Brake problem?

I bought a 1990 Ram brand new, and still have it. REAR wheel ABS was standard equipment, as is stainless exhaust system.
My ABS does not work correctly anymore, but the brakes operate normally. I bled my system the old fashioned way, and got all the air out.
There is also a bleeder mounted directly on the ABS block, which is mounted inside the frame C channel, over the drivers side rear axle.
If you bleed it well, and still have a pedal that goes to the floor, the master cylinder is leaking down, and needs to be replaced.

Good Luck.

George