I lost the power steering in my sierra today after i did a 180 in the grass. I just gave it a shot of gas to swing the ass end around and it lost the power steering. I was in 2 wheel drive there's no leaks or noises from the pump I checked to see if i pinched a line in the fender well but there fine and not near anything that can pinch them. Could it be a valve or something in the pump? Any help would be appreciated