90-up fog light wiring

 

Mine looks similar to the 1990 posted above:

 

I had similar issues on my AUDI with LED tail lights and it turned out the I needed to install some LED resistors. You may want to look into that first since it would be on the headlight side and easier than running a new harness with relays.

 

Has anyone tried just an LED H4 (low/high beam) bulb?

 

Interesting, had not seen those before. Looks like we need a guinea pig.

 

I finally heard back from Daniel Stern yesterday, I will not be buying anything from him.

I've been thinking about the fog light issue and I may possibly be onto something simpler than the relay harness. Since apparently the fix to the fogs is to get the headlights grounded directly, rather than through the factory lighting harness, I'm going to try these. I'll just cut the ground wire on these adapters and then run the ground direct from the headlights to the frame. I ordered these off ebay last night but won't get a chance to do the install until the week of Christmas. I'll take pics and report back with the results then.





H4 light extensions

 

Why not?

 

The email I got back from him was very condescending in regard to the whole fog light issue in general. While he undoubtedly knows his stuff I just didn't care for the tone.

 

Good to know.. Has a feel that is what it was and get I have never communicated with him

 

I think you said you had an early 90's 'vette, if thats the case your fogs are already directly grounded to the frame, unlike the fogs in my '89. Check out the schematics posted above.

Your simple possible solution is exactly what I have been saying. No need to run a redundant headlight harness, find a way to power the fogs directly, bypassing the OEM harness design that doesn't allow the fogs and hi-beams to lite together. The thing is I'm not sure running a direct ground from the OEM headlight harness will correct this problem for your model year, but it may actually work for my '89 that doesn't have grounds running directly from the OEM fogs. Interesting!

It looks like you need study the foglight relay circuit and find a simple work around for that. On my '89 it appears the fogs are grounded thru the pass. side headlight, no OEM relays for me, they don't have a direct independent ground like you have. This would require a different solution for you than for me.

Let us know what you find out, or if you configure something that works for your model year 'vette.

 

Mine's actually a 96, which I understand has the fogs grounded through the high beam filament. You're right, I do need to spend some time studying that schematic. I paid less than $9 for those adapters so if they don't work out then at least I'm not out much money. It'll be a couple weeks before I get the chance to work on this but I'll report my results back.

 

You sure about that? I would think your wiring schematic is similar or the same as the one posted for the '90 above. Model years '90 up to '96 had the "new" interior designed dash that was different than the '84~'89 Atari dashed interiors. You should have an OEM fog light relay which I do not have. You may need to get an actual wiring schematic for your specific model year to be certain though.

This is how GM designed the fog lamp circuit to operate;
If you look at the fog lamp relay, 12 volts comes from the Tail 15 amp. fuse when the Headlight switch is in Park or Head and applied to the Fog lights when the relay closes. The relay will energize when the Fog lamp switch is on, as long as the High beams are not on. If the High beams are on, 12 volts will be on both sides of the primary coil of the Fog light relay which will not allow the relay to energize. If the High beams are off. the 12 volts for the primary of the relay coil from the Fog lamp switch will travel through the headlight high beam filament to ground and the relay will energize. The Fog light relay is located under the passenger side of the dash and mounted along the front bottom edge of the dash.

Keep us posted.

 

Our fogs are grounded through the high beam filament...If you ground them directly it is almost guaranteed your high beam indicator will come on and stay on when you flip the fogs on. I know, go ahead and say I'm wrong and you'll clue us in when you find the "correct" solution.

 

That might just work! Good luck with it.

 

You didn't mention what year you have. If your particular wiring schematic looks anything like the one posted above for a '90 the OEM fogs don't appear to be grounded thru the hi-beam filiament although the switch may be? My '89 however does appear to be grounded thru the OEM headlights & gdl2165's idea may actually work for my model year.

If you now concede that a simple grounding solution "might work"....... Tell use which solution do you recommend as "correct" now??
Would you still advocate installing a redundant wiring harness that isn't really necessary when all that was ever required was a way to ground the OEM fogs in a relatively simple way!

 

All 91'-96' Corvettes had the fog lights grounded through the high beam filament. This has been established throughout the years on this forum. I know this for a fact because my fogs no longer worked on my 1994 once I installed HID headlamps (which have no filament). If you directly ground the fogs (which I initially did), it will make the high beam indicator come on when you turn the fogs on. The fogs will still light no problem if the high beam indicator isn't a big deal to you. It has been a while (early 2012) since I did all this, but you can go under the dash on the passenger side, and jump two wires on a relay to directly ground the fogs, without doing any cutting or splicing. This allows the fogs and high beams to be on at the same time. It is documented in a thread somewhere on this forum with pics. I have been through this before, I am not just speculating on what will and won't work.

gdl2165- I got the same vibes from Daniel Stern, but he is very knowledgable. I did end up buying a few bulbs through him, but I sourced everything else myself.

 

Ok if that's the way GM wired your OEM fogs I believe your must know your own 'vette. My comments were specifically directed at the two wiring schematics that were posted in this thread, one for an '89 and one for a '90. I assumed all '90 & up 'vettes made after the interior redesign were the same as the '90 schematic posted by Pete above. If you know this to be true I'll take your word for it, I don't have a FSM for a '91~'96 'vette.

I still maintain..... and this is where we disagree...... that it is completely unnecessary to run an entire redundant wiring harness to get the OEM fogs to work with aftermarket LED headlights! We need to figure out a way to ground the OEM fogs using a different path to ground than the one GM provided that doesn't allow the fogs and hi-beams to operate at the same time.

 

Here's my promised update. Unfortunately, my little experiment was a failure. Grounding the headlights directly via the short extensions I bought made no difference whatsoever, turning on the fog lights still causes the high beams to come on. Oh well, I may eventually try the relay harness but honestly I'm not overly concerned about being able to use the fogs.

 

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If the fogs are grounding thru the headlights and are power switched (have not looked at any diagrams just going by what was posted) then wouldn't it be simpler to just ground the fog lights directly and remove the ground lead that's there already from them?