73-77 A-body TECH Includes 73GTO, LeMans, Grand Am, Can Am

          
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Old 04-12-2026, 11:42 PM
Flashflood Flashflood is offline
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Default Headlights not working with brand new high and lows

My high and low beams are not working after I switched over to new headlights. The runners brake and turn single all work. The headlights were working perfectl, just old before I took the header panel off. I'm going try cleaning the contacts and checking fuses tomorrow. But wouldn't that cause all my other lights not to work?
Thanks Andrew

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Old 04-13-2026, 12:55 AM
SRGN SRGN is offline
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Did you unplug the main headlight harness when you were removing things?

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Old 04-13-2026, 01:19 AM
Flashflood Flashflood is offline
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Did you unplug the main headlight harness when you were removing things?
Just unplugged the bulb socket that's it.

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Old 04-13-2026, 08:48 PM
Mr. G Mr. G is offline
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Try plugging the bulb sockets into the old bulbs without mounting them just to verify the new bulbs are not defective.

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Old 04-13-2026, 10:29 PM
SRGN SRGN is offline
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Just unplugged the bulb socket that's it.
Did you go LED? Sometimes the LED headlights have the polarity wrong at the connector, and since they're diodes they don't take too kindly to that. Otherwise, do as posted above and verify the original bulbs work.

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Old 04-18-2026, 09:08 PM
Flashflood Flashflood is offline
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Well update I'm not getting any power through the headlight socket any idea if these have separate fuses for headlights and runners.

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Old 04-19-2026, 12:30 AM
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OG68 OG68 is offline
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Headlights do not have a fuse. Circuit breaker internal to the switch. Circuit breaker is suppose to open when it sees a short in the wiring, then reset when the short is removed. But sometimes they don't. You may need a new switch
Running and gauge lights are fused from the fuse panel. Two separate circuits

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Old 04-22-2026, 04:52 PM
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Well new switch still nothing can anyone tell me where the headlight harness connection is so I can check that.

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Old 04-25-2026, 04:31 PM
Mr. G Mr. G is offline
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Just a stab in the dark. No pun intended. Is it possible that when you removed the header panel that there were ground wires attached to some part of that which were not reattached?

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Old 06-14-2026, 07:07 PM
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Well new switch still nothing can anyone tell me where the headlight harness connection is so I can check that.
Well new brights switch still no front lights. Runners still work.

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Old 06-16-2026, 12:08 PM
mlewisariz mlewisariz is offline
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Check your headlight dimmer switch.

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Old 07-12-2026, 01:18 AM
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I'm going to update this. I went ahead and rewired the whole car. Headlights are now working. But I found out the select only makes an early model switch. But know im having a problem with my gauges pegging out when I turn on the lights.

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Old 07-12-2026, 01:23 AM
SRGN SRGN is offline
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Turn the gauge dimmer all the way down/off and see if the gauges still peg with the lights on.

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Old 07-12-2026, 07:24 PM
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Turn the gauge dimmer all the way down/off and see if the gauges still peg with the lights on.
Any idea why that would happen!?

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Old 07-12-2026, 09:39 PM
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Any idea why that would happen!?
If the gauges are getting a ground from the dimmer circuit, they will lose ground whenever the lights are on and go to full sweep.

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Old 07-12-2026, 10:39 PM
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If the gauges are getting a ground from the dimmer circuit, they will lose ground whenever the lights are on and go to full sweep.
Dude that turning the dimmer down worked thank you for that. Any idea what's causing them to do that. Bulbs such such i have all the grounds hooked up? Literally im like omg when that worked cause I was at such a loss.

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Old 07-12-2026, 11:03 PM
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There's a poor or missing ground. It happens, look at the wiring to the dash bulbs. They aren't grounding, separate the dash bulb ground circuit and give them their own dedicated ground. There may be other ground issues going on as well, I always run a ground strap from the block to the chassis, and make sure the ground wire from the battery negative terminal is hooked up to the radiator support.

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Old 07-14-2026, 01:26 AM
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I think I may rename this thread to flashs 77 lemans wiring hell. I took a break from the gauge cluster and figure i did at least wire in the turn single switch to see if my brake lights or any of that works. Guess what! Nope. Erg this is driving me nuts.

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