Burning up headlight switches
 

I have been posting on other forums, and getting nowhere. So here goes. I have been having trouble with my dash lights and parking lights for some time. It all started with the dash lights flickering and going out. Then they would come back on and go off randomly, and go out for good. I thought the problem was the headlight switch, so I replaced it. The new switch was OK for a while, but it eventually did the same thing. Now, I can see that there is a problem with the truck. I replaced all of the connectors going into the headlight switch, traced the harness going to the switch until it disappeared into the main harness, replaced the switch again, and I still can't find the issue. Recently I discovered a new problem. The 15 amp fuse for the parking lights was loose in the socket. I tweaked the legs on the fuse so it would make good contact, and it was OK. I checked the power wires for continuity to ground, and have not found any shorted. All ground wires are grounded as well. I can blow the fuse for park lamps if the switch is installed and I wiggle the knob around. Sometimes there is a spark and the fuse blows. If the switch is just hanging out of the opening I cannot get the fuse to blow. I know this was a long post, but I am at my wits end. Just give me what ya got!

Here's your cheap and simple way to fix it, with another new switch that is. This replacement harness comes with it's own relay's that take all the load off the switch in the truck. It becomes nothin more then a trigger to turn them on and off, no current flows through it anymore.

The headlight switches in these trucks are a known problem of catching on fire at worst and just melting at best. There was a factory recall on your 1 ton but for some reason they didn't include the 3/4 ton trucks even though they are the same thing.

It also seems to speed up the burnout process if you use the dimmer control on your dash lights. Makes the switch even hotter.

https://www.dieselbombers.com/5-9l-2...t-harness.html

Would that affect the dash light/parking light circuit, though? The headlights are on a different circuit.

Here's another post with your exact same problem. https://www.dieselbombers.com/diesel...e-cummins.html

Since the headlight switch is the trigger for both set's of lights I would have to assume that they both start at the same place, just branch off to different fuses. Keeping in mind that electrical issues are not my strong point to say the least.

There is a RED wire with YELLOW tracer that supplies power into the switch for the headlights, and a PINK wire with a RED tracer feeding the park/dash lamps. That is why I assume different circuits.

Here's the wiring diagram for the headlamp switch showing the routing for the instrument cluster in case it helps you out.
Attachment 6567

Sounds to me like you have a wire with the insulation broken somewhere. You said it will do it when the headlight switch is in its proper place but when you just let it hang out by the wires it doesn't do it? That would be my guess anyways.
Take an ohmeter if you got one and pull the parking lamp fuse out and the attach the meter to ground and the parking lamp circuit. Make sure you put on the same side as the switch! Then jiggle the wires behind the switch to see if it ever shorts to ground. Thats what I would do anyways.
I totally agree with Bubba though that the stock headlight switch needs some improvement.

I did that kazairl. Nothing. I, too, think there is a naked wire somewhere, but I don't know where it could be. I traced the switch wiring to where it enters the main bundle and did not find any exposed wiring. It all appeared to be in good shape.

I had the same thing with my truck and drove me crazy!!! It ended up being a pinched wire in the steering column. How that affected the lights I dont know but it fixed my problem. When I would adjust the steering column the lights would go out but not all the time.