been using my D3 since 2007 and i had a back-up camera too. my problem is sometimes the camera doesn't work. when i put into reverse image is green sometimes purple and sometimes its stuck on the image. i didn't use a relay when i installed it. i connected and tapped the 12V wire of the camera to the H/U 12v wiring and the ground as well and for the reverse wire i tapped it to the reverse lamp wire from the rear and connected the RCA at the back of the HU. its really annoying when its not working. thank you! btw, i don't know how to wire a relay... here are the pics of the image when backing up.. it happens occasionally...

anyone?

almost 2 years now and still no reply? planing to change my back-up camera to BOYO VTL354 and i don't know if they are the same wiring from my audiovox..

still no reply? 

planning to install RELAY but don't know how to..

I can't answer your questions but I can help with the relay. Overall, relays are pretty simple to install. Here is a quick schematic to show the overall layout for a standard 12V relay:

The basics are, you're shifting from powering your accessories from what ever ignition controlled source you're using now to the battery. However, instead of leaving everything connected to the battery constantly (resulting in a dead battery when you get back to the car) you install a 'switch' to turn things on for you. The relay is that switch. Although, for the sake of the drawing, the switch in it is referring to the ignition (turning the car on), you will use this to then turn on the relay. When the relay is turned on, it will then shut the connection from the battery to your toys. I hope this helps.