New vehicle front end suspension began to randomly violently shake at different speeds (once @ 55 mph & once @ 70 mph). The shaking was so bad that the driver could barley hold the wheel straight to avoid losing control & crashing. While this was happening the vehicle 4 wd light was blinking despite the fact that the vehicle was in 2 wd. Once driver was able to pull over he inspected the outside of the vehicle to find no mechanical issues (no flat tires, things in the wheels, etc...). driver then began driving again & the vehicle was fine as if nothing happened. Driver called onstar & they stated there were no fault codes in the system. Several days later the same thing happened while driving at 70 mph. This time the driver nearly got into a roll over accident. He was able to get the vehicle to the side of the road. Upon inspection there were again no mechanical issues. Owner drove to dealer & was told to bring back the next day. Owner inquired if vehicle was safe to drive & was told "I hope so" by the service technician. GM customer care was called & stated they were not aware of any issues with the 2011 hd vehicles. Owner took vehicle to dealer next morning & several hours later was called & told it was mud in wheels (not possible since the first time it happened there was no mud). Owners son then looked on internet to see many people having the same issue in this model year vehicle. The son then found that a tsb was issued by GM to all dealers for a sticky break pedal that when stuck (even though it appears visually to not be stuck) will at random times cause the ABS to activate violently. Tsb# pit5037B. Dealer was then told by owner about the tsb & dealer was not aware of tsb. Repair was performed & the vehicle has not shook since. Owner was suppose to be pulling a 30 ft 5th wheel with a 15 ft trailer attached to it (45 ft. Total). If they had been they likely would have been in major accident with possible loss of life due to the sway it causes when it occurs.

- Filion, MI, USA