I recently purchased a used 2000 Mercury Mountainer. The original owners had a DVD player built in to the vehicle. After we bought the vehicle the people took out their system and put in the factory installed cd player back in. When they did this, they took out the ground wire that made the DVD player work. I have no idea what this is, and how I can make the DVD player work now?? What is a ground wire, where can I get one, and how can I hook it up to make my DVD player work? Thanks!