Fog Lights Cut Out, already did Corral fix

[Bill Cool]

When I first bought my Stang about 5 years ago, I did the fog light fix w/the relay and such...never had a problem except the random bulb failure... About 2 weeks ago, I got my steering rack replaced, and about 4 days ago I noticed my fog lights wouldn't go on. I tried replacing the bulbs, but they still wouldnt light. What gives? What specifically should I check?

 

[Mavrick]

Fuse? I dunno.. trace wires maybe, see if anything got pinched or something?

 

[iwashmycar]

Probably a pinched/ shorted wire, but maybe check the bulb housing where the bulbs sit. That is where they ground and sometimes it gets all corroded.

Also....remove one bulb and see if the other works, and vice-versa.
On mine I did that and it turned out to be a bad bulb. It wasn't even blown looking....fillament was good.

 

[Bill Cool]

I already checked the fuse, it's fine... And I tried w/one bulb in as well... I'll start looking for pinched wires this weekend, just wanted to know if there was anything else I should look for...thanks everyone...

 

[r6bullet]

Can you hear your relay click when you power up the fog lights? You could have a burned/sticking relay. I would make sure the relay is getting power, and check the relay with a multimeter. And if that all works get under the car and play with the fog light connecters. Mine will sometimes go out the I just wiggle the harness a little and it comes back on.

 

[TheUser]

instead of messing around visually looking for pinched wires, might be a good idea to use a multimeter and check the resistance of the wires. Maybe use a test light to probe different parts of the wires to see if it lights up?

 

[HISSIN50]

Can you hear your relay click when you power up the fog lights? You could have a burned/sticking relay. I would make sure the relay is getting power, and check the relay with a multimeter. And if that all works get under the car and play with the fog light connecters. Mine will sometimes go out the I just wiggle the harness a little and it comes back on.

i agree, this would be my first check. test each terminal of the relay for proper power, ground, trigger and output.

 

[Bill Cool]

Good call...'cept it means pulling the dash apart, but oh well. I'll check that out this weekend, thanks!

 

[89MustangGX]

If it's a standard relay you should be able to hear it click when it turns on -- no need to pull anything apart to check that.

If it doesn't click, it means power's either not getting to it or switched power isn't gettign to it, or it's not grounded.

If it clicks, it means power's not getting out to the lights or the lights aren't grounded.

Easy way to narrow down your search before taking anything apart.

 

[Bill Cool]

Thanks for the tip Adam... Just went out and listened, and the relay clicks on... So I tested the voltage at the lights, and I get nothing... So I looked to see where the wires went, and there's no freaking way I'm going to trace them to see where there's a kink or cut... How would I go about running new wires? Any idea which wire is pos and neg at the light? I'm assuming I can just cut the wires near the plug, run one to a ground and the other to the "out" connection on the relay...

 

[89MustangGX]

Well, my next step before taking all that apart and runnign new wires (I try to do as little as possible!) would be to recheck the connections. Easiest one is right at the lights. I'd unplug them and take some sandpaper or something you can get inside the connector and make sure you can see some bright metal. Then check for power. If that doesn't work...then I'd take apart the dash and check the wires that you put in that go from the relay to the factory harness, and you can also check the relay at that point -- but I think it will be fine.

 

[Bill Cool]

I'll do that in the AM...

 

[HISSIN50]

that is one reason i put the relays in the engine compartment, not behind the dash.

Adam, i have had Bosch style SPDT relay fail to where they had no output, but still clicked. also, if he lost the input or output wire connection (30 and 87) at the relay, it would still 'click' but not energize the circuit.

Adam - i do agree with ya, but wanted to toss that little bit of info out (for whatever it is worth). i often like to test for juice at the lights, maybe check input/output at the switch, and then hit the relay, as you can really quickly find what direction you need to go in.

last thing, in trying to determine causation. the most likely area the shop could have messed with is the ground wire (i honestly dont know where the ground wire terminates - ive never looked). but if it gets bolted on somewhere on the front end, the shop could have undone it for some reason while doin the rack.

good luck.

 

[89MustangGX]

I see what you're saying -- and you're 100% right about the relays failing like that.

Hopefully it's an easy fix at the lights or the ground wire -- if not, he'll have to dig into the relay like you said.

 

[HISSIN50]

I see what you're saying -- and you're 100% right about the relays failing like that.

Hopefully it's an easy fix at the lights or the ground wire -- if not, he'll have to dig into the relay like you said.

i never understood the write-ups that recommended putting the relay behind the stock headlight switch.. if you lose the relay in the middle of the night you are sunk. it is just fogs so it is not too crucial. i put relays on lows, highs and fogs, and even if space was not a constraint, i would have still put the relays in the engine compartment where i can get to them.

for the fogs alone, they say that the relay is less likely to fail when inside the car, but it is just for fogs, so if it fails a little prematurely, who cares. if you have a spare in the glove box, you are in business in 2 minutes.

how did i get off on that? i should be trying to get my headrests out. LOL.

 

[Bill Cool]

OK - the fuse (I forgot that when I did "the fix" I put a fuse in-line...doh!) was totally melted. So I replaced that, and the relay which stopped working today, but still no dice. I get power into the relay (12..5ish volts) and when I turn the switch on I get power at the "to switch" and "to ground" connections (about 11.5 volts), but still nothing coming out of the "to lights" connection on the relay. If I connect the "to lights" wire to the "power" wire, I get lights - so the problem is somewhere in the relay? No? I'm totally lost...

 

[89MustangGX]

Sounds like the relay to me now...either it's bad or not wired correctly???

You should have power into the relay from the battery, power going into the relay from your switch, then a good ground, and then power coming out of the relay when it is switched on. Those should be the four connections. Make sure you didn't swap any when you changed it.

 

[Bill Cool]

Actually I did swap the wires - the schematic on the back of the relay package had the power-in and power-out wires in the opposite position as the Corral's how-to has them...so I switched them and wiggled the wires around at the switch, and finally got the fogs to turn on, but they don't stay on. If you hit the switch, they go off - so it must be the switch.

I'm pretty sure I've heard of switches going back, no? I'm going to try replacing the plug first, but my money's on the switch itself...

 

[89MustangGX]

I love electrical problems.

So it's working now, but if you bump the switch they go out? I'd check all the connections around there that you might have crimped or soldered on as well...bumping the switch might jar one loose rather than just being the switch itself.

 

[HISSIN50]

yep - and if you can predictably jiggle it to kill it, check for power at the trigger (often 86 on a blazer relay) - if you maintain power after jiggling, id think relay (you would have all the components needed, but the metal in the relay, etc is not staying energized.
if the trigger goes dead after jiggling, check the terminals at the switch. if you have juice at both (input from fusebox, etc) and output, but nada at the relay trigger input, you have a bad wire. i doubt this possibility.

im in a rush, but i think this sounds right. good luck.