Fog lights malfunctioning any tips on testing
Thread Starter
Joined: Apr 2004
Posts: 1,378
Likes: 14
From: Atlanta, GA Ft. Walton Beach, FL
Fog lights malfunctioning any tips on testing fog lights have been acting up past couple of months, now they don't come on at all.
I looked at the switch it has like 5 wires which ones are for the lights all of them? I was expecting to see 3 at most, maybe each light is wired to the switch individauly?
I have not yet tested the light bulbs.
any tips on testing the switch please include wire color & tips on testing the relay in engine area.
thanks for any help
I looked at the switch it has like 5 wires which ones are for the lights all of them? I was expecting to see 3 at most, maybe each light is wired to the switch individauly?
I have not yet tested the light bulbs.
any tips on testing the switch please include wire color & tips on testing the relay in engine area.
thanks for any help
Joined: Nov 2003
Posts: 11,330
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Camaro or Firebird? The two have their fog light switches wired quite differently.
However, the most important two wires are the same on both. The brown wire provides power input from the parking light circuit and the yellow wire is the output to the fog light relay under the hood. The other wires are used for the ON indicator light and switch illumination.
The relay has four wires - yellow, brown, purple and light green. The yellow is trigger power from the switch. Brown is power from the parking light circuit to power the lamps. Purple is the output to the lamps. Light green is the trigger coil ground but it grounds through the high beam lamps (that's why the fog lights shut off when you use your high beams).
However, the most important two wires are the same on both. The brown wire provides power input from the parking light circuit and the yellow wire is the output to the fog light relay under the hood. The other wires are used for the ON indicator light and switch illumination.
The relay has four wires - yellow, brown, purple and light green. The yellow is trigger power from the switch. Brown is power from the parking light circuit to power the lamps. Purple is the output to the lamps. Light green is the trigger coil ground but it grounds through the high beam lamps (that's why the fog lights shut off when you use your high beams).
Thread Starter
Joined: Apr 2004
Posts: 1,378
Likes: 14
From: Atlanta, GA Ft. Walton Beach, FL
fog lights
Originally Posted by WhiteBird00
Camaro or Firebird? The two have their fog light switches wired quite differently.
However, the most important two wires are the same on both. The brown wire provides power input from the parking light circuit and the yellow wire is the output to the fog light relay under the hood. The other wires are used for the ON indicator light and switch illumination.
The relay has four wires - yellow, brown, purple and light green. The yellow is trigger power from the switch. Brown is power from the parking light circuit to power the lamps. Purple is the output to the lamps. Light green is the trigger coil ground but it grounds through the high beam lamps (that's why the fog lights shut off when you use your high beams).
However, the most important two wires are the same on both. The brown wire provides power input from the parking light circuit and the yellow wire is the output to the fog light relay under the hood. The other wires are used for the ON indicator light and switch illumination.
The relay has four wires - yellow, brown, purple and light green. The yellow is trigger power from the switch. Brown is power from the parking light circuit to power the lamps. Purple is the output to the lamps. Light green is the trigger coil ground but it grounds through the high beam lamps (that's why the fog lights shut off when you use your high beams).
thanks for the infor
this is what I have checked so far
I've tested the continuity between the brown & yellow wires at the switch it's good. but the yellow light built into the switch do'es not come on.
I've also tested the continuity between the yellow & lt. green wires under the fog light relay also good.
Any tips on testing my fog lights is appreciated
Joined: Nov 2003
Posts: 11,330
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Well, you're going to have to test for power and ground at the switch first and then at the relay.
First, at the switch, check that the brown wire has power when the headlights/running lights are on. This shouldn't be a problem since it comes directly from the headlight switch and you would have noticed if your taillights weren't working (but check anyway just to be sure). Next, turn the fog light switch on (leave the headlight switch on) and test for power at the yellow wire. This will ensure that the switch is working - really just a repeat of your continuity test. The yellow wire goes from the switch to the trigger coil of the relay so your next step is to test that you actually have power at the yellow wire under the relay. Also test that you have power on the brown wire at the relay (that's the actual source of power for the fog lights coming from the headlight/running light circuit). Next, test that the relay tripped properly by checking for power output on the purple wire. If all this checks out then the problem is someplace in the wiring between the relay and the lights. Otherwise, check that you have a good ground for the relay on the light green wire. This ground won't be perfect (because it actually goes through the highbeam circuit rather than directly to the chassis) but it should be good enough to let the relay operate. None of these wires are connected to sensitive electronics so a simple test light will work as well as a multimeter for testing.
If you find one of these connections isn't working properly then you should check for broken wires leading up to the point you tested - either the switch or the relay.
As far as the switch's ON indicator light not working, you'll have to let me know if you have a Camaro or Firebird because they are wired quite differently.
First, at the switch, check that the brown wire has power when the headlights/running lights are on. This shouldn't be a problem since it comes directly from the headlight switch and you would have noticed if your taillights weren't working (but check anyway just to be sure). Next, turn the fog light switch on (leave the headlight switch on) and test for power at the yellow wire. This will ensure that the switch is working - really just a repeat of your continuity test. The yellow wire goes from the switch to the trigger coil of the relay so your next step is to test that you actually have power at the yellow wire under the relay. Also test that you have power on the brown wire at the relay (that's the actual source of power for the fog lights coming from the headlight/running light circuit). Next, test that the relay tripped properly by checking for power output on the purple wire. If all this checks out then the problem is someplace in the wiring between the relay and the lights. Otherwise, check that you have a good ground for the relay on the light green wire. This ground won't be perfect (because it actually goes through the highbeam circuit rather than directly to the chassis) but it should be good enough to let the relay operate. None of these wires are connected to sensitive electronics so a simple test light will work as well as a multimeter for testing.
If you find one of these connections isn't working properly then you should check for broken wires leading up to the point you tested - either the switch or the relay.
As far as the switch's ON indicator light not working, you'll have to let me know if you have a Camaro or Firebird because they are wired quite differently.
Thread Starter
Joined: Apr 2004
Posts: 1,378
Likes: 14
From: Atlanta, GA Ft. Walton Beach, FL
fog Thanks guys for the advice I had a spare relay in my box of spare stuff
now everything is fine.
I'm hoping this relay will not blow soon, I actually replaced that same relay about 2 year's ago, replaced due to mis use (relay did'nt burn up on it's own)
Thanks again
now everything is fine.
I'm hoping this relay will not blow soon, I actually replaced that same relay about 2 year's ago, replaced due to mis use (relay did'nt burn up on it's own)
Thanks again
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The relay has four wires - yellow, brown, purple and light green. The yellow is trigger power from the switch. Brown is power from the parking light circuit to power the lamps. Purple is the output to the lamps. Light green is the trigger coil ground but it grounds through the high beam lamps (that's why the fog lights shut off when you use your high beams).
That brown wire can take a hike. It's already powering four lights. It's slot will be filled with something thick and whatever allows me to use fogs without turning the parking lights on. How do the DRLs do it?? The tiny purple wire (from fuse box alllllllllllll the way to each fog light) is coming completely out in favor of the 12 Ga.
The terminals are MetriPack 280... 10¢ each from Waytek. But you can also rummage through junked GM vehicles till you find your desired color wire and gauge with the terminal already attached!
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