I have had a 2channel rear view camera system fitted with a 7" TFT monitor the system is used for rear view via a camera on the back of the truck for rear view that is wired as channel 1 there is another camera centrally mounted over the towbar with backup lines on that makes backing up to hitch the caravan on a doddle on my own that works on channel two this camera picks it's power feed up from the reversing lights and connected to a 4 pin plug taking the signal back to the monitor when towing the caravan this camera is unpluged then another camera that is mounted on the back of the caravan is plugged in . A short time ago I had a mishap with the caravan camera cable and pulled it apart I now find after rewiring it that that camera won't work the camera it's self is fine as I have tryed it on the other channel the backup camera allso works plugged in to the same socket allso works my thoughts were that there was no power getting to the camera but when I tested the socket I have power there even if I test the camera at the front close to the monitor before the cable run it does not work but if I put it on the other channel it does my thought are that the monitor has become damaged on that channel unless it gets the powers source from the reversing lights has any one any other ideas thanks