I just started using an Ipad/leadnav in my prerunner and it makes quite a bit of "noise" when plugged into 12v. My car has a USB port wired into the dash. I plugged the Ipad directly into that. I am using a good Apple cord but the noise is too annoying to keep it plugged in. The wiring for the plug goes directly into the harness, so I don't know where the ground actually goes. The car was wired by Alumicraft so I am assuming it's done right. Humm, now that I think about it, it was a 12v cigarette type plug that I changed out to a USB port (if that would have anything to do with the noise). Ideas?