Five problems related to automatic transmission have been reported for the 2001 GMC Sierra. The most recently reported issues are listed below.
While driving on the hwy. Towing my 28 ft 5th wheel trailer on level ground we experienced a loud bang and the feeling like something in the driveline had broken. No engine malfunction indicators were displayed on the console. No further incidents have happened yet, but it is constantly on my mind.
We have a 2001 GMC crew cab that we have had for 26 months. Be bought it brand new so we would be less likely to have problems. We have had 3 new transmissions (not including the factory one). It is in the repair shop again because when you put the truck in reverse it dies. Not every time but it happens quite often. It was in the shop before for the same exact problem which resulted in 1 of the 3 new transmissions. Lets hope it doesn't need another one. This is getting old!!!!!!!!!!!.
Consumer states when applying brakes, the vehicle downshifted to a low gear and would not shift out, the back tires locked up and caused the vehicle to lock up and fishtail.
The transmission violently shifts into gear upon acceleration from a stop or slow speed. This problem has occurred as many as ten times since the original date of purchase. On may 4th it occured so violently that the passenger in the rear hit his head on the rear window. In this incident the shift was so hard the rear wheels left the ground(all 4) and then the truck lurched forward. This is a serious defect that could caused harm to those inside the truck and could harm other drivers or pedestrians. The truck seems to go to a neutral operation even though you are in drive then when the rpm"s icrease to above 2,000 it suddenly shifts. I have taken the truck to the dealer 5 times and recently completed arbitration to take the truck back. The GMC represenitive claimed that this was normal for a "heavy duty" transmission such as the allison. The best discription of the problem is it feels as if you have been hit from the rear by another vehicle at 15-20 mph.
The transmission has a problem that causes the truck to lurch forward just after coming to a complete stop. The lurch can be quite strong causing the vehicle to jump forward in excess of a foot. The lurch occurs at unpredictable times and without warning. The best description I can offer is that it feals as if the vehicle has been hit in the rear by another vehicle. It has occured at least 6 times on various occasions.