One problem related to power assist brake vacuum has been reported for the 2001 GMC Sierra. The most recently reported issues are listed below.
Steering wheel jerks in hand when depressing brakes while making a right hand turn. This can be duplicated with the vehicle idling in neutral or park. Dealership attempted to fix problem on 01/25/02 by replacing the power steering pump and brake booster. When I attempted to pick up my truck on the 25th, I was notified by marcus that they had not found the problem and that they considered the problem a safety issue, I wasn't allowed to have the vehicle but was given a loaner to drive. My vehicle was returned on the 29th and I was told that since the dealership could duplicate the "problem" on another new vehicle on the lot, gm had determined it was not a problem but a "characteristic" of this vehicle with the power assist. I contact gm customer assistance to make them aware of my concern with the safety of this vehicle but to no avail. I asked them to document my concerns. It is apparent that the dealership was initially concerned that there was a safety issue with this vehicle or they would have returned it on the 25th. I am concerned with gm's response that this is a "characteristic" of the vehicle just because some others exhibit the same problem. I was just recently made aware of your website and would greatly appreciate your assistance with this matter. Thank you! scott.