On our DP, periodically the wires under the dash that plug into the camera vibrate loose. Unplug and plug them back in. Another place where the camera can come unplugged is at the camera. Our access is in the closet. Another thing that happens with our camera is that if the batteries are ever disconnected with the inverter off, our camera needs to be reprogrammed to accept the camera. We found the instructions in the user manual. You might be able to find the manual online if you have the model number. Ours is Pioneer.