I put a new brake light switch in my 56 f100, and now they brake lights stay on. If you push in the pedal just a little, not to the point of applying the brakes though, the light cuts off, then when you hit the brakes the lights come on again. Sometimes, you can let the pedal out all the way, the light doesnt come on, and then like a minute later it comes back on again. Do the brakes just need to be bled or something? Thanks

 

If you have the original brake light switch on the back of the master cyclinder pull the wire going to the brakes and check the switch with a tester. Also you may have contact inside your tail lights to make both of them come on. Tou will need to trace the wire with the tester with/without them being hooked to the tail lights. Its pretty simple you just have to take some time tracing and testing each wire. Lastly check the GROUND WIRE that could be the problem.
Jaye

 

The original switch is a pressure switch and your new one may be more sensitive than your old one. Try backing off the rod that goes into the front of the master cylinder, as you may have resaidual pressure that triggers your switch. Mine did the same thing until I backed it off 1/4 turn.

 

Check the new switch. When the brake lights are on and shouldnt be, unplug the wires and check across both terminals of the switch with an OHM meter and see if its open or closed. If there is continuity between the two terminals of the switch, then either one of two things is wrong. First the new switch may be bad. Second, there may be residual pressure being maintained inside causing the switch to have continuity.

I would do the OHM meter check first and let us know,
Kevin

 

OK guys thanks for all your replies. I bled the brakes today, and so far everythings ok. It might come back on though, thats kinda what it did the other day. If it does, ill be sure to double check the wiring and go buy another ohm meter ( man i bet ive bought ten of em and cant find one) THanks