I have a 1955 Ford F-100. It has manual brakes, with the hydraulicy operated brake light switch. I replaced all the wiring and it worked up unitl now. The brake lights are always on, i have to unplug the battery so it won't drain. Is this a faulty brake switch or is it in the light switch? Help I am trying to get this thing street legal.

 

If you've kept the brake circuit stock, the hydraulic brake switch has to be closed to turn the brake lights on. I can think of only two ways the brake lights can be stuck on. First, you have a bad brake light switch. Second, you actually have enough residual pressure in your brake system to activate the switch. Easiest way to check is to get a new brake switch - it's cheap and easy to replace. You'll probably have to bleed the brakes after you replace the switch. If that doesn't fix the problem and you are sure you don't have residual pressure in your brakes, the only other option is that the brake light circuit is no longer wired the same way as the stock system. Good luck.

 

Take the 2 wires off the brake light switch on the master cyl. The light should go out. Put the 2 wires together and the light should come on. If it does, most likely is the switch.
Fred

 

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Faulty switch. It takes a lot of pressure to make the switch. When I went to power brakes, I had to put a microswitch on the pedal to get them to work.

 

I have heard that the older hydraulic style switches are notorious for failing. As fking1 stated, you should be able to pull oen of the wires off of the switch (either one should work) if the lights go out then it's more than likely the switch.
I switched my truck over to a hanging pedal with disc brakes. I still need ta fabricate a bracket on my pedal assy to attach a mechanical brake light switch to. I figure I'll get to it when I start installing the wiring harness.......hopefully soon

Good luck

Bobby