i replaced my break light switch on my 86 f250 and checked all the fuse and none where bad but the break lights still dont light up when i push the breaks. what could cause this.

thank you

 

Do the rear turnsignals work correctly? If they do, I would suspect your turnsignal switch is bad.

 

both of my turn singles work. but when i hit the break pedal no brake light. i did what you said and replaced both turn single fuse do hoppers. part number 552. still no brake light, when i hit the pedal. but if i run a wire from the pos side of the fuse box to one wire to the brake switch then i have brake lights when i hit the brakes. very strange.

 

The power for the brake lights runs from the fuse box to one side of the brake switch on the pedal. After the brake switch, it then runs to the turnsignal switch where it gets mixed with the flasher signal. It then runs to the rear to the lights which share the turnsignal and brake signal duties.

Since you put power on the brake pedal switch, and it started working, then you must have a problem from the brake switch to the fuse box. You can be sure by getting a testlight or meter and measuring the brake pedal switch. One side should be hot all the time.

I would trace the wire back to the fuse box, and I would also pull the fuse for the brake lights and check for power there. One side of the fuse socket should have power with the fuse removed. If it does, make sure the contacts are not spread open too far or corroded in the socket for the fuse.

 

I was going to post a similar problem as a reply, but will just start a new thread.