Brake Light Switch, Short?

Chadillac · Sep 23, 2015

So, on my 96 GT vert, the brake light switch keeps shorting out. Ill return home from work and find my brake lights constantly burning. Looked under the dash and the brake switch plug was completely melted and disfigured. it was insanely hot. touched it and got a blister almost immediately. Ive taken the female leads out of the melted base and attached them directly to a new switch. the problem was solved for maybe two months... now its happened again. Ive changed brake switches 4 times now. The wires feel ridiculously hot. I'm running stock wattage incandescent bulbs and a sequential harness. (the first time this happened was 4 months prior to the install of the sequential harness)

Any electrical savvy folks, PLEASE HELP

ttocs · Sep 24, 2015

well it sounds like it is pulling too much current for one reason or another. First off if it is fused correctly the ability to do this would or maybe should be protected from getting too hot so lets start there. I am not sure which one is for the brake lights on that year so you will need to check your manual to see here it is and its rating. Verify that it has not been upgraded to a larger value at some point.

Have you done an modifications to your lights or the areas around them? Had the dash out recently for a heater core or done any work in the kick panel areas.

Chadillac · Sep 24, 2015

Never done anything to it. The entire car is 95% stock. Im
going to pull the fuse and see what I can discover today. Thanks for the suggestions! I just don't understand how or what is causing it to draw such a large current

Chadillac · Sep 24, 2015

Update: pulled the fuse (15 amp) it's not blown. Used a meter to measure the draw with the car off. 7.2 amps with car off. I'm officially bewildered. Gonna try changing out the fuse with another of equal value

CC'S95GT · Sep 24, 2015

Pull the headlight connector off and look at connector itself.
They're known for getting hot and melting.

ttocs · Sep 24, 2015

Chadillac said:
Update: pulled the fuse (15 amp) it's not blown. Used a meter to measure the draw with the car off. 7.2 amps with car off. I'm officially bewildered. Gonna try changing out the fuse with another of equal value

Just wanted to make sure that you measured the current on that by putting the meter in series? This would mean you needed to either cut a wire and insert the meter into the circuit rather then just touching the two electrodes like you do to test voltage on a battery. a lot of people get this confused so I just wanted to check it out first.

Now unfortunately with electrical gremlins it often just come down to tracing the wires to find out where there is a short/cut/bare wire that could cause problems. This sucks since the wiring is often difficult to trace/follow to see where it goes, but there really isn't a better way too go about it. You say its 95% stock, what has been done to it? It doesn't have a remote start in it by chance? That is about the only piece of aftermarket equipment I can think of that wires into the brake wire except of course for the modern video stereos that often require a connection to the parking brake or foot brake so it will not allow video in motion. Finally the only other possibility I can think of is that maybe the switch not mounted correctly and maybe causing it to bind up and stay on. Since brake lights are not on all the time its possible that if it get stuck on for too long that it could continue to build up heat and then melt the switch to where it has to stay on.

CC'S95GT said:
Pull the headlight connector off and look at connector itself.
They're known for getting hot and melting.

The headlight switch and harness is known for problems but I am not aware that the brake lights go through it.

CC'S95GT · Sep 25, 2015

probably not the brake lights but the tail light do.

ttocs · Sep 25, 2015

yes the tail lights do go through the switch but not the brake lights so I am not sure how the head light switch melting could cause the brake light switch to melt. But electronics does strange stuff and its possible and only takes removing two screws out to check it out.

I had another idea that could be a problem although I am not sure if its really possible. Its possible for the filament in one of the brake/tail lights has come loose and is maybe shorting out the brake light inside of it and back feeding voltage into the switch. This is a bit of a long shot since either the parking/head lights would need to be on or we would need some source of constant voltage in the back to keep them on all day/night. Try pulling the bulbs out and see if you can see anything that looks bad or different. If you want to be sure that they are not the problem you could replace them anyway and if I were back there checking all of them I probably would replace all the bulbs to save from doing it later.