go to step 4.
2. Ensure ignition is still on and radiator fan control relay is still actuated. Wiggle wiring harness and connectors from radiator fan control relay to PCM while noting operation of radiator fan. Radiator fan relay is located behind right bumper fascia, below right headlight assembly. PCM is located on firewall in right rear corner of engine compartment. If radiator fan operation was not interrupted while wiggling wiring harness and connectors, go to next step. If radiator fan operation was interrupted while wiggling wiring harness and connectors, repair wiring harness as necessary where wiggling caused radiator fan operation to be interrupted.
3. Turn ignition off. Inspect wiring and connectors between radiator fan relay and PCM. If no problems exist, test is complete. If any problems exist, repair wiring or connectors as necessary.
4. Turn ignition off. Disconnect radiator fan relay connector. Radiator fan relay is located behind right bumper fascia, below right headlight assembly. Measure resistance and Black wire at radiator fan relay connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire between ground and radiator fan relay.
5. Ensure ignition is off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/Pink wire between radiator fan relay harness connector and terminal No. 17 at PCM C2 connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Pink wire.
6. Measure resistance between ground and terminal No. 17 (Dark Blue/Pink wire) at PCM C2 harness connector. (Scheme 29) If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Pink wire.
7. Reconnect radiator fan relay connector. Connect one end of a jumper wire to terminal No. 17 (Dark Blue/Pink wire) at PCM C2 harness connector. Briefly tap other end of jumper wire to ground and observe radiator fan operation. If radiator fan turns on, go to next step. If radiator fan does not turn on, replace radiator fan relay.
8. At this time, PCM is assumed to be defective. Replace PCM.

DTC P1492: AMBIENT/BAT TEMPERATURE SENSOR VOLTAGE TOO HIGH

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-3 under VERIFICATION TESTS to ensure system is functioning properly.

Ambient/battery temperature sensor is also referred to as Battery Temperature Sensor (BTS). BTS voltage is monitored with ignition on. DTC P1492 will set in Powertrain Control Module (PCM) memory when PCM senses voltage from BTS is more than 4.9 volts for 3 seconds. Possible causes for DTC to set are: defective BTS, defective PCM, defective connectors or defective wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1492 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P1492 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect BTS connector. BTS is located in bottom of battery tray and has a Black 2-pin connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Black/Light Blue wire between BTS harness connector and terminal No. 4 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
3. Measure resistance of Violet/Light Green wire between BTS harness connector and terminal No. 15 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Violet/Light Green wire.
4. Reconnect PCM connectors. Start engine and allow it to idle. Measure voltage between ground and Violet/Light Green wire at BTS harness connector. If voltage is 5.5 volts or less, go to next step. If voltage is more than 5.5 volts, repair short to voltage in Violet/Light Green wire.
5. Turn ignition off. Using scan tool, read AMBIENT/BAT TMP VLT value. Note voltage reading. Connect a jumper wire between BTS harness connector terminals and note voltage reading. Voltage should change from more than 4.5 volts to less than one volt. If voltage is not as specified, go to next step. If voltage is as specified, replace BTS.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine. Wiggle BTS connector and wiring harness while monitoring scan tool display. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.

DTC P1493: AMBIENT/BAT TEMPERATURE SENSOR VOLTAGE TOO LOW

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-3 under VERIFICATION TESTS to ensure system is functioning properly.

Ambient/battery temperature sensor is also referred to as Battery Temperature Sensor (BTS). BTS voltage is monitored with ignition on. DTC P1493 will set in PCM memory when PCM senses voltage BTS is less than 0.5 volt for 3 seconds. Possible causes for either DTC to set are: defective BTS, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1493 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P1493 or displayed count is not "0", go to step 6 .
2. Turn ignition off. Using scan tool, read AMBIENT/BAT TMP VLT value. Note voltage reading. Disconnect BTS connector and note voltage reading. Voltage should change from less than one volt to more than 4.5 volts. If voltage is not as specified, go to next step. If voltage is as specified, replace BTS.
3. Disconnect BTS connector. BTS is located in bottom of battery tray and has a Black 2-pin connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Violet/Light Green wire at BTS harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair short to ground in Violet/Light Green wire.
4. Measure resistance between Violet/Light Green and Black/Light Blue wires at BTS harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Violet/Light Green and Black/Light Blue wires are shorted together. Repair wiring as necessary.
5. At this time, PCM is assumed to be defective. Replace PCM.
6. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine. Wiggle BTS connector and wiring harness while monitoring scan tool display. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.

DTC P1494: LEAK DETECTION PUMP SW OR MECHANICAL FAULT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-6 under VERIFICATION TESTS to ensure system is functioning properly.

