P0688-AUTO SHUTDOWN RELAY SENSE CIRCUIT LOW

For a complete wiring diagram Refer to Section 8W.

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

Possible Causes

(A924) FUSED B+ CIRCUITS

(A142) ASD RELAY OUTPUT CIRCUIT OPEN

ASD RELAY

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Diagnostic Test

1.VERIFY ASD DTC

NOTE: Diagnose P0685 - Auto Shutdown Relay Control Circuit first if it set along with this DTC.

Does the DTC reset?

Yes

Go To 2

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

2.ENGINE OPERATION

Does the engine start?

Yes

Go To 3

Go To 4

3.(A142) ASD RELAY OUTPUT 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.

Is the resistance below 5.0 ohms?

Yes

Go To 7

Repair the open in the (A142) ASD Relay Output circuits.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

4.ASD RELAY

Does the DTC reset?

Yes

Go To 5

Replace the ASD Relay.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

5.(A924) FUSED B+ CIRCUITS

Does the test light illuminate brightly?

Yes

Go To 6

Repair the open or short to ground in the (A924) Fused B+ circuits. Inspect the related fuse and repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

6.(A142) ASD RELAY OUTPUT CIRCUIT OPEN

Is the resistance below 5.0 ohms?

Yes

Go To 7

Repair the open in the (A142) ASD Relay Output circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

7.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Were there any problems found?

Yes

Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)