heckw

I posted this over at Renntech also because I'm out in the middle of Wyoming and would love to get some advice before I start heading back to Nevada. My appologies for cross posting.

The strangest thing is happening and I have searched but can't seem to find a post with the same symptoms. I have a 2002 C4S. The cruise has stopped working but more importantly the PSM and ABS fails when the headlights (or even the parking lights) are switched on. The brake lights work from the brake pedal when the headlights are off but when the headlights are turned on the brake lights come on (including the center light) and stay on. I'm thinking headlight switch but that doesn't explain why the cruise control doesn't work when the lights are off. When the headlights are off ABS and PSM are fine.

Thanks for any help you can offer.
Bill

Diamond Blue 4S tip

Sorry to hear about your problem, Bill. The braking system is the common theme with all your symptoms, so I would suspect a short in the wiring somewhere. The cruise seems to be getting a signal that the brakes are applied. The brake lights coming on with the headlights leads me to think it is a short.

At first, I was thinking maybe it was a bad bulb in one of the taillight assemblies, but that doesn't make as much sense as a short.

I am not a mechanic, just my .02

Good luck getting home and figuring out the problem.

heckw

A short is definately a possibility. I suppose I can check for continuity between the running and stop lights with the lights out to verify that. I was kind of hoping the brake lights ran through the headlamp switch. The problem seemed to start when I stopped for a minute in Beautiful Beaver Utah. Stopped with no problem - 5 minutes later I turn on the headlight switch and the PSM/ABS annunciater lights come on and the MFD is directing me to go to the shop. When I shut down the ABS/.PSM system is fine until the headlights are turned on again.

Thanks

heckw

Just a little update. The brake lights are coming on with the right side parking lamps so I suppose it is looking more like a short...

wwest

LED bulbs......???

heckw

FIXED! Sort of. Just in case someone else might run into this problem...The spring contact in the right rear stoplight assembly broke and shorted to the running lights. I pulled the broken contact out and everything is working again. Now I just need to find the socket for the bulb and all will be as it should. (Right now I'm running down one running light)

Thanks

gota911

I guess as a "temporary fix" you could swap the fog light socket with the brake light socket, since the right fog light socket has no power running to it anyway. (Well, mine does, but that's another story! ) That might keep you from getting a ticket.

I looks like you will be a wiring harness (#2) in the PET diargam below. Part number:
- 996 631 445 00 for a '98 or
- 996 631 446 00 for a '99 - '04.
The third part number shown is for a C4S.

heckw

Thanks gotta911. I had toyed with the idea of trying to fix the contact but replacing the wiring harness is the right thing to do.