Dtcs P0645 to P1593: Other Jeep Commander I

Monitor Conditions

1. When Monitored: With the ignition on. Battery voltage greater than 10 volts. A/C Switch on.

Set Conditions

1. Set Condition: An open or shorted condition is detected in the A/C Clutch Relay control circuit. One Trip Fault. Three good trips to turn off the MIL.

Possible Causes

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 430

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Scheme 432

Scheme 433

1. 1) ACTIVE DTC Start the engine. Allow the engine to reach normal operating temperature. Turn the A/C on. With a scan tool, select View DTCs and record the related Freeze Frame data. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) A/C CLUTCH RELAY RESISTANCE Turn the ignition off. Remove the A/C Clutch Relay from the IPM. Measure the resistance of the A/C Clutch Relay Coil. Is the resistance between 60 to 80 ohms? Yes Go to 3) . No Replace the A/C Clutch Relay. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
3. 3) (F942) FUSED IGNITION SWITCH OUTPUT CIRCUIT Ignition on, engine not running. Using a 12-volt test light connected to ground, probe the (F942) Fused Ignition Switch Output circuit in the connection. Does the test light illuminate brightly? Yes Go to 4) . No Repair the open or short to ground in the (F942) Fused Ignition Switch Output circuit. Check and replace any open fuses. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) (A917) FUSED B+ CIRCUIT Using a 12-volt test light connected to ground, probe the (A917) Fused B+ circuit in the connection. Does the test light illuminate brightly? Yes Go to 5) . No Repair the open or short to ground in the (A917) Fused B+ circuit. Check and replace any open fuses. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
5. 5) (C13) A/C CLUTCH RELAY CONTROL CIRCUIT OPEN Turn the ignition off. Disconnect the C3 PCM harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Measure the resistance of the (C13) A/C Clutch Relay Control circuit from the relay connection to the appropriate terminal of special tool #8815. Is the resistance below 5.0 ohms? Yes Go to 6) . No Repair the open in the (C13) A/C Clutch Relay Control circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) (C13) A/C CLUTCH RELAY CONTROL CIRCUIT SHORTED TO GROUND Measure the resistance between ground and the (C13) A/C Clutch Relay Control circuit at the IPM. Is the resistance below 5.0 ohms? Yes Repair the short to ground in the (C13) A/C Relay Clutch Control circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 7) .
7. 7) POWERTRAIN CONTROL MODULE (PCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the A/C Clutch Relay and the Powertrain Control Module (PCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the A/C Clutch Relay and Powertrain Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

Scheme 434

1. When Monitored: Ignition on.

1. Set Condition: When the PCM recognizes the Auxiliary 5-volt Supply circuit voltage is too low. One Trip Fault. ETC light is flashing.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 435

Scheme 436

1. 1) ACTIVE DTC NOTE: Improperly installed aftermarket accessories can cause this DTC to set. Check for any improperly installed aftermarket accessories before continuing with this test. Start the engine and allow it to idle for at least 60 seconds. WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death. With a scan tool, select View DTCs. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) (F856) AUXILIARY 5-VOLT SUPPLY SHORTED TO GROUND Turn the ignition off. Disconnect the C1 PCM harness connector. Disconnect all the Sensors that share the (F856) Auxiliary 5-volt Supply circuit. Measure the resistance between ground and the (F856) Auxiliary 5-volt Supply circuit in the CMP Sensor harness connector. Is the resistance below 100 ohms? Yes Repair the short to ground in the (F856) Auxiliary 5-volt Supply circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 3) .
3. 3) CMP SENSOR Turn the ignition off. Reconnect all the previously disconnected Sensors except for the CMP Sensor harness connector. Ignition on, engine not running. Measure the voltage on the (F856) Auxiliary 5-volt Supply circuit in the CMP Sensor harness connector. Is the voltage below 4.5 volts? Yes Go to 4) . No Verify that there is good pin to terminal contact in the CMP Sensor and Powertrain Control Module connectors. If OK, replace the Camshaft Position Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) 5-VOLT SENSOR SHORTED TO GROUND Measure the voltage on the (F856) Auxiliary 5-volt Supply circuit at the CMP Sensor harness connector. NOTE: You must Turn the Ignition OFF when disconnecting any of the Sensor harness connectors and Turn the Ignition On to check the voltage readings. While monitoring the voltage, disconnect each Sensor harness connector that shares the (F856) Auxiliary 5-volt Supply circuit, one at a time. Does the voltage increase above 4.5 volts when disconnecting any of the Sensor harness connectors? Yes Verify that there is good pin to terminal contact in the related Sensor and Powertrain Control Module connectors. If OK, replace the Sensor that causes the (F856) Auxiliary 5-volt Supply circuit voltage to increase when disconnected. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 5) .
5. 5) POWERTRAIN CONTROL MODULE (PCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the related Sensors and the Powertrain Control Module (PCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related Sensor and Powertrain Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

1. When Monitored: Ignition on.

1. Set Condition: When the PCM recognizes the Auxiliary 5-volt Supply circuit voltage is too high. One Trip Fault. ETC light is flashing.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

1. When Monitored: With ignition on. Battery voltage above 10 volts.

1. Set Condition: The actual ASD state is not equal to the desired ASD state. One Trip Fault. Three good trips to turn off the MIL.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 437

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Scheme 439

1. 1) ASD RELAY OPERATION Ignition on, engine not running. With a scan tool, select View DTCs. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) (A924) FUSED B+ CIRCUITS Turn the ignition off. Remove the ASD Relay from the IPM. Using a 12-volt test light connected to ground, probe the (A924) Fused B+ circuits in the IPM. Does the test light illuminate brightly? Yes Go to 3) . No Repair the open or short to ground in the (A924) Fused B+ circuits. Inspect and replace any open fuses. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
3. 3) ASD RELAY Measure the resistance of the ASD Relay Coil. Is the resistance between 60 to 80 ohms? Yes Go to 4) . No Replace the ASD Relay. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) (K342) ASD RELAY CONTROL CIRCUIT OPEN Disconnect the C3 PCM harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Measure the resistance of the (K342) ASD Relay Control circuit from the IPM to the appropriate terminals of special tool #8815. Is the resistance below 5.0 ohms? Yes Go to 5) . No Repair the open in the (K342) ASD Relay Control circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
5. 5) (K342) ASD RELAY CONTROL CIRCUIT SHORTED TO GROUND Measure the resistance between ground and the (K342) ASD Relay Control circuit in the IPM. Is the resistance below 100 ohms? Yes Repair the short to ground in the (K342) ASD Relay Control circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 6) .
6. 6) POWERTRAIN CONTROL MODULE (PCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ASD Relay and the Powertrain Control Module (PCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the ASD Relay and Powertrain Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

1. When Monitored: With ignition key on. Battery voltage greater than 10 volts.

1. Set Condition: No voltage sensed at the PCM when the ASD relay is energized. One Trip Fault. Three good trips to turn off the MIL.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 440

1. 1) VERIFY ASD DTC NOTE: Diagnose P0685 - Auto Shutdown Relay Control Circuit first if it set along with this DTC. With a scan tool, erase the DTC. Attempt to start the engine. If the engine will not start, crank the engine for at least 15 seconds. It may be necessary to repeat several times. Does the DTC reset? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) ENGINE OPERATION Attempt to start the engine. Does the engine start? Yes Go to 3) . No Go to 4) .
3. 3) (A142) ASD RELAY OUTPUT CIRCUIT OPEN Turn the ignition off. Remove the ASD Relay. Disconnect the C3 PCM harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Measure the resistance of the (A142) ASD Relay Output circuit from the Relay connection to the appropriate terminals of special tool #8815. Is the resistance below 5.0 ohms? Yes Go to 7) . No Repair the open in the (A142) ASD Relay Output circuits. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) ASD RELAY Turn the ignition off. Install a substitute relay in place of the ASD Relay. Ignition on, engine not running. With a scan tool, erase DTCs. Attempt to start the engine. With a scan tool, select View DTCs. Does the DTC reset? Yes Go to 5) . No Replace the ASD Relay. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
5. 5) (A924) FUSED B+ CIRCUITS Turn the ignition off. Using a 12-volt test light connected to ground, probe the (A924) Fused B+ circuits at the Relay connection. Does the test light illuminate brightly? Yes Go to 6) . No Repair the open or short to ground in the (A924) Fused B+ circuits. Inspect the related fuse and repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) (A142) ASD RELAY OUTPUT CIRCUIT OPEN Disconnect the C3 PCM harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Measure the resistance of the (A142) ASD Relay Output circuit from the Relay connection to the appropriate terminals of special tool #8815. Is the resistance below 5.0 ohms? Yes Go to 7) . No Repair the open in the (A142) ASD Relay Output circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
7. 7) POWERTRAIN CONTROL MODULE (PCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ASD Relay and the Powertrain Control Module (PCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the ASD Relay and Powertrain Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

