brake light issue

[kglowacky]

Well my worst nightmare is upon me. I am a person of many skills BUT electrical is not one of them. My brake lights quit working today. All other lights work fine or did until I took it to my mechanic. Now I have no rear turn signals but brake lights. He decided to spice some wires together and low and behold I got a mess. It is a painless aftermarket system. He thinks the fuse box power failed. He jumped power directly to the green and yellow wires to the rear but because the wires are for both turn signals and brake lights it appears I am getting no power for the rear blinkers. Front work fine. I am going to go reverse everything he did. Any Ideas. I changed the brake switch already. I can put power to the green and yellow wires at the firewall after the fuse box to the rear and get lights, so I know the exterior wiring is good.

trying to move this to the electrical section with no success.

Tring to reason this out. If the blinkers are working, then the column switch has to be working. So when I reverse what the mechanic did I will get my blinkers back I assume since I had them before this mess started. Somewhere between the brake switch and the two rear brake light wires to the back is the problem. If power is leaving the brake switch, why is it not getting to the right and left taillight wires? Anyone know how these two wires get power from the wire switch. They have to be getting power independently from each other.

[72c20customcamper]

Column switch can do this too as it overrides the brake light on the side that the blinker is on . Other side gets power as usual.

[ray_mcavoy]

Originally Posted by kglowacky

If power is leaving the brake switch, why is it not getting to the right and left taillight wires? Anyone know how these two wires get power from the wire switch. They have to be getting power independently from each other.

Power from the brake light switch goes directly to the turn signal switch. From there, the turn signal switch sends it out to the yellow & green wires that run back to the rear lights.

Since the brake & turn signals use shared bulbs, the turn signal switch is responsible for overriding the brake light on one side or the other when signaling for a turn. In other words, when you signal for a left turn, the turn signal switch disconnects the brake power input from the left rear and connects it to the power input from the turn signal flasher instead.

So it is possible for a turn signal switch to be faulty (not allowing the brake lights to work) but still function okay for the turn signal portion of the circuit.

[Corts60]

X2 the above and also suggest never going back to that mechanic.

[kglowacky]

this info is what I am looking for. Thanks, I guess I will need to replace the column switch.. I have a 1980 tilt column in my truck.

LOL on the mechanic. He is young and learning and already wants to make it right. He knows he screwed up and I will let him make it right as long as I am standing there watching. These young mechanics have no idea how these old cars operate if they can't hook up a scanner even then not sure they could diagnose anything.