Swapping out factory radio