Leak Detection Pump (LDP) switch operation is monitored immediately after a cold start, with ambient temperature 40-90°F (4-32°C) and engine coolant temperature within 10°F (-12°C) of ambient temperature. DTC will set in Powertrain Control Module (PCM) memory when PCM senses a change in switch state is not sensed when LDP solenoid is energized following an engine start. Possible causes for DTC to set are: defective LDP, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1494 and displayed count is "0", go next step. If GOOD TRIP counter is not displayed for DTC P1494 or displayed count is not "0", go to step 7.
2. Turn ignition off. Disconnect engine vacuum supply hose at LDP. LDP is located on left front corner of engine compartment, under air filter housing. (Scheme 39) Install a vacuum gauge to disconnected vacuum hose. Start engine and observe vacuum gauge. If vacuum gauge reads 13 in. Hg or more, go to next step. If vacuum gauge reads less than 13 in. Hg, repair vacuum leak or vacuum obstruction as necessary.
3. Turn ignition off. Disconnect LDP connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Orange/Pink wire between LDP harness connector and terminal No. 14 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange/Pink wire.
4. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. With scan tool in INPUTS/OUTPUTS, read LEAK DETECT SW state. While observing scan tool, connect a jumper wire between positive battery terminal and Orange/Pink wire at LDP harness connector. If LEAK DETECT SW state does not change, go to next step. If LEAK DETECT SW state changes, replace LDP.
5. Turn ignition off. Disconnect PCM connectors. Measure resistance between ground and terminal No. 14 (Orange/Pink wire) at PCM C3 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Orange/Pink wire between LDP and PCM.
6. At this time PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Using scan tool, perform LEAK DETECTION PUMP (LDP) TEST. Using scan tool, monitor LDP switch state while wiggling wiring harness from LDP to PCM. LDP is located on left front corner of engine compartment, under air filter housing. (Scheme 39) PCM is located on firewall in right rear corner of engine compartment. If LDP switch state stops toggling while wiggling wiring harness, repair wiring harness where wiggling caused toggling to stop. If LDP switch state does not stop toggling while wiggling wiring harness, go to next step.
8. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, go to next step.
9. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P1494: LEAK DETECTION PUMP SW OR MECHANICAL FAULT is present, go to step 2. If DTC P1494: LEAK DETECTION PUMP SW OR MECHANICAL FAULT is not present, no problem is indicated at this time. Test is complete.

DTC P1495: LEAK DETECTION PUMP SOLENOID CIRCUIT

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-6 under VERIFICATION TESTS to ensure system is functioning properly.

Leak Detection Pump (LDP) solenoid operation is monitored when ignition is on, and battery voltage is more than 10.4 volts. DTC will set in Powertrain Control Module (PCM) memory when PCM senses state of solenoid does not change. Possible causes for DTC to set are: defective Leak Detection Pump (LDP), defective PCM, defective LDP solenoid, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for P1495 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P1495 or displayed count is not "0", go to step 8.
2. Turn ignition off. Disconnect LDP connector. LDP is located on left front corner of engine compartment, under air filter housing. (Scheme 39) Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. If connector is okay, turn ignition on. With a test light connected to ground, probe Light Blue/Red wire at LDP harness connector. If test light illuminates brightly, disconnect test light and go to next step. If test light does not illuminate brightly, repair open in Light Blue/Red wire. See WIRING DIAGRAMS article.
3. Using scan tool, actuate leak detection pump. With a test light connected to positive battery terminal, probe White/Dark Green wire at LDP harness connector. If test light flashes on and off, go to next step. If test light does not flash on and off, go to step 5.
4. At this time, LDP is assumed to be defective. Replace LDP.
5. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and terminal No. 10 (White/Dark Green wire) at PCM C3 harness connector. (Scheme 29) If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in White/Dark Green wire between LDP and PCM.
6. Measure resistance of White/Dark Green wire between LDP harness connector and terminal No. 10 at PCM C3 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in White/Dark Green wire.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, go to next step.
9. Turn ignition on. Using scan tool, actuate LDP solenoid. Listen to LDP solenoid while wiggling wiring harness from LDP to PCM. LDP solenoid is located integral to LDP. LDP is located on left front corner of engine compartment, under air filter housing. (Scheme 39) PCM is located on firewall in right rear corner of engine compartment. If LDP solenoid stops clicking at any time while wiggling wiring harness, repair wiring harness as necessary where wiggling caused solenoid to stop clicking. If solenoid does not stop clicking, no problem is indicated at this time.