Scheme 441

1. When Monitored: Ignition on with the Cooling fan No. 1 Relay actuated.

1. Set Condition: The FCM recognizes and open or short to ground in the Cooling Fan Relay No. 1 Control circuit.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 442

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Scheme 444

1. 1) LOW SPEED RADIATOR FAN RELAY OPERATION Ignition on, engine not running. With a scan tool, actuate the Low Speed Radiator Fan Relay. Is the Cooling Fan Relay operating? Yes Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure. No Go to 2) .
2. 2) INTERNAL FUSED B+ CIRCUITS Turn the ignition off. Remove the Low Speed Radiator Fan Relay. Using a 12-volt test light connected to ground, probe the Internal Fused B+ circuits. Does the test light illuminate brightly? Yes Go to 3) . No Repair the open or short to ground in the Internal Fused B+ circuits. Inspect the related fuse and repair as necessary. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) .
3. 3) LOW SPEED RADIATOR FAN RELAY RESISTANCE Measure the resistance of the Low Speed Radiator Fan Relay Coil. Is the resistance between 60 to 80 ohms? Yes Go to 4) . No Replace the Low Speed Radiator Fan Relay. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) .
4. 4) (N201) COOLING FAN NO. 1 CONTROL CIRCUIT OPEN Disconnect the IPM FCM 49 way harness connector. Measure the resistance of the (N201) Cooling Fan No. 1 Relay Control circuit from the Relay to the IPM FCM harness connector. Is the resistance below 5.0 ohms? Yes Go to 5) . No Repair the open in the (N201) Cooling Fan No. 1 Relay Control circuit. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) .
5. 5) (N201) COOLING FAN NO. 1 CONTROL CIRCUIT SHORTED TO GROUND Measure the resistance between ground and the (N201) Cooling Fan No. 1 Relay Control circuit at the Relay connection. Is the resistance below 100 ohms? Yes Repair the short to ground in the (N201) Cooling Fan No. 1 Relay Control circuit. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) . No Go to 6) .
6. 6) FRONT CONTROL MODULE (FCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Cooling Fan Relay and the Front Control Module (FCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Cooling Fan Relay and Front Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) . No Replace Front Control Module per Service Information. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) .

1. When Monitored: Ignition on with the Cooling Fan No. 1 Relay powered on.

1. Set Condition: The FCM detects the Cooling Fan No. 1 Relay voltage above the acceptable voltage at the FCM. The circuit is continuously monitored.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 445

1. 1) LOW SPEED RADIATOR FAN RELAY OPERATION Ignition on, engine not running. With a scan tool, actuate the Low Speed Radiator Fan Relay. Is the Cooling Fan Relay operating? Yes Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure. No Go to 2) .
2. 2) (N201) COOLING FAN NO. 1 RELAY CONTROL CIRCUIT SHORTED TO VOLTAGE Turn the ignition off. Remove the Low Speed Radiator Fan Relay. Disconnect the FCM 49 way harness connector. Ignition on, engine not running. Using a 12-volt test light connected to ground, probe the (N201) Cooling Fan No. 1 Relay Control circuit at the Relay terminal. Does the test light illuminate brightly? Yes Repair the short to voltage in the (N201) Cooling Fan No. 1 Relay Control circuit. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) . No Go to 3) .
3. 3) LOW SPEED RADIATOR FAN RELAY RESISTANCE Measure the resistance of the Low Speed Radiator Fan Relay Coil. Is the resistance between 60 to 80 ohms? Yes Go to 4) . No Replace the Low Speed Radiator Fan Relay. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) FRONT CONTROL MODULE (FCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Cooling Fan Relay and the Front Control Module (FCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Cooling Fan Relay and Front Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) . No Replace Front Control Module per Service Information. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) .

Scheme 446

1. When Monitored: Ignition on and the High Speed Radiator Fan Relay is powered on.

1. Set Condition: The FCM detects and open or short in the Cooling Fan No. 2 Relay Control circuit. The circuit is continuously monitored.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 447

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Scheme 449

1. 1) HIGH SPEED RADIATOR FAN RELAY OPERATION Ignition on, engine not running. With a scan tool, actuate the High Speed Radiator Fan Relay. Is the Cooling Fan Relay operating? Yes Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure. No Go to 2) .
2. 2) (A16) FUSED B+ CIRCUITS Turn the ignition off. Remove the High Speed Radiator Fan Relay. Using a 12-volt test light connected to ground, probe the (A16) Fused B+ circuits in the Relay connection. Does the test light illuminate brightly? Yes Go to 3) . No Repair the open or short to ground in the (A16) Fused B+ circuits. Inspect the related fuse and repair as necessary. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) .
3. 3) HIGH SPEED RADIATOR FAN RELAY RESISTANCE Measure the resistance of the High Speed Radiator Fan Relay Coil. Is the resistance between 60 to 80 ohms? Yes Go to 4) . No Replace the Relay. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) (N112) COOLING FAN NO. 2 CONTROL CIRCUIT OPEN Disconnect the IPM FCM 49 way harness connector. Measure the resistance of the (N112) Cooling Fan No. 2 Relay Control circuit from the Relay connection to the IPM FCM harness connector. Is the resistance below 5.0 ohms? Yes Go to 5) . No Repair the open in the (N112) Cooling Fan No. 2 Relay Control circuit. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) .
5. 5) (N112) COOLING FAN NO. 2 CONTROL CIRCUIT SHORTED TO GROUND Measure the resistance between ground and the (N112) Cooling Fan No. 2 Relay Control circuit at the Relay connection. Is the resistance below 100 ohms? Yes Repair the short to ground in the (N112) Cooling Fan No. 2 Relay Control circuit. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) . No Go to 6) .
6. 6) FRONT CONTROL MODULE (FCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Cooling Fan Relay and the Front Control Module (FCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Cooling Fan Relay and Front Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) . No Replace the Front Control Module per Service Information. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) .

1. When Monitored: Ignition on with the Cooling Fan No. 2 Relay powered on.

1. Set Condition: The FCM detects the Cooling Fan No. 2 Relay voltage above the acceptable voltage at the FCM. The circuit is continuously monitored.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 450

1. 1) LOW SPEED RADIATOR FAN RELAY OPERATION Ignition on, engine not running. With a scan tool, actuate the High Speed Radiator Fan Relay. Is the Cooling Fan Relay operating? Yes Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure. No Go to 2) .
2. 2) (N112) COOLING FAN NO. 2 RELAY CONTROL CIRCUIT SHORTED TO VOLTAGE Turn the ignition off. Remove the High Speed Radiator Fan Relay. Disconnect the IPM FCM 49 way harness connector. Ignition on, engine not running. Measure the voltage on the (N112) Cooling Fan No. 2 Relay Control Circuit at the Relay terminal. Is there any voltage present? Yes Repair the short to voltage in the (N112) Cooling Fan No. 2 Relay Control circuit. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) . No Go to 3) .
3. 3) HIGH SPEED RADIATOR FAN RELAY RESISTANCE Measure the resistance of the High Speed Radiator Fan Relay Coil. Is the resistance between 60 to 80 ohms? Yes Go to 4) . No Replace the High Speed Radiator Fan Relay. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) FRONT CONTROL MODULE (FCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Cooling Fan Relay and the Front Control Module (FCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Cooling Fan Relay and Front Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) . No Replace Front Control Module per Service Information. Perform «BODY VERIFICATION TEST»(ref-288232-S30638820392008062000000) .

