the RABS on my 1992 f350 will not let the rear brakes work at all. So the brakes work very poorly, Was working find and just stopped working. How do I test to find out if the RABS module is bad.

 

RABS Is the right term that I was asking about.

 

Have someone hold the pedal down while you loosen the line going into the RABS valve. It should leak fluid out and the pedal should drop. Tighten it back up then do the same with the line coming out. It should do the same thing. If not the RABS is in fact causing your rear brakes to not work. You can bypass the RABS valve if it is bad. The system never was all that good.