2003 Grand Cherokee, 4.0

So the A/C, all windows and interior lights stopped working. I am thinking it is a problem with the BCM.

A/C - Proper Charge, Compressor Clutch works when jumped, swapped relay, A/C Light turns green showing on, no leaks, no blown fuses works when I jump the relay

Windows - No windows work, no switches, up on down, no noise when hitting the buttons. All fuses good, wiring in door jamb is fine, repaired at some point but solid connections otherwise. No switch on any door works

Locks - work fine
Power Mirrors - Work Fine

Interior lights - wok when tuned on but do not seem to work when the door is opened or when the vehicle is locked/unlocked.

Air Bag light also came on solid.

The vehicle was running fine, everything worked 100% and it all just seem to quit at once.

Dash and Gauges work fine, no issues, sun roof opens and closes, wipers, lights all working. Odometer also lit, radio works as well.

I connected a scan tool, high quality snap-on and not able to connect to the BCM or Air Bag Module, no connection, no communication errors found.

I am thinking either the BCM is out or I have a power issue to the BCM.

Does anyone have a pin-out for the BCM wiring? Any other ideas?



Appreciate your feedback

 

Well, the good news is that I got it working after doing a BCM Reset. Disconnected the battery, shorted the terminals and reconnected. All is working fine again now.


I'm just not sure why it happened. I did reseat the relays while it was unplugged, all wiring looks good, fuses are good. A/C and Windows work fine, all windows all switches.


I am thinking maybe the BCM is on the way out? Ideas?

 

I think it sounds plausible the BCM might be on it's way out. Something happened!

They are all computers on a communications network., and computers sometimes crash and/or do strange things, have glitches, etc...

A reboot may have been all that was needed, and this was maybe just a one-time ordeal? If not, it could be any one of the many computers (modules) to cause something like this to happen.

 

If you have a wiring diagram or FSM to trace the circuits, look for a twisted pair of wires and inspect them for damage or loose connections. That's the CAN-BUS communication network. If any part on the network signal is pulled to ground, it's like losing the phone lines between modules.