need help big time.

Bit of history. needed new front rotors so i decided to replace them as well as do all four sets of brake pads. When depressing the right front calipers they started to leak so i replaced the caliper with a new one.

Took it down to have brakes flushed (4 wheel ABS so it requires the scan tool) and they couldnt get it to stop delivering bubbles. determined that master cylinder was bad so replaced it. back to shop and they got all bubbles out but still did not have good pedal. still a little mushy. they determined i may have gotten a bad Master cylinder so i replaced it again and bled brakes on my own.

Brakes are mush better now but new problems. Brake light goes through check at starting, goes off but then comes back on and stays on. ABS goes through check at starting then goes off and stays off but ABS system engages with very little brake pressure at low speed like backing out of the driveway but will not engage at high speed.

any help or input would be great.

 

Thanks: Elkhunter, but I have replaced all the brakes and new rotors and new drums and shoes and pads, plus a new master cyl. I also flushed out the system with new fluid and still a soft pedal. I wonder if I can bye pass the ABS all together, it doesn't act like it is working at all, in the snow I can not get this truck to slide and the ABS will not work.