replaced rear brakes, (shoes & drums) on my 90 f250, but pedal still soft. Tried to bleed but no preasure in the back. Put on new master cylinder but still the same. ???? Front brakes seem to work fine.

 

The correct bleed sequence is right rear, left rear, RABS module, right front, left front.
The RABS module is bolted to the inside of the left side frame rail about level with the drivers feet, there is a standard bleed screw on it.

 

thx for your response. I tried to bleed the rt rear first but there is no preasure. Could this be a problem with rabs module? the light did come on briefly.

 

Yes it could be. One of the solenoid valves, when activated, shuts off fluid to the rear brakes.
Best bet might be to start loosening pipe nuts to see where you have fluid. Loosen the pipe nut on the pipe to the rear brakes at the master cyl and see if you have fluid there. If so then go to the other end of that pipe (at the RABS module) and loosen the nut there and see if you have fluid there. If yes then loosen the outlet pipe nut at the module and see if you have fluid there. If not try unplugging the electrical plug at the module and see if that helps.

 

ok I loosened the back pipe at the master cylinder, and had no preasure there. I had preasure there when I bled it in the vise. I have preasure in the front pipe. Don't get it.

 

Did you "bench bleed" the master before installing it?

 

Then the proportioning valve is bad, I would think ( cylinderical part screwed into rear brake port on master cyl.).

 

thx! Would never have thought of that. I'll check that out.