[sbsisco]

My thoughts as well on the master cylinder. thats my next investment if todays bleeding doesn't help. I've had a lot of master cylinders go out on classic cars I've owned and my way of testing for that was to sit stopped while pushing hard on the pedal and waite to see if it'll slowly start to sink to the floor. This won't do that..yet,,,it may later on if its is an o ring in the MC. My main reason for posting is to see if anyone has had this issue and what it ended up being. I only have my years of mechanical experience on the old cars without all the extras to the brake system. Tearing into a new hummers brake system seams a little scary to me if it could be caused by some kind of sensor or eletronic issue I don't understand...all comments or suggestions are greatly appriciated...thanks...