Replaced break booster still getting "Service break booster" and breaks SUCK. Ideas?
 

My breaks suck something horrible. Thoungt my vacuum booster was bad so I replaced it. its an 04 4x4 1500 seirra btw. My pads arent perfect but not done for either. Ive bled them twice at the master cylinder. I can slam on the breaks with all my might and hit the bottom and im still rolling. Never a hint of wheel slip or ABS reacting. With my boat or trailer it gets scary, ive lucked out and had a place to dodge out of the way both times. Im out of ideas and dont really trust or want to pay the guys at my local gm place. Thanks and sorry its so long its just getting rediculous.

Sounds like your master cylinder is leaking internally. If you have no other external leaks, replace the master cylinder. Does the red brake light come on? You really need a Tech 2 to do an automated bleed to be sure you dont have air in the EBCM

Did you bench bleed the master cylinder?

I just played with my brake system... The service brake booster message is driven by a switch in the vacuum assist pump. A pressure difference between the booster and the vacuum assist pump. Check for vacuum leaks and since you changed out the booster maybe the assist pump is bad.

If the pedal is going to the floor I'm with these other guys. Either the master cylinder or air in the lines. From everything I've read if you do get air into the anti-lock actuator you will have to get to a dealer and a tech 2 to cycle the ABS pump to get the brakes bled properly.

No the red brake light doesnt come on just the service brake booster. Thanks guys I guess i will just have to suck it up and dish out the cash to get the pros to fix it. I guess theres no winning this battle by myself. thanks again