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Old 02-22-2022, 07:20 AM   #1
71gmcC15
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Re: Headlights don't work and it's not the dimmer swich.

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Originally Posted by BigBird05 View Post
If you are running a relay do you have power into and out of the relay? What is your power source into the relay?
I will have to check. To see if power is coming out of the relays. I know power is going in. Fuses is good and is hooked straight to battery. Then the relay gets. triggered by the factory wiring to swich between hi and low beam. But the thing is it's done this before I ever installed the HD harness. But was always able to get them back. The only reason I installed the harness is because the dimmer would get so hot and melt the terminals. Maby it damaged the headlight swich to and now it Finlay gave out?. As in it sends power to the dimmer but the circuit braker tripes and doent send power out to to headlights idk. I'll check the relays when I get a chance though.
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Last edited by 71gmcC15; 02-22-2022 at 07:26 AM.
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Old 02-21-2022, 11:49 PM   #2
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Re: Headlights don't work and it's not the dimmer swich.

If you can hear a relay click and since you have eliminated some other areas, take a good look at your relay(s). Some relays have built-in blade fuses that might be bad.
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Old 02-22-2022, 07:48 AM   #3
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Re: Headlights don't work and it's not the dimmer swich.

If the dimmer gets that hot, you have to big of a power draw. Can you draw a schematic of how you have your relays wired?
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Old 02-22-2022, 11:50 AM   #4
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Re: Headlights don't work and it's not the dimmer swich.

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If the dimmer gets that hot, you have to big of a power draw. Can you draw a schematic of how you have your relays wired?
It doent get hot anymore with the relay kit. It's basically the same thing as the lmc harness but actually works.
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94 chevy k1500 350 tbi 373 rear gears 4l60e one wheel peel. Gutless
07 gmc sierra classic rcsb 4.3 lt 5 speed w/t
04 chevy Silverado 1500 ext cab 5.3 4l60e.
81 chevy Scottsdale k10 muncie sm465 Np208 10 bolt 8.2 ( Old Green)
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Old 02-23-2022, 07:55 PM   #5
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Re: Headlights don't work and it's not the dimmer swich.

So the headlight relay harness upgrade. Something like https://www.lmctruck.com/1967-72-che...dlight-harness
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Old 02-23-2022, 08:43 PM   #6
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Re: Headlights don't work and it's not the dimmer swich.

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So the headlight relay harness upgrade. Something like https://www.lmctruck.com/1967-72-che...dlight-harness
Yes. But mine actually works. The lmc one is wired wrong.
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94 chevy k1500 350 tbi 373 rear gears 4l60e one wheel peel. Gutless
07 gmc sierra classic rcsb 4.3 lt 5 speed w/t
04 chevy Silverado 1500 ext cab 5.3 4l60e.
81 chevy Scottsdale k10 muncie sm465 Np208 10 bolt 8.2 ( Old Green)
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Old 02-23-2022, 08:47 PM   #7
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Re: Headlights don't work and it's not the dimmer swich.

Update. Got it fixed. No this sounds stupid and believe me it was the first thing I checked. But the fuse on the HD harness was bad. It didn't blow it just bad looked likea good fuse. Changed it and they work now. I feel so dumb now. Lol thanks everyone for helping me and my stupidity. But I was right it wasn't the dimmer. Lol
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( second times the charm) 71 gmc c15 307 sbc 373 rear gears positrac sm 465 trans. ( not listed on spid but is original )
94 chevy k1500 350 tbi 373 rear gears 4l60e one wheel peel. Gutless
07 gmc sierra classic rcsb 4.3 lt 5 speed w/t
04 chevy Silverado 1500 ext cab 5.3 4l60e.
81 chevy Scottsdale k10 muncie sm465 Np208 10 bolt 8.2 ( Old Green)
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Old 02-23-2022, 08:55 PM   #8
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Re: Headlights don't work and it's not the dimmer swich.

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Update. Got it fixed. No this sounds stupid and believe me it was the first thing I checked. But the fuse on the HD harness was bad. It didn't blow it just bad looked likea good fuse. Changed it and they work now. I feel so dumb now. Lol thanks everyone for helping me and my stupidity. But I was right it wasn't the dimmer. Lol
We all have similar stories. We messed with a speed warning buzzer the other day for an hour. It had an inline fuse. The last thing we checked.
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Old 02-23-2022, 09:52 PM   #9
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Re: Headlights don't work and it's not the dimmer swich.

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Originally Posted by 71gmcC15 View Post
Update. Got it fixed. No this sounds stupid and believe me it was the first thing I checked. But the fuse on the HD harness was bad. It didn't blow it just bad looked likea good fuse. Changed it and they work now. I feel so dumb now. Lol thanks everyone for helping me and my stupidity. But I was right it wasn't the dimmer. Lol
Don't give up that easy. Maybe the dimmer blew the fuse. Something blew the fuse, right?
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Old 02-23-2022, 11:05 PM   #10
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Re: Headlights don't work and it's not the dimmer swich.

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Don't give up that easy. Maybe the dimmer blew the fuse. Something blew the fuse, right?
I don't think the fuse actually blew. Mainly becuse like I said in the first post when the light whare working I switched to hi beam they whent out. Spamed the dimmer they came back on then hit it again then off. A blown fuse wouldn't of came back for one more round. I think the cheap fuse that was in it actually broke. It came out in peaces. Pulled just the plastic out first. Then one side of it then the other. If I have this happen again then I'll look deeper but for now I'm going to leave well enough alone.
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( second times the charm) 71 gmc c15 307 sbc 373 rear gears positrac sm 465 trans. ( not listed on spid but is original )
94 chevy k1500 350 tbi 373 rear gears 4l60e one wheel peel. Gutless
07 gmc sierra classic rcsb 4.3 lt 5 speed w/t
04 chevy Silverado 1500 ext cab 5.3 4l60e.
81 chevy Scottsdale k10 muncie sm465 Np208 10 bolt 8.2 ( Old Green)
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Old 02-23-2022, 09:05 PM   #11
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Re: Headlights don't work and it's not the dimmer swich.

Glad you got it fixed! You're not the first one to be fooled by a fuse's appearance....
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Old 02-23-2022, 09:26 PM   #12
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Re: Headlights don't work and it's not the dimmer swich.

I worked as a mechanic for many years, and learned to not believe a good looking fuse. It only takes a couple of hours for that lesson to stick.
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Old 02-23-2022, 10:20 PM   #13
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Re: Headlights don't work and it's not the dimmer swich.

You are so right Steeveedee. If its one thing you learn in electrical is don't assume anything and check everything. In the old days I had a circuit breaker I could put inline to replace the fuse.
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Old 02-23-2022, 10:35 PM   #14
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Re: Headlights don't work and it's not the dimmer swich.

Yep. Been there. I had good fuses on a ‘67 mercury restoration. Continuity when checking the fuse. Fuse holder was corroded slightly and didn’t send power out of it.
Again the cheap light 12 volt tester will find it.
Best $15 you will spend for electrical problems.
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Old 02-23-2022, 11:13 PM   #15
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Re: Headlights don't work and it's not the dimmer swich.

A lot of junk china fuses are out there. When I go junk yarding I always buy some of the original GM fuses.
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Old 02-24-2022, 12:35 AM   #16
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Re: Headlights don't work and it's not the dimmer swich.

We bought a new Honda Accord in 1979 and had it 4 years. Sometime in the early Eighties, it started acting up intermittently. You'd be driving normally and it would die, than before long everything was fine again. It had the old glass cartridge fuses, same as our trucks. Can't recall which circuit it was but one fuse was bad. It was very hard to see the fault, which was a hairline fracture of the filament. Most of the time the ends touched enough to make a connection. But once in awhile it would go open. Hard to pinpoint, easy to fix.
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