OK, so I have had the front and rear brakes changed, rear drums replaced, from rotors cut, calipers replaced and the master cylinder replaced (3 times) and the booster tested in my 99 Tahoe LS. Now my pedal goes to the floor and it wasn't doing that before! Everyone has been scratching their head here and no one can think of what it could be! ( Even a tech that has worked for GM for over 20 years!) Has anyone had this issue and figured out how to fix it?

 

It sounds like you have air trapped in the lines. Was the master cylinder bench-bled before installing?

I'd say start with a gravity bleed, then pressure bleed in order of RR, LR, RF, LF, keeping the master cylinder full at all times. Then take a short test drive in a gravel parking lot or something, and get up to 15 mph, then slam on the brakes to make the ABS pump motor activate. Do that ABS stop 3 times in a row.

Then pressure bleed the brakes in order again. After all that, you should be all set.

 

Like Roger said, the ABS pump motor can be a PITA to get the air out of. The ABS pump can also be cycled with a TECH 2 if you have access to one. Pressure bleeding them is the way to go.

 

Maybe calipers are reversed, if the bleeder isnt at the top you will never get a pedal.

 

Thanks guys We will try it in the morning!!