Fog light wiring question
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Fog light wiring question
I am looking at the fog light wiring, based on the manual there is a purple wire which is hot with lights on, with the high beam power lead attached to the other side of the bulb (light green wire). How does that complete the circuit when in low beams or parking?
I get why fog lights won't turn on with high beams on, same voltage on both sides of the circuit, but with high beams off what is the path to ground? Is the high beam circuit grounded in the dimmer when high beams are off?
I want to rewire so fog lights stay on with high beams on. I am thinking I can cut the green at each high beam and ground the lead coming off the bulb.
I get why fog lights won't turn on with high beams on, same voltage on both sides of the circuit, but with high beams off what is the path to ground? Is the high beam circuit grounded in the dimmer when high beams are off?
I want to rewire so fog lights stay on with high beams on. I am thinking I can cut the green at each high beam and ground the lead coming off the bulb.
Last edited by auburn2; Jan 13, 2019 at 07:42 PM.
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First I did not ask if that was legal, I asked a question about the wiring. Even if it was illegal (which it isn't), there is plenty of discussion on this forum of things that are illegal, like disabling EGR, removing AIR, removing catalytic converters ..... and speeding.
Second I don't for one second believe that it is actually illegal. Can you cite a federal law that makes using fog lights with high beams illegal? What I am doing is certainly no more illegal than the numerous other running lights or aftermarket light bars I could mount on my car. If it is in fact illegal at all it is only a state or local regulation and it would likely only apply to use or operation on the road, not actually modifying the wiring.
Sorry if my tone is a bit controversial, but I don't get why you chose my post to respond like you did.
Last edited by auburn2; Jan 13, 2019 at 10:04 PM.
Drifting
Joined: Jan 2005
Posts: 1,354
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From: San Antonio Tx
That should work. I do believe when high beams are off, the green wire's path to ground is through the Hi beam indicator. The early c4 fog lights are independent from the headlights and one side of the bulb is directly grounded so they work on low or high beam.
Race Director
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From: Lansing MI
Seems to me that the fog light relay coil is grounded through the high beam filaments in the headlight bulbs. So when you turn on the high beams, the relay coil loses its ground and the fog lights turn off. Seems to me the answer you are looking for is to ground the fog light relay coil to any other ground.
Drifting
Joined: Jul 2004
Posts: 1,356
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From: MA
PatternDayTrader is correct. You will have to find this relay on my 96 it was under the passenger side dash.
I posted the mode some time ago if you search through all the LED headlight questions. But after you locate the wire from the relay to the high beam filament you will want to cut it and then put some heat shrink tubing over the high beam side of the wire, you won't use it anymore.
Then take the cut relay side and connect it to a good ground.
You are done, driving lights will work fine and so will your headlights.
Yes, the driving lights can be turned on when the high beams are on. I don't know about the legal implications but speeding is also illegal and we have all done that.
I posted the mode some time ago if you search through all the LED headlight questions. But after you locate the wire from the relay to the high beam filament you will want to cut it and then put some heat shrink tubing over the high beam side of the wire, you won't use it anymore.
Then take the cut relay side and connect it to a good ground.
You are done, driving lights will work fine and so will your headlights.
Yes, the driving lights can be turned on when the high beams are on. I don't know about the legal implications but speeding is also illegal and we have all done that.
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Drifting
Joined: Oct 2015
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From: Shit Creek, USA
I am looking at the fog light wiring, based on the manual there is a purple wire which is hot with lights on, with the high beam power lead attached to the other side of the bulb (light green wire). How does that complete the circuit when in low beams or parking?
I get why fog lights won't turn on with high beams on, same voltage on both sides of the circuit, but with high beams off what is the path to ground? Is the high beam circuit grounded in the dimmer when high beams are off?
I want to rewire so fog lights stay on with high beams on. I am thinking I can cut the green at each high beam and ground the lead coming off the bulb.
I get why fog lights won't turn on with high beams on, same voltage on both sides of the circuit, but with high beams off what is the path to ground? Is the high beam circuit grounded in the dimmer when high beams are off?
I want to rewire so fog lights stay on with high beams on. I am thinking I can cut the green at each high beam and ground the lead coming off the bulb.
Check it here, good photos and instructions. https://www.corvetteforum.com/forums...-solution.html
Last edited by Renfield; Jan 14, 2019 at 07:48 AM.
