Diesel Engine Equipped Vehicles With P0381 And P0650 - keywords 6.6 diesel glow glowplug indicator instrument LBZ light LLY LMM P0381 P0650 panel plug start wait

This PI was superseded to update all information learned from the engineering investigation. Please discard PIP3603A.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

The dealer may encounter a customer concern of a SES light with the Wait to Start Control Circuit DTC P0381 or P0650 Malfunction Indicator Lamp (MIL) Control Circuit found.

If the DTC P0381 code cannot be duplicated, and it's only found as a history code, clear the DTC and evaluate the concern.

Engineering has been involved and investigated P0381/P0650 codes.

In most cases DTCs P0381 and P0650 will occur after a repair, during a radio upfit, an add-on dash switch modification, or upfitting of other aftermarket components.

For GMT900 Light Duty Trucks:

1. If P0381 and P0650 have set together after some type of electrical or under-dash repair, clear the DTCs and verify they do not reset after cleared. If the PC is unplugged and the key is cycled once you will set P0650. If the key is cycled a second time P0381 will be set along with P0650. If the power feed to the IPC is lost both P0381 and P0650 may set.
2. If DTC P0381/P0650 was not set before initial repair/modification, and only starting setting after repairs were completed, the repair needs to be rechecked. Connections and wiring to IPC (instrument panel cluster) should be inspected and repaired. If modification was made to original wiring harness it needs to be removed and setting of DTCs evaluated.
3. If P0650 is set by itself and was the original vehicle concern, complete the current SI diagnostics. ECM replacement is not suggested for P0650 set by itself. ECMs returned and inspected by engineering have been found no trouble found. Most P0650 codes have been repaired by either a wiring or IPC repair.

For GMT560 Medium Duty Trucks:

1. If P0381 has set after some type of electrical repair, center console repair, or under-dash repair clear the DTCs and verify they do not reset after cleared.
2. If DTC P0381 was not set before initial repair/modification, and only starting setting after repairs were completed, the repair needs to be rechecked. Connections and wiring to IPC(instrument panel cluster) should be inspected and repaired. If modification was made to original wiring harness it needs to be removed and setting of DTCs evaluated.
3. If P0381 is set by itself and was the original vehicle concern, complete the current SI diagnostics. ECM replacement is not suggested for P0381 set by itself. ECMs returned and inspected by engineering have been found no trouble found. Most P0381 codes have been repaired by either a wiring or IPC repair.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.