C5 fog lamp problem
Thread Starter
Instructor
Joined: Oct 2006
Posts: 130
Likes: 0
From: Bentonville AR
C5 fog lamp problem
My 1997's fog lamps are turning themselves on (without any other lights on, keys not even in the ignition). The only way to turn them off is to pull the fog lamp fuse. While the fog lamsp are on, the fog lamp relay buzzes. I've swtiched out the buzzing relay with another one, and the new one buzzes as well, so the problem is not fuse or relay-related. Any ever experience this odd problem? Thank you!
Racer
Joined: Dec 2001
Posts: 452
Likes: 2
From: Lynnfield MA
This sounds like a short to the relay control circuit, and a nasty
one at that.
Does the light on the dash toggle on and off?
This circuit is controlled by the body computer. The dash switch
is just a momentary, and the body computer toggles the led on
the switch and the fog light relay itself. This is a ground-completion
circuit like most relays, so there must be power to the relay, plus
the relay must be grounded for it to activate, so you actually have
to have two problems for this to happen with the key out of the
ignition, unless the body computer is bad, which is a possibility...
one at that.
Does the light on the dash toggle on and off?
This circuit is controlled by the body computer. The dash switch
is just a momentary, and the body computer toggles the led on
the switch and the fog light relay itself. This is a ground-completion
circuit like most relays, so there must be power to the relay, plus
the relay must be grounded for it to activate, so you actually have
to have two problems for this to happen with the key out of the
ignition, unless the body computer is bad, which is a possibility...
Thread Starter
Instructor
Joined: Oct 2006
Posts: 130
Likes: 0
From: Bentonville AR
The switch on the dash is totally inoperative since I developed the problem. If it's the body computer, ($$), I'll probably just continue to do without fog lamps, which is kind of a shame. Thanks for your help!
Racer
Joined: Dec 2001
Posts: 452
Likes: 2
From: Lynnfield MA
looking at a body computer failure.
Have you had the passenger kick plate off to check for moisture
in the computer compartment? This is a common problem when
the drain udders for the cowl get clogged up and water starts to
seep into the passenger compartment. If you do find moisture
in there, so a search on "udders", and clean them out, that
might actually solve your problem, and prevent some new ones!
