Brake Switch Wires Overheating – Any Comments Appreciated

[tony 63C 14]

My first winter project is replacement of the power brake booster which sprung an internal vacuum leak just before it was time to put the car into hibernation. In process of removing the booster I spotted some heat damage to the brake switch wiring. Picture attached below showing melted insulation jacket on both conductors leading to the switch.

 

Fuses are correctly sized and not blown.

 

The brake switch functions properly, but could there be a problem with the switch causing it to draw too much current?

 

The other thought I had was that about two years ago I put in LED sequential taillights (“Mustang Project” IIRC). Is it possible that this conversion could cause overheating of the brake light wiring?

 

The wiring evidently got very hot and needless to say, I want to prevent any possible fire hazard. I’m most grateful for any input / suggestions.

 

Many thanks in advance for your comments. Cheers,

 

Tony

[MikeStang 247]

Thats interesting.

I know that the LED bulbs that I installed would not even work in my car, and had to go back to 1157s.

I would check the whole brake lighting system and see what kinda current its sucking up

[Protowrxs 111]

I would venture to say that the wires got caught up in the brake pedal action or something moving under the dash maybe?

 

Could have shorted to ground or something?

 

With them being exposed in the exact location is suspicious to me.

 

Just saying...

 

Stephen

[Midlife 814]

I would venture to say that the wires got caught up in the brake pedal action or something moving under the dash maybe?

 

Could have shorted to ground or something?

 

With them being exposed in the exact location is suspicious to me.

 

Just saying...

 

Stephen

I agree. If there was a short somewhere that lasted a bit of time, then the insulation would be melted up and down the wires. To me, the wire insulation got nicked over time without cutting the copper strands.

 

As for the wires getting hot, how hot are they? At worst, they should be warm to the touch, but you should be able to hold them. There is no fuse for the brake switch; power is routed through a circuit breaker on the RH side of the car and goes to the emergency flasher before coming to the brake switch (green/red wire), then out to the turn signal switch (green wire).

[CarZombie 25]

My blower motor started giving me problems, it would not work on high fan. To cut to the chase, I found it was corrosion on the terminals. I also had evidence of over heating on terminals and wiring. I would try cleaning the terminals, as the corrosion increases, it will increase the resistance. However, having said that, your picture does not look anything like what I experienced, but electricity is weird!

[tony 63C 14]

Thanks guys. A current draw test is definitely in order and I'll do that once everything is reassembled. Thanks Mike.

 

Stephen, I started thinking along the same lines after noticing in the close up picture that one wire appears to have the insulation abraded away as if by contact with a sharp metal surface whereas the other wire is clearly overheated evidenced by the melted insulation. There is no evidence at all of any heat damage to this side. A short to ground from this location could be responsible for the overheating in the other wire. I suppose it's coincidence that the heat damage occurred across from the friction damage.

 

>>> As for the wires getting hot, how hot are they? At worst, they should be warm to the touch, but you should be able to hold them. <<<

 

Will check this after reassembly.

 

>>> There is no fuse for the brake switch; power is routed through a circuit breaker on the RH side of the car and goes to the emergency flasher before coming to the brake switch (green/red wire), then out to the turn signal switch (green wire).<<<

 

Thanks for adding this Midlife as I was wondering about how this wiring was fused. I could not see a fuse dedicated to protecting this portion of the electrical system.

 

>>> I found it was corrosion on the terminals. I also had evidence of over heating on terminals and wiring.<<<

 

All clear, no corrosion and connections tight. But thanks nonetheless for your input.

 

Many thanks again guys for giving me some pointers to work with. Sincerely appreciated.

 

Cheers,

Tony

[danno 128]

This look like evidence of someone doing some custom electrical work. If someone had added aftermarket cruise control, or a remote starter, or a car alarm, they could have added some circuit to the brake wires.

 

As for the heating, sometimes the LED tail lights have resistors added to them so the flashers will work. You should check that resistor, if you added it. Otherwise return the tailights to the original bulbs and see if it still gets hot.

[tony 63C 14]

Thanks for your input Danno. The electrical harness on the car has not been messed with much if at all over its life, and I’ve gone through most everything on the car during my at my five years of ownership. No cruise control, sound system, remote start or alarm, but I did tap power off the fuse block for the electric choke. Although I can’t see that being a cause of this problem.