1. When Monitored: Ignition on and battery voltage greater than 10 volts.

1. Set Condition: An active DTC is stored in the TCM. One Trip Fault. Three good trips to turn off the MIL.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

1. When Monitored: Ignition on.

1. Set Condition: When the PCM recognizes Brake Switch No. 2 voltage is not equal to the applied value at the PCM when Brake Switch No. 1 is applied. This could be a normal condition. If this condition is seen repeatedly by the PCM the fault is set. Cruise will not work for the rest of the key cycle.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 451

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Scheme 454

Scheme 455

1. 1) ACTIVE DTC NOTE: Make sure the Stop Lamp Switch is adjusted properly before continuing. NOTE: Make sure the Stop Lamp Switch is properly wired, such as (B15) Brake Switch No. 1 and (B16) Brake Switch No. 2 Signal circuit are not switched at the harness connector. Ignition on, engine not running. With a scan tool, select View DTCs. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) (F942) FUSED IGNITION SWITCH CIRCUIT Turn the ignition off. Disconnect the Stop Lamp Switch harness connector. Using a 12-volt test light connected to ground, probe the (F942) Fused Ignition Switch Output circuit in the Stop Lamp Switch harness connector. Does the test light illuminate brightly? Yes Go to 3) . No Repair the open or short to ground in the (F942) Fused Ignition Switch Output circuit. Inspect the related fuse and repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
3. 3) STOP LAMP SWITCH Turn the ignition off. Measure the resistance between the (F942) Fused Ignition Switch Output circuit terminal and the (B16) Brake Switch No. 2 Signal circuit terminal in the Stop Lamp Switch. Measure the resistance between the (Z904) Ground circuit terminal and the (B15) Brake Switch No. 1 Signal terminal in the Stop Lamp Switch. Apply and release the Stop Lamp Switch while monitoring the ohmmeter. Does the resistance change from below 5.0 ohms to open circuit for each circuit check? Yes Go to 4) . No Replace the Stop Lamp Switch. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) (B16) BRAKE SWITCH NO. 2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE Disconnect the C3 PCM harness connector. Measure the voltage on the (B16) Brake Switch No. 2 Signal circuit in the Stop Lamp Switch harness connector. Ignition on, engine not running. Is the voltage above 0 volts? Yes Repair the short to battery voltage in the (B16) Brake Switch No. 2 Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 5) .
5. 5) (B16) BRAKE SWITCH NO. 2 SIGNAL CIRCUIT OPEN Turn the ignition off. Measure the resistance of the (B16) Brake Switch No. 2 Signal circuit from the Stop Lamp Switch harness connector to the appropriate terminal of special tool #8815. Is the resistance below 5.0 ohms? Yes Go to 6) . No Repair the open in the (B16) Brake Switch No. 2 Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) (B16) BRAKE SWITCH NO. 2 SIGNAL CIRCUIT SHORTED TO GROUND Measure the resistance between ground and the (B16) Brake Switch No. 2 Signal circuit in the Stop Lamp Switch harness connector. Is the resistance below 5.0 ohms? Yes Repair the short to ground in the (B16) Brake Switch No. 2 Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 7) .
7. 7) (B15) BRAKE SWITCH NO. 1 SIGNAL CIRCUIT OPEN Measure the resistance of the (B15) Brake Switch No. 1 Signal circuit from the Stop Lamp Switch harness connector to the appropriate terminal of special tool #8815. Is the resistance below 5.0 ohms? Yes Go to 8) . No Repair the open in the (B15) Brake Switch No. 1 Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
8. 8) PCM NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

Scheme 456

1. When Monitored: Continuously with the transmission in Park, Neutral, or Drive and NOT in Limp-in mode.

1. Set Condition: This code will set if the PCM detects an incorrect Park/Neutral switch state for a given mode of vehicle operation. Two trip fault. Three good trips to turn off the MIL.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 457

Scheme 458

1. 1) ACTIVE DTC NOTE: Check the TCM for DTCs, if P0706 is set in the TCM diagnose the TCM code before continuing. Ignition on, engine not running. While moving the gear selector through all gear positions (Park to 1 and back to Park). Using a scan tool, select View DTCs. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) TRS (T41) SENSE (P/N SENSE) CIRCUIT OPEN Turn the ignition off. Disconnect the C3 PCM harness connector. Disconnect the Transmission Range Sensor harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Measure the resistance of the TRS (T41) Sense (P/N Sense) circuit from the TRS harness connector to the appropriate terminal of special tool #8815. Is the resistance below 5.0 ohms? Yes Go to 3) . No Repair the open in the TRS (T41) Sense (P/N Sense) circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
3. 3) TRS (T41) SIGNAL CIRCUIT SHORTED TO GROUND Measure the resistance between ground and the TRS (T41) Sense (P/N Sense) circuit at the TRS harness connector. Is the resistance above 100k ohms? Yes Go to 4) . No Repair the short to ground in the TRS (T41) Sense (P/N Sense) circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) TRANSMISSION RANGE SENSOR Measure the resistance between ground and the (T41) TRS Sense (P/N Sense) circuit while moving the gear selector through each gear in the TRS connector. NOTE: The circuit is grounded in Park and Neutral and open in the other positions. Did the resistance change from above 100 kohms (open) to below 10.0 ohms (grounded)? Yes Go to 5) . No Verify that there is good pin to terminal contact in the TRS and Powertrain Control Module connectors. Replace the Transmission Range Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
5. 5) POWERTRAIN CONTROL MODULE (PCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Transmission Range Sensor and the Powertrain Control Module (PCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the TRS and Powertrain Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

Scheme 459

1. When Monitored: Ignition on and battery voltage greater than 10 volts.

1. Set Condition: Ambient Air, Engine Coolant, and Intake Air Temp sensor inputs are compared under cold start conditions. After start up the temp readings are monitored. If two of the three readings agree and the third doesn't, a DTC is stored. Two Trip Fault. Three good trips to turn off the MIL.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 460

Scheme 461

Scheme 462

Scheme 463

Scheme 464

Scheme 465

Scheme 466

Scheme 467

Scheme 468

1. 1) ACTIVE DTC Ignition on, engine not running. With a scan tool, select View the DTCs. NOTE: All ECT, Intake Air, and Ambient Air Temperature Sensor codes must be diagnosed and repaired before continuing. NOTE: In cold weather, this DTC could be set by a high powered block heater and no repair would be required. NOTE: It may be necessary to test drive the vehicle to get the fault to an Active or Pending state because it takes two failed trips to set. Is the DTC Active or Pending at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) TEMPERATURE SENSOR CIRCUIT With a scan tool, read the ECT, Ambient Air Temp, and Intake Air Temp Sensor temp values. Start the engine. Allow the engine to reach normal operating temperature while monitoring the three Sensor temperature values. Is the temperature for each of the Sensors increasing properly? Yes Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure. No Go to 3) .
3. 3) TEMPERATURE SENSOR Disconnect the suspected sensor. Ignition on, engine not running. With the scan tool, read the voltage of the suspected Sensor. Connect a jumper wire between the Sensor Signal circuit and the Sensor ground circuit. Did the voltage reading start at 4.8 to 5.0 volts and decrease to 0 volts when the jumper wire was installed? Yes Replace the Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 4) . NOTE: Remove the jumper wire before continuing.
4. 4) EXCESSIVE RESISTANCE IN THE TEMPERATURE SENSOR SIGNAL CIRCUIT Turn the ignition off. Disconnect the C2 PCM harness connector. Disconnect the C2 FCM harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Measure the resistance of the Sensor Signal circuit from the Sensor harness connector to the appropriate terminal of special tool #8815 for the ECT Sensor and IAT Sensor. Measure the resistance of the (G31) AAT Sensor Signal circuit from the Sensor harness connector to the C2 FCM harness connector. Is the resistance above 5.0 ohms. Yes Repair the excessive resistance in the Temperature Sensor Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 5) .
5. 5) EXCESSIVE RESISTANCE IN THE SENSOR GROUND CIRCUIT Measure the resistance of the (K900) Sensor ground circuit from the ECT Sensor and IAT Sensor to the appropriate terminal of special tool #8815. Measure the resistance of the (G931) Sensor ground circuit from the AAT Sensor harness connector to the C2 FCM harness connector. Is the resistance above 5.0 ohms. Yes Repair the excessive resistance in the Sensor ground circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 6) .
6. 6) PCM NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

1. When Monitored: Engine running in closed loop mode.

1. Set Condition: Enable conditions are met and the 02 sensor has not been in closed loop control at least once on each of the two consecutive trips, the MIL illuminates and the DTC is set. Two Trip Fault. Three good trips to turn off the MIL

