[seattle gmc]

Started intermitently but now everytime I turn off the truck and pull the key from the ignition the radio and gauge cluster will not turn off when you open the door. This started a few months ago. I would like to fix this but i don't know where to start. luckily everything turns off after at set amount of time. Where do i start looking? Is there a switch some where behind door panel? Is it something witht the vehicle settings? My truck is a 2007 sliverado 1500HD classic.