My rebel had this problem. sometimes the rear view camera would work and sometimes it wouldn't. a black screen would appear. This made me very angry. At first I thought that the problem was in the camera, but if I slammed the back door hard, sometimes it started to work. So I realized that the problem was poor contact. I examined the contacts on the connections near the camera and under the back door near the license plate. everything is fine there. After connecting and disconnecting everything worked, but not for long.