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 469

Scheme 470

1. 1) ACTIVE DTC Diagnose all other trouble codes before continuing. Start the engine. Allow the engine to reach normal operating temperature. With a scan tool, select View DTCs. NOTE: It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data. Is the DTC Active or Pending at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) CHECKING FUEL PRESSURE WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in personal injury or death. Turn the ignition off. Install a fuel pressure gauge to the fuel rail. Ignition on, engine not running. With a scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge. NOTE: Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi). Turn the ignition off. Choose a conclusion that best matches your fuel pressure reading. Within Specification Go to 3) . Above Specification Replace the fuel filter/pressure regulator. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . Below Specification Go to 12) . CAUTION: Stop All Actuations.
3. 3) O2 SENSOR OPERATION Start the engine. Allow the engine to reach normal operating temperature. NOTE: If one of the O2 Sensor's Signal or Return circuit is shorted to ground the scan tool will display all O2 Sensor voltage readings low. The O2 Sensor that is shorted to ground will display a voltage reading near or at 0 volts. NOTE: If one of the O2 Sensor Signal or Return circuits are shorted to voltage, the scan tool will display all O2 Sensor voltage readings high. NOTE: After the repairs have been made, verify proper O2 Sensor operation. If all the O2 Sensor voltage readings have not returned to normal, follow the diagnostic procedure for the remaining O2 Sensors. With a scan tool, monitor all of the O2 Sensor voltage readings. Is the voltage switching between 2.5 and 3.4 volts for all the O2 Sensors? Yes Go to 4) . No Go to 8) .
4. 4) 1/1 O2 SENSOR HEATER OPERATION Turn the ignition off. NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test. Allow the O2 Sensor voltage to stabilize at 5.0 volts. Ignition on, engine not running. With a scan tool, actuate the 1/1 O2 Heater Test. With the scan tool, monitor 1/1 O2 Sensor voltage for at least 2 minutes. Does the voltage stay above 4.5 volts? Yes Verify that there is good pin to terminal contact in the 1/1 O2 Sensor and Powertrain Control Module connectors. If OK, replace the 1/1 O2 Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 5) .
5. 5) MAP SENSOR OPERATION Turn the ignition off. Connect a Vacuum Gauge to a Manifold Vacuum source. Start the engine. Allow the engine to idle. NOTE: If engine will not idle, maintain a constant RPM above idle. With the scan tool, read the MAP Sensor vacuum value. Is the scan tool reading within 1" of Hg on the Vacuum Gauge reading? Yes Go to 6) . No Verify that there is good pin to terminal contact in the MAP Sensor and Powertrain Control Module connectors. If OK, replace the MAP Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) ECT SENSOR OPERATION NOTE: For this test to be valid, the thermostat must be operating correctly. NOTE: This test works best if performed on a cold engine (cold soak) Ignition on, engine not running. With a scan tool, read the Engine Coolant Temperature (ECT) Sensor value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature. NOTE: If engine coolant temperature is above 82° C (180° F), allow the engine to cool until 65° C (150° F) is reached. Start the Engine. During engine warm-up, monitor the ECT Sensor value. The temperature value change should be a smooth transition from start up to normal operating temperature 82° C (180° F). The value should reach at least 82° C (180° F). Did the ECT value increase smoothly and did it reach at least 82° C (180° F)? Yes Go to 7) . No Verify that there is good pin to terminal contact in the ECT Sensor and Powertrain Control Module connectors. If OK, replace the Engine Coolant Temperature Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
7. 7) ENGINE MECHANICAL PROBLEM Turn the ignition off. Check for any of the following conditions/mechanical problems. AIR INDUCTION SYSTEM - must be free from leaks. ENGINE VACUUM - must be at least 13 inches in neutral ENGINE VALVE TIMING - must be within specifications ENGINE COMPRESSION - must be within specifications ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks. ENGINE PCV SYSTEM - must flow freely TORQUE CONVERTER STALL SPEED - must be within specifications POWER BRAKE BOOSTER - no internal vacuum leaks FUEL - must be free of contamination FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector Are there any engine mechanical problems? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 11) .
8. 8) 1/1 O2 SENSOR Ignition on, engine not running. Disconnect the 1/1 O2 Sensor harness connector. With a scan tool, monitor the 1/1 O2 Sensor voltage. O2 Sensor voltage should read between 4.1 and 5.0 volts on the scan tool with the connector disconnected. Connect a jumper wire between the (K41) Signal circuit and the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector. NOTE: The voltage should drop from between 4.1 and 5.0 volts to 2.5 volts with the jumper wire in place. Did the O2 Sensor voltage change from between 4.1 and 5.0 volts to 2.5 volts with the jumper wire installed? Yes Verify that there is good pin to terminal contact in the O2 Sensor and Powertrain Control Module connectors. If OK, replace the O2 Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 9) . NOTE: Remove the jumper wire before continuing.
9. 9) (K41) O2 SENSOR 1/1 SIGNAL CIRCUIT With a scan tool, monitor the 1/1 O2 Sensor voltage reading with the jumper wire removed. NOTE: The scan tool will display all O2 Sensor voltage readings approximately 5.0 volts when only one O2 Sensor's Signal circuit is shorted to voltage. NOTE: The scan tool will display one O2 Sensor voltage close to zero and the others will read lower than normal when one O2 Sensor Signal circuit contains excessive resistance. Is the voltage between 4.1 and 5.0 volts? Yes Go to 10) . No Check the (K41) O2 Sensor 1/1 Signal circuit for a short to ground, open, or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
10. 10) (K902) O2 RETURN UPSTREAM CIRCUIT Measure the voltage on the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector. Is the voltage at 2.5 volts? Yes Go to 11) . No Check the O2 Return Upstream circuit for a short to ground, open, or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
11. 11) POWERTRAIN CONTROL MODULE (PCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the related Sensors and the Powertrain Control Module (PCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related Sensor and Powertrain Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
12. 12) RESTRICTED FUEL SUPPLY LINE WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in personal injury or death. Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module. Install special 5/16 fuel line adapter tool #6539 between disconnected fuel line and the fuel pump module. Attach a fuel pressure test gauge to the T fitting on tool #6539. Ignition on, engine not running. With a scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge. NOTE: Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi). Is the fuel pressure within specification? Yes Repair or replace fuel supply line as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 13) . CAUTION: Stop All Actuations.
13. 13) FUEL PUMP INLET STRAINER WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Turn the ignition off. Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer. Is the Fuel Inlet Strainer plugged? Yes Replace the Fuel Pump Inlet Strainer. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 14) .
14. 14) FUEL PUMP MODULE If there are no possible causes remaining, view repair. Repair Verify that there is good pin to terminal contact in the Fuel Pump Module, Relay, and Powertrain Control Module connectors. If OK, replace the Fuel Pump Module. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

1. When Monitored: Engine running in closed loop mode.

1. Set Condition: Enable conditions are met and the 02 sensor has not been in closed loop control at least once on each of the two consecutive trips, the MIL illuminates and the DTC is set. Two Trip Fault. Three good trips to turn off the MIL

