On my 69, when I turn on the low beam headlights the brights also come on very dimly. The brights light right up when I tap the toe switch for them, but do come on very dimly even when they should be off. Now I know this is a ground problem, so I was just wondering if anybody has ever had this happen before, and was it a ground up near the core support, or is it a ground on the headlight switch, or the dimmer switch. I am hoping it is not the headlight switch as the dash is a pain to pull out, by I want to get this corrected.

Thanks guys,

Jeff

I don't see how it's a ground problem. The high beams, and low beams, are always grounded but high beams should only get 12v when the high beam switch is on. Where is the voltage coming from when the high beam switch is off? Sorry, maybe I'm missing something but I can't see how a ground problem would cause what you describe. Dim or no light when it should be on, ground problem. Dim or lit when it should be off, not a ground problem. I would suspect a faulty dimmer switch.

I don't see how it's a ground problem. The high beams, and low beams, are always grounded but high beams should only get 12v when the high beam switch is on. Where is the voltage coming from when the high beam switch is off? Sorry, maybe I'm missing something but I can't see how a ground problem would cause what you describe. Dim or no light when it should be on, ground problem. Dim or lit when it should be off, not a ground problem. I would suspect a faulty dimmer switch.

I have a new NOS dimmer switch in it and I tested that and it is doing what it is supposed to do.

After doing some searching here I found this problem a few other times and it appears it comes down to grounds or the wires going into the low beams are not in the correct order, like the black, orange, and green wires are in the incorrect positions. The reason it can be a ground problem is because one headlight grounds through the other, which if you have a bad ground would put a potential on the filament.

The more I tink about it, the more I think it is likely a problem with the wires being in the incorrect positions on the back of the headlamp. I just can't see both sides of my headlights having the same ground issue, I can however see myself screwing up putting the wires on the headlights as I would have put them on the same on both sides.

Thanks, Jeff

Ok, still don't understand your ground theory. You say a bad ground could put a potential on it. What do you consider a bad ground? I think of a bad grd as a poor connection which won't cause a potential across the filament. If you're thinking a short then that's different. I can see where mis-wiring would feed power through low-beams and high-beams in series. Which would cause them to be dim, getting only 6v instead of 12v. I'll go look at my connectors, it's a 70 but probably the same color wires.

EDIT: Well maybe they are different. Looking at driver's side lights I have black on the left, driver's side. The black is connected from low to high then grounded to rad support. Right connector is green on both, connected together, this would be high-beam source. Middle connector of low beam is brown/tan, low-beam source.

I just rewired my 69 & ground the headlights to the core support & they work fine.

I just rewired my 69 & ground the headlights to the core support & they work fine.

Is it possible you can tell which way the wires connect to the headlights, I really think mine are screwed up.

Jeff

Is it possible you can tell which way the wires connect to the headlights, I really think mine are screwed up.
Jeff

Looking at driver's side lights I have black on the left, driver's side. The black is connected from low to high then grounded to rad support. Right connector is green on both, connected together, this would be high-beam source. Middle connector of low beam is brown/tan, low-beam source.
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Hank

This is for "single headlights" just add 2 inner high beams (light green & black)

http://www.chuckschevytruckpages.com/images/80hlightschematic.jpg