When I press on my brake petal, my voltage meter drops to 0. When I let off, it rises back where it should be. I know I have a short in wire #5 on the brake light switch. Does anyone know where that wire goes to so I can replace it?

 

Pin 1 is voltage for the brake light switch.
Pin 2 is goes to the brake light circuit.

Pin 3 is voltage for the PCM signal.
Pin 4 goes to the PCM. It signals the PCM to disengage the cruise control and unlock the torque converter.
Pin 5 is ground for the PCM signal.

Pins 1 and 2 make up a normally open single pole switch. When the brake pedal is pressed, the contacts close and power is sent to the brake lights.

Pin 3, 4 and 5 make a double pole switch. Normally, pin 4 is grounded via pin 5. When the brake is pressed, pin 4 gets voltage from pin 3.

 

Would the brake light switch being bad cause the issue that I am having?

 

I don't see how. If you were dead shorting anything in the brake switch to ground, it would blow a fuse. In the few cases I've experienced where there has been a short to ground without blowing a fuse, it at least kills the engine.

My best guess would be a wire chafing against the brake pedal or something connected to it. Probably a power wire going to the console. I would look for a wire that is coming in contact with the brake pedal that has insulation worn off.

 

What makes me think it is the brake switch doing it is when you unplug it the voltage meter does not drop when you hit the brake pedal.

 

wow you said a mouth full. If i could understand all that i probably would not have to ask question. LOL