Hi guys,
I am troubleshooting non-working factory fog lights on my '92 MTech Cab.
Here is where I am with it, maybe there is some well known failure point that someone can share before I start ripping the dash apart.
1) The fog lights do work when jumped 12v direct to their fuses.
2) Fog Light Relay has 12v to pin 30 and Pin 86, Ground to pin 87 with Key ON, Headlights ON.
3) I think the problem is continuity from Fog Light Relay socket for pin 85 to Fog Light Switch, which is the Grey wire that runs through C103 on pin 14.
Under no circumstances power on, lights on, lights off can I establish continuity from Fog Light switch grey wire to socket 85 on fog light relay.
The Blue / Grey wire on the other side does establish continuity to Ground as its supposed to.
My theory is somewhere there is an air gap in that grey wire between the fog light switch and pin 85 on the Fog Light Relay, and in-between those two devices is C103.
Wondering:
• If anyone has run into this before?
• If my diagnosis sounds correct?
• If there is any known failure mode of that grey wire between Fog Light Switch and pin 85 of the relay?
Full disclosure, this car's lighting was heavily modified when I got it.
It had some kind of HIDs in the low beams and fogs, City Lights, it was jumpered all over to make all 6 lights operate at one time.
I have stripped all that away and returned everything to stock components operating on stock wiring.
I now have all lighting working exactly as BMW intended but the fog lights.
I "think" I am almost there if I can establish continuity from switch to Pin 85 (or at least thats how I am reading the ETK and all the posts I have searched through on here).
I just cannot find via searching this exact problem.
Any thoughts or help appreciated.
I am troubleshooting non-working factory fog lights on my '92 MTech Cab.
Here is where I am with it, maybe there is some well known failure point that someone can share before I start ripping the dash apart.
1) The fog lights do work when jumped 12v direct to their fuses.
2) Fog Light Relay has 12v to pin 30 and Pin 86, Ground to pin 87 with Key ON, Headlights ON.
3) I think the problem is continuity from Fog Light Relay socket for pin 85 to Fog Light Switch, which is the Grey wire that runs through C103 on pin 14.
Under no circumstances power on, lights on, lights off can I establish continuity from Fog Light switch grey wire to socket 85 on fog light relay.
The Blue / Grey wire on the other side does establish continuity to Ground as its supposed to.
My theory is somewhere there is an air gap in that grey wire between the fog light switch and pin 85 on the Fog Light Relay, and in-between those two devices is C103.
Wondering:
• If anyone has run into this before?
• If my diagnosis sounds correct?
• If there is any known failure mode of that grey wire between Fog Light Switch and pin 85 of the relay?
Full disclosure, this car's lighting was heavily modified when I got it.
It had some kind of HIDs in the low beams and fogs, City Lights, it was jumpered all over to make all 6 lights operate at one time.
I have stripped all that away and returned everything to stock components operating on stock wiring.
I now have all lighting working exactly as BMW intended but the fog lights.
I "think" I am almost there if I can establish continuity from switch to Pin 85 (or at least thats how I am reading the ETK and all the posts I have searched through on here).
I just cannot find via searching this exact problem.
Any thoughts or help appreciated.
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