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 471

Scheme 472

1. 1) ACTIVE DTC Diagnose all other trouble codes before continuing. NOTE: Check for contaminants that may have damaged an O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant. Start the engine. Allow the engine to reach normal operating temperature. With a scan tool, select View DTCs. NOTE: It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data. Is the DTC Active or Pending at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) CHECKING FUEL PRESSURE WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in personal injury or death. Turn the ignition off. Install a fuel pressure gauge to the fuel rail. Ignition on, engine not running. With the scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge. NOTE: Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi). Turn the ignition off. Choose a conclusion that best matches your fuel pressure reading. Within Specification Go to 3) . Above Specification Replace the fuel filter/pressure regulator. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . Below Specification Go to 12) . CAUTION: Stop All Actuations.
3. 3) O2 SENSOR OPERATION Start the engine. Allow the engine to reach normal operating temperature. NOTE: If one of the O2 Sensor's Signal or Return circuit is shorted to ground the scan tool will display all O2 Sensor voltage readings low. The O2 Sensor that is shorted to ground will display a voltage reading near or at 0 volts. NOTE: If one of the O2 Sensor Signal or Return circuits are shorted to voltage, the scan tool will display all O2 Sensor voltage readings high. NOTE: After the repairs have been made, verify proper O2 Sensor operation. If all the O2 Sensor voltage readings have not returned to normal, follow the diagnostic procedure for the remaining O2 Sensors. With the scan tool, monitor the 2/1 O2 Sensor voltage reading. Is the voltage switching between 2.5 and 3.4 volts? Yes Go to 4) . No Go to 8) .
4. 4) 2/1 O2 SENSOR HEATER OPERATION Turn the ignition off. NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test. Allow the O2 Sensor voltage to stabilize at 5.0 volts. NOTE: Perform the following test on all O2 Sensors. Ignition on, engine not running. With a scan tool, actuate the 2/1 O2 Heater Test. With the scan tool, monitor 2/1 O2 Sensor voltage for at least 2 minutes. Does the voltage stay above 4.5 volts? Yes Verify that there is good pin to terminal contact in the 2/1 O2 Sensor and Powertrain Control Module connectors. If OK, replace the 2/1 O2 Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 5) .
5. 5) MAP SENSOR OPERATION Turn the ignition off. Connect a Vacuum Gauge to a Manifold Vacuum source. Start the engine. Allow the engine to idle. NOTE: If engine will not idle, maintain a constant RPM above idle. With the scan tool, read the MAP Sensor vacuum value. Is the scan tool reading within 1 inch of Hg on the Vacuum Gauge reading? Yes Go to 6) . No Verify that there is good pin to terminal contact in the MAP Sensor and Powertrain Control Module connectors. If OK, replace the MAP Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) ECT SENSOR OPERATION NOTE: For this test to be valid, the thermostat must be operating correctly. NOTE: This test works best if performed on a cold engine (cold soak). Ignition on, engine not running. With the scan tool, read the Engine Coolant Temperature (ECT) Sensor value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature. NOTE: If engine coolant temperature is above 82° C (180° F), allow the engine to cool until 65° C (150° F) is reached. Start the Engine. During engine warm-up, monitor the ECT Sensor value. The temperature value change should be a smooth transition from start up to normal operating temperature 82° C (180° F). The value should reach at least 82° C (180° F). Did the ECT value increase smoothly and did it reach at least 82° C (180° F)? Yes Go to 7) . No Verify that there is good pin to terminal contact in the ECT Sensor and Powertrain Control Module connectors. If OK, replace the Engine Coolant Temperature Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
7. 7) ENGINE MECHANICAL PROBLEM Turn the ignition off. Check for any of the following conditions/mechanical problems. AIR INDUCTION SYSTEM - must be free from leaks. ENGINE VACUUM - must be at least 13 inches in neutral. ENGINE VALVE TIMING - must be within specifications. ENGINE COMPRESSION - must be within specifications. ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks ENGINE PCV SYSTEM - must flow freely. TORQUE CONVERTER STALL SPEED - must be within specifications. POWER BRAKE BOOSTER - no internal vacuum leaks. FUEL - must be free of contamination. FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector. Are there any engine mechanical problems? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 11) .
8. 8) O2 SENSOR Ignition on, engine not running. Disconnect the 2/1 O2 Sensor harness connector. With the scan tool, monitor the 2/1 O2 Sensor voltage. O2 Sensor voltage should read between 4.1 and 5.0 volts on the scan tool with the connector disconnected. Connect a jumper wire between the (K43) O2 Sensor 2/1 Signal circuit and the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector. NOTE: The voltage should drop from between 4.1 and 5.0 volts to 2.5 volts with the jumper wire in place. Did the O2 Sensor voltage change from between 4.1 and 5.0 volts to 2.5 volts when the jumper wire was installed? Yes Verify that there is good pin to terminal contact in the 2/1 O2 Sensor and Powertrain Control Module connectors. If OK, replace the 2/1 O2 Sensor. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 9) . NOTE: Remove the jumper wire before continuing.
9. 9) O2 SENSOR SIGNAL CIRCUIT With the scan tool, monitor all the O2 Sensor voltage reading with the jumper wire removed. NOTE: The scan tool will display all O2 Sensor voltage readings approximately 5.0 volts when only one O2 Sensor's Signal circuit is shorted to voltage. NOTE: The scan tool will display one O2 Sensor voltage close to zero and the others will read lower than normal when one O2 Sensor Signal circuit contains excessive resistance. Is the voltage between 4.1 and 5.0 volts? Yes Go to 10) . No Check all the O2 Signal circuits for a short to ground, open, or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
10. 10) (K902) O2 RETURN UPSTREAM CIRCUIT Measure the voltage on the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector. Is the voltage at 2.5 volts? Yes Go to 11) . No Check the (K902) O2 Return Upstream circuit for a short to ground, open, or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
11. 11) POWERTRAIN CONTROL MODULE (PCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the related Sensor and the Powertrain Control Module (PCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related Sensor and Powertrain Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
12. 12) RESTRICTED FUEL SUPPLY LINE WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in personal injury or death. Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module. Install special 5/16 fuel line adapter tool #6539 between disconnected fuel line and the fuel pump module. Attach a fuel pressure test gauge to the T fitting on tool #6539. Ignition on, engine not running. With the scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge. NOTE: Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi). Is the fuel pressure within specification? Yes Repair or replace fuel supply line as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 13) . CAUTION: Stop All Actuations.
13. 13) FUEL PUMP INLET STRAINER WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Turn the ignition off. Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer. Is the Fuel Inlet Strainer plugged? Yes Replace the Fuel Pump Inlet Strainer. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 14) .
14. 14) FUEL PUMP MODULE If there are no possible causes remaining, view repair. Repair Verify that there is good pin to terminal contact in the Fuel Pump Module, Relay, and Powertrain Control Module connectors. If OK, replace the Fuel Pump Module. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

Scheme 473

1. When Monitored: Engine running.

1. Set Condition: The EGR flow or valve movement is not what is expected. A rationality error has been detected for the EGR Open Position Performance. Two trip fault.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 474

Scheme 475

Scheme 476

Scheme 477

1. 1) ACTIVE DTC NOTE: Diagnose and repair any EGR signal circuit high or low DTCs before continuing with this procedure. Turn the ignition on. With the scan tool, select View DTCs. Record DTC and Freeze Frame information. Start the engine and allow it to reach operating temperature. WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose fitting clothing. Failure to follow these instructions can result in personal or fatal injury. WARNING: The normal operating temperature of the EGR system is very high. Never work around or attempt to service any part of the EGR system until it has cooled. NOTE: Attempt to operate the vehicle under conditions similar to which the DTC was set. NOTE: It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set. With a scan tool, select View DTCs. Is the DTC Active or Pending at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) EXCESSIVE RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT Turn the ignition off. Disconnect the EGR Solenoid harness connector. Disconnect the C1 and C2 PCM harness connectors. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Measure the resistance of the (F856) 5-volt Supply circuit from the EGR Solenoid harness connector to the appropriate terminal of special tool #8815. Is the resistance below 5.0 ohms? Yes Go to 3) . No Repair the excessive resistance in the (F856) 5-volt Supply circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
3. 3) (K35) EGR SOLENOID CONTROL CIRCUIT OPEN Measure the resistance of the (K35) EGR Solenoid Control circuit from the EGR Solenoid harness connector to the appropriate terminal of special tool #8815. Is the resistance below 5.0 ohms? Yes Go to 4) . No Repair the open in the (K35) EGR Solenoid Control circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) (K34) EGR SENSOR SIGNAL CIRCUIT SHORTED TO GROUND Measure the resistance between ground and the (K34) EGR Sensor Signal circuit in the EGR Solenoid harness connector. Is the resistance below 5.0 ohms? Yes Repair the short to ground in the (K34) EGR Sensor Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 5) .
5. 5) (Z42) GROUND CIRCUIT OPEN OR HIGH RESISTANCE Turn the ignition off. Disconnect the EGR Valve Assembly harness connector. Using a 12 volt test light connected to the 12 volts, check the (Z42) Ground circuit in the EGR Valve Assembly harness connector. NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery. Is the test light illuminated and bright? Yes Go to 6) . No Repair the (Z42) Ground circuit for an open circuit of high resistance. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) (K35) EGR CONTROL CIRCUIT HIGH RESISTANCE Turn the ignition off. Connect the EGR Valve Assembly connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis. Using a voltmeter, perform a voltage drop test by backprobing the (K35) EGR Control circuit at the EGR Valve Assembly harness connector and probing the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so that positive polarity is displayed on the voltmeter. Start the engine and allow it to reach operating temperature. WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death. With the scan tool, perform the EGR System Test. Select OPEN to open the EGR valve. Monitor the circuit voltage on the voltmeter. Is the voltage below 0.5 volts when the valve was opened during the system test? Yes Go to 7) . No Repair the (K35) EGR Control circuit for excessive resistance. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
7. 7) EGR SOLENOID ASSEMBLY Connect the Powertrain Control Module (PCM) connector. Turn the ignition on. With the scan tool, actuate the EGR Valve Solenoid Duty Cycle. Select the Duty Cycle reading of 79.9% Using a 12 volt test light connected to ground, check the (K35) EGR Control circuit in the EGR Valve Assembly harness connector. NOTE: If the DTC is active, the actuation test may not be allowed by the PCM. If may be necessary to clear the DTCs before starting the actuation. NOTE: The voltage supplied to the solenoid circuit during the actuation may be less than battery voltage. The test light should be illuminated, but may not be as bright as a direct connection to the battery. NOTE: The test light should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery. Is the test light illuminated during the actuation? Yes Go to 8) . No Verify that there is good pin to terminal contact in the Solenoid and Powertrain Control Module connectors. If OK, replace the EGR Solenoid Assembly per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
8. 8) POWERTRAIN CONTROL MODULE (PCM) Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the EGR Solenoid Assembly and the Powertrain Control Module (PCM). Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Solenoid and Powertrain Control Module connectors. Refer to any Technical Service Bulletins that may apply. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

Scheme 478

When all criteria has been met, power is supplied to each MDS Solenoid when the engine is making a transition from 8 cylinder mode to 4 cylinder mode. By actuating the solenoid, oil pressure is raised to the pair of lifters that coincide with each particular solenoid. The oil pressure pushes in the locking pins that allows the lifter to collapse, decoupling the valves and camshaft.

