HOT headlight Switch? Don't know why

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Calipag

Calipag

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1970 Dart 318 12v factory harness. We have been chasing this electrical problem for a while and for the life of us can not figure out why our LGN wire coming off the headlight switch to the foot dimmer switch is getting HOT. We have checked both the L3- 18R and L4- 16V* from the headlights to see if they had a short to ground and they are not, unless we have the headlights plugged in. Which I believe is correct because it runs thru the headlight to the ground? We replaced both the headlight switch and foot dimmer switch with no positive result, we still get a very hot LGN wire at the headlight switch and the foot dimmer. We ran a jumper from the battery to the H connector on the under dash harness which is the LGN wire to eliminate the headlight switch and other wires in that connector and the LGN wire from the headlight switch to the foot dimmer is still getting hot, as if it was going to ground.

We have rung out the wires from the headlights to the bulkhead connector and checked to see if they were grounded and they do not seem to be grounded. We have checked the LGN wire to ground and there is nothing unless the headlights are plugged in.

Not sure why this wire is getting hot, it got so hot it melted the headlight switch. This is what started this hair pulling adventure.

Any help or direction on where keep looking would be a huge help.
 
Resistance causes heat, 1 cause, possible loose dirty connections at headlight or dimmer switch.
 
It's hot because it's normal. With no relays in the headlight circuit, the headlight switch carries all the load and it gets hot. The stock switches are simply inadequate to carry the load. That's why I upgraded to @crackedback" headlight relay harness. It removes the load from the headlight switch and only uses it to trigger the relays turning the lights on. It also puts alternator voltage to the headlights and makes them noticeably brighter. I highly recommend the upgrade. It's well worth the money.
 
Do you have stock headlights or super bright?

I agree that most likely (short is a short) your connections on the headlight switch, the high low beam switch and the bulkhead connectors and at the headlights themselves are corroded and you have a bunch of resistance over the headlight itself.

Most likely you will need to replace the plastic terminal holders in a few of those locations.

May even need to replace some of the terminals as when they get hot enough they loose temper and can never bite hard enough in the future
 
Thank you all for the quick responses. We have the super bright headlights. This wire gets so hot it glows! I've reached out to @crackedback in hopes to order that from him. This is driving us bananas!
 
Calipag said:
Thank you all for the quick responses. We have the super bright headlights. This wire gets so hot it glows! I've reached out to @crackedback in hopes to order that from him. This is driving us bananas!
Click to expand...
That'll fix it. Won't hurt a thing to clean all the brass connectors in that whole circuit, though. They've been around a while!
 
I did the same as Rusty, except a different brand. 1 relay for each 6024 halogen.

Assuming the wire is getting hot with the lamps on. So wire from headlight switch to dimmer gets overheated. But from dimmer to lamps the wires feel normal? What gauge wire from the headlight switch to the dimmer? Try a 14 gauge wire or even a 10. Don't rule out the lamps as being the problem. Original lamps were non halogen. So if your running halogens. There's the problem. Your wiring is too small.
 
Make sure the grounds from the lights to the radiator support, battery to engine block, battery to radiator support, and engine to firewall are all accounted for and in good shape. Sounds to me like you have lights that pull a little more than “stock” amperage, and your grounds are inadequate.
 
Calipag said:
Thank you all for the quick responses. We have the super bright headlights. This wire gets so hot it glows! I've reached out to @crackedback in hopes to order that from him. This is driving us bananas!
Click to expand...
What do you mean? Is this an actual brand name headlight? Is it an LED, or what?

CURRENT DRAW is the clue. As Rusty indicated, if these draw more current than originals, then adding relays is the answer
 
@crackedback Received our kit and installed. Simply the best money spent to solve our problem. Wins all the way around with this, fixes our smoking hotwire situation, and got us much brighter lights. Thank you all for the help. This forum does have the best community of people!
 
Thanks for the compliment. Awesome that the kit did what it is designed to do and solved you wiring issue with your lights. Surprising how much brighter the lights get when they get solid voltage!

Appreciate the purchase and recommendation from other members. Word of mouth is the best advertising you can get IMO. Thanks again!
 
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