video system

[dpounders]

My 2000 Expedition has an lcd flip screen mounted in the roof as well as a vcr which is mounted over the 3rd seat. When I bought the car the video system wasn't working nor were any of the dome/vanity lights. I found that the problem was the same for both. The were several burn't wires in the wiring harness located in the side floor channel passenger side front of vehicle. When I spliced the dome/vanity wire back together the video system came on as well. I found where whoever installed the video system used the supply wire that supplies power to the dome/vanity lights to wire the video system in. The system looks like it's factory and made for the vehicle but I couldn't believe that whoever installed the system spliced it into the dome/video supply wire as the wire is so small. The wires supplying the video power for the lcd screen, vcr & an fm modulator is a larger wire (smaller gauge). Does anyone know if this is the recommended method for wiring a video system? I would think that you would wire it independently.