case 621 b brake pressure

[dieselfuel007]

I'm currently working on a case 621b the brake pressure warning light is on and it won't move in first and second gear with I think is what its suppost to do from what i've read so far we've replace the relief valve and pressure switch cause our dealer said the problem is probably in the valve well they were wrong. So I guess i need to start checking pressures starting at the pump does anyone know what the pressures should be or have any other suggestions also is there another source for any of these brake valve parts?thanks my dealer seems clueless

 

[casetech7]

these are wet brakes in the axle housing correct? or the older air assisted disc brakes?

 

[GaryHoff]

Is your brake pressure actually low? These machines are old and are prone to wiring issues. You can just jump the relay under the dash. Last one I had with a brake issue, had a weak brake pump, it was just worn out.