Originally Posted by Suba-dog
The HU has to sense when the car is in reverse to switch the display to the camera image. My camera has no "reverse" wire, it only has a long cable with proprietary connector that plugs into the HU. Camera has power from this connection. The reverse wire is in the HU wiring harness. Pioneer in my GMC truck was similar. I know the reverse light is an option, but I'd rather not have to run the HU cable all the way back, as I've already buttoned everything up from the camera install. There has to be a 12V+ reverse wire somewhere up front.
It's honestly like less than a ten minute job.
Just tap into the reverse light on the passenger side, route the wire behind the interior trunk covering, pull out the back seat and route the wire under it, push it under the trim around the doors, and route to the stereo.