Service 4 Wheel Drive Lamp On With DTC C0388 Rear Differential Lock Control Circuit Fault Setting Current Or Intermittently - keywords axle MIL repeat

This PI is being superseded to update subject and recommendations. Please discard PIP3925.

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

Current, intermittent or history service 4x4 lamp illuminated and dtc c0388 rear differential lock control circuit fault.

Inspect the terminal connections and pin drag at the TCCM (transfer case control module) connector for being loose and repair as necessary. Also inspect connector C200 under the instrument panel and C150 under the hood for loose terminals or connectors.

Note 1: Pay particular attention to the terminal crimps at the TCCM on connector C1, terminal B8 circuit 1725 and terminal A2 circuit 2659, the terminals should be re-tensioned or replaced as necessary on both circuits and pin drag checked with the proper tool to ensure a proper connection. The TCCM can be accessed through the right hand i/p end cap.

Note 2: Make sure when testing the rear differential clutch coil resistance the vehicle is turned off and very stable. Any movement of the rear differential can skew the coil resistance readings and lead to unnecessary coil replacement.

If the clutch coil does fail the resistance test, remove the rear differential cover and inspect the wiring for possibly being cut by the ring rear bolts. If the wiring is cut the coil will require replacement.

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.