DTC P1499: HYDRAULIC FAN SOLENOID CIRCUIT (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Possible causes for DTC to set are: defective radiator fan solenoid, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, actuate radiator fan and check fan operation. If radiator fan is on, go to next step. If radiator fan is off, go to step 4.
2. Ensure ignition is still on and radiator fan is still actuated. Wiggle wiring harness and connectors from hydraulic cooling module to PCM while noting operation of radiator fan. PCM is located on firewall in right rear corner of engine compartment. If radiator fan operation was not interrupted while wiggling wiring harness and connectors, go to next step. If radiator fan operation was interrupted while wiggling wiring harness and connectors, repair wiring harness as necessary where wiggling caused radiator fan operation to be interrupted.
3. Turn ignition off. Inspect wiring and connectors between hydraulic cooling module and PCM. If no problems exist, test is complete. If any problems exist, repair wiring or connectors as necessary.
4. Ensure ignition is still on and radiator fan is still actuated. Disconnect hydraulic cooling module 2-pin connector. Measure voltage between ground and Orange/Dark Green wire at hydraulic cooling module harness connector. If voltage is more than 12 volts, go to next step. If voltage is 12 volts or less, repair power circuit (Orange/Dark Green wire) to hydraulic cooling module.
5. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/Red wire between hydraulic cooling module harness connector and terminal No. 17 at PCM C2 connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Red wire.
6. Measure resistance between ground and terminal No. 17 (Dark Blue/Red wire ) at PCM C2 connector. (Scheme 29) If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Red wire.
7. Reconnect all connectors. Backprobing, connect one end of a jumper wire to terminal No. 17 (Dark Blue/Red wire) at PCM C2 harness connector. Turn ignition on. Briefly tap other end of jumper wire to ground and observe radiator fan operation. If radiator fan turns on, go to next step. If radiator fan does not turn on, replace hydraulic cooling module.
8. At this time, PCM is assumed to be defective. Replace PCM.

DTC P1598: A/C PRESSURE SENSOR VOLTS TOO HIGH (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

A/C pressure sensor may also be referred to as A/C pressure transducer. A/C pressure sensor voltage is monitored with ignition on, engine is running and A/C clutch relay is energized. DTC may be stored in Powertrain Control Module (PCM) if A/C pressure sensor signal at PCM is more than 4.9 volts. Possible causes are: defective A/C pressure sensor, defective PCM, or defective connectors or wiring.

Note. Ensure A/C system is properly charged with refrigerant.

1. Start engine and allow it to idle. Using scan tool, read A/C pressure sensor voltage. If voltage is more than 4.6 volts, go to next step. If voltage is 4.6 volts or less, go to step 8.
2. Turn ignition off. Disconnect A/C pressure sensor connector. A/C pressure sensor is located on A/C refrigerant line and has a 4-pin connector. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between Dark Blue and Violet/White wires at A/C pressure sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Dark Blue and Violet/White wires are shorted together. Repair wiring as necessary.
3. Ensure ignition is off. Reconnect PCM connectors. Turn ignition on. Measure voltage between ground and Dark Blue wire at A/C pressure sensor harness connector. If voltage is 5.2 volts or less, go to next step. If voltage is more than 5.2 volts, repair short to voltage in Dark Blue wire between A/C pressure sensor and PCM.
4. Turn ignition off. Connect a jumper wire between Dark Blue and Black/Light Blue wires at A/C pressure sensor harness connector. Turn ignition on. Using scan tool, read A/C pressure sensor voltage. If voltage is one volt or more, disconnect jumper wire and go to next step. If voltage is less than one volt, replace A/C pressure sensor.
5. Turn ignition off. Disconnect PCM connectors. Measure resistance of Dark Blue wire between A/C pressure sensor harness connector and terminal No. 19 at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue wire.
6. Measure resistance of Black/Light Blue wire between A/C pressure sensor harness connector and terminal No. 4 at PCM C1 harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Blue wire.
7. At this time, PCM is assumed to be defective. Replace PCM.
8. Ensure engine is idling. Using scan tool, read A/C pressure sensor voltage while wiggling wiring harness and connectors between A/C pressure sensor and PCM. A/C pressure sensor is located on A/C refrigerant line and has a 4-pin connector. PCM is located on firewall in right rear corner of engine compartment. If voltage does not change while wiggling wiring harness and connectors, go to next step. If voltage changes while wiggling wiring harness and connectors, repair wiring harness as necessary where wiggling caused voltage to change.
9. Inspect wiring harness and connectors between A/C pressure sensor and PCM. If any problems exist, repair wiring or connectors as necessary. If no problems exist, test is complete. Check for any technical service bulletins that may apply.

DTC P1599: A/C PRESSURE SENSOR VOLTS TOO LOW (4.7L)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Note. Ensure A/C system is charged properly.

A/C pressure sensor may also be referred to as A/C pressure transducer. A/C pressure sensor voltage is monitored with ignition on, engine is running and A/C clutch relay is energized. DTC may be stored in Powertrain Control Module (PCM) if A/C pressure sensor signal at PCM is less than 0.6 volt. Possible causes are: defective A/C pressure sensor, defective PCM, or defective connectors or wiring.

1. Start engine and allow it to idle. Using scan tool, read A/C pressure sensor voltage. If voltage is less than 0.6 volt, go to next step. If voltage is 0.6 volt or more, go to step 10.
2. Turn ignition off. Disconnect A/C pressure sensor connector. A/C pressure sensor is located on A/C refrigerant line and has a 4-pin connector. Turn ignition on. Measure voltage between ground and Violet/White wire at A/C pressure sensor harness connector. If voltage is 4.5-5.2 volts, go to next step. If voltage is not 4.5-5.2 volts, go to step 7.
3. Using scan tool, read A/C pressure sensor voltage. If voltage is 0.6 volt or less, go to next step. If voltage is more than 0.6 volt, replace A/C pressure sensor.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Dark Blue wire at A/C pressure sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue wire between A/C pressure sensor and PCM.
5. Measure resistance between Dark Blue and Black/Light Blue wires at A/C pressure sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, Dark Blue and Black/Light Blue wires are shorted together. Repair wiring as necessary.
6. At this time, PCM is assumed to be defective. Replace PCM.
7. Turn ignition off. Ensure A/C pressure sensor is disconnected. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance between ground and Violet/White wire at A/C pressure sensor harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Violet/White wire between PCM and A/C pressure sensor. NOTE: In the following step, the 5-volt supply circuit to the A/C pressure sensor changes wire color. The supply circuit is a Violet/Black wire at terminal No. 31 of PCM C2 harness connector and a Violet/White wire at A/C pressure sensor. Wire changes color at spice S102. Splice is located in engine wiring harness near breakout for ignition coil No. 1.
8. Measure resistance between Violet/White wire at A/C pressure sensor harness connector and terminal No. 31 (Violet/Black wire) at PCM C2 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in 5-volt supply circuit.
9. At this time, PCM is assumed to be defective. Replace PCM.
10. Ensure engine is idling. Using scan tool, read A/C pressure sensor voltage while wiggling wiring harness and connectors between A/C pressure sensor and PCM. A/C pressure sensor is located on A/C refrigerant line and has a 4-pin connector. PCM is located on firewall in right rear corner of engine compartment. If voltage does not change while wiggling wiring harness and connectors, go to next step. If voltage changes while wiggling wiring harness and connectors, repair wiring harness as necessary where wiggling caused voltage to change.
11. Inspect wiring harness and connectors between A/C pressure sensor and PCM. If any problems exist, repair wiring or connectors as necessary. If no problems exist, test is complete. Check for any technical service bulletins that may apply

DTC P1685: WRONG OR INVALID KEY MESSAGE RECEIVED FROM SKIM

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform SKIS VERIFICATION TEST under VERIFICATION TESTS to ensure system is functioning properly.

Transponder ID (in ignition key) is monitored with ignition on. DTC will set in Powertrain Control Module (PCM) memory when transponder ID read by Smart Key Immobilizer Module (SKIM) does not match any transponder ID's stored in SKIM memory. Possible causes for DTC to set are: invalid SKIM KEY, defective PCM, defective connectors or defective wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P1685 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P1685 or displayed count is not "0", go to step 7 .
2. Using scan tool, attempt to communicate with SKIM. If scan tool communicates with SKIM, go to next step. If scan tool does not communicate with SKIM, check for open bus circuits from SKIM. See COMMUNICATIONS under SYSTEM TESTS in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.
3. Using scan tool, check for SKIM DTCs. If no DTCs are present, go to next step. If any DTCs are present, repair SKIM DTCs before continuing with this test. See BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.
4. Using scan tool, display Vehicle Identification Number (VIN) that is programmed into PCM. If VIN is programmed into PCM, go to next step. If VIN has not been programmed into PCM, use scan tool and program VIN into PCM and retest.
5. Using scan tool, display VIN that is programmed into PCM. If correct VIN is displayed, go to next step. If correct VIN is not displayed, replace PCM.
6. Turn ignition off. Replace SKIM and program new SKIM. See REMOVAL & INSTALLATION in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT. Attempt to start engine. Using scan tool, read PCM DTCs. If DTC P1685: INVALID SKIM KEY resets, replace PCM. If DTC P1685: INVALID SKIM KEY does not reset, no problem is indicated at this time. Test is complete.
7. DTC P1685 may have been set if SKIM was disconnected or recently replaced. All customer's ignition keys for this vehicle must be tested at this time. Turn ignition off and remove ignition key. Using another customer key, turn ignition on and attempt to start engine. If engine starts, this usually indicates a good key. Continue using remaining ignition keys. Using scan tool, check for DTCs. If all keys start engine and DTC P1685: INVALID SKIM KEY does not reset, no problem is indicated at this time. Problem may have been an actual theft attempt. Test is complete. If any key does not start engine, replace ignition key that would not start engine. Program new key. See SENTRY KEYS under PROGRAMMING in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.

DTC P1686: NO SKIM BUS MESSAGE RECEIVED

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform SKIS VERIFICATION TEST under VERIFICATION TESTS to ensure system is functioning properly.

Smart Key Immobilizer Module (SKIM) bus is monitored with ignition on and continuously during engine operation. DTC will set in Powertrain Control Module (PCM) memory when SKIM status bus message was not received from the SKIM for 20 seconds. Possible causes for DTC to set are: defective SKIM, defective PCM, defective connectors or defective wiring.

1. Turn ignition on. Using scan tool, check for any PCM DTCs. If DTC P1686: NO SKIM BUS MESSAGE RECEIVED is present, go to next step. If DTC P1686: NO SKIM BUS MESSAGE RECEIVED is not present, go to step 5.
2. Using scan tool, attempt to communicate with SKIM. If scan tool communicates with SKIM, go to next step. If scan tool does not communicate with SKIM, check for open bus circuits from SKIM. See COMMUNICATIONS under SYSTEM TESTS in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.
3. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Disconnect SKIM 6-pin connector. SKIM is mounted underneath steering column. On all models, inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of PCI bus circuit between terminals No. 5 (Yellow/Violet/Black wire) at SKIM harness connector and No. 30 (Yellow/Violet wire) at PCM C3 harness connector. (Scheme 29)and (Scheme 40). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in PCI bus circuit. See DATA LINK CONNECTORS article in WIRING DIAGRAMS.
4. Turn ignition off. Replace SKIM and program new SKIM. See REMOVAL & INSTALLATION in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT. Turn ignition on. Using scan tool, clear all PCM and SKIM DTCs. Perform 5 ignition cycles (key on/key off) leaving key on for 90 seconds per key cycle. Using scan tool, read PCM DTCs. If DTC P1685: INVALID SKIM KEY resets, replace PCM. If DTC P1685: INVALID SKIM KEY does not reset, no problem is indicated at this time. Test is complete.
5. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review FREEZE FRAME data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.

Scheme 40

DTC P1696: PCM FAILURE EEPROM WRITE DENIED

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

DTC P1696 indicates PCM failure EEPROM write denied and is monitored with ignition on. DTC will set in Powertrain Control Module (PCM) memory when PCM's attempt to program/write to internal EEPROM fails. Possible cause for DTC to set is: defective PCM.

1. Turn ignition on, with engine off. Using scan tool, perform SRI MEMORY TEST. If scan tool displays WRITE REFUSED, go to next step. If scan tool does not display WRITE REFUSED, no problem is indicated at this time. Test is complete.
2. Using scan tool, repeat SRI MEMORY TEST. If scan tool displays WRITE REFUSED, replace PCM. PCM is located on firewall in right rear corner of engine compartment. If scan tool does not display WRITE REFUSED, no problem is indicated at this time. Test is complete.

DTC P1698: NO BUS MESSAGE FROM TCM

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform TEST VER-1 under VERIFICATION TESTS to ensure system is functioning properly.

Messages from Transmission Control Module (TCM) are monitored when engine is running. The Powertrain Control Module (PCM) and TCM communicate messages across the Chrysler Collision Detection (CCD) bus, as information from either module is needed to operate their respective systems. DTC will set in PCM memory if no CCD bus messages are received from TCM for 10 seconds. Possible causes for DTC to set are: open circuit on CCD bus, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter for DTC P1698 is displayed and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P1698 or displayed count is not "0", go to step 6.
2. Ensure ignition is on. Using scan tool, select ENGINE MODULE. Using scan tool, check for DTCs. If DTC is also set for NO SKIM BUS MESSAGE and/or NO MIC BUS MESSAGE, go to next step. If DTC is not also set for NO SKIM BUS MESSAGE and/or NO MIC BUS MESSAGE, go to NO RESPONSE FROM TCM under SYSTEM TESTS in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.
3. Using scan tool, select the following control modules and note if they communicate with scan tool. Using scan tool, select BODY then BCM. Using scan tool, select DOOR MODULES. Using scan tool, select ANTI-LOCK BRAKES. Using scan tool, select ELECTRO-MECHANICAL CLUSTER (MIC). Using scan tool, select PASSIVE RESTRAINTS then AIR BAG. If one or more modules communicated with scan tool, go to next step. If no modules communicated with scan tool, go to PCI BUS COMMUNICATION FAILURE under COMMUNICATIONS in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.
4. Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, ensure scan tool is connected to Data Link Connector (DLC). Connect Scope Input Cable (CH7058) to channel one connector on scan tool. Obtain Red and Black test probes from DRBIII(R) scan tool test kit. Connect Red and Black test probe leads to Probe Adapter (CH7062). Connect probe adapter to scope input cable. Using scan tool, select DRB STANDALONE, LAB SCOPE, LIVE, then 12 VOLT SQUARE WAVE. Using scan tool, press F2 for scope. Press F2 again and arrow down until 20-volt scale is selected. Press F2 again when complete. Connect Black test probe to ground and Red test probe to terminal No. 30 (Yellow/Violet wire) at PCM C3 harness connector. (Scheme 29) Turn ignition on and observe voltage displayed on DRBIII(R) lab scope. If voltage pulses from zero volts to about 7.5 volts, go to next step. If voltage is a constant zero volts, repair open PCI bus circuit (Yellow/Violet wire). See WIRING DIAGRAMS article.
5. PCM has an internal open PCI bus circuit. Replace PCM.
6. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, no problem is indicated at this time. Check for any related technical service bulletins that may apply.

DTC P1899: P/N SWITCH PERFORMANCE (4.0L A/T)

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components. Perform TRANSMISSION VERIFICATION TEST under VERIFICATION TESTS to ensure system is functioning properly.

Park/Neutral Position (PNP) switch operation is monitored when transmission is in Park, Neutral or Drive and not in limp-in mode. DTC will set in Powertrain Control Module (PCM) memory if PCM detects an incorrect transmission range sensor state for a given mode of vehicle operation. Possible causes for DTC to set are: defective transmission PNP switch, defective PCM, or defective connectors or wiring.

1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1899 and displayed count is "0", go to next step. If GOOD TRIP counter is not displayed for DTC P1899 or displayed count is not "0", go to step 7.
2. Apply parking brake. Turn ignition on. Using scan tool, monitor PNP switch input state while moving shift lever from Park to 1st, then back to Park. If scan tool did not indicate correct gear shift positions, go to next step. If scan tool indicated correct gear positions, no problem is indicated at this time. Test is complete.
3. Ensure ignition is off. Disconnect PNP switch connector located on side of transmission. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Brown/Yellow wire between PNP switch harness connector and terminal No. 6 at PCM C1 harness connector. (Scheme 29) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Brown/Yellow wire.
4. Measure resistance between ground and terminal No. 6 (Brown/Yellow wire) at PCM C1 connector. (Scheme 29) If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Brown/Yellow wire between PNP switch and PCM.
5. Reconnect PNP switch connector. Measure resistance between ground and terminal No. 6 (Brown/Yellow wire) at PCM C1 connector while moving shift lever from Park to 1st, then back to Park. If resistance changes from more than 10 ohms to less than 10 ohms, go to next step. If resistance does not change from more than 10 ohms to less than 10 ohms, PNP switch is stuck or defective. Replace PNP switch.
6. At this time PCM is assumed to be defective. Replace PCM.
7. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P1899: P/N SWITCH PERFORMANCE is present, go to step 2. If DTC P1899: P/N SWITCH PERFORMANCE is not present, no problem is indicated at this time. Check for any related technical service bulletins that may apply.

VERIFICATION TESTS

Note. Perform the following verification test only when directed to. Only verification tests that are applicable to diagnostic tests in this article have been included.

FUEL SYSTEM/MISFIRE MONITOR VERIFICATION TEST

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM and vehicle is equipped with a Smart Key Immobilizer Module (SKIM), secret key data must also be updated to enable engine starting.

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If any DTCs have not been diagnosed, perform appropriate diagnostic test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If all DTCs have been diagnosed and repaired, go to next step.
2. Connect scan tool to Data Link Connector (DLC), if not previously done. Ensure fuel tank is at least 1/4 full. Ensure A/C is off. Go to next step.
3. If repair procedure did not include replacing PCM, or PCM has been replaced and has already been programmed, go to next step. If PCM has been replaced but has not been programmed, program PCM and clear DTCs. See «PROGRAMMING»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) . After PCM has been programmed, go to next step.
4. Ensure misfire detection is enabled if a misfire DTC was repaired. Low fuel level or an unlearned adaptive numerator can disable the misfire monitor. If PCM has been replaced or disconnected during testing, the adaptive numerator must be relearned in order for misfire monitor to run.
5. Using scan tool, monitor SIMILAR CONDITIONS and attempt to duplicate conditions during which vehicle was operating at when DTC was set. If conditions can be duplicated, GOOD TRIP counter will change to one or more. If conditions cannot be duplicated, clear DTCs. If OBD-II monitor failed after running, repair is not complete. Check for technical service bulletins that apply to symptom. Go to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom.
6. If repaired DTC has reset, proceed to appropriate DTC test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If monitor ran and GOOD TRIP counter changed to one or more, repair was successful and test is now complete.

SKIS VERIFICATION TEST

Note. Sentry Key Immobilizer Module (SKIM) will only remain in secured access mode for 60 seconds. If incorrect unique Personal Identification Number (PIN) is entered 3 times, SKIM will be locked for one hour. To unlock SKIM, turn ignition on for one hour. When SKIM is locked, scan tool will display BUS +/- SIGNALS OPEN.

1. Obtain vehicle's unique Personal Identification Number (PIN) assigned to SKIM from vehicle owner or manufacturer. Remove all test equipment and jumper wires. Connect any disconnected components. Go to next step.
2. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, select SKIM MODULE REPLACEMENT. Enter 4-digit PIN number to put SKIM in access mode. Go to next step.
3. Using scan tool, select THEFT ALARM, SKIM, MISCELLANEOUS, then select desired procedure and follow steps displayed on scan tool. If SKIM has been replaced, ensure all keys and remote transmitters to be used with vehicle are programmed into SKIM. Go to next step.
4. Using scan tool, clear Diagnostic Trouble Codes (DTC). Perform 5 ignition cycles (key on/key off) leaving key on for 90 seconds per key cycle. Using scan tool, retrieve DTCs from all modules. If no DTCs exist, system is operating correctly and customer's complaint cannot be duplicated, repair is complete. If any DTCs exist, perform appropriate test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS.

POWERTRAIN VERIFICATION TEST VER-1

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM and vehicle is equipped with a Smart Key Immobilizer Module (SKIM), secret key data must also be updated to enable engine starting.

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If repair procedure did not include replacing PCM, or PCM has been replaced and has already been programmed, go to next step. If PCM has been replaced but has not been programmed, program PCM and clear DTCs. See «PROGRAMMING»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) . After PCM has been programmed, go to next step.
2. Inspect engine oil for fuel contamination. Change engine oil and filter as necessary. Attempt to start engine. If engine starts and stays running, test is complete. If engine does not start, check for related technical service bulletins. If necessary, go to TROUBLE SHOOTING - NO CODES article for additional testing.

POWERTRAIN VERIFICATION TEST VER-2

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM and vehicle is equipped with a Smart Key Immobilizer Module (SKIM), secret key data must also be updated to enable engine starting.

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If test is being performed after performing a repair that did not involve a Diagnostic Trouble Code (DTC) test, go to next step. If test is being performed after performing a repair that involved a DTC test, go to step 3 .
2. Check if initial symptom still exists. If initial or another symptom exists, repair is not complete. Check for technical service bulletins that apply to symptom. Go to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom. If initial symptom no longer exists and no DTCs are present, test is complete.
3. If repair procedure did not include replacing PCM, or PCM has been replaced and has already been programmed, go to next step. If PCM has been replaced but has not been programmed, program PCM and clear DTCs. See «PROGRAMMING»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) . After PCM has been programmed, go to next step.
4. Road test vehicle for at least 5 minutes. If repair involved A/C relay control circuit, ensure A/C is on during road test. Road test vehicle at a speed of at least 40 MPH at some point during road test. Stop vehicle. Turn engine off for at least 10 seconds. Start engine and continue road test. Ensure transmission shifts through all gears. After road test, turn engine off and go to next step.
5. Using scan tool, read DTCs. If original DTC did not return and there are no new DTCs, test is complete. If original DTC returns or another DTC is present, perform appropriate diagnostic test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS.

POWERTRAIN VERIFICATION TEST VER-3

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM and vehicle is equipped with a Smart Key Immobilizer Module (SKIM), secret key data must also be updated to enable engine starting.

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If repair procedure did not include replacing PCM, or PCM has been replaced and has already been programmed, go to next step. If PCM has been replaced but has not been programmed, program PCM and clear DTCs. See «PROGRAMMING»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) . After PCM has been programmed, go to next step.
2. Ensure no other charging problems exist before continuing. Start engine. Ensure generator output voltage is okay. Raise engine speed to 2000 RPM for at least 30 seconds. Allow engine to idle. Turn ignition off.
3. Turn ignition on. Using scan tool, read DTCs. If original DTC did not return and there are no new DTCs, test is complete. If original DTC returns or another DTC is present, perform appropriate diagnostic test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS.

POWERTRAIN VERIFICATION TEST VER-5

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM and vehicle is equipped with a Smart Key Immobilizer Module (SKIM), secret key data must also be updated to enable engine starting.

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If any DTCs have not been diagnosed, perform appropriate diagnostic test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If all DTCs have been diagnosed and repaired, go to next step.
2. Connect scan tool to Data Link Connector (DLC), if not previously done. Ensure fuel tank is at least 1/4 full. Ensure A/C is off. Go to next step.
3. If repair procedure did not include replacing PCM, go to next step. If PCM has been replaced and has already been programmed, go to next step. If PCM has been replaced but has not been programmed, program PCM and clear DTCs. See «PROGRAMMING»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) . After PCM has been programmed, go to next step.
4. Ensure all DTCs are cleared from PCM. Proper way to ensure DTC is properly repaired is to allow PCM to run the OBD-II monitor. OBD-II monitor operation may be observed on the scan tool. In order for OBD-II monitor to be run, certain pretest enabling conditions must be met. Refer to applicable OBD-II monitor pretest screen on scan tool for monitor enabling conditions.
5. Operate vehicle within enabling conditions and allow applicable OBD-II monitor to run. While OBD-II monitor is running, scan tool will beep and IN PROGRESS will be displayed on the OBD-II monitor screen. After OBD-II monitor is complete, view the results. OBD-II monitor may have to fail more than once in order for DTC to be stored in PCM. If OBD-II monitor fails, repaired DTC has reset, or any DTCs exist, repair is not complete. Check for related technical service bulletins and proceed to appropriate DTC test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If catalytic converter was replaced, select MISCELLANEOUS, then CATALYST REPLACED and press enter. If GOOD TRIP counter changed to one or more and no new DTCs exist, repair was successful and test is now complete.

POWERTRAIN VERIFICATION TEST VER-6

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM and vehicle is equipped with a Smart Key Immobilizer Module (SKIM), secret key data must also be updated to enable engine starting.

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If repair procedure did not include replacing PCM, go to next step. If PCM has been replaced and has already been programmed, go to next step. If PCM has been replaced but has not been programmed, program PCM and clear DTCs. See «PROGRAMMING»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) . After PCM has been programmed, go to next step.
2. If any DTCs have not been diagnosed, perform appropriate diagnostic test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If all DTCs have been diagnosed and repaired, go to next step.
3. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If any DTCs have not been diagnosed, perform appropriate diagnostic test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If all DTCs have been diagnosed and repaired, go to next step.
4. Connect scan tool to Data Link Connector (DLC), if not previously done. Ensure all accessories are off. Start engine and allow it to idle. Ensure shift lever is in Park and throttle is in idle position. Place scan tool in LDP DEALER TEST MODE and follow instructions as displayed on scan tool. If a DTC for a small leak is set, repair is not complete. Check for related technical service bulletins and return to diagnostic test from which you came. If any other DTC exists, perform appropriate diagnostic test(s). See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If all DTCs have been diagnosed and repaired, test is complete.

TRANSMISSION VERIFICATION TEST

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM and vehicle is equipped with a Smart Key Immobilizer Module (SKIM), secret key data must also be updated to enable engine starting.

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If any DTCs have not been diagnosed, perform appropriate diagnostic test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If all DTCs have been diagnosed and repaired, go to next step.
2. If repair procedure did not include replacing PCM, go to next step. If PCM has been replaced and has already been programmed, go to next step. If PCM has been replaced but has not been programmed, program PCM and clear DTCs. See «PROGRAMMING»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) . After PCM has been programmed, go to next step.
3. Using scan tool, clear PCM and TCM DTCs. Ensure transmission fluid is at proper level. Ensure fuel tank is at least 1/4 full and all accessories are off. Road test vehicle. Using scan tool, monitor engine RPM. Make 15-20 1st-2nd, 2nd-3rd and 3rd-4th upshifts. Perform shifts from a standing start to 45 MPH with a constant throttle opening of 20-25 degrees.
4. With vehicle speed less than 25 MPH, make 5-8 wide open throttle kickdowns to 1st gear. Allow at least 5 seconds each in 2nd and 3rd gear between each kickdown.
5. Using scan tool, monitor SIMILAR CONDITIONS and attempt to duplicate conditions during which vehicle was operating at when DTC was set. If conditions can be duplicated, GOOD TRIP counter will change to one or more. If repaired DTC resets, proceed to appropriate DTC test. See «DTC MESSAGES & CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/testing-diagnostics/#engine-controls-self-diagnostics-grand-cherokee) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If conditions cannot be duplicated and GOOD TRIP counter changed to one or more, repair was successful and test is now complete.

See also:
• TRIP INDICATOR
• MONITORED CIRCUITS
• RETRIEVING DIAGNOSTIC TROUBLE CODES
• HARD FAILURES
• INTERMITTENT FAILURES
• SIMILAR CONDITIONS WINDOW
• FUEL SYSTEM PRESSURE RELEASE
• PROGRAMMING
• VISUAL INSPECTION
• P0031
• P0051
• P0071
• P0107
• P0108
• P0112
• P0113
• P0117
• P0118
• P0121
• P0122
• P0123
• P0125
• P0131
• P0132
• P0133
• P0135
• P0136
• P0137
• P0138
• P0139
• P0141
• P0151
• P0152
• P0153
• P0155
• P0157
• P0158
• P0159
• P0161
• P0171
• P0172
• P0174
• P0175
• P0201
• P0202
• P0203
• P0204
• P0205
• P0206
• P0207
• P0208
• P0300
• P0320
• P0340
• P0351
• P0352
• P0353
• P0354
• P0355
• P0356
• P0357
• P0358
• P0420
• P0432
• P0441
• P0442
• P0443
• P0460
• P0462
• P0463
• P0500
• P0505
• P0522
• P0523
• P0601
• P0645
• P0700
• P1195
• P1196
• P1282
• P1294
• P1296
• P1297
• P1299
• P1388
• P1389
• P1391
• P1398
• P1486
• P1491
• P1492
• P1493
• P1494
• P1495
• P1499
• P1598
• P1599
• P1685
• P1686
• P1696
• P1698
• P1899
• POWERTRAIN VERIFICATION TEST VER-5
• FUEL SYSTEM/MISFIRE MONITOR VERIFICATION TEST
• POWERTRAIN VERIFICATION TEST VER-6
• POWERTRAIN VERIFICATION TEST VER-2
• POWERTRAIN VERIFICATION TEST VER-3
• SKIS VERIFICATION TEST
• TEST VER-1
• TRANSMISSION VERIFICATION TEST