One problem related to automatic transmission control module has been reported for the 2011 GMC Sierra. The most recently reported issues are listed below.
On July 29, 2015, while driving at approximately 45 mph, the vehicle suddenly downshifted itself into first gear causing the vehicle to slow down suddenly with no notice. I was able to get the vehicle off the road and into a gas station. After the fact the check engine light was illuminated. The vehicle was towed to the dealership. I was told the tcm (transmission control module) needed replacing and that there is a known issue with this year truck. This is a very dangerous situation to have your vehicle suddenly slow down while driving at speed. If gm knows that the part is faulty why is there not a recall? will it take multiple deaths before gm takes responsibility?.
| Power Train problems | |
| Automatic Transmission Control Module problems | |
| Automatic Transmission Torque Converter problems |