Wiring Brake light / TCC

[tbrown5079]

Using the 4 post stoplight switch. I have the 2 wires from the chassis harness to wire the brakelights (orange and white). I wire the TCC wire and 12v to the other end of the switch. There is a wire in the harness from the computer (pin 43 in green section) that says stoplight. Where does this go?
2 more questions
1. Does it matter which end of the brake switch to use for brake or TCC hookup? Is the end with the plunger the front or back.
2. Where does the wire on the master cylinder come from?

[BR3W CITY]

Stoplight refers to the "on when pressed" side.

The end with the plunger is the "front" in my mind. One side is normally open, one side is normally closed.

What wire on the master cylinder? There isn't anything electronic on the master, its just a fluid pump (unless there is a low-brake fluid level sensor). Was the master sourced from something latemodel?

[tbrown5079]

The master cylinder is from CPP and has a wire in the top of the proportioning valve.

[elimontfort]

That wire goes to the brake warning light.

[BP Automotive]

The two terminals away from the plunger are the TCC Circuit. How the switch is meant to be installed is the plunger is pressed by the pedal in the resting position, then when the pedal is pressed the plunger OPENS and is not pressed. This closes the front two contacts by the plunger.

When installed and the brake pedal NOT pressed, the plunger WILL be pressed.

[BR3W CITY]

Thats really confusing....when the pedal isn't pressed, the plunger is?? In my truck, when you press the brakes, the pedal arm pushes the plunger, which completes the stop lamp circuit.

[dayj1]

Originally Posted by BR3W CITY

Thats really confusing....when the pedal isn't pressed, the plunger is?? In my truck, when you press the brakes, the pedal arm pushes the plunger, which completes the stop lamp circuit.

BP Automotive is correct on that one. From the factory, the '67-'72 Chevy trucks (and the '73-'87) all have brake switches where the switch plunger is pressed when the brake is NOT pressed. The switch plunger releases when the pedal is pushed. I don't know about the earlier trucks but my '57 BelAir also works as I just described.

[BR3W CITY]

Not the case for the 64-66 at least, there wouldn't be a good place to fit the plunger facing the other way. Weird.

[ls1nova71]

Originally Posted by BR3W CITY

Not the case for the 64-66 at least, there wouldn't be a good place to fit the plunger facing the other way. Weird.

That doesn't make sense. Post a pic of your switch if you can.

[tbrown5079]

Thanks BP automotive. That makes sense to me. You could figure out how the switch works by checking continuity once you figured out which end to use but I wanted a professional opinion, Also, you wouldn't want to activate the switch by pushing on it. It would be very hard to adjust to pedal pressure. Thanks everyone.

[BR3W CITY]

I'll see if I can get one, the truck is under a cover, moving blankets, and a garage covered in snow lol.

The bracket that holds my brake pedal has a hole for the switch. I never had the old switch, and due to room it mounts from the back, with the plunger facing right into the back of the pedal arm. (and all my lights and tcc works, so it can't be that wrong)

I'm gonna laugh if my sh!t has been succesfully backwards for like 3 years.