[mr48chev]

The only reason that the headlight switch would have anything to do with the stop lights is if the bi-mental spring in the switch overheated and shut the power off. This is on an original wiring harness where the light switch works as the connection block rather than running everything to an aftermarket fuse block.

I'm believing that the brake light wire runs to the fuse block and not the headlight switch.

Lets go back to the first post and start over.

To quote Evilokc:
i have a 53 chevy with an EZ wiring harness. i didn't install the wiring which was a big mistake. you can't trust anyone anymore. the issue is the brake lights. they have been working for years and now they don't.

the lights themselves are LED with the tail, brake, and turn all using the same leds. the taillights still light up. the turn signals still work but when i hit the brake nothing happens. my first thought was brake switch.

I tested it with a power light and its good. not believing it i replaced it anyway with a new one that tested good but still no brake lights. at the rear light plug there are two wires per side. one for power the other for turn signal. with the taillights on the power wire has power. with the turn signal on they both have power.

I push the brake and both wires lose power. the tech line said to check the wires from the steering column to the brake switch and its good. then they said check brake switch and its good. then they said if both of those are good then you have brake lights. I don't though. I'm out of ideas. I've started pulling the two wires out of the loom the whole length of the harness to see if i can find anything. since they have power individually, I can't imagine what i would find? the only thing i can think to do that i haven't is to run two new wires from the fuse panel to the brake light plug to see what happens. again, since everything has power, I don't know what I'm expecting to be different. ideas would be greatly appreciated. this has gone on far too long.



Turn signals seem to work without an apparent issue. That eliminates the turn signal/stop light wire

Taillights seem to work without an issue and the turn lights work when the taillights are on, I assume.

There could be a ground issue though. Bad grounds will sometimes cause the turn or tail to ground though the other side.

Meaning before you go further check your grounds to your taillights. I'd run an extra ground wire to clean bare metal on the frame and not totally trust the bed to be grounded right.

That brings things back to the internal connections in the turn signal switch. I'm still not convinced that the turn signal switch itself isn't part of the issue.

I'm thinking that the brake lights don't work if you have the 4 way flasher switch on and don't work at all if you don't have a flasher in the 4 way plug and have the switch on. It works fine if the 4 way switch is off though. That is the way it works on a 77 Ford F-250 but I am not sure on a mid 70's Chevy. You do have a working 4 way flasher in place?