1. When Monitored: Transition from 4 to 8 cylinder mode.

1. Set Condition: The MDS fails to disengage for cylinder 1. One trip fault.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 479

Scheme 480

Scheme 481

Scheme 482

1. 1) ACTIVE DTC NOTE: Diagnose any Misfire DTCs before continuing. Start the engine and allow it to reach normal operating temperature. WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death. NOTE: It may be necessary to test drive the vehicle in order for this DTC to set. With a scan tool, select View DTCs. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) (K451) MDS SOLENOID NO. 1 CONTROL CIRCUIT SHORTED TO VOLTAGE Turn the ignition off. Disconnect the C3 PCM harness connector. Disconnect the C112 In-line harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Turn the ignition on. Measure the voltage on (K451) MDS Solenoid No. 1 Control circuit in the appropriate terminal of special tool #8815. Is there any voltage present? Yes Repair the short to voltage in the (K451) MDS Solenoid No. 1 Control circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 3) .
3. 3) MDS SOLENOID RESISTANCE Turn the ignition off. Reconnect the C112 In-line harness connector. Measure the resistance between the (Z42) Ground Circuit and the (K451) MDS Solenoid No. 1 Control Circuit in the appropriate terminals of special tool #8815. NOTE: It is important to follow the below temp/resistance values to ensure an accurate reading. MDS SOLENOID RESISTANCE TEMPERATURE VALUE ± -7° C (20° F) RESISTANCE (OHMS) ±.25 ohms -18° C (0° F) 8.8 ohms 0° C (32° F) 9.5 ohms 20° C (68° F) 10.3 ohms 38° C (100° F) 11 ohms 66° C (150° F) 12.2 ohms 93° C (200° F) 13.4 ohms 121° C (250° F) 14.4 ohms 149° C (300° F) 15.6 ohms Is the resistance within an acceptable range? Yes Go to 4) . No Visually and Physically inspect the wiring harness between the C112 In-line connector and the MDS Solenoid connector. Repair as necessary. If OK, replace the MDS Solenoid in accordance with the Service Information.
4. 4) PCM CONTROL Turn the ignition off. Reconnect the C3 PCM harness connector. Disconnect the C112 In-line harness connector. Ignition on, engine not running. Using a 12-volt test light connected to the (Z42) Ground circuit, probe the (K451) MDS Solenoid No. 1 Control circuit in the C112 In-line harness connector (PCM side). With a scan tool, actuate the MDS Solenoid. NOTE: The test light should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery. Does the 12-volt test light flash on and off? Yes Go to 5) . No Replace and program the Powertrain Control Module in accordance with the Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
5. 5) MDS SOLENOID 1 Turn the ignition off. Remove the Intake Manifold per Service Information. Turn the ignition on. With the scan tool actuate the MDS Solenoid 1. Can you feel and hear the Solenoid Actuating? Yes Go to 6) . No Remove the Solenoid (1) and check for any debris that may be blocking the oil passages (3) to the Solenoid. If the passages are clogged, clean the passages and replace the MDS Solenoid 1. If the passages are not clogged with debris, replace the MDS Solenoid 1. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) OIL PASSAGES RESTRICTED Turn the ignition off. Remove both Solenoids on Bank 1 of the engine block. Remove the Bank 1 Cylinder Head per Service Information. Remove the Lifters from the left engine bank. Inspect the oil passages to the Solenoids and from the Solenoids to the lifters. Are the passages blocked? Yes Clean the oil passages as necessary. If the entire engine is restricted disassembly of the entire engine block may be necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace both sets of lifters if no other possible causes remain. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

1. When Monitored: Transition from 4 to 8 cylinder mode.

1. Set Condition: The MDS fails to disengage for cylinder 4.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 483

Scheme 484

1. 1) ACTIVE DTC NOTE: Diagnose any Misfire DTCs before continuing. Start the engine and allow it to reach normal operating temperature. WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death. NOTE: It may be necessary to test drive the vehicle in order for this DTC to set. With a scan tool, select View DTCs. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) (K452) MDS SOLENOID NO. 4 CONTROL CIRCUIT SHORTED TO VOLTAGE Turn the ignition off. Disconnect the C1 PCM harness connector. Disconnect the C112 In-line harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Turn the ignition on. Measure the voltage on (K452) MDS Solenoid No. 4 Control circuit in the appropriate terminal of special tool #8815. Is voltage present? Yes Repair the short to voltage in the (K452) MDS Solenoid No. 4 Control circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 3) .
3. 3) MDS SOLENOID RESISTANCE Turn the ignition off. Reconnect the C112 In-line harness connector. Measure the resistance between the (Z42) Ground Circuit and the (K452) MDS Solenoid No. 4 Control Circuit in the appropriate terminals of special tool #8815. NOTE: It is important to follow the below temp/resistance values to ensure an accurate reading. MDS SOLENOID RESISTANCE TEMPERATURE VALUE ± -7° C (20° F) RESISTANCE (OHMS) ±.25 ohms -18° C (0° F) 8.8 ohms 0° C (32° F) 9.5 ohms 20° C (68° F) 10.3 ohms 38° C (100° F) 11 ohms 66° C (150° F) 12.2 ohms 93° C (200° F) 13.4 ohms 121° C (250° F) 14.4 ohms 149° C (300° F) 15.6 ohms Is the resistance within an acceptable range? Yes Go to 4) . No Visually and Physically inspect the wiring harness between the C112 In-line connector and the MDS Solenoid connector. Repair as necessary. If OK, replace the MDS Solenoid in accordance with the Service Information.
4. 4) PCM CONTROL Turn the ignition off. Reconnect the C1 PCM harness connector. Disconnect the C112 In-line harness connector. Ignition on, engine not running. Using a 12-volt test light connected to the (Z42) Ground circuit, probe the (K452) MDS Solenoid No. 4 Control circuit in the C112 In-line harness connector. With a scan tool, actuate the MDS Solenoid. NOTE: The test light should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery. Does the 12-volt test light flash on and off? Yes Go to 5) . No Replace and program the Powertrain Control Module in accordance with the Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
5. 5) MDS SOLENOID 4 Turn the ignition off. Remove the Intake Manifold per Service Information. Turn the ignition on. With the scan tool actuate the MDS Solenoid 4. Can you feel and hear the Solenoid Actuating? Yes Go to 6) . No Remove the Solenoid (1) and check for any debris that may be blocking the oil passages (3) to the Solenoid. If the passages are clogged, clean the passages and replace the MDS Solenoid 4. If the passages are not clogged with debris, replace the MDS Solenoid 4. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) OIL PASSAGES RESTRICTED Turn the ignition off. Remove both Solenoids on Bank 2 of the engine block. Remove the Bank 2 Cylinder Head per Service Information. Remove the Lifters from the left engine bank. Inspect the oil passages to the Solenoids and from the Solenoids to the lifters. Are the passages blocked? Yes Clean the oil passages as necessary. If the entire engine is restricted disassembly of the entire engine block may be necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace both sets of lifters if no other possible causes remain. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

