Richard, thanks for the vote of confidence!

If the hydraulic system has a failure and the master cylinder runs dry: When you apply the brakes, the master cylinder pushes air into the inlet ports of the ABS unit, where it can get trapped in the solenoids. Fluid does not compress, air does, and that's why the pedal is mushy. The air acts as a "shock absorber" or "cushion" in the hydraulic system when you apply the brakes. To bleed the system, you've got to start at the point where the air was injested, in your case, the master cylinder. The air needs to be forced through the entire system and out through the bleeders. Gravity bleeding, or using a power bleeder, is far more efficient than pumping the pedal. Not 100% certain on your 1993 system, but if I remember correctly, it has two bleeders at the ABS unit. They are used to bleed both the ABS unit and the master cylinder. When it comes out clear, then bleed at each wheel. If you can't get the air out by doing the gravity bleed, you'll need someone to do a pressure bleed. Dealers will have the machine, or check around at local independent shops. It's called a pressure bleeder, or power bleeder, same tool, different names. It attaches to the top of the master cylinder and pressurizes the system with new brake fluid. Open each bleeder seperately until the fluid comes out clear. Gravity bleeding does basically the same thing using the weight of the fluid to bleed itself.

 

cap hook: i am late posting this,but, thank you for the advice on my 93 blazer brake problem. i did eventually get the system bled of all air. used a hand vacuum pump and the gravity bleed you suggested. brakes work good now.

 

Great! Thanks for posting back.