Hi,
I've attached the full wiring diagrams for the front foglights for your custom. Sounds to me like you'll need to start poking around with a multimeter.
Screenshot 2023-05-29 at 01.40.34.png
This is the wiring from the BCM to the lights and grounds. It's unlikely both grounds are bad, and the diagram indicates other devices use those grounds. I'd be checking with a multimeter whether you're getting any voltage at the bulb connector, (the bulbs not lighting suggests you're not), but maybe also check with a different ground.
Tracing back from there, I'd be looking at the output from the BCM with the multimeter to see if you get voltage at this point, if you do, then you've probably got a broken wire to the bulbs. If not, then also check that there's voltage getting to fuse F8 with the multimeter, which should have 12V at all times.
If nothing by this point, it probably leaves the relay inside the BCM, and the signal reaching the relay to activate the coil. This will be much harder to check, as it's buried in the BCM and theoretically not serviceable. That said, the diagram suggests it's an actual relay - do you hear any stereotypical relay clicking noises when you press the button?
Screenshot 2023-05-29 at 01.40.25.png
In the first generation models like yours, the light control buttons were connected by a LIN bus to the BCM instead of individual wires for the buttons (on later models). That's harder to diagnose without an oscilloscope, but if the other lights are working, then you can assume the connection between the switches and BCM is good, but it won't rule out the button itself. At that point you'd likely need to swap out another switch module to confirm.
Hope this gives you a start on fixing it!
Noel
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