Page 727 of 5267

4.S/C SWITCH (RESUME/ACCEL)
Turn the ignition off.
Disconnect the S/C RESUME/ACCEL Switch harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
With the scan tool in Sensors, read the S/C Switch volts in the ECM.
Did the S/C Switch volts go above 4.0 volts?
Ye s>>
Replace the Resume/Accel Switch.
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
5.CLOCKSPRING SHORTED TO GROUND
Turn the ignition off.
Disconnect the clockspring6-way harness connector (instrument panel
wiring side).
Turn the ignition on.
With the scan tool in Sensors, read the S/C Switch volts in the ECM.
Did the S/C Switch volts change to 5.0 volts?
Ye s>>
Replace the Clockspring.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
No>>
Go To 6
6.S/C SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the S/C ON/OFF Switch harness connector.
Disconnect the ECM harness connectors.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the S/C Switch Signal circuit and
ground (B-) at S/C ON/OFF Switch harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Repair S/C Switch Signal Circuit for a short to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
No>>
Go To 7
Page 729 of 5267
P0581-HIGH VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH
For a complete wiring diagramRefer to Section 8W.
Page 730 of 5267

When Monitored:
Key on or Engine running.
Set Condition:
Speed Control MUX switch above 11.5 volts for 5 seconds.
Possible Causes
S/C WIRING HARNESS OBSERVABLE PROBLEM
CLOCKSPRING SIGNAL/GROUND CIRCUIT OPEN
SPEED CONTROL ON/OFF SWITCH
S/C SWITCH SIGNAL CKT SHORTED TO VOLTAGE
S/C SWITCH SIGNAL CIRCUIT OPEN ECM TO CLOCK SPRING
S/C SWITCH SIGNAL CIRCUIT OPEN CLOCKSPRING TO S/C SWITCH
S/C SWITCH GROUND CIRCUIT OPEN CLOCKSPRING TO S/C SWITCH
S/C SWITCH GROUND CIRCUIT OPEN ECM TO CLOCKSPRING
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.Scan tool SHOWS SPEED CONTROL SWITCH ON/OFF
Turn the ignition on.
With the scan tool in Inputs/Outputs, read the Speed Control inputs state inECM.
While monitoring the scan tool, push the Speed Control On/Off Switch several times, then leave it on.
Did the scan tool show Speed Control Switch off and on?
Ye s>>
Go To 2
No>>
Te s t C o m p l e t e .
2.S/C WIRING HARNESS OBSERVABLE PROBLEM
Turn the ignition off.
Using the Schematics as a guide, inspect the Wiring and Connectors.
Were any problems found?
Ye s>>
Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 3
Page 734 of 5267
P0602-CHECKSUM ERROR
For a complete wiring diagramRefer to Section 8W.
When Monitored:
While the ignition is on.
Set Condition:
A deviation between the ECM memory and a stored calibration.
Possible Causes
FLASH ECM
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.FLASH ECM
Using the scan tool, reflash the ECM with the proper calibration for the particular truck.
Is the flash successful?
Ye s>>
Repair complete.
No>>
Go To 2
2.ECM
With the scan tool, read DTCs.
Did P0602 set after the reflash?
Ye s>>
Replace the ECM.
No>>
Te s t C o m p l e t e .
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Page 735 of 5267
P0604-ECM SOFTWARE ERROR
For a complete wiring diagramRefer to Section 8W.
When Monitored:
Whilethekeyison.
Set Condition:
Internal ECM software error.
Possible Causes
REFLASH ECM
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.REFLASH ECM
Using the scan tool, reflash the module with latest calibration
Was the flash successful?
Ye s>>
Go To 2
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)
2.ECM
Run the engine for one minute and shut off.
With the scan tool, read DTCs.
Did P0604 set?
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 736 of 5267
P0606-ECM HARDWARE ERROR
For a complete wiring diagramRefer to Section 8W.
When Monitored:
With the key on or engine running.
Set Condition:
ECM had detected internal failures.
Possible Causes
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.ECM
Turn the ignition on.
NOTE: This DTC is caused by an internal Engine Control Module failure. Repairs are not possible to the
ECM.
With the scan tool, erase DTCs.
Is the DTC still set?
Ye s>>
Replace and program the ECM in accordance with the Service Information.
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 737 of 5267
P0607-ECM INTERNAL FAILURE
For a complete wiring diagramRefer to Section 8W.
When Monitored:
With the key on or engine running.
Set Condition:
ECM had detected internal failures.
Possible Causes
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.ECM
Turn the ignition on.
NOTE: This DTC is caused by an internal Engine Control Module failure. Repairs are not possible to the
ECM.
Is the DTC P0606 set?
Ye s>>
Replace and program the ECM in accordance with the Service Information.
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 738 of 5267
P0622-GENERATOR FIELD NOT SWITCHING PROPERLY
For a complete wiring diagramRefer to Section 8W.