I installed the LMC Heavy Duty Relayed Headlamp Harness tonight on my D350. A couple of thoughts. For those who are electrically challenged like myself, this kit really fits the bill. It literally took 10 minutes to install. I know it comes with cheap relays and that is a bit of a concern but the only other thing I didn't care for was that I couldn't route it the way I wanted because it wasn't long enough.(Just ran the passenger side in front of the radiator instead of routing under it) These are universal kits so that was kind of expected. For the 30 bucks I spent it was well worth me not having to build a harness myself.

On a side note. I know this harness takes the load off the ignition switch which is good. I noticed the other night that the lead that goes into the back of the fuse box on the row that has the headlamp fuse gets extremely HOT. I'm not sure that is normal. All operation was good even before the new harness but with the headlamps on that lead will burn the mess out fo you. Is that normal? What would cause that? Anyway to take the load off that lead? Thanks in advance.

 

I think you should unhook what you have done and post up exactly where and to what you hooked your wires. It's not normal, that wire should have 1/100 of the load it had before.

The fused supply lines that run to the #30 pins on your relay should see all the load now

 

So the lead was getting hot before the harness and relays were installed correct?

There are bimetal contacts in the headlamp switch and those contacts get worn and dirty which could cause excessive resistance in that circuit causing the heat.

Is the wire still getting hot? If so and even if not I would replace the headlamp switch.

 

But relaying the headlamps takes the load of the two headlamps off of the headlamp switch (leaving taillight and running light load only on the switch) -- so the overheating problem should be getting better and not worse?


On another note, a very simple high-quality relay kit is available (and the wires are of sufficient length) -- Painless Performance, part #30815. Unfortunately this kit has now become ridiculously expensive ($179 at Jegs), but I can vouch that it works well and installation requires less than 15 minutes.

 

This is true, it has taken the heavy load off but there is still a load that would still have excessive resistance which is why I asked if it is still getting hot. Maybe I should have asked if it is still getting as hot.

 

I had just replaced my headlamp switch and cleaned up a bunch of wiring before doing this. The new harness receives its signal from the drivers side factory headlamp socket and then routes off to each headlamp with grounds and a positive connection to the battery. The fuse box lead was very hot before the install and is still very hot. The headlamp switch is new. The pigtail for the headlamp switch is new. The headlamps are new and the relayed harness is new. Its confusing as to why that fuse box lead gets so hot.

 

What's the benefit of this mod if you don't mind me asking?

 

Its to take the load off the ignition switch and provide full voltage to the lights making them brighter.

 

I see thanks.

 

Did you ever consider making your own, such as Jim Lane did in the sticky ? I put my headlamp relay kit together for I think about $25 in parts. Labor ? well, that took me a few hours to make and install, but it was well worth it...


And BTW.... I'm not exactly great with doing electrical troubleshooting myself, so I can't help you. My experience with Jim's work is that he makes it easy enough for a monkey to do, or at least a guy who slept in a holiday inn express, last night..

https://www.dieseltruckresource.com/...82&postcount=7

 

I'll be the jerk.

A relay kit takes the high current headlamp load off the headlight/running lights switch.

 

No, youre not allowed !....thats my job
8-)

 

Clean As many of your grounds that you can find. Then look for more.
Add A larger Ground wire #4 or bigger from the battery to the truck body.

When adding ground wire to body dont use a silly sheet metal screw. Remove paint (clean up expose some bare metal) Nut washers & bolt that wire to the body.

 

Whoops, lol ....Thanks for the correction. Got mixed up with the "Blower motor relay harness"....another issue I plan on dealing with.

 

I have considered it and I still plan on making one for my 91.5. I got the LMC catalog in the mail and saw the harness in there. I figured for 30 bucks it wouldn't hurt to give it a shot. Guess I'll go to chasing grounds and checking wires again. It operates fine but I'm sure that lead is not supposed to be that hot.