Hi guys, just got a ‘20 Silverado 1500 LTZ, love it! When I open the rear door after the truck has been off for a while, a motor activates that sounds like it might be from an electronic running board. The truck didn’t come with running boards (it was used, though). Is this noise normal? Any ideas of what it could be? I have to check and see if it does it when the engine is running, I guess.