I just get a black screen and message on screen when i put it in reverse I had a d1 in there and never had any problems just hooked it up the same way, am I missing something on the D3

Are you sure you connected to the right wire ? If so are your backup lights coming on when it's put in reverse ? Also check the fuse in the reverse lead.

reverse lights are fine i even checked the camera in the video input of the d3 and still nothing i rechecked all my connections everything is secure. I took out my d1 and put in this d3 everything works except camera I dont have original nave discs, I bought this unit on ebay could that be the issue?

my camera is Audiovox - Rearview Color CMOS Camera worked great with the D-1

are you using the included fuse/resistor that came with violet/white lead?