I have a '78 and I have changed over to a rectangular headlight set up using the lights from an '86 era camaro. All was well and I did a mock up about a year ago and it all seemed to work fine. Somehow I misplaced one of the low beams and replaced it with a new Wagner H4656 now that I am finishing up the install. I have relays for the hi and the low beams. And a new headlight switch. When I turn the lights on they are bright, and when I turn the hi' s on they are also bright with all 4 bulbs lit up. But when I have just the lows on the filament in both hi's glow. Not enough to light up the bulbs but there is a slight yellow glow, almost like a glowing ember in a fire. If I swap out one of the low beams with an older round bulb, the glow goes away. I have gone through my connections and they all seem good and I believe I have good, dedicated grounds to each side. I do not have any of the side lights hooked up, but don't believe they would be connected in any way. Any ideas would be welcome. Thx.

 

You certain you have all the wires in the right places? The high beam wire on the dual bulbs, (low beam bulbs) should be on the right side of the car. The low beam wire on the dual filament bulb should be on the top. The ground wire to the left side, (Drivers side) of the car. On the high beam only bulbs. Ground also to the left, power to the right.
it sounds as though your back feeding through your high beam bulbs on low beam, which indicates incorrect wiring.

 

A back feed seems right to me too but why not when I put the old style round bulb in. I think I am going to just pull it out across the front of the car and actually put my hands on each wire. I have a tendency ( more as I get older) to just rush thru things. This is all custom wiring so it is possible I put the wrong wire to the wrong terminal on the bulb. OMG don't let my wife know I admitted that I MIGHT be wrong. Thx.

 

They are different as far as wiring- the ground and high beams are swapped-
The glow is from the current flowing though the high beam filament (acts as a resistor) to a ground.

 

I think I'd listen to Richard. He knows more about headlights than anyone on this forum. The wiring I described is for round headlights. If Richard says those rectangular ones are wired differently. Listen to Him!

 

I have been listening to Richard for almost 100 years now, or so it seems. Starting when I installed my electric headlight buckets which was before he started selling them. And he was able to explain to me, in very simple terms, how a relay works and how to wire them. I went out to the car earlier and I must be looking right at the issue without seeing it. Here is a diagram that I used to wire these up. And it doesn't appear that there is any difference between the round or rectangular bulbs. But maybe that is what I am not seeing.


The only difference is that I have 2 feed wires going up from a junction box under the hood, one on each side of the car. And 2 separate grounds, again, one on each side. I even pulled out the old OEM wiring to compare things and I am not seeing a difference. As for the ground and high beams terminals being switched, I was able to just turn the plugs over 180 degrees since there were only 2 terminals. I have dedicated grounds to each light going directly to a common ground strip under the hood. Turning the plugs either way didn't make a difference. So I am taking a few days off to play, taking a road trip in my C6 to Atlanta ( what fun!) to visit friends but when I come back I plan on taking all 4 bulbs out along with the relays, laying it out on the hood and making some jumpers to go from terminal to terminal and see if I can get it all to work. I end up confusing myself when I lay down under the car looking up, which is right or left? Ha! Would it be possible for one of the high beams to short out somehow without blowing out the bulb? Maybe a bad filament? I will learn more next week. And I will follow up on this thread when I figure it out. Thank you both for the input.

 

Here you go-

Just re-pin the plug for the lights-

 

Richard, thanks, now I get the switching back and forth between the 2 leads. It appears that my confusion in reading the schematic I posted above was knowing the placement of the center lug. It isn't very clear. If the bulb is upside down, the center lug is at the top and the lug to the right is the ground. But if the bulb is right side up, the center lug is now at the bottom and the one to the right is the hi beam. Then there was the issue of looking at the front of the plug or the back of the plug until my head almost exploded. I do better with visual aids, so I took the bulbs out, laid them on the hood and that's when I figured out that with the bulb righside up, the center lug is on the bottom and it all worked. For reference in the pic the white leads are the grounds. And no one needs to point out that the lights are facing backwards thank you very much. Thanks all for your thoughts and helping an old guy.