ngd5005

I have a 65 V8 convertible with aftermarket power brakes. It is a recent restoration. After I installed the engine wiring harness I tested all of my electrical components. I noticed my brake lights won't turn off and my headlights won't turn on. I'm pretty sure the headlights aren't turning on because the bulbs are out and I just haven't gotten new ones yet.

In attempt to fix this, first I replaced my brake light switch and triple checked it's installation. I have the plastic washer and bushing in the proper place and the pedal is all the way forward. When that didn't work I replaced the high beam switch. I have already cleaned all the grounds. When that didn't work I replaced the headlight switch. Any help would be greatly appreciated.

fastbackford351

It sounds to me like you are doing the master cylinder push rod dick dance which can happen when you deviate from the factory setup.

If the push rod is too long then the pedal can not return far enough to release the pressure from the switch allowing it to open and break the circuit.

But just to be sure to test the switch grab your test light and remove the switch from the pedal but leave the wires connected. With no pressure on the switch it should be open and have power to only one terminal = no brake lights.

When you close the switch like it would when you step on the pedal and the switch pushes against the push rod that should complete the circuit and give you power to both terminals = brake lights.

There are adjustable push rods available but have you called the company you bought the brakes from to pick their brains?

ngd5005

I unplugged the switch from the harness and the lights went out. Then I bypassed the switch and they turned on. The problem is the switch. I don't want to make the same mistake again and buy the wrong switch or a cheap switch. Can anyone recommend a Autozone/NAPA part number? I heard that the problem might also be that I used a switch for manual brakes when I should have used a switch for power brakes off of a 71 mustang.

fastbackford351

Well of course if you unplug the switch the lights will go out because there is no juice flowing to them.

How did you bypass the switch? Put a jumper between the two harness terminals? That would certainly turn the brake lights on but proves your wiring and nothing else.

Take the switch off the pedal but leave it plugged in, what happens?


I went through the same thing when I changed my master cylinder. It's the push rod length, I'd almost guarantee it.

scootchu

I had to grind down the end of my pushrod a bit so my switch would disengage.

ngd5005

Thanks! This worked perfectly.