HOT Headlight switch

[Stoutscout]

Does anyone else have a hot switch at the end of a long drive? I usually drive with low beams and fog lights on. After an hour or two the switch is pretty hot. I'm having flash backs to my first junkyard car and wiring power with audio wire:--) I was 15, it seemed like a "sound" principal... sniff sniff HEY FIRE! FIRE! quick grab the super big gulp... splash fizz fizz...

Seriously, any input would be great.

 

[JAK]

The dimmer control is usually what creates all the heat. It's just a resistor to dim the dash lights. If the dimmer is turned all the way up or all the way down, it doesn't get as hot as if you have it in the middle somewhere.

 

[SS]

Yep, they get quite warm to the touch. Especially if you run with the fog lamps and dim the interior lights to their minimum. The dimmer wheel and the area next to it are the warmest - the headlamp mode selector switch shouldn't be too bad. I'm on my 4th truck with this switch and have not had any trouble, but I think a few guys have.

 

[Crazy Horse]

The dimmer the switch is set for the dash lights, the hotter it will get due to the resistance you are putting to the switch. You are reducing the voltage to dim, thus causing the resistance (Ohms) to rise. Resistance = Heat.

 

[Stoutscout]

RIGTH ON!!!



Thanks for the quick input, I'll try futzing with the dimmer and report the findings if anyone cares.

 

[tgbol]

I drilled a 5/16 hole in the top of the A/C duct under the switch. The heat sink on the switch is in dead air under the dash. It allows air to circulate around the heat sink on the switch. After a 6 hour drive across the desert at night this summer I could still touch the switch. Even in the winter with the heater on enough air moves around to cool the switch.

 

[Stoutscout]

KISS approach

Turned the switch up and the problem diminished. Simple problem - simple solution. Not so sure about the drilling the dash idea though.

 

[tgbol]

Stoutscout

If you pull off the facia around the gauges and expose the air duct, then you will see where I mean. When you put the facia back on you will not see the hole. The hole is not big enough to affect air flow through the duct, it only creates a small draft to move air around the switch. The heat sink is really pretty big but there is no air flow over it.

Tom

 

[Un-Hemi]

I'd like to be able to run at night with the dash lights out. Once up on cruise control, all that's required are the alarm indicators. I'll add a switch real soon now.



The dimmer resistor gets even hotter when several additional instrument lights are added. I'm working on a circuit that takes all the load off the dimmer resistor and transfers it to a transistor circuit with a much larger remote heat sink. I've got the prototype working on the bench; now just trying to source the most efficient parts to do the job. Anybody interested?