Issue #1-while driving the vehicle stablitrak warning light, traction control, engine power reduced, and brake light all came on. Vehicles engine power was suddenly reduced to about 10 mph while driving on the interstate in which I found to be very dangerous! had to pull over, turned off vehicle, lights went off, started driving again, vehicle did the same thing. Had to take in for mechanical repairs. Issue #2- key ignition switch just started locking up on the vehicle, would not turn back to normal to position, had to repeatedly keep jiggling for over 30 minutes or so to get the vehicle started back up?? had to take vehicle to dealer for repairs also. These are very unsafe and costly issues that GMC should be mandatorily required to have recalled and immediately addressed for the safety of the general public!!

- Birmingham, AL, USA

- ÇÈÇÇ, AR, USA

Went about a mile was getting ready to make a left across md rt 4 when I lost power and reduced engine power light came, had a close call, on did some research and found a technical notice about throttle body and injector sensors they need a recall.

- Arlington, VA, USA

The contact owns a 2011 GMC Sierra 1500. The contact stated that the vehicle was powered on and in park when it lunged forward abnormally. The contact had to jump in the vehicle and depress the brakes to stop it from traveling any farther. The vehicle was taken to a dealer for diagnosis however, the dealer was unable to determine the cause of the failure. The vehicle was not repaired. The manufacturer was not notified of the issue. The approximate failure mileage was 90,000.

- Shelby Township, MI, USA

I was going 40mph when I went to stop quick to avoid an accident. I pressed on brakes truck did not slow down then all of a sudden it did down shift but at that the truck lunged forward causing me to clip the truck in front of me.

- Westfield, MA, USA

2011 GMC Sierra 1500 sle crew cab Z71 4X4 coming off of the expressway and coming to a stop at a traffic light I applied brake pressure. The brake pedal was unusally stiff then all of a sudden the engine revved to over 5000 RPM's and starting to move forward. I had my foot pushed firmly on the brake and the vehicle remained revving and moving forward. I quickly put it in park and turned off vehicle. Started back up and no issues on remaining drive. Cruise control was not engaged. Vehicle has less than 1400 miles on it.

- Bay City, MI, USA

Second report - sudden acceleration. 2011 GMC Sierra pu truck. On December 20, 2010 I was traveling to visit friends. While on highway I set the cruise control for 70 mph. I exited the freeway and traveled approximately 5 miles on city streets. Upon entering a bedroom township known for speed traps I attempted to engage the cruise control for 30 mph. When pressing the cruise control to set the speed I was traveling (30 mph) the truck down shifted and accelerated rapidly (to 4000 RPM). I immediately tapped the brake and the cruise control disengaged. This is the second time for this truck to down shift and accelerate rapidly. A previous report was made in November 2010.

- Houston, TX, USA