Hello,


I just bought a 55 F100. Original braking system. I have had it less than 24 hours. For some reason I don't understand, the brake lights come on every once in a while, while it is sitting in the garage, all by themselves! I will go into the garage to get something and find the brake lights on! Then I will step on the brake and release and they turn off. Doesn't happen all the time. Does anyone have idea what is causing this and what the solution is?


Thanks,


Gary

 

What type of switch is on it, could be just a matter of adjustment.

 

either a faulty brake pressure switch or the brake master cyl rod is out of adjustment and keeping brake pressure applied even when released, Does it feel like there is any "free play" in the brake pedal?


Just another reason for me to have a master shut off switch on these old vehicles,

 

Welcome to the board!!


I'm guessing that it has the original style hydraulic brake light switch that threads into the brake line near the master cylinder. Its very common for these switches to go bad and start staying on.
Luckily the switches are readily available and you should be able to pick one up at your local parts store.


Good luck
Bobby

 

Maybe a ghost trying to steal your truck?

 

Did you maybe make her mad by leaving her out in the cold to long. LOL

 

I was having this issue but it wasn't happening randomly; only after I drove it. Mine was from what Bigwin56f100 said above....

I needed to turn the bolt below the brake pedal under the truck as it was causing my truck to keep pressure on the brakes and hence, the brake lights staying on after driving it. If you get under your truck on the driver's side, you will see the master cylinder. On the end of it, is the brake light switch. You will see wires go to it. Before you go to too much trouble, you may want to just check these that they are not bare and touching...good luck. And welcome to the forums. There is lots of info here and friendly people to help.

 

The pressure type brake switches can go bad in three ways. I've seen all three.
1.They can corrode internally and turn the brake lights on at random.
2. They can fail to turn the lights on.
3. They can require way too much pressure to turn the lights on. You want the lights to come on with slight pressure such as a slow rolling stop.

 

You might want to check your brake pedal return spring. It could be weak or broken, the weight of the pedal can apply enough pressure to trip the switch.
Bruce

 

My 48 would do the same thing. I ended up replacing the master cylinder.

 

Thanks everyone for your input on why my brake lights are staying on.
upon further inspection, I see a lot of rust on brake lines and master cylinder and have decided to replace the master cylinder and brake lines. Hopefully, through this process, the brake lights on problem will be solved as well.


Thanks Again,

Gary

 

I recommend a two stage (dual) master cylinder. If you're going to replace it and the lines anyway, I personally think it's the way to go. Running the brake lines will be the hard part, not upgrading the MC.

 

I had this same problem one day after about a 10 mile drive to my parents' house. I finally discovered a frayed wire with ONE single copper strand touching the hot line going toward the brake light switch. Look VERY closely at the wires.