Doesn't LMC sell that harness as an "upgrade"?

If you run HID's in your truck, is it seriously going to fry wires and blow fuses? I don't understand why they would need to offer that kind of harness unless you plan to throw some major power at your headlights, and the HID ballasts handle that anyway, so what gives?

 

I'm pleased with the LMC harness, I had no length problems , no shorting out problems. I agree that the LMC harness may not be the best out there, but for the price it's very hard to beat. If you take your time and install it properly it will be trouble free.

 

If you have half a brain you can make a harness for about 15 bucks. Relay socket from auto parts store a relay and 15 feet of 12g wire. It does involve some cutting and splicing of the factory harness but is simple as pie. Double the cost for low and high to be relay controlled. After you eat your third headlight switch you will see the value of the relay upgrade.

 

But I only have a 1/4 of a brain.

I still don't understand why you need to upgrade the harness, when all you're doing is adding ballasts. I would think that it should handle it just fine.

I used to have a crotch rocket I installed some on, and the fuse would blow if I started the bike with the high beams on. Otherwise low beam was always fine. They just plugged right in, no need for a new harness for anything.

 

Hid and even halogen pull more current through the headlight switch than the sealed beams these trucks were designed with. With cheap crappy replacements its only a matter of time before headlights start to flicker from bad contacts in the switch. Using the stock circuit as a relay trigger gives full. Batt voltage to the lights.....instead of the 11 volts they see going through the switch.

 

Upgrade your headlight's wiring harness for maximum light output with this Heavy-Duty Headlight Harness. If you are adding brighter bulbs or upgrading to high power halogen lights, then you need to improve your wiring to take full advantage of the extra light output.

This Headlight Harness draws power directly from your battery whereas your original wiring draws its power from your headlight switch. Heavy-Duty Harness is complete with separate relays for low and high beams and features OE style headlight sockets for easy installation with no splicing or cutting required




Lifted from LMC truck catalog !

 

Do a little search online and you will see how to make your own relay harness, very simple.

As for why you NEED it..

The battery supplies the power to the headlights, but not directly. 1st it has to go thru the headlight switch with is a PISSPORE design that only typically allows about 10volts to get to the headlights. And no one makes and upgraded one and for good reason.

What the relay harness does is send battery voltage Right from the battery directly to the headlights with no middle man taking his cut(no long wires, no scavenging switch)

I put my 1st LMS harness in my truck and I should of made the second for my buddies 79. BOTH were short and are pulled tight. And they both use taiwan cheap relays when Bosch ones are probe $2 a piece more

 

Are you aware that Bosch relays are not even made by Bosch anymore? Tyco Electronics or TE Connectivity make them. Portugal or China respectively. Even Hella sources to China.

If you want the last relay you will buy, go to the junkyard and find a mid 80's GM product. Snag relays at will. Also, a good source for sockets.

 

At least the are QUALITY