Team Owner
Joined: Sep 2003
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I am looking at the fog light wiring, based on the manual there is a purple wire which is hot with lights on, with the high beam power lead attached to the other side of the bulb (light green wire). How does that complete the circuit when in low beams or parking?
I get why fog lights won't turn on with high beams on, same voltage on both sides of the circuit, but with high beams off what is the path to ground? Is the high beam circuit grounded in the dimmer when high beams are off?
I want to rewire so fog lights stay on with high beams on. I am thinking I can cut the green at each high beam and ground the lead coming off the bulb.
I get why fog lights won't turn on with high beams on, same voltage on both sides of the circuit, but with high beams off what is the path to ground? Is the high beam circuit grounded in the dimmer when high beams are off?
I want to rewire so fog lights stay on with high beams on. I am thinking I can cut the green at each high beam and ground the lead coming off the bulb.
You might find it helpful to mention year regardless of the question you post. Early C4 fogs vary by year. Yours I believe is an '89. This should confirm also your question. One simple post! Your thoughts were correct. On your '89 fogs (after the modification) should run I believe 'independently' requiring neither high or low. I didn't check a wiring diagram for an '89.
https://www.corvetteforum.com/forums...post1555890226
Last edited by WVZR-1; Jan 14, 2019 at 09:07 AM.
Safety Car
Joined: Jul 2003
Posts: 3,500
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From: Saratoga Springs NY
2024 C4 of the Year Finalist - Modified
2022 C4 of the Year Finalist - Modified
Post #5 confirms/agrees your thoughts
You might find it helpful to mention year regardless of the question you post. Early C4 fogs vary by year. Yours I believe is an '89. This should confirm also your question. One simple post! Your thoughts were correct. On your '89 fogs (after the modification) should run I believe 'independently' requiring neither high or low. I didn't check a wiring diagram for an '89.
https://www.corvetteforum.com/forums...post1555890226
You might find it helpful to mention year regardless of the question you post. Early C4 fogs vary by year. Yours I believe is an '89. This should confirm also your question. One simple post! Your thoughts were correct. On your '89 fogs (after the modification) should run I believe 'independently' requiring neither high or low. I didn't check a wiring diagram for an '89.
https://www.corvetteforum.com/forums...post1555890226
Thread Starter
Pro
Joined: Jun 2018
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PatternDayTrader is correct. You will have to find this relay on my 96 it was under the passenger side dash.
I posted the mode some time ago if you search through all the LED headlight questions. But after you locate the wire from the relay to the high beam filament you will want to cut it and then put some heat shrink tubing over the high beam side of the wire, you won't use it anymore.
Then take the cut relay side and connect it to a good ground.
You are done, driving lights will work fine and so will your headlights.
Yes, the driving lights can be turned on when the high beams are on. I don't know about the legal implications but speeding is also illegal and we have all done that.
I posted the mode some time ago if you search through all the LED headlight questions. But after you locate the wire from the relay to the high beam filament you will want to cut it and then put some heat shrink tubing over the high beam side of the wire, you won't use it anymore.
Then take the cut relay side and connect it to a good ground.
You are done, driving lights will work fine and so will your headlights.
Yes, the driving lights can be turned on when the high beams are on. I don't know about the legal implications but speeding is also illegal and we have all done that.
Thread Starter
Pro
Joined: Jun 2018
Posts: 532
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Going by how you describe what you see in the diagram for YOUR car, the fogs ground through the high beam bulb filament to ground. Look at the headlights with the fogs on in PARK, headlights OFF. The headlights "glow" a dull-brown color. It works because the resistance of the high beam filament is lower than the resistance of the fog light filaments.
If you DO have a 1989, the above applies to your Corvette. AFAIK, 1989 is the ONLY year the fog lights are wired this way. In 90 they begin to use a relay. 88 and down the fogs are grounded to the chassis, and operate in both low and high beam. No relay either until 1990.
The only remedy for 89 is to find the ground wires from the fog lights, DISCONNECT them from wherever they go now, and ground them directly to the chassis.
If you DO have a 1989, the above applies to your Corvette. AFAIK, 1989 is the ONLY year the fog lights are wired this way. In 90 they begin to use a relay. 88 and down the fogs are grounded to the chassis, and operate in both low and high beam. No relay either until 1990.
The only remedy for 89 is to find the ground wires from the fog lights, DISCONNECT them from wherever they go now, and ground them directly to the chassis.
Thanks, this makes sense, it is an 89 and it would agree with the manual.
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Not sure that will work for my year though.