Symptom:
P0520- OIL PRESS SENSOR CIRCUIT MALF PLAUSIBILITY
When Monitored and Set Condition:
P0520- OIL PRESS SENSOR CIRCUIT MALF PLAUSIBILITY
When Monitored: At engine start-up.
Set Condition: The oil pressure signal is below the lower limit for four seconds after
engine start-up.
POSSIBLE CAUSES
5-VOLT SUPPLY CIRCUIT OPEN
ECM - OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
ECM - OIL PRESSURE SENSOR SIGNAL SHORT TO GROUND
INCORRECT OIL PRESSURE
OIL PRESSURE SENSOR FAILURE
OIL PRESSURE SENSOR SIGNAL CIRCUIT OPEN
OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO SENSOR GROUND
OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
SENSOR GROUND CIRCUIT OPEN
INTERMITTENT CONDITION
TEST ACTION APPLICABILITY
1NOTE: If DTC P0641 or P0651 is present with this DTC, diagnose these
DTC's before diagnosing this DTC.
Turn the ignition on.
With the DRB III, erase ECM DTCs.
Cycle the ignition key on and off several times, leaving the key on for at least 10
seconds at a time.
Test drive the vehicle.
With the DRB III, read ECM DTCs.
Did this DTC reset?All
Ye s®Go To 2
No®Go To 10
2 Refer to the Service Information and perform the Oil Pressure Test.
Is the oil pressure within specification?All
Ye s®Go To 3
No®Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
107
DRIVEABILITY - DIESEL
Symptom:
P0685-ECM/PCM RELAY CONTROL CIRCUIT SHUTS OFF TOO
EARLY
When Monitored and Set Condition:
P0685-ECM/PCM RELAY CONTROL CIRCUIT SHUTS OFF TOO EARLY
When Monitored: During after-run.
Set Condition: The internal ECM timer determines that the ECM/PCM Relay has shut
off before the AFTER-RUN mode of operation has been completed.
POSSIBLE CAUSES
CHECK FOR OTHER DTCS
INTERMITTENT CONDITION
SUBSTITUTE ECM/PCM RELAY
ECM/PCM RELAY CONTROL CIRCUIT OPEN INTERMITTENTLY
ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, check for additional DTCs.
Are other DTCs present?All
Ye s®Refer to the Symptom List for diagnosis of the other DTCs before
continuing.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 2
2 Turn the ignition on.
With the DRB, erase ECM DTCs.
Perform several ignition key cycles, pausing for at least 10 seconds between each
cycle.
Turn the ignition on.
With the DRB, read ECM DTCs.
Did this DTC reset?All
Ye s®Go To 3
No®Go To 5
145
DRIVEABILITY - DIESEL
TEST ACTION APPLICABILITY
3 Turn the ignition off.
Install a substitute relay in place of the ECM/PCM Relay.
Perform several ignition key cycles, pausing for at least 10 seconds between each
cycle.
Turn the ignition on.
With the DRB, read ECM DTCs.
Did this DTC reset?All
Ye s®Go To 4
No®Replace the ECM/PCM Relay.
Perform ROAD TEST VERIFICATION - VER-2.
4 Turn the ignition off.
Remove the ECM/PCM Relay from the IPM.
Disconnect the ECM harness connectors.
Measure the resistance of the ECM/PCM Relay Control circuit while wiggling the
wiring harness and connectors between the ECM and the IPM.
Was the resistance above 5.0 ohms at any time while wiggling the wiring harness and
connectors?All
Ye s®Repair the ECM/PCM Relay Control circuit for an intermittent
open.
Perform ROAD TEST VERIFICATION - VER-2.
No®Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
5WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?All
Ye s®Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No®Test Complete.
146
DRIVEABILITY - DIESEL
P0685-ECM/PCM RELAY CONTROL CIRCUIT SHUTS OFF TOO EARLY Ð
Continued
Symptom:
P0685-ECM/PCM RELAY CONTROL CIRCUIT SHUTS OFF TOO
LATE
When Monitored and Set Condition:
P0685-ECM/PCM RELAY CONTROL CIRCUIT SHUTS OFF TOO LATE
When Monitored: During after-run.
Set Condition: The internal ECM timer determines that the ECM/PCM Relay remains on
too long when AFTER-RUN mode of operation has been completed.
POSSIBLE CAUSES
CHECK FOR OTHER DTCS
INTERMITTENT CONDITION
SUBSTITUTE ECM/PCM RELAY
ECM/PCM RELAY CONTROL CIRCUIT SHORTED TO GROUND INTERMITTENTLY
ECM/PCM RELAY OUTPUT CIRCUIT SHORTED TO VOLTAGE
ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, check for additional DTCs.
Are other DTCs present?All
Ye s®Refer to the Symptom List for diagnosis of the other DTCs before
continuing.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 2
2 Turn the ignition on.
With the DRB, erase ECM DTCs.
Perform several ignition key cycles, pausing for at least 10 seconds between each
cycle.
Turn the ignition on.
With the DRB, read ECM DTCs.
Did this DTC reset?All
Ye s®Go To 3
No®Go To 6
147
DRIVEABILITY - DIESEL
TEST ACTION APPLICABILITY
3 Turn the ignition off.
Install a substitute relay in place of the ECM/PCM Relay.
