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Melted headlight switch and connector


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Bought a 1988 Comanche as a project for my son and I. We are fixing it up gradually. All the lights work but the dash lights. Come to find out the headlight switch and its connector had gotton hot and melted. It's a wonder any lights worked. The switch itself seems easy to get but having a hard time finding a repair connector pigtail. I have googled my self to death. HELP!!

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The junkyard is your friend.  Go with a pair of wire cutters and cut the connector out when you pull the switch.  Google how to depin the connector or if you preserve enough of the harness you can just spice it in.  Our jeeps have a poorly designed electrical system and a big load goes thru the headlight switch, and it is imperative that you buy and install the headlight upgrade harness that puts the load thru relays instead of your switch.

Full details on this mod can be found on this forum and it is super easy to do.  Early Cherokees are exactly the same as our Comanches from the B pillar forward.

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While not wrong, I don't think that's a good explanation.

Just about every XJ you find will have some melting going on at the headlight switch. Whether it's poorly designed is up in the air. In most cases it lasts quite a long time before anything happens.

The headlights are wired from the factory the same way your house lights are. Everything goes through the switch. AMC being just about broke probably did it to save costs. They also pulled the switch out of the parts bin instead of designing a new one. As such it did what it was designed to do, save the company money. And it did work. I find it hard to believe that many Jeeps set themselves on fire in the 80's, otherwise they would have changed it. But they didn't.

However yes, the switch is the bare minimum to sustain the load of the headlights. As the wiring ages, corrodes, etc., the resistance builds and the load through the switch increases, and it starts getting a bit hot. When I said they catch fire, well, I can't guarantee they all will, but mine did. I fortunately was on the ball and managed to put mine out before it was too severe, others haven't been so lucky.

The upgrade harness as mentioned is a relay harness. It's supplemental, completely plug and play. It plugs into one of the existing headlight sockets, using the factory headlight wiring to trigger the relays, enormously reducing the load on the switch. You're under no obligation to buy a pre-made harness, although there are a few popular ones by putco and others, an H4 relay harness is what you'd be looking for. You can also make your own if you choose. I would recommend going that route, as it also easily permits you to upgrade your headlights in the future, if you want. The harness I put together will actually support over 300W of light because I used 10awg for the power feed to each filament, although I haven't upgraded my headlights yet. After installing the upgrade harness, you'll also notice that your headlights are much brighter, partly why I haven't upgraded the lights just yet.

 

Going back to your original question, there are still plugs that will work. I got one from Airtex I think, not sure on the part number just now but I'm sure I could find it if you need. I've also seen them replaced simply with insulated spade terminals as well, female, 1/4". But having the connector makes it easier, less guessing if you have to replace the switch again.

And some advise on Googling. You can try using the search feature on this site, although I find it better sometimes to use google, with the term site:comancheclub.com to restrict the search to just this site. That's not to say CC's search isn't any good, google just brings up a different set of results.

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The problem isn't the switch design so much as the design being asked to handle all of the headlight current.  This is one of the big reasons why I did a relay setup to power the headlights directly off the battery, and the headlight switch just triggers the relays and pulls a lot less current through it.  As a nice side effect, the headlights see close to 14V when the truck is running, which makes them much brighter.

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I'll point out that if that's the one Hornbrod recommended to me a few years ago, I did have to hack a contact or two off the outside of it to make it work. Not a huge deal. It was pretty obvious what needed to go once I tried to plug it in. Protip, make sure it fits while you have both the switch and connector out of the truck, much easier to modify it before everything's attached.

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Yes, it's classified as a "universal" headlamp switch connector and can be modified to fit several vehicles. It's the only one I've found that will work with our rigs, outside of trying to find a decent connector you can hack off at the junkyard.

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While you're down there either replacing OR upgrading the headlight switch, do yourself a favor and run a 12" or so 10GA wire from the ground point on the dash to the rear of the gas pedal where the solid steel plate mounts onto the firewall. That will considerably beef up the ground running to all of the inside lights in the truck (gauge cluster, radio, dome, etc.)

 

May sound pointless, but my truck is running the original AMC switch from '87; noticed that my lights were dimming some whenever I was running a full load at night with the headlights on and every other electrical device active. Took a lot of the strain off now that it's got a better ground running to the body; was one of the first modifications I did back when I got it some years ago. I highly recommend it to everyone because it's cheap, and efficient. Did it to my XJ with similar results.

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  • 10 months later...

While you're down there either replacing OR upgrading the headlight switch, do yourself a favor and run a 12" or so 10GA wire from the ground point on the dash to the rear of the gas pedal where the solid steel plate mounts onto the firewall. That will considerably beef up the ground running to all of the inside lights in the truck (gauge cluster, radio, dome, etc.)

 

May sound pointless, but my truck is running the original AMC switch from '87; noticed that my lights were dimming some whenever I was running a full load at night with the headlights on and every other electrical device active. Took a lot of the strain off now that it's got a better ground running to the body; was one of the first modifications I did back when I got it some years ago. I highly recommend it to everyone because it's cheap, and efficient. Did it to my XJ with similar results.

Instrument panel ground upgrade:

http://cruiser54.com/?p=110

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  • 6 years later...

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