hey guys..........i have a lmc heavy duty headlight harness w/80w-100w bulbs. i went to change a burnt out bulb and had a hard time unpluging it. when it finally came out the harness plug was melted and i went over to the other side and unpluged the bulb and it was even harder. when it finally came out the harness plug was melted more than the passenger side and 1 of the prongs for the bulb was stuck in the plug and i needed a pliers to pull the prong out. can someone tell what happened and what went wrong for the plug to melt. i will be getting another harness for the bulbs i have........thanks for the feed back in advance..............

 

Was it a so called "upgrade" harness? If not I would think the connectors were too small for the higher wattage bulbs and there for the resistance caused enough heat to cause your problem..

 

Id try this if you're gonna get a new harness.

RJM Injection Tech — Headlight Harness

 

No wonder it melted.

 

I'm surprised the bulbs didn't melt the housings too.

 

whats up guys...........i ordered the rjm harness. the wires look more heavy duty than lmc wires. thanks for all the feed back. merry xmas to all.

 

Glad to help. Let is know how the RJM kit install goes. Been looking at one myself.

 

i have a question on these aftermarket harnesses...im having the hardest time trying to find where it plugs into the factory harness.

...where would I find this? And/or a wiring diagram for the 87-91 setup? diesel?

this is what i have...no idea where it came from (brand)

<a href="http://s1095.photobucket.com/albums/i463/91dirtydiesel/?action=view&amp;current=eb25679b.jpg" target="_blank"><img src="http://i1095.photobucket.com/albums/i463/91dirtydiesel/eb25679b.jpg" border="0" alt="Uploaded from the Photobucket iPhone App"></a>

 

Pic's not real clear regardless I'd imagine its as simple as unplugging the head lights, plugging that harness into the truck harness (drivers side IIRC?) then plugging the headlights directly into that harness.

What I mean by "drivers side", I believe the trucks main harness connects to the drivers side headlight then follows rad support across terminating at passenger side head light. Unplug driver side head light plug harness into the truck harness where the head light was plugged in.

Then connect the power supply ("red" and fused seen in pic) to the battery on the positive side and looks like you need to supply ground both ends near the each head light.

Then the headlight switch provides the on off control via relays, power is direct from the battery to headlights via the relays built into that harness.

Main power for lights no longer enters/exits cab to switch and back, with it only low amp circuit needed to trigger relays, turn off/on hi/lo beam control.

If that doesn't sound feasible? perhaps posting another clearer picture of it would allow for any adjustment needed make it work as intended/correct.

If post new shots get clear overall and end details.

 

Most of these headlight relay harnesses receive their signal power from the passenger side headlight plug while the driver side factory plug remains unused/dormant. High current power for the headlights can be tapped from the starter relay or the positive battery terminal.

I would highly commend this upgrade to anyone. While I cannot speak to the quality of all such units on the market, the ones we have used have all worked very well.

Not only does such a circuit modification generally mean more light on the roadway it reduces or virtually eliminates the heat buildup and resistance related problems of running the full headlight current through the multi-function switch.

dn.

 

This harness/ plugs are for a 85 but will work for up to 91...with the change of the plug ends. The plug on the far right says plug into existing harness. That's the only thing I don't understand

<a href="http://s1095.photobucket.com/albums/i463/91dirtydiesel/?action=view&current=407901cf.jpg" target="_blank"><img src="http://i1095.photobucket.com/albums/i463/91dirtydiesel/407901cf.jpg" border="0" alt="Photobucket Pictures, Images and Photos" /></a>

 

That would be in the right (if my sources are right) headlight socket.

 

Oh its inside? Ok thanks I'll check into it

 

The plug you are talking about should take place of the headlight bulb in your truck harness..

I know what I'm talking about, I just can't get the words to come out right... Ever have that problem?

 

The headlight plugs on the harness are female. The plug that I'm talking about is male ... Are we on the same page with what one were talking about?