Perform several ignition key cycles, pausing for at least 10 seconds between each
cycle.
Turn the ignition on.
With the DRB, read ECM DTCs.
Did this DTC reset?All
Ye s®Go To 4
No®Replace the ECM/PCM Relay.
Perform ROAD TEST VERIFICATION - VER-2.
4 Turn the ignition off.
Remove the ECM/PCM Relay from the IPM.
Disconnect the ECM harness connectors.
Measure the resistance between ground and the ECM/PCM Relay Control circuit
while wiggling the wiring harness and connectors.
Was the resistance below 5.0 ohms at any time while wiggling the wiring harness and
connectors?All
Ye s®Repair the ECM/PCM Relay Control circuit for an intermittent
short to ground.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 5
5 Turn the ignition off.
Remove the ECM/PCM Relay from the IPM.
Turn the ignition on.
Measure the voltage of the ECM/PCM Relay Output circuit.
Is the voltage below 0.5 volt?All
Ye s®Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No®Repair the ECM/PCM Relay Output circuit for a short to voltage.
Perform ROAD TEST VERIFICATION - VER-2.
6WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?All
Ye s®Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No®Test Complete.
148
DRIVEABILITY - DIESEL
P0685-ECM/PCM RELAY CONTROL CIRCUIT SHUTS OFF TOO LATE Ð
Continued
Symptom:
P1605-IGNITION SWITCH PLAUSIBILITY
When Monitored and Set Condition:
P1605-IGNITION SWITCH PLAUSIBILITY
When Monitored: With the ignition on.
Set Condition: The ECM detects a short to voltage on the Ignition Switch Sense circuit.
POSSIBLE CAUSES
INTERMITTENT CONDITION
ECM/PCM RELAY
ENGINE CONTROL MODULE
IGNITION SWITCH SENSE CIRCUIT SHORTED TO VOLTAGE
ECM/PCM RELAY OUTPUT CIRCUIT SHORTED TO VOLTAGE
ECM/PCM RELAY CONTROL CIRCUIT SHORTED TO GROUND
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, erase ECM DTCs.
Cycle the ignition switch on and off several times, pausing for at least 10 seconds at
each key off and key on.
Turn the ignition on.
With the DRB, read ECM DTCs.
Did this DTC reset?All
Ye s®Go To 2
No®Go To 6
2 Turn the ignition off.
Disconnect the ECM harness connectors.
Measure the voltage of all cavities in the ECM harness connectors.
Is the voltage above 2.0 volts on any of the cavities?All
Ye s®Go To 3
No®Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
3 Turn the ignition off.
Disconnect the ECM harness connectors.
Measure the voltage on ECM harness connector C1, cavity 22.
Is voltage present on ECM harness connector C1, cavity 22?All
Ye s®Go To 4
No®Repair the Ignition Switch Sense circuit that measured above 2.0
volts for a short to voltage.
Perform ROAD TEST VERIFICATION - VER-2.
166
DRIVEABILITY - DIESEL
Symptom List:
P1685-SKIM SYSTEM INVALID KEY CODE RECEIVED
P1685-SKIM SYSTEM INVALID SECRET KEY IN EEPROM
P1685-SKIM SYSTEM KEY COMMUNICATION TIMED OUT
P1685-SKIM SYSTEM SKIM ERROR
P1685-SKIM SYSTEM WRITE ACCESS TO EEPROM FAILURE
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P1685-SKIM SYSTEM INVALID
KEY CODE RECEIVED.
When Monitored and Set Condition:
P1685-SKIM SYSTEM SKIM ERROR
When Monitored: With the ignition on and the immobilizer disarmed.
Set Condition: The ECM detects an open, short to ground, or short to voltage on the
immobilizer signal circuit.
P1685-SKIM SYSTEM WRITE ACCESS TO EEPROM FAILURE
When Monitored: With the ignition on.
Set Condition: The ECM determines that the coded message from the PCM does not
match the message programmed into memory.
POSSIBLE CAUSES
SKIM
INTERMITTENT CONDITION
CHECK FOR SKIM COMMUNICATION AND DTCS
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, check for Sentry Key Immobilizer Module communication and DTCs.
Are any SKIS problems or DTCs present?All
Ye s®Refer to symptom list for problems related to SKIM Communica-
tion and DTCs before continuing.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 2
168
DRIVEABILITY - DIESEL
TEST ACTION APPLICABILITY
2 Turn the ignition on.
With the DRBIIIt, erase ECM DTCs.
Turn the ignition on and off several times pausing 10 seconds between each key cycle.
With the DRBIIIt, read the ECM DTCs.
Are any P1685 DTCs present?All
Ye s®Go To 3
No®Go To 4
3 Replace and program the SKIM in accordance with the Service Information.
Turn the ignition on.
With the DRBIIIt, erase ECM DTCs.
Turn the ignition on and off several times pausing for 10 seconds between key cycles.
With the DRBIIIt, read ECM DTCs.
Are there any P1685 DTC's present?All
Ye s®Replace and program the ECM in accordance with the Service
Information.
Perform ROAD TEST VERIFICATION - VER-2.
No®Test Complete.
4WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?All
Ye s®Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No®Test Complete.
169
DRIVEABILITY - DIESEL
P1685-SKIM SYSTEM INVALID KEY CODE RECEIVED ÐContinued