seastreet

2001 Jeep Grand Cherokee WJ with 4.0L V6.

Weird electrical issues related to lights (interior and headlights) flickering, dashboard indications resetting and door chime intermittently ringing. Replaced battery (bad cell), cleaned all grounds, checked relays and fuses, and today I replaced the headlight switch on the steering column. Each time, it works great after replacing a fuse or switch or battery disconnected, but after the next cold start, it starts again. Now it’s worse than ever. Beyond frustrated and need fresh ideas and leads.

Here’s a video of the chaos tonight...

94zj318

Could be the BCM going bad. The BCM (Body Control Module) controls all of the interior electrical systems in the WJ. In 1999, they redesigned it from what the ZJ (1993-98 models) had so it's a single wiring harness running to different parts of the Jeep.

-Vince

dave1123

Have you tried resetting the computer? Disconnect the battery and short both terminals together, then turn the headlights on and off to drain the computer's memory. Reconnect the battery and turn the key on to the run position. The warning lights should come on for a bulb test, cycle off, and remain steady waiting for you to crank it.

This vehicle works on a can-bus system where all the modules talk to each other, running diagnostics constantly. Sometimes a loss of this link can cause weird stuff to happen.

seastreet

Swapped out the BCM and ignition switch with parts from the local pick-n-pull yard and all the electrical issues vanished. What a relief. Thanks for the advice.

BlueRidgeMark

You've cleaned ALL the grounds? How about the battery cables? They can be corroded inside the jacket with no external sign.

seastreet

I cleaned every ground I could find in the engine bay, which was six. Battery cables were fine.

The BCM appears to be the culprit. Amazingly, a bunch of little electrical quirks I had attributed to the vehicle being old have been remedied with the BCM replacement. Even the remote entry works properly again. Had a rear drivers side running light that was intermittently dysfunctional working again without problem.

Never knew that one module mounted to the rear of the dashboard fuse block could cause so much havoc.

taylor martin

I have the same issue and I am waiting on a reman and flashed PCM to come in to fix the issue in my 2000 WJ. It is strange how one simple computer can screw up everything like that

dave1123

It's not a simple computer in the WJ. These jeeps operate on the Can-Bus system in which all the modules constantly talk to one another and transfer information over a dedicated circuit consisting to a twisted pair of wires. The 99 models were the first of many vehicles to use this system and now most have systems that are more complex than you can imagine.

seastreet

Been a couple of weeks now and since I replaced the BCM, it’s been running good. All electrical issues fixed. Got the BCM out of a pick & pull yard for $40.

BlueRidgeMark

Great! Thanks for checking back.


Now about that.... I"m pretty sure you don't have a 4.0L V6.

The 4.0 is an inline 6, not a V. Got pics?