Brake pedal draws power stalls car

[Paul91]

I have a 73 duster 318/auto(originally slant 6 auto). The other day I was driving and hit the brakes and it turned off the radio, all my gauges died, stalled car. I have an electronic ignition, if you 2 foot the car you can feel the power draw on the ignition and it causes a missfire and the car even over heats. The ammeter bottoms out as soon as I touch the brakes. What could be wrong? I had a similar issue last year but my tail lights weren't working and it turned out to be the light switch. Could it be the same problem again? My lights still work this time but same symptoms.

 

[72Dart6pack]

Sounds more of a vacuum leak at brake booster if you have one? You did not say.

 

[TrailBeast]

You have an electrical short in the wire harness somewhere between the brake light switch and the rear lights.
I don't think you were overheating, just that the gauge got more power put into it than it is supposed to have.

There is an electrical connector for the rear lights behind your drivers side kick panel.
If it were my car I would disconnect that and try it again.
I have even seen screws that were too long put in the trim panel along the carpet edges that went into those wires and caused a bunch of mixing of the lighting. (like dash lights coming on when the brakes were applied)

 

[Johnny Mac]

Also... The brake light switch on these cars is merely a spring loaded pin that rides on the brake pedal arm when you depress the pedal. After years of use, and possibly even "messing" with the MC, or the brake rod, these can catch, ground out, and snag on the pedal arm. I had some finicky issues with mine that ran me in circles for a bit when i changed to manual brakes and over extended the pedal position upward. It bent the tab and brake switch, and it doesn't take much to goof up a pin that rides on a 1/2 inch thick edge, traveling in a linear motion.

 

[Paul91]

This car has manual brakes so I'm assuming its not a vacuum leak. As soon as the pedal is touched the ammeter pegs out to zero and the car stalls. The car has an electronic ignition and if I hit my brakes and gas at the same time it missfires pretty bad, so something is drawing a lot of power when I hit my brakes. I'm going to start tracing wires tomorrow and see what I find

 

[1969383S]

Don't forget the Turn Signal Switch. Aftermarket steering wheel?

 

[Mopar to ya]

Some of my wiring ran behind the booster and when I applied the brake the pivot pinched and grounded a wire and my Dart died every time. Fixed the wire and rerouted it and the problem was solved. Maybe you have the same issue?

 

[BillGrissom]

... the ammeter pegs out to zero ...

Great responses. I'll just add that if your ammeter is normally showing "C" or "D", something is wrong. It should only go to charge for a short time after starting, while the battery is re-charging. It might show slight discharge at idle w/ full load (headlights, brake lights, stereo, for sure if a radiator elec fan). Otherwise, it should stay about zero, so if not something is wrong, but probably unrelated to your main issue unless it indicates a constant short to ground that gets worse when you push the brake pedal.