wiring, which has a reverse light wire that supplies 12v only when the truck is in reverse. I hooked that wire up to the camera's positive and then (in parrallel) spliced that wire to run to the cab of the truck where it connects to the 12v input for the monitor switch. the camera is grounded t the frame at the rear bumper. it seemed to work perfect until i realized that the monitor momentarily flickers about 1/10th of the time that i depress the brake pedal. annoying is right. with a multimeter on the 12v wire going to the input of the monitor, it occasionally reads a negative voltage when i press the brakes. I don't know how to fix this. could a diode wired in line stop this negative signal?