Six problems related to brake master cylinder have been reported for the 1999 GMC Sierra. The most recently reported issues are listed below.
While driving my vehicle I was stopping and the brakes were shot. I had to push the pedal as hard as possible to the floor to get it to stop. Luckily I narrowly avoided an accident with the person in front of me. I took the truck to get looked at and the break lines are leaking from the master cylinder to the abs unit. They are extremely rusted and they need to be replaced. The estimate was over $1000.
While on an errand there seemed to be a sudden, extreme decrease in braking ability. We were still able to stop with brake to the floor if we allowed plenty of time to do so, however, it felt very unsafe to drive. Upon a mechanic's inspection it was determined that the group of brake lines from the abs to master cylinder were completely rusted through and needed to be replaced. The total cost of repairs was $684. 95.
Dealer diagnosis is engine knock hot or cold see history piston moving in cylinder making noise operating to manufactures specs at this time---performed decarb 2 times per gm recommendations noise returns currantly no resolutins per gm for noise. That means that I pay thousands of dollars for a deffective turck, the factory warranty it going to expire when the truck hits the 36000 miles dealer explain to me that when gm find how to fix the problem I can go back and gm going to fix the engine of my truck, I'm sceptical for this comment. Gm built thousands of this kind of engines and I dont think that gm going to expend money and time to fix engines when the wararnty al ready expire.
While driving brake pedal has to be depressed down to the floor to get the vehicle to stop. Dealer has replaced the anti lock brake control module and the master cylinder, but the problem still exists.
While driving and upon depressing brake pedal to make a normal stop, brakes held for a brief moment and then released, causing extended stopping distance. Also excessive amount of force was applied to the brake pedal in order to stop vehicle. Consumer has contacted dealer. Dealer replaced the master cylinder, but problem still occurs. Please provide any further details.
Upon brake failure, the master cylinder on this vehicle has been repaired or replaced 4 times. The first failure occurred at 86 miles, 2nd at 2,729 miles, 3rd at 43,014 miles, and most recently at 57,270 miles. We are concerned for our safety in this vehicle finding the brake system faulty.