I'll keep it short as possible. I have already searched this forum several times looking for my answer, to no avail. I got tons of info and am grateful, so I decided to sign up.
Just bought my daughter a 98 Blazer, 151,000, in great shape. My son owns a 99 jimmy, 185,000.

Problem = My daughters brake pedal "slips" or "pushes-in" at the end of travel only when going around 5mph. My gut instinct and the fact my sons jimmy did this, and this forum has me convinced its the abs system/sensors falsely firing.

Corrections made: 4 new rotors, new pads all the way around, new master cylinder, cleaned out both front abs sensors, yet problem persists. Tired of messing with it, I installed a new Timken driver side hub/abs sensor assembly. No help. Unplug abs 60 watt fuse; problem gone.

What would you do next? No I don't have $$ to throw away, but was totally OK replacing all these parts as she will keep this vehicle for at least 5 years, and at 151,000 miles a new master cylinder and front hub will hurt nothing.

ALSO, I was not able to bench bleed the master cylinder, so had to do it ol fashion way in vehicle. Am I right to assume a tiny bit of air is not to blame for this? It brakes just fine in all other capacities. Could air be stuck in the abs box?

 

Here's an old GM TSB. It doesn't specifically mention your 1998, but the same procedure applies: http://ww2.justanswer.com/uploads/GM...s_bulletin.pdf

As for bleeding.... after replacing the master cylinder, you can try gravity bleeding the system at each wheel, (don't pump the pedal). If that doesn't work, the ABS unit must be bled using the "automated bleed" which is initiated only by using an ABS scan tool capable of initiating the procedure. You'll probably end up having to take it to a shop for the procedure. Without doing it, you'll never get the air out of the ABS unit.

 

Thanks, for the bulletin. I'll go from there.