The contact owns a 2014 GMC Sierra 1500. The contact stated while driving at an undisclosed speed and attempting to turn the steering wheel, the vehicle lost power steering functionality. The contact stated that the failure had recurred intermittently and had progressively worsened. A message advising of a power steering failure and to drive safely was displayed. The vehicle was not diagnosed or repaired by an independent mechanic or the dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 150,000.