Jerry
Jerry UltraDork
1/22/17 3:14 p.m.

Trying to figure out why the OEM foglights aren't working in this xB I bought in October. First thing I checked was the fuse, it's fine. (Yes I made sure the headlights were on as well.)

Today I popped out both housings and both bulbs look brand new, no burn marks and the filaments look intact. I thought it might be the switch, popped it out and stuck a wire between the two terminals. I hear a faint clicking sound somewhere in the dash (not 100% sure where the relay is) every time I wiggle the wire.

It seems to be between the switch, or the relay. Would a faulty relay also make clicking noises? If so it's still one or the other (maybe both). Not a big deal, but I'd actually like these foglights to work.

Knurled
Knurled MegaDork
1/22/17 3:21 p.m.

If the relat clicks, that only means that the relay is being controlled. And the relay coil is good. It could still have a bad connection at either end of the relay's switched side (no power going to it or no path for power to go out, IE bad component or component ground) or the contacts could be junk.

But you know everything on the control side of the relay is good.

bentwrench
bentwrench Dork
1/22/17 3:41 p.m.

A test light is your friend....

Knurled
Knurled MegaDork
1/22/17 4:15 p.m.

Oddly enough, my favorite "test light" is a relay. Two long chunks of wire and some spade terminals on the 85 and 86 terminals, and you can just hold the relay and feel it click.

Woody
Woody MegaDork
1/22/17 4:37 p.m.

I've had clicky relays that don't work.

BrokenYugo
BrokenYugo MegaDork
1/22/17 5:03 p.m.

They can click with bad contacts or other internal issues. If it clicks but doesn't work proceed to the relay socket and check for power there, then bypass it with a jumper and see if the lights come on, if that's all good it's the relay. Or if you have an identical relay on the panel you can try trading them out and see if the problem follows.

eastsidemav
eastsidemav SuperDork
1/22/17 6:32 p.m.

Any chance the PO had some aftermarket lights they wired in to be controlled with the fog light switch? May want to see if you can trace the wiring from the fog lights back a bit, and see if they've been cut.

Slippery
Slippery Dork
1/22/17 6:50 p.m.

I would get a test light, like suggested above, and start tracing from the light plug towards the relay.

Jerry
Jerry UltraDork
1/23/17 7:04 a.m.

Hm. The switch had some scuff marks on it, like it's been pulled before. I'm guessing maybe he tried to diagnose as well. Maybe also why the bulbs look brand new... Maybe I'll find/replace the relay and see what happens. Can't be too much $.

mazdeuce
mazdeuce UltimaDork
1/23/17 7:18 a.m.

You need to spend $10 on a cheap multimeter/test light.

Grtechguy
Grtechguy MegaDork
1/23/17 8:09 a.m.
Woody wrote: I've had clicky relays that don't work.

Same here. mechanically they might work, but aren't making electrical contact due to defect or corrosion.

Jerry
Jerry UltraDork
1/23/17 10:54 a.m.

In reply to Grtechguy:

With all the corrosion on the battery ground contacts, this might be it.

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