AUChevy11

I have a 2007 Chevy 1500 4x4 and have noticed that at certain times the brake pedal will lock up and no matter how hard i push it will not move. The first time i noticed this was in the mud when sliding, I had traction control on (which got me stuck) at first then took traction control off. The brake pedal still locked up whether it was on or off when playing in the mud. I then noticed that with traction control off i was still not getting all four tires spinning. I found out if you push and hold the traction control button you will get true four wheel drive (that is a pain), but the brak pedal still locked up. The next time i noticed this issue was on an incline. I was moving my truck out of the way and just put the truck in neutral with the engine off and letting it roll. When i went to brake, i could not push the brake pedal even with both feet. I had to use the emergency bake to keep from going through the garage door. Both times it felt like i was pushing against a brick wall and had a slight grinding feel to it. Is this normal or am i having issues? This also happened to a buddy of mine at a boat ramp except he ended up in the river up to the windows in water.

AUChevy11

To clear things up, it was acting as if it would not let me brake when sliding through the mud which almost cost be the back end of my truck, then when moving the truck in neutral with the engine off i have always been able to brake except when on an incline. I know the vacuum booster needs the engine running but i don't think it would not let you compress the brake pedal. My brake lines are fine and bled, brake fluid is fine, had rotors turned and new brake pads. My truck brakes fine when driving otherwise.

tech2

you will only have one or 2 assisted brake applications with the engine off. Once the vacuum reserve of the booster is depleted you will have manual brakes like the old days.

when the rotors are submerged the friction co-efficients are low so the pads can't hold the rotor.