1994 Pontiac Transport bleeding the system

DANWILCOX

MEMBER
1994 PONTIAC TRANSPORT
6 CYL
FWD
AUTOMATIC
212,000 MILES

The right rear wheel cylinder leaked so I replaced it and the short length of line leading to the cylinder. All was well for a few days ( about 40 miles of country paved roads) then the pedal went to the floor, I rechecked the res and found no fluid loss, tryed to re bleed the brakes but can not get ANY pressure at the rear wheels, both fronts develop pressure ok. I then proceeded to try bleeding at the 2 bleed screws on the ABS unit (attached to the master cyl.)(Vehicle has 4whl abs) got good flow but NO AIR. I know how to bleed master cyl.S but this one has the ABS unit attached directly and I am unsure as to how the M/C bleeding proceedure is performed on this model. I am ASE master certified but never had to work on an integrated M/C ABS system. Also thought that this was a "cross braking ' system but the fronts both work and both rears don't. Any ideas?

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

Bleed this like any other system, but start at the master rearward then forward bleeders, then go to the rear and bleed as a diagonal system. These rears are non servo, so if one wheel cyl was bad, replace both. Is ABS light on? We might need to pull codes!
To check clamp rear hoses, does the pedal come back up?