I have a 1998 chevy k1500 4wd, front brakes wer bad and I had to replace the front pads and calipers. Now the pedal while vehicle is running is soft, when I first hit the peddle, I can pump it and and its a little harder. Vehicle always stops. When vehicle is off pedal is hard and holds pressure. When running pedal goes soft. I un hook vacum line to booster and the pedal is hard, hook vacum line back up peddle is soft. Does this mean the booster is bad? Can I drive with the vacum line pluged till I replace the booster if it is bad?
All GM pedals are soft when the engine is running but what you will find is that it doesn't require anywhere near that force to stop the vehicle. If it's not stopping the vehicle, then you may still have air in the system. Many of them require an electronic scan tool to bleed the system internally through the ABS unit.