Also were is the PC located? If its in the rear, I suggest looking for the bolt that attaches the rear seat to the inside of the trunk and sand it like crazy.... until you see nothing but bare metal on the bolt and hole..... Also make sure your ground is as short as posible. It should only be about 3 to 6 ft max length. If that fails look for a ground point that the manufatuerer uses. For my truck I used a factory ground point, and have no issues. I also installed a system in my little brothers car but did the first step and all is fine.