While driving a while back I was applying the brakes and hit a small pot hole and my brakes went to the floor. No matter how many times I pumped them they still wouldn't hold. I managed to get the van home and the next day the brakes were fine. A couple of months later the same thing occured (applying the brakes and hitting a bump) this time the problem has hasn't gone away. I bled the brakes with a pneumatic bleeder and the only change is if I pump the brakes 3 or 4 times I have good pedal but the next time I apply the brakes they go to the floor. It stops fine with the little pedal I have but obviously there's a problem. Any ideas?

 

An idea, among a few,
Maybe, a questionable wheel bearing or loose connection at a wheel speed sensor allowing loss of the wheel speed sensor signal leading the ABS to think a wheel is locking up and dumping the hydraulic pressure. See if there are any codes in the system to help provide some direction.