Re the LED lights, at one point I installed an add-on component from the manufacturer to make the familiar clicking noise when using the signal lights. The original LED kit as supplied from the manufacturer is silent. This clicker ended up being faulty and did not work. So I reverted it back to non-clicking. Perhaps this faulty part might have might have caused a current surge ?? We’ll never know.

Anyway, after reassembling everything I’ll run the tests discussed previously and hopefully everything will function normally.

Many thanks again,

Tony

[Dave R. 85]

I'm with protowrx. The wires look as if they were damaged by the brake pedal linkage or the steering shaft? With the wires being damaged in exactly the same spot is curious. A fuse not blowing is also strange. Isn't one of the big advantages to LED's their smaller current draw? If the copper itself seems to be intact at those damaged spots, I would tape them up, reinstall the switch and wires as they should be and test that circuit. Pump the brake pedal repeatedly and monitor those wires for excessive heat. If all is OK then repair the damaged insulation properly. Make sure the wires don't interfere with any moving parts under there. Dave R.

[tony 63C 14]

Hi Dave, thanks for your input. One of the wires definitely overheated as the insulation melted. In the picture you can just make out some of the burned remnants on the left side wire.

As far as LED’s, yes, low current draw is the big plus, but each of these taillights actually consist of something over 60 LEDS. I’m not sure if the total current draw is less than an 1157 bulb.

I’ll try to get everything together this weekend. Rest assured everything will be thoroughly tested and will be watched for quite a while. The last thing I need is a car fire.

Lastly, re your comment to “repair the damaged insulation properly”, I’d like to use heat shrink tubing. But I don’t see how I can slip the tubing over the wires without cutting them. Cutting and soldering the wires is something I’d like to avoid if at all possible. And I don’t see how the wires can be detached from the harness connector at the switch. Is there another approach that could be taken? .

Cheers,

Tony

[Dave R. 85]

Hi Dave, thanks for your input. One of the wires definitely overheated as the insulation melted. In the picture you can just make out some of the burned remnants on the left side wire.

 

As far as LED’s, yes, low current draw is the big plus, but each of these taillights actually consist of something over 60 LEDS. I’m not sure if the total current draw is less than an 1157 bulb.

 

I’ll try to get everything together this weekend. Rest assured everything will be thoroughly tested and will be watched for quite a while. The last thing I need is a car fire.

 

Lastly, re your comment to “repair the damaged insulation properlyâ€, I’d like to use heat shrink tubing. But I don’t see how I can slip the tubing over the wires without cutting them. Cutting and soldering the wires is something I’d like to avoid if at all possible. And I don’t see how the wires can be detached from the harness connector at the switch. Is there another approach that could be taken? .

 

Cheers,

Tony

 

Tony, I am not sure about this switch but sometimes the wires have a crimped on connector that pushes into the hole on the switch body and it is held by small fins. IF the switch and wires are set up like this those little fins can be manipulated with a very small stiff wire or ice pick type of tool and the wires pulled out of the switch. If that can't be done then I would cut the wires in the middle of the already bare spots, slide on the shrink wrap, solder them back and shrink the wrap. First make sure what the cause of the problem was in the first place. Dave.

[Midlife 814]

Hi Dave, thanks for your input. One of the wires definitely overheated as the insulation melted. In the picture you can just make out some of the burned remnants on the left side wire.

 

As far as LED’s, yes, low current draw is the big plus, but each of these taillights actually consist of something over 60 LEDS. I’m not sure if the total current draw is less than an 1157 bulb.

 

I’ll try to get everything together this weekend. Rest assured everything will be thoroughly tested and will be watched for quite a while. The last thing I need is a car fire.

 

Lastly, re your comment to “repair the damaged insulation properlyâ€, I’d like to use heat shrink tubing. But I don’t see how I can slip the tubing over the wires without cutting them. Cutting and soldering the wires is something I’d like to avoid if at all possible. And I don’t see how the wires can be detached from the harness connector at the switch. Is there another approach that could be taken? .

 

Cheers,

Tony

Nope. Cut the wires, and re-splice them.