Headlight switch

Tiny
355CID
  • MEMBER
  • 1994 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 13,500 MILES
Keeps melting the parking lamp circuit in the headlight switch. I checked that it had the correct fuse and it does. It calls for a 20A fuse and it doesn't blow the fuse. The wire that supplies power to that part of the switch has been really hot and the wire coming out of the switch on that circuit is almost melted as well. I stuck a 10A fuse in that circuit and it did NOT blow the 10A fuse. We tow a trailer with it sometimes but all the wiring checks out and it should blow the fuse before it melts the switch if there is a short somewhere. I'm stumped! Where do I go from here? Thanks.
Tuesday, June 1st, 2010 AT 5:21 PM

5 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,762 POSTS
Hi 355cid.

I would replace the wiring connectors which can have bad connections from current going through excessive resistance. Lewts check the OHMs through the wiring here is a guide to help us get started with the headlight wiring diagrams below.

https://www.2carpros.com/articles/how-to-check-wiring

I have seen the headlight switch cause this problem as well.

Check out the diagrams (Below). Please let us know what happens.
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Tuesday, June 1st, 2010 AT 8:23 PM
Tiny
355CID
  • MEMBER
  • 4 POSTS
Thanks for the help I ended up changing the switch and one connector with all need headlights and the problem is fixed! Thanks I love this site.
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Wednesday, June 2nd, 2010 AT 5:14 PM
Tiny
JAKECAN2
  • MEMBER
  • 10 POSTS
  • 1992 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 230,850 MILES
I recently bought a used 1992 chevy silverado. I installed 7 marker lights on the plastic skirt beneath the bumper wired into the parking lamps (4 wired to the right lamp) (3 to the left). These worked without incident for two days. I switched on the headlights and parking lights the other day and a puff of white smoke came from the switch. Fearing a fire I uninstalled the switch and took the cover off the switch to look for signs of a fire and I found it had been arcing on the inside. So I coated the metal inside with the grease already inside the switch and reinstalled it after uninstalling the marker lights. I switched on the headlights and the switch was giving off an electrical/sweet smell so still fearing a fire I uninstalled the switch again. What could be the problem? Do I need a new switch?
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Friday, January 25th, 2019 AT 2:49 PM (Merged)
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,749 POSTS
Replace the switch and look at the connector going to switch, you will find that the terminals will be loose. Using a small pick pry the terminals tighter to prevent the high resistance and remove all the grease.
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Friday, January 25th, 2019 AT 2:49 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,762 POSTS
Replace the switch, and cut out the burned terminals from the melted plastic connector body. You'll find at least two wires are hardened on the first four inches or so. That's from being hot. Solder won't stick to it and crimp-on terminals won't make a good connection. That will lead to a repeat failure.

Cut off that hardened part of the wires, splice in new sections, solder them, and be sure no sharp points of wire are sticking up, then seal them with heat-shrink tubing. Crimp on new terminals but then solder them too. Cut the melted plastic away from the connector body, then plug the new terminals onto the switch separately. Be sure they're tight. Loose connections cause resistance which causes heat, and a repeat failure.
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Friday, January 25th, 2019 AT 2:49 PM (Merged)

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