Warm light switch

[heroszeros]

All, I have just gotten my car back together after a hazard switch short circuit caused a little partial meltdown. I removed the wiring harness (all of it) and replaced the wires that looked suspect. The car has a new hazard switch and also I placed the light switch ( the dimmer had shorted out also). Also the fuse box was replaced. Everything seems to work well now, but I have one issue that I don't feel certain about.

Currently the light switch is hooked up and working well, but it is not installed into the instrument panel just yet.. When driving the car with the lights on, the switch itself gets warm. I'm not having any more plastic burning smell ( thankfully) but the warm switch has me a little on edge. it seems to get to a certain temperature and stay there when the lights are on. All of the fuses are new, and there aren't any blown fuse issues.

Has anyone else experienced the same issue? Is the warm switch normal? Am I being paranoid? Thanks in advance-

 

[Honolulu]

I can't offer a definitive answer, but I'd expect the light switch to get warm since the interior lights are on a dimmer circuit that is resistance controlled in the switch itself. You might experiment a bit - does the temp of the switch get higher when the panel lights are brighter, or dimmer?

 

[Arde]

Heat means that there is resistance in the switch. If the switch is new the resistance of the contacts should be minimal, so it could be the resistance of the dimmer, although the current in the instrument light circuit should be low.

The easy ways to figure things out are:
1) Compare how warm it gets when the driving lights are on vs. just the parking lights (for the same dimmer position). If it is warmer with driving lights then it is the contact resistance and can be only solve by adding a relay to that circuit.

2) Bring the dimmer to maximal brightness, usually dimmers do not go through the resistor in that position but rather short the circuit, so the heat should be minimal.

It is possible that the switch being new has low resistance, but the wire contacts of the existing cables have their own resistance due to dirt and corrosion.

 

[Stevehose]

As Arde says, I also highly recommend relaying the low beam circuit, your headlights will be brighter and less amperage will be running through the switch and will be safer all around. This was a design flaw from the beginning, now with 40 year old wires it's even worse.

 

[heroszeros]

Thanks for the advice all, I'll run the car around today and see if I can find the heat build up to relate to any of the dimmer switch positions. I'll check on past posts to see what the best way/location/type of relay to put on the low beam circuit.

Thanks again-

 

[Joep]

I had the same issue with the light switch heating up, which I noticed when I was searching for the casue of my low beams not working, whilst the rest did work.

Turned out that my low beam relais was not functioning properly, after replacing: no more heat build up in the switch. Since my car is after 74 and has a relais on the low beam this might be a different configuration than yours. In case you have this config, the relais is the first one on the left, within the compartment to open the hood.