Hello, I have a 2014 GMC Sierra 1500. It has 130k miles. I just bought it. When I put the vehicle in reverse, the screen turns grey. The lines appear on the grey screen, and they turn as I turn the wheel. No picture, just lines on a grey screen. After a few seconds, the screen stays grey but the lines disappear and a message comes up that says “Service Rear Vision System”. I am wondering where I should start. Are there common problems that lead to this? I’ve searched for answers, but most people describe a blue screen. Anyone have experience with this or know where to start? I did unplug and clean the connection by the spare tire, but nothing changed. Thanks in advance!