Like the time says, my head lights dim when the fog lights are on. I replaced the fog light bulbs yesterday because there is a lot of fog where I am currently living. Last night on freeway they were fine for 30 minutes of easy driving. Then tonight driving a friend home, I smell burning electrics. I figure out that it is associated with the foglights being on. I also notice that the head lights go dim when they are, sounds about right if there is an electrical fault.

I reinstalled the old fog lights which were working, just dim. The problem continued after the old bulbs were installed. I decided to say enough is enough, and just pulled the whole assembly out. Well the smell has gone away, but the head lights still dim when the fog light switch is turned on.

My first step in testing the electrical system was to check the headlight fuse under the hood. I checked it out, fuse is still solid and allowing current to pass. My next thought is just to pull the cable from fog light switch, unless someone has a more insight full answer, which I hope that you do!

TIA!
Chris

oh yeah 94 touring 66k miles

 

Any thoughts on what could be causing this issue?

 

add/upgrade your grounds. Good place to start

 

Which grounds should I be checking? I've gone through an followed the shop manual for testing the connections. The fog light switch on the console seems to be ok. Although when I turn it on there is a HUGE voltage drop, from 11.75 to ~4. The fog lights have stopped turning on now. What else can I check, and which grounds should I check?

 

11.75?

How's the condition/age of your battery? alternator? If both are working properly, the car should be getting over 13 volts at idle.

You can clean your battery terminals with a wire brush, this is pretty basic troubleshooting.

 

Oh sorry, the car was off, only on battery. The battery had run down while I was tinkering.

 

Update!

So I finally got around to playing with the car some more.

The fog light switch appears to be fine.

The fog lights light up when power is externally applied.

I get a reading of 0 resistance(not overload) when I check the connector for the switch. This leads me to think that the wires have melted together, along with the burning smell I get.

My question is, where I can access the fog light harness on the cabin side of the firewall to check for continuity of the wires. Then my plan would be to replace them.

TIA!

 

Evening bump!

Is there a main block that the wires will go into before going through the firewall? I have the schematics for the electrics, but it does tell me where things are physically are in the car.

Any advice would be great!

 

Well I spent an entire day trouble shooting it, but I have it fixed! I made some cuts in the wires so that I could segregate them. I then used a long wire I had laying around to test each wire to see if I could eliminate the problem. The problem ended up showing in the harness for the fog light them selves. It was in the "y" that leads to the lights them selves. There was a great in the ground, although I do not see where that was possible. As far as the eye could see everything was intact. So I ran new ground wires to them, and now everything works!