Jeez.... I'm having the same issue here.....I have an 05 Chevy G3500 cutaway box van with the 6.0l v8. I'm looking for the backup wire for the monitor. I tied my rear camera to the backup light, and that's all fine, but I don't really want to run another wire all the way back to the cab from the light just to power the screen. For now I have the screen hooked up to constant 12v, and can leave it on, but its just a blue screen until I put it into reverse and the camera is powered on. Can anyone please tell me where the reverse power wire is?