Head lights go out

[tshancock]

I have a 36 Model 68. When I touch the brakes the headlights go out, when I release they come back on. So far I have replaced the voltage regulator, rebuilt the generator, replaced the brake switch, lastly I'm ready to replace the headlight switch because looking at the wiring diagram it seems everything runs through it. This car has aftermarket blinkers on it and the front ones are in what used to be the horn holes. The car has all new wiring. I also noticed that when applying the brake the brake light bulb remains on the single stage of it's filament even with the headlights in the off position. When I use the blinkers both filaments come on. Pretty stumped. Help would be appreciated.

[cas3]

Since you dont have a stock system, it will be hard for any of us to diagnose. I would start by disconnecting the turn signals, and see what you have there

[tshancock]

Thanks for the responses. The system that runs the blinkers is separate with exception of being tied in to the brake lights

[koates]

Bad ground connection on one or both of the rear light housings where they bolt on will cause that problem. Regards, Kevin.

[corvette8n]

Originally Posted by koates

Bad ground connection on one or both of the rear light housings where they bolt on will cause that problem. Regards, Kevin.

+1 on a bad or missing ground.

[cas3]

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Bad grounds can do funny things, however I dont see how the brake light circuit can have any effect on the headlight circuit. They do not share a common ground, or power feed

[drolston]

Did by any chance your '36 single fuse and ignition resistor panel get replaced by a later model circuit breaker? If, so, a short in the brake light circuit would cause the headlights to also go off.

[cas3]

Thats a good thought !

[tshancock]

Thank you all for your responses. I will check all of these possibilities.

[rotorwrench]

Is a direct short kicking the circuit breaker?

[drolston]

Originally Posted by rotorwrench

Is a direct short kicking the circuit breaker?

Stock '36 came with a 30 amp fuse. But it might have been replaced with a circuit breaker. Waiting to find out.

[TJ]

Are you using the stock '36 headlight switch or an aftermarket switch?

[Bob C]

Originally Posted by cas3

Bad grounds can do funny things, however I dont see how the brake light circuit can have any effect on the headlight circuit. They do not share a common ground, or power feed

If you have a stock headlight switch then the headlights and brake lights
share a common power feed.

[ford38v8]

Previous owner may have installed halogen brake lights, which pull a very large amp draw causing symptoms as you describe.

[tshancock]

Stock switch

[tshancock]

Checked those and they're 6 volt

[tshancock]

They did have halogen headlights but I changed them out for LED 6 volt bulbs with new reflectors so I could have the original headlight lenses.

[tshancock]

They do share a common power. I look at the wiring diagram from Van Pelts. Everything dealing with the exterior lights goes through that switch it seems.

[rotorwrench]

Light emitting diodes such as those used for the headlamp bulbs, are sensitive to current draw changes related to the system circuit. A lot of folks that change over to LED tail and park lamps have problems with the system when they install a turn signal kit due to the current draw of the flasher unit. The brake light circuit may be doing the same thing to the headlamps. Does this car have LED stop/turn rear bulbs or is it still using incandescent bulbs? Grounding is very important to LED bulbs. Headlamps and tail lamps can have a lot of obstacles to grounding on these old cars.

If there was a dead short, the fuse would blow if this is a car with a main fuse. It sounds more like an LED grounding or current draw problem.

[richard crow]

life long question. where do the lights go when they go out