Expert: autohelp - 8/5/2005

Question
My 94 lumina euro with 4w disk antilock brakes has very week braking. I have brand new calipers, rotors, and pads in the rear and 1 year old calipers, rotors, and pads in the front that are still in very good condition. All calipers are operating. There is new fluid and they have been repeatedly bled at all four wheels. No air in lines. For the first half of pedal travel there is almost no response. As you get the pedal closer to the floor you get some but not great brakes. You can not pump them up either. You can force the pedal to the floor and then it stops sharp but not super sharp. Maybe master cylinder? Thank you in advance, Bryan

Answer
Sounds more like a faulty master cylinder or a stuck brake equalizer valve or modulator solenoid or a faulty brake control module. All these require special pressure testers to properly diagnose.

If you want to guees, Which I do NOT like to do, I would go with the master cylinder and then the pressure equalizer valve.