Page 745 of 5267
P0629-HIGH VOLTAGE DETECTED AT THE FUEL LIFT PUMP
For a complete wiring diagramRefer to Section 8W.
Page 746 of 5267

When Monitored:
Whilethekeyison.
Set Condition:
The commanded signal to the fuel lift pump relay does not match the feedbacksignal from the fuel lift pump
relay.
Possible Causes
DAMAGED WIRING HARNESS
LIFT PUMP DRIVER CIRCUIT SHORTED TO GROUND
ECM
TIPM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.LIFT PUMP DRIVER CIRCUIT SHORTED TO GROUND
Turn the ignition on, engine off.
Disconnect the ECM and TIPM connectors.
NOTE: Check connectors - Clean/repair as necessary.
Using an ohmmeter, measure the resistance of the lift pump driver wire between the ECM connector and ground.
Is the resistance less than 10 Ohms?
Ye s>>
Fix or repair the wire harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 2
2.ECM
Turn Ignition off.
Connect the ECM and TIPM connectors.
Turn the ignition on, engine off.
Using a back probing tool 6801, back probe the lift pump logic pin in from TIPM connector.
Toggle the lift pump actuator with the Electronic Service Tool.
Using a 12 volt test light connected to battery negative, check the lift pump circuit at the TIPM connector.
NOTE: The test light must illuminate brightly.
Compare the brightness to that of a direct connection to the battery.
Does the test light cycle on and off and illuminate brightly?
Ye s>>
Go To 3
No>>
Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Page 747 of 5267
3.TIPM
Using a back probing tool 6801, back probe the lift pump power pin in from TIPM connector.
Toggle the lift pump actuator with the Electronic Service Tool.
Using a 12 volt test light connected to battery negative, check the lift pump circuit at the TIPM connector.
NOTE: The test light must illuminate brightly.
Compare the brightness to that of a direct connection to the battery.
Does the test light cycle on and off and illuminate brightly?
Ye s>>
Te s t c o m p l e t e .
Perform Intermittent Condition test. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No>>
Replace the TPIM
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Page 748 of 5267
P0630-VIN NOT ENTERED ERROR
For a complete wiring diagramRefer to Section 8W.
When Monitored:
Whilethekeyison.
Set Condition:
The VIN was not calibrated into the ECM.
Possible Causes
VIN NOT CALIBRATED INTO ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.VIN NOT CALIBRATED INTO ECM
Using the scan tool, recalibrate the ECM with the proper VIN.
Did the DTC P0630 reset?
Ye s>>
Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Te s t C o m p l e t e .
Page 749 of 5267

P0633-SKIM SECRET KEY NOT ENTERED
For a complete wiring diagramRefer to Section 8W.
When Monitored:
Whilethekeyison.
Set Condition:
TheSKIMsecretkeywasnotcalibratedintotheECM.
Possible Causes
IMPROPER IGNITION KEY IS BEING USED
SKIM DTC’S
SKIM NOT CALIBRATED PROPERLY
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.SKIM DTC’S
With the scan tool, read SKIM DTCs.
Are any SKIM DTC’s present?
Ye s>>
Repair all SKIM DTC’s first.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 2
2.IMPROPER IGNITION KEY IS BEING USED
Verify that the proper ignition key is in the ignition lock on the steering column.
Are the proper keys being used?
Ye s>>
Go To 3
No>>
Use the proper key for the vehicle.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
3.SKIM NOT CALIBRATED PROPERLY
Using the scan tool, recalibrate the ECM with the proper SKIM secret key.
With the scan tool, erase DTCs.
Cycle the ignition switch from on to off to on.
With the scan tool, read DTCs.
Did the DTC reset?
No>>
Te s t C o m p l e t e .
Ye s>>
Verify information is correct and replace ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Page 750 of 5267
P0642-LOW VOLTAGE AT THE #2 SENSOR SUPPLY CIRCUIT
For a complete wiring diagramRefer to Section 8W.
Page 751 of 5267

When Monitored:
With the key on.
Set Condition:
Voltage detected on the #2 sensor supply circuit is below a calibrated value.
Possible Causes
FAN CLUTCH ASSEMBLY
(K668) 5-VOLT SHORTED TO GROUND
(K668) 5-VOLT SUPPLY SHORTED TO ANOTHER CIRCUIT
FA N D T C
INTERMITTENT CONDITION
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.FAN CLUTCH ASSEMBLY
Disconnect the Fan clutch harness connector.
NOTE: Check connectors - Clean/repair as necessary.
With the scan tool, read DTCs.
Did P0483 set?
Ye s>>
Replace the Fan clutch assembly.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 2
2.(K668) 5-VOLT SHORTED TO GROUND
Turn the ignition off.
Disconnect the ECM harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the (K668) #2 5-volt supply (fan speed
sensor power) circuit in the sensor harness connector and battery neg-
ative.
Is the resistance greater than 100k Ohms?
Ye s>>
Go To 3
No>>
Repair the #2 (K668) 5-volt supply shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 752 of 5267
3.(K668) 5-VOLT SUPPLY SHORTED TO ANOTHER CIRCUIT
Measure the resistance between the sensor (K668) #2 5-volt supply
(fan speed sensor power) circuit in the ECM harness connector to all
other circuits in the ECM harness connectors
Is the resistance greater than 100k Ohms?
Ye s>>
Go To 4
No>>
Repair the 5-volt supply shorted to another circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
4.FA N D T C
Reconnect the ECM harness connectors.
Reconnect the disconnected Fan harness connector.
Turn the ignition on.
With the scan tool, read DTCs.
Is DTC P0483 set?
Ye s>>
Repair the Fan DTC.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 5