LMC Headlight Upgrade Wiring Harness

[PatronMotorsports]

Has anybody tried to hook up this kit The LMC kit is not a direct R&R and there is no way to connect their harness(3 Blade) to the trucks 2 Blade connector. LMC is clueless and suggests calling Taiwon and asking the Mfg.
Thanks in advance

[dallas71]

Which kit did you buy??? I did a couple of years ago and i didnt have to modify nothing.

[PatronMotorsports]

It's the 100/90W Hi-Grade Head Lamp Tune Up KIT P/N 36-3580.
Looks like we both have 66 Chev LWB Trucks

[TR65]

I purchased that kit too and I expected the connector thru the radiator support to be the factory connection but it wasn't as you found out.

I basically stripped out that harness and used the wiring, the headlight connectors and the relays. I bought a harness from Classic Industries to get the correct connector. Here is what I did.

http://67-72chevytrucks.com/vboard/s...d.php?t=397695

You do need three wires through the radiator support because you need a new power wire since the old two wire rig just operates the relays, doesn't carry the headlight power.

I shoud have sent the LMC harness back but I made do.

Good luck,

TR

[PatronMotorsports]

Thanks a lot TR, Just what I was looking for. And the explanation makes sense too. Kind of makes you wonder why LMC hasn't posted a work-around.

[Fred T]

No workaround because they don't have a clue. All they do is sell parts. I recommend buying from a business that uses what they sell.

[PatronMotorsports]

Sometimes their catalog is good for solving assembly issues, their blow-up pix are pretty accurate. Saves dragging the assembly manuals out into the shop. But I'm afraid your right, their fitment and tech support are not always up to par.

[McC_65_91]

did one a while ago on my 65 gmc, its 4 head lights. i dont remember much about doing it but it still doesnt work right. The high beams run all the time but dim when i set it to low beams, (where they should go off right??). I thought maybe i used high/low beam bulbs for the high rather than just high beam bulbs, but thats not it, dunno what else it could be,but i can deal with it, dont drive it at night much anyway

[TopFuel1966]

I believe the 36-3580 harness is meant to be used with the halogen bulbs which take a 3-prong connector.

[TR65]

Top,

The bulb connectors are correct, the third prong is for the ground.

The issue is the connector thru the radiator support. It won't fit the stock hole, and they don't give you the mating connector.

TR

[TopFuel1966]

OK.........I was looking at the wrong end of the harness.

[PatronMotorsports]

In this case it would be impossible to plug a round rubber two wire plug into a much larger plastic three wire receptical. Granted I'm not sure what modifications may have been made to the factory harness in the last 40+ years. It still remains that I have found no one that has found the kit to be plug and play as advertised. In the meantime I'll cut it up and use what I can to make it work. Not something I would want my CE to have to do on my Longbow.

[markeb01]

Did LMC happen to provide a schematic for their harness? It shouldn’t be that difficult to modify for use with the stock bulkhead connector. In the stock harness there are only 2 wires going to the lamps from the dimmer switch - 1 for high beams, and 1 for low beams. Ground goes straight from the bulbs to a sheet metal connection.

If the 3rd wire in the new harness is in fact ground, the terminals could be slipped out of the new coupler, reinserting the high and low beam wires into the original connector, and ground connected separately (assuming they used stock male/female terminal orientation). For maximum light output, the ground should be routed back to the battery ground either on the engine block or frame rather than screwed to sheet metal.

Assuming you’re intending to add relays to go along with the new harness, here’s a schematic in case you don’t already have one.



And here is the layout of the factory plug so the wire terminals end up in the correct slot:

[John Gilbert]

You guys I think know where things went wrong. My guess is the stock headlight harness that runs on the '60-66 core support is being eliminated, instead of retaining and plugging LMC Truck's Heavy-Duty harness into it.

Here's a link to the story I just did for CCT on my '79 C10 using the Heavy-Duty harness. I've also included a shot of LMC's Heavy-Duty harness on my '88 C/K which hasn't appeared in a magazine tech. I looked under the hood of my '66 to get a better idea, but as you can see it's been stripped of all wiring.

The idea behind the Heavy-Duty harness besides improving light quality is to be reversible which means it easily unplugs and the truck can be returned to stock.

Here's some photos: If anyone would like an explanation of what's being shown, I'll be glad to expand on what I was trying to get across.

[John Gilbert]

Oops, I can already see I had better explain what's here.

top photo: Looking straight down onto '88-98 C/K arrangement. I mounted the relays close to the battery, and LMC's plugs, plugged into existing GM plugs.

second from top: My '66 is stripped out, so I couldn't show what's involved, but I'm sure its not much different from the C/K or '73-87 C10.

Third photo is my '79 C10

Fourth photo shows how the stock C10 driver side plug is left hanging, and the Heavy Duty harness plugs directly into the headlight.

Here's the link http://www.customclassictrucks.com/t...c10/index.html