1968 Ford F-100 no pressure/ no braking power

ROGER KOHLS

MEMBER
1968 FORD F-100

Brakes problem
1968 Ford F-100 V8 Two Wheel Drive Manual

I recently installed a new ignition on my truck. When I plugged it in, one of the wires immediately smoked and melted the insulation. I disconnected this wire from the ignition and everything seems to work fine. I traced this wire to my pressure differential valve. Now my breaks practically do not work at all. I bled the system at each wheel in the correct order. I also replaced the master cylinder because it had a small leak but seemed to have no effect. What now?

1 Reply

MIKE H R

MECHANIC
3,094 POSTS

The pressure differental valve turns on the brake light on the dash if there is a brake failure. If the truck braked all right before you changed ignition switch then there may be a crossed wire. It sounds like the wire was shorted out. Check the fuses and if you have a vacuum assist on the truck, some truck have them and some don't you to do check for a vacuum leak. If there is a vacuum leak the brakes will work but you have to push on them hard. It's like driving a mac truck with no brakes. Here is a web site that deals with 1960s ford trucks and complete wiring diagrams.

http://www.fordification.com/forum-ref-gallery.htm#Body