LED Lights strange behavior
Thread Starter
Melting Slicks
Joined: Jul 2002
Posts: 2,223
Likes: 556
From: Tallahassee fl
LED Lights strange behavior
I did 2 different sets of led lights on 2 C4's. 1993... works quite well plug and play except the fogs won't run when the lights are on. I can live with that. 2nd set on my GS... well, this didn't go the same. Fogs work just fine. High beam indicator always on with the lights in any position besides off. I read this thread https://www.corvetteforum.com/forums/c4-tech-performance/4388761-1991-1996-corvette-full-exterior-led-conversion-how-to.html
Which should solve my first issue of the high beam indicator always on by grounding the fogs (I think).
But my second issue is about 15 minutes at dusk on my first drive with just the fogs on. The headlights rolled 50% open at random. I turned the lights full on and they opened and worked just fine besides the high beam indicator. So what in the heck would trigger a half opening of the lights? Will the grounding of the fogs fix this too?
Which should solve my first issue of the high beam indicator always on by grounding the fogs (I think).
But my second issue is about 15 minutes at dusk on my first drive with just the fogs on. The headlights rolled 50% open at random. I turned the lights full on and they opened and worked just fine besides the high beam indicator. So what in the heck would trigger a half opening of the lights? Will the grounding of the fogs fix this too?
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
That headlights moving uncommanded is odd. We’re you driving perhaps with fog lights on only? EDIT: that’s exactly what you said…. That should not be related.
the fog light relay grounds through the high beam bulb element when high beams are off. When high beam comes on it does not allow the fog lamp relay to “ground” since the element is now powered/high resistance and thus turns the fogs off if they were on. I may not be staying that exactly correctly but it’s close. This is why switching to LED headlights causes issues with this circuit.
You should look at the circuit doctor fix, for both cars. Simple, cheap, effective, and fully recreates the stock functionality and grounding behavior. Only a small load of a “bulb” when the high beams are on, otherwise nada…and no factory wiring changes whatsoever. this is what I did on my 93.
the fog light relay grounds through the high beam bulb element when high beams are off. When high beam comes on it does not allow the fog lamp relay to “ground” since the element is now powered/high resistance and thus turns the fogs off if they were on. I may not be staying that exactly correctly but it’s close. This is why switching to LED headlights causes issues with this circuit.
You should look at the circuit doctor fix, for both cars. Simple, cheap, effective, and fully recreates the stock functionality and grounding behavior. Only a small load of a “bulb” when the high beams are on, otherwise nada…and no factory wiring changes whatsoever. this is what I did on my 93.
Last edited by pedricd; Mar 9, 2023 at 10:44 PM.
