84 quad lights, pass low beam works only with high beam

[Bobby Pootz]

Hello,

I've tried to search but have found no answers, I swear I read it last year while looking at headlight threads.

The passenger side low beam light does not go on. It will only come on with the high beams on.

I've done nothing recently to change anything electrical, I also checked to be sure the ground was good and it was.

Any help would be great, I know it's not the bulb. Thanks in advance!

Rob

[xs-style]

I'll bump this one back up. I recently had the same issue after installing an aftermarket headlight harness. I never did figure out the problem. Maybe someone with an idea on this issue will lead to a solution on mine too.

[TKCR]

Check your connection at the headlights. Could just be a loose connection or wire

[TKCR]

It could also be that the low beam bulb is burned out. Might just need new headlights. But check the connections first.

[Bobby Pootz]

Originally Posted by TKCR

It could also be that the low beam bulb is burned out. Might just need new headlights. But check the connections first.

My wires are all good, the connections are solid.

I know the bulb works because it comes on when I switch to high beams. I inspected the three prong male side of the bulb and can only see that it might be an internal issue.

All wires are good, connections are good. Just an odd scenario, and seeing how xs-style also has the same issue at least makes me feel like I'm not crazy!

For now I just unplugged the high beams and run the lights on high beams so the low beams can function.

Thanks for the help!

[Dayton601]

I would try a new switch, or borrow one that is working, the one that switches from high to low, they cant be that expensive,

[TKCR]

Originally Posted by Bobby Pootz

My wires are all good, the connections are solid.

I know the bulb works because it comes on when I switch to high beams. I inspected the three prong male side of the bulb and can only see that it might be an internal issue.

All wires are good, connections are good. Just an odd scenario, and seeing how xs-style also has the same issue at least makes me feel like I'm not crazy!

For now I just unplugged the high beams and run the lights on high beams so the low beams can function.

Thanks for the help!

The beams are two completely independent filaments, so one can work while the other doesn't. And I would still fill the connector plug with electrical grease, it wouldn't hurt regardless

[xs-style]

For another weird twist, my lights will work as they should without the harness. They only have the symptoms you have with the relay harness installed.

[Bobby Pootz]

Originally Posted by TKCR

The beams are two completely independent filaments, so one can work while the other doesn't. And I would still fill the connector plug with electrical grease, it wouldn't hurt regardless

The low beam bulbs have two filaments? This would be surprising to hear since there's four lights and I thought there were just single filament bulbs each.

[TKCR]

You guys aren't using LED bulbs by any chance? I know I tried changing all my bulbs over to LED's. Talk about weird issues, I had all kinds of issues. Switched them back and everything was fine.

[TKCR]

Originally Posted by Bobby Pootz

The low beam bulbs have two filaments? This would be surprising to hear since there's four lights and I thought there were just single filament bulbs each.

Duh, that's right, you have quad headlights. That would only be for a single headlight, they have two filaments.

[xs-style]

I dunno about the op, but I'm just using standard Sylvania bulbs in my case

[BHTH]

In this thread (great thread by the way) look at X8430 and find the quad headlight diagram. There are three pins and two elements in the lowbeam (even in a quad light system). Your one element is burned out, the other is still good.

http://67-72chevytrucks.com/vboard/s...d.php?t=545416

Originally Posted by TKCR

Duh, that's right, you have quad headlights. That would only be for a single headlight, they have two filaments.

[TKCR]

Originally Posted by BHTH

In this thread (great thread by the way) look at X8430 and find the quad headlight diagram. There are three pins and two elements in the lowbeam (even in a quad light system). Your one element is burned out, the other is still good.

http://67-72chevytrucks.com/vboard/s...d.php?t=545416

Thanks for that link, I keep forgetting that hatzie posted all of those schematics. And I'm happy to see I wasn't being a ding-a-ling after all.

[Bobby Pootz]

Originally Posted by xs-style

I dunno about the op, but I'm just using standard Sylvania bulbs in my case

I also have standard Sylvania bulbs

Originally Posted by BHTH

In this thread (great thread by the way) look at X8430 and find the quad headlight diagram. There are three pins and two elements in the lowbeam (even in a quad light system). Your one element is burned out, the other is still good.

http://67-72chevytrucks.com/vboard/s...d.php?t=545416

Awesome thread for sure, thanks for confirming my problem!

Originally Posted by TKCR

Thanks for that link, I keep forgetting that hatzie posted all of those schematics. And I'm happy to see I wasn't being a ding-a-ling after all.

Looks like you were right after all!

I ordered another bulb and will post once it's in and hopefully working again.

Thank you everyone for your help!

Rob