Headlight switch "sparking?"
 

I've noticed a small "click" noise every so often while driving my truck at night. It's seemed to come without warning, and usually from the left side of the dash. But I never have seen anything (until Saturday night) and it's maybe once every month or so that it happens.

So Satruday, after having run 45 minuites or so, I happened to look down by the headlight switch *just in time* as that little "click" occured. I was shocked to see, back inside the swich itself, what looked like a very small blue or white "arc." It looked like a spark had occured. There was not change in the lights (no dimming or flicker.) Just that little click, the arc, and that was it. Nothing else at all.

So this has me moderatly concerned, since other have reported fires sourced from this switch. Do anyone know of a pending recall? Or anything else I could do that have this fixed or replaced? Or am I being just a bit too paranoid.

Also, there was no heating of the plastics around the switch or the switch itself. Any ideas?

It isn't that hard to pull. Check for a loose or chafed wire. The overheating issue is usually from having the instrument lights dimmed. While you have the bezel removed drill some holes in the top of the dash air outlet tube below the switch. The switch is located up there where no air circulates.

My headlight switch melted pretty bad
So bad it smelled horrible, had to put both windows down.

I'd replace it and if you tow trailers, make sure your trailer wiring is not going thru the headlight switch. My truck didn't have the 'factory tow package' so the trailer lights were plugged in thru the tail lights. That's a [nonono] for the headlight switch.

I corrected my trailer wiring and got a new switch. No problems since.

Out of ignorance, I ask, how do having lights dimmed create this problem? Good or bad, I like to keep my lights dimmed but will stop the practice if I am inviting a bad situation. Thanks!

Potentiometers and Rheostats (not sure which the headlight switch would be) both adjust voltage through resistance and this causes heat. Basically what you don't use for powering the lights gets changed into heat and as you dim the lights more is turned to heat than if you turn it brighter.

I think the best course of action would be to put in a seperate relay that the headlight switch controls which would reduce the load on the circuit a lot. I plan to do this on mine soon.

Joel

I keep the dash lights dimmed also because doing that increases your vision outside. After about a half hour of night driving place your hand on top of the dash directly above the switch. If it is barely warm, no problem. Drilling the holes will dissipate the heat from the heat sink that is attached to the switch. On my 3500 I also replaced all the running lights and tail lights with leds, which made quite a bit of difference. I also have my trailer lights on a separate circuit through a fuse and toggle switch. If your harness is burned there is an improved version available. A search should give you the part #.

Thanks for your response to my question joelayan and GAmes.
I thought that might be the reason but I like to ask when in doubt. Is this a problem with certain years of trucks or all of them?

The burned wires is a problem in 96 and earlier 3500s due to the amperage draw of the running lights. The new wire harness is installed in 97s. 2500s don't usually have a problem, and I have never heard of the overheating causing sparks, thus my original recommendation to look for loose or chafed wires.

Thanks GAmes!

My 97 melted the harness. I changed it some years ago and no problems since.

my 96 2500 CTD overheated bad. Melted the switch really bad. Almost caught fire by the smell of it.

I had to replace the switch in my previous 95 1500 360 gasser too

I went through about 5 headlight switches.

About 2 years ago, I took the headlights and the parking lights off the headlight switch. I ran the headlight wires to a 50amp toggle and the parks to a 25amp toggle. Absolutely no problems ever since.

I still have my dash dimmers and turn for interior on the "old" switch.

Between that and my "pull cable" solenoid, it makes for good theft deterrent. "Not only will it not start, the headlights woun't come on"[laugh]

I found a used H/L switch lasat spring and installed it..the used one now is starting to go bad..Ill look for a new aftermarket one this time...