1. When Monitored: Transition from 4 to 8 cylinder mode.

1. Set Condition: The MDS fails to disengage for cylinder 6.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 485

Scheme 486

Scheme 487

1. 1) ACTIVE DTC NOTE: Diagnose any Misfire DTCs before continuing. Start the engine and allow it to reach normal operating temperature. WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death. NOTE: It may be necessary to test drive the vehicle in order for this DTC to set. With a scan tool, select View DTCs. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) (K453) MDS SOLENOID NO. 6 CONTROL CIRCUIT SHORTED TO VOLTAGE Turn the ignition off. Disconnect the C2 PCM harness connector. Disconnect the C112 In-line harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Turn the ignition on. Measure the voltage on (K453) MDS Solenoid No. 6 Control circuit in the appropriate terminal of special tool #8815. Is there any voltage present? Yes Repair the short to voltage in the (K453) MDS Solenoid No. 6 Control circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 3) .
3. 3) MDS SOLENOID RESISTANCE Turn the ignition off. Reconnect the C112 In-line harness connector. Measure the resistance between the (Z42) Ground Circuit and the (K453) MDS Solenoid No. 6 Control Circuit in the appropriate terminals of special tool #8815. NOTE: It is important to follow the below temp/resistance values to ensure an accurate reading. MDS SOLENOID RESISTANCE TEMPERATURE VALUE ± -7° C (20° F) RESISTANCE (OHMS) ±.25 ohms -18° C (0° F) 8.8 ohms 0° C (32° F) 9.5 ohms 20° C (68° F) 10.3 ohms 38° C (100° F) 11 ohms 66° C (150° F) 12.2 ohms 93° C (200° F) 13.4 ohms 121° C (250° F) 14.4 ohms 149° C (300° F) 15.6 ohms Is the resistance within an acceptable range? Yes Go to 4) . No Visually and Physically inspect the wiring harness between the C112 connector and the MDS Solenoid connector. Repair as necessary. If OK, replace the MDS Solenoid in accordance with the Service Information.
4. 4) PCM CONTROL Turn the ignition off. Reconnect the C2 PCM harness connector. Disconnect the C112 In-line harness connector. Ignition on, engine not running. Using a 12-volt test light connected to the (Z42) Ground circuit, probe the (K453) MDS Solenoid No. 6 Control circuit in the C112 In-line harness connector (PCM side). With a scan tool, actuate the MDS Solenoid. NOTE: The test light should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery. Does the 12-volt test light flash on and off? Yes Go to 5) . No Replace and program the Powertrain Control Module in accordance with the Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
5. 5) MDS SOLENOID 6 Turn the ignition off. Remove the Intake Manifold per Service Information. Turn the ignition on. With the scan tool actuate the MDS Solenoid 6. Can you feel and hear the Solenoid Actuating? Yes Go to 6) . No Remove the Solenoid (1) and check for any debris that may be blocking the oil passages (3) to the Solenoid. If the passages are clogged, clean the passages and replace the MDS Solenoid 6. If the passages are not clogged with debris, replace the MDS Solenoid 6. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) OIL PASSAGES RESTRICTED Turn the ignition off. Remove both Solenoids on Bank 2 of the engine block. Remove the Bank 2 Cylinder Head per Service Information. Remove the Lifters from the right engine bank. Inspect the oil passages to the Solenoids and from the Solenoids to the lifters. Are the passages blocked? Yes Clean the oil passages as necessary. If the entire engine is restricted disassembly of the entire engine block may be necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace both sets of lifters if no other possible causes remain. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

1. When Monitored: Transition from 4 to 8 cylinder mode.

1. Set Condition: The MDS fails to disengage for cylinder 7. One trip fault.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 488

Scheme 489

Scheme 490

1. 1) ACTIVE DTC NOTE: Diagnose any Misfire DTCs before continuing. Ignition on, engine not running. With a scan tool, select View DTCs. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) (K454) MDS SOLENOID NO. 7 CONTROL CIRCUIT SHORTED TO VOLTAGE Turn the ignition off. Disconnect the C3 PCM harness connector. Disconnect the C112 In-line harness connector. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Turn the ignition on. Measure the voltage on (K454) MDS Solenoid No. 7 Control circuit in the appropriate terminal of special tool #8815. Is there any voltage present? Yes Repair the short to voltage in the (K454) MDS Solenoid No. 7 Control circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 3) .
3. 3) MDS SOLENOID RESISTANCE Turn the ignition off. Reconnect the C112 In-line harness connector. Measure the resistance between the (Z42) Ground Circuit and the (K454) MDS Solenoid No. 7 Control Circuit in the appropriate terminals of special tool #8815. NOTE: It is important to follow the below temp/resistance values to ensure an accurate reading. MDS SOLENOID RESISTANCE TEMPERATURE VALUE ± -7° C (20° F) RESISTANCE (OHMS) ±.25 ohms -18° C (0° F) 8.8 ohms 0° C (32° F) 9.5 ohms 20° C (68° F) 10.3 ohms 38° C (100° F) 11 ohms 66° C (150° F) 12.2 ohms 93° C (200° F) 13.4 ohms 121° C (250° F) 14.4 ohms 149° C (300° F) 15.6 ohms Is the resistance within an acceptable range? Yes Go to 4) . No Visually and Physically inspect the wiring harness between the C112 connector and the MDS Solenoid connector. Repair as necessary. If OK, replace the MDS Solenoid in accordance with the Service Information.
4. 4) PCM CONTROL Turn the ignition off. Reconnect the PCM harness connector. Disconnect the C112 In-line harness connector. Ignition on, engine not running. Using a 12-volt test light connected to the (Z42) Ground circuit, probe the (K454) MDS Solenoid No. 7 Control circuit in the C112 In-line harness connector. With a scan tool, actuate the MDS Solenoid. NOTE: The test light should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery. Does the 12-volt test light flash on and off? Yes Go to 5) . No Replace and program the Powertrain Control Module in accordance with the Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
5. 5) MDS SOLENOID 7 Turn the ignition off. Remove the Intake Manifold per Service Information. Turn the ignition on. With the scan tool actuate the MDS Solenoid 7. Can you feel and hear the Solenoid Actuating? Yes Go to 6) . No Remove the Solenoid (1) and check for any debris that may be blocking the oil passages (3) to the Solenoid. If the passages are clogged, clean the passages and replace the MDS Solenoid 7. If the passages are not clogged with debris, replace the MDS Solenoid 7. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
6. 6) OIL PASSAGES RESTRICTED Turn the ignition off. Remove both Solenoids on Bank 1 of the engine block. Remove the Bank 7 Cylinder Head per Service Information. Remove the Lifters from the right engine bank. Inspect the oil passages to the Solenoids and from the Solenoids to the lifters. Are the passages blocked? Yes Clean the oil passages as necessary. If the entire engine is restricted disassembly of the entire engine block may be necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace both sets of lifters if no other possible causes remain. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

Scheme 491

1. When Monitored: Ignition on and vehicle moving. Cruise is learned and customer is trying to use the Cruise.

1. Set Condition: The PCM recognizes rear wheel speed is greater than front wheel speed. One trip fault.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

1. When Monitored: Ignition on and vehicle moving. Brake pedal must not be applied.

1. Set Condition: The PCM recognizes front axle speed is greater than rear axle speed. One trip fault.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

1. When Monitored: Engine Running.

1. Set Condition: Using the oil pressure, oil temperature and other vital engine inputs the PCM can determine the engine oil viscosity. Incorrect viscosity will effect the operation of the MDS by delaying cylinder activation.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

1. When Monitored: Ignition on. In plant mode only.

1. Set Condition: PCM recognizes the Brake Pedal could not electrically indicate the applied (On) position with both switch inputs. One trip fault.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

1. When Monitored: Ignition on, In plant mode passed the Applied test.

1. Set Condition: PCM recognizes the Brake Pedal could not electronically indicate the released (Off) position with both switches. If P1572 sets, P1573 will also set. One trip fault.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 492

1. 1) ACTIVE DTC NOTE: Make sure the Stop Lamp Switch is adjusted properly before continuing. Ignition on, engine not running. With a scan tool, select View DTCs. It may be necessary to press and release the Brake Pedal to get the code to become Active. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) STOP LAMP SWITCH OPERATION Turn the ignition off. Disconnect the Stop Lamp Switch harness connectors. Measure the resistance between the (Z904) Ground circuit terminal and the (B15) Brake Switch No. 1 Signal terminal in the Stop Lamp Switch. Apply and release the Stop Lamp Switch while monitoring the ohmmeter. Does the resistance change from below 5.0 ohms to an open circuit when pressing and releasing the brake switch? Yes Go to 3) . No Replace the Stop Lamp Switch. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
3. 3) STOP LAMP SWITCH OPERATION Measure the resistance between the (F942) Fused Ignition Switch circuit terminal and the (B16) Brake Switch No. 2 Signal circuit terminal in the Stop Lamp Switch. Apply and release the Stop Lamp Switch while monitoring the ohmmeter. Does the resistance change from below 5.0 ohms to an open circuit when pressing and releasing the Stop Lamp switch? Yes Go to 4) . No Replace the Stop Lamp Switch. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
4. 4) (B16) BRAKE SWITCH NO. 2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE Disconnect the C3 PCM harness connector. Ignition on, engine not running. Measure the voltage on the (B16) Brake Switch No. 2 Signal circuit in the Stop Lamp Switch harness connector. Is the voltage above 1.0 volt? Yes Repair the short to battery voltage in the (B16) Brake Switch No. 2 Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 5) .
5. 5) (B15) BRAKE SWITCH NO. 1 SIGNAL CIRCUIT SHORTED TO GROUND Turn the ignition off. Measure the resistance between ground and the (B15) Brake Switch No. 1 Signal circuit in the Stop Lamp Switch harness connector. Is the resistance below 100 ohms? Yes Repair the short to ground in the (B15) Brake Switch No. 1 Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 6) .
6. 6) PCM NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .

