LMC HD headlight harness review

[Pyrotechnic]

I just received mine in the mail for my 77. First thing I did was sheer off the yellow jacketing because it looks hideous. I'll be replacing it with black split loom.

The wire is thicker gauge than stock which I was shooting for. Some people had problems with these being wired incorrectly but I checked mine and it looks fine. If you buy one, it's probably a good idea to double check it.

One thing I found out the hard way is that with H4 headlights, the stock headlight connectors grip the bulb way too tight. The bulbs are held in with spring clips, so if the connector is too tight, the spring clips flex when you try remove the connectors, it's a little scary.

The connectors on the new harness slide on and off just like they should.

Since the harness has better connectors and thicker gauge wire, I'm going to graft it in as part of the wiring harness and get rid of the factory connectors and wiring.

Over all I'm pretty happy with it. For $30 I was willing to give it a try. I've heard a lot of people say just grab some relays and do the mod yourself, but thicker gauge wires, better connectors all pre assembled for you is a real time saver.

Another complaint I heard was the lack of fuses. This concerned me at first, but upon closer inspection, it appears that the first section of the power leads before the ring terminals might actually be fusible link wire. There are no markings on it but it has the super soft and flexible feeling that i've only seen with fusible link wire. I'm not sure if I want to use this or just go ahead and replace them with ATC blade fuses.

I also bought the round H4 headlights too, I'll let you all know how those work out as well.

[LBJ]

Looks like a pretty nice setup. I used a Painless wiring mod on my 91 GMC to make all 4 headlights work at once on high beams. Cheap mod and good idea.

What WOULD happen if you ran the high power bulbs without all the extra wiring mods (just changing out the connectors)? Anyone tried it?

[BaddBusa2005]

Before I buy this for mine, I would like to know if anyone has used the 4 HL setup and has the H4 conversion with the H1 high beams. When I plug all four in all of them come one, I never could figure out why.

[beaterC10]

Originally Posted by BaddBusa2005

Before I buy this for mine, I would like to know if anyone has used the 4 HL setup and has the H4 conversion with the H1 high beams. When I plug all four in all of them come one, I never could figure out why.

I wired up a 4 HL system using H1 and H4 bulbs and after much effort went back to H1 and halogens. With low beams selected, the H1 elements glowed dim. With high beams, the H1 and H4 hi elements glowed dim. Was your experience anything similar?

[BaddBusa2005]

Originally Posted by beaterC10

I wired up a 4 HL system using H1 and H4 bulbs and after much effort went back to H1 and halogens. With low beams selected, the H1 elements glowed dim. With high beams, the H1 and H4 hi elements glowed dim. Was your experience anything similar?

Yep same exact thing. I have just the sealed halogens and h1's back in the truck. Kind of sucks that I have money in the h4 and conversion and cannot use it.

[beaterC10]

Originally Posted by BaddBusa2005

Yep same exact thing. I have just the sealed halogens and h1's back in the truck. Kind of sucks that I have money in the h4 and conversion and cannot use it.

Hey, at least I don't feel so bad about it now. I messed with it around Thanksgiving and just gave up in disgust.

[Pyrotechnic]

I don't have much experience with the square 4 headlight setups but maybe I can help. When you guys say H4, are you using combined high and low beam 9003 H4 bulbs in those ? H4 really wouldn't apply to 80's 4 headlight trucks because they have 1 lamp dedicated to low beam, and 1 lamp dedicated to high beams on each side.

[baggedcten]

Originally Posted by beaterC10

I wired up a 4 HL system using H1 and H4 bulbs and after much effort went back to H1 and halogens. With low beams selected, the H1 elements glowed dim. With high beams, the H1 and H4 hi elements glowed dim. Was your experience anything similar?

same here but i didnt want to put the halogens back in so i just diconnected the high beams.

[BaddBusa2005]

Originally Posted by Pyrotechnic

I don't have much experience with the square 4 headlight setups but maybe I can help. When you guys say H4, are you using combined high and low beam 9003 H4 bulbs in those ? H4 really wouldn't apply to 80's 4 headlight trucks because they have 1 lamp dedicated to low beam, and 1 lamp dedicated to high beams on each side.

That is what I do not get. If a standard halogen sealed beam only had one filament dedicated to low beam, why are there three wires to the lowbeam headlight?

[Pyrotechnic]

Originally Posted by BaddBusa2005

That is what I do not get. If a standard halogen sealed beam only had one filament dedicated to low beam, why are there three wires to the lowbeam headlight?

What are the part numbers printed on the bulbs for your high and low beam ?

[BaddBusa2005]

Originally Posted by Pyrotechnic

What are the part numbers printed on the bulbs for your high and low beam ?

lowbeam is h4656
high beam is h4651

The swap that I have uses the H4 for the lows and an H1 for the highs.

[Pyrotechnic]

If wired correcty, you should be able to run a H4 as a low beam and run a H1 as a high beam. It's all in the wiring. You just would never light the 2nd filament of the H4 bulbs.

[BaddBusa2005]

Originally Posted by Pyrotechnic

If wired correcty, you should be able to run a H4 as a low beam and run a H1 as a high beam. It's all in the wiring. You just would never light the 2nd filament of the H4 bulbs.

That is about what I figured, i just havent put much effort into it. When I was swapping the housings I think three or 4 of the adjesters broke, and the autozone ones suck.

[beaterC10]

I'm pretty sure the factory used the high elements in all four bulbs in a dual headlight installation. At least that's how mine worked with the factory harness.