Scheme 493

1. When Monitored: Ignition on.

1. Set Condition: Cruise Switch inputs are not coherent with each other. Example: PCM is reading Switch No. 1 as Accel and Switch No. 2 as Coast at the same time. One trip fault.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Scheme 494

Scheme 495

Scheme 496

Scheme 497

Scheme 498

Scheme 499

Scheme 500

Scheme 501

Scheme 502

Scheme 503

1. 1) ACTIVE DTC Ignition on, engine not running. NOTE: This DTC may be the result of pressing two Speed Control Switch buttons simultaneously for more than 450 msec. Ask the customer if it is possible that two buttons were pressed at the same time before this DTC set. If this is the case, no repair is necessary. Is the DTC Active at this time? Yes Go to 2) . No Refer to «INTERMITTENT CONDITION»(ref-288287-S02739760862008062000000) Diagnostic Procedure.
2. 2) SPEED CONTROL ON/OFF SWITCH With the scan tool, monitor the Speed Control Switch voltage. Disconnect the Speed Control On/Off Switch harness connector. Did the voltage change to above 4.8 volts? Yes Replace the Speed Control On/Off Switch. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 3) .
3. 3) SPEED CONTROL RESUME/ACCEL SWITCH With the scan tool, monitor the Speed Control Switch voltage. Disconnect the Speed Control Resume/Accel Switch harness connector. Did the voltage change to above 4.8 volts? Yes Replace the Speed Control Resume/Accel Switch. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 4) .
4. 4) SPEED CONTROL SWITCHES Turn the ignition off. Remove and disconnect the Speed Control Switches from the steering wheel per Service Information. Measure the resistance across each Speed Control Switch. Monitor the ohmmeter while pressing each function button on each switch. The following resistance specs are taken between terminals (V372) S/C Switch No. 2 Signal and (V397) S/C Switch Return circuits of the Switch when holding the switch button in the following position. Not pressing any switch - 20.5 kohms On/Off - 8.87 kohms Set - 0.825 kohms Coast - 0.47 kohms Cancel - 3.92 kohms Resume/Accel - 1.87 kohms The following resistance specs are taken between terminals (V371) S/C Switch No. 1 Signal and (V397) S/C Switch Return circuits of the Switch when holding the switch button in the following position Not pressing any switch - 20.5 kohms On/Off - 0.47 kohms Set - 5.49 kohms Coast - 2.94 kohms Cancel - 1.24 kohms Resume/Accel - 15.4 kohms Does the function on the Speed Control Switches have the correct resistance value? Yes Go to 5) . No Replace the Speed Control Switch that had the incorrect resistance value. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
5. 5) S/C SWITCH SIGNAL CIRCUIT SHORTED TO VOLTAGE Disconnect the C3 PCM harness connector. Ignition on, engine not running. Measure the voltage on the (V371) and (V372) S/C Switch Signal circuits at both Speed Control harness connectors. Is there any voltage present? Yes Repair the short to voltage in the (V371) or (V372) S/C Switch Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 6) .
6. 6) STEERING COLUMN CONTROL MODULE Turn the ignition off. Disconnect the C1 and C3 SCCM harness connectors per Service Information. Measure the resistance of the (V371/V71) and (V372/V72) S/C Switch Signal circuits between the C1 and C3 SCCM connectors. Measure the resistance of the (V397/V937) Switch Return circuit between the C1 and C3 SCCM connectors. Is the resistance above 5.0 ohms? Yes Replace the SCCM per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 7) . NOTE: Connect the Steering Column Control Module harness connectors per Service Information before continuing.
7. 7) S/C SWITCH SIGNAL CIRCUIT OPEN CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis. Measure the resistance of the (V371/V71) and (V372/V72) S/C Switch Signal circuits from both Speed Control harness connectors to the appropriate terminals of special tool #8815. Is the resistance below 5.0 ohms for each measurement? Yes Go to 8) . No Repair the excessive resistance in the (V371/V71) or (V372/V72) S/C Switch Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
8. 8) (V397/V937) SWITCH RETURN CIRCUIT OPEN NOTE: The measurement must be taken from both Speed Control Switch harness connectors. Measure the resistance of the (V397/V937) Switch Return circuit from both Speed Control harness connector to the appropriate terminal of special tool #8815. Is the resistance below 5.0 ohms for both measurements? Yes Go to 9) . No Repair the excessive resistance in the (V397/V937) Switch Return circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .
9. 9) S/C SWITCH SIGNAL CIRCUITS SHORTED TO THE (V397/V937) SWITCH RETURN CIRCUIT Measure the resistance between the (V397) Switch Return circuit and both of the (V371) and (V372) S/C Switch Signal circuits in the Speed Control harness connector. Is the resistance below 5.0 ohms? Yes Repair the short between the (V397/V937) Switch Return circuit and the (V371/V71) or (V372/V72) S/C Switch Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 10) .
10. 10) (V371/V71) S/C SWITCH NO. 1 SIGNAL CIRCUIT SHORTED TO THE (V372/V72) S/C SWITCH NO. 2 SIGNAL CIRCUIT Measure the resistance between the (V371/V71) S/C Switch No. 1 Signal circuit and the (V372/72) S/C Switch No. 2 Signal circuit at both Speed Control harness connectors. Is the resistance below 100 ohms for each circuit? Yes Repair the short between the (V372/V72) S/C Switch No. 2 Signal circuit and the (V371) S/C Switch No. 1 Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 11) .
11. 11) S/C SWITCH SIGNAL CIRCUITS SHORTED TO GROUND Measure the resistance between ground and the (V371/V71) and (V372/V72) S/C Switch Signal circuits at both Switch harness connectors. Is the resistance below 100 ohms? Yes Repair the short to ground in the (V371/V71) or (V372/V72) S/C Switch Signal circuit. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 12) .
12. 12) SPEED CONTROL SWITCH VOLTAGE VALUES CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 and #8815-1 to perform diagnosis. Using a voltmeter check the voltage on the (V37) S/C Switch No. 1 Signal circuit and the (V38) S/C Switch No. 2 Signal circuit at the appropriate terminals of the special tool #8815. WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death. Start the engine and allow it to reach normal operating temperature. Monitor the voltmeter. Allow the engine to idle. With a scan tool, monitor the S/C Switch voltage readings. SWITCH POSITION SWITCH No. 1 VOLTAGE VALUE SWITCH No. 2 VOLTAGE VALUE NO SWITCHES PRESSED 4.31 to 4.78 volts 4.31 to 4.78 volts ON/OFF PRESSED 0.59 to 1.13 volts 3.53 to 3.92 volts RES/ACCEL PRESSED 3.88 to 4.17 volts 2.04 to 2.47 volts SET PRESSED 3.16 to 3.56 volts 1.17 to 1.56 volts COAST PRESSED 2.57 to 2.94 volts 0.77 to 1.09 volts CANCEL PRESSED 1.59 to 1.99 volts 2.84 to 3.25 volts Compare the voltage readings on the voltmeter to what the scan tool displayed. Are the voltage readings out of the listed specification and is there less than a 0.2 of a volt difference between the voltmeter switch values and the scan tool switch values? Yes Replace the Speed Control Switch. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Go to 13) .
13. 13) PCM NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits. Were there any problems found? Yes Repair as necessary. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) . No Replace and program the Powertrain Control Module per Service Information. Perform «POWERTRAIN VERIFICATION TEST»(ref-288299-S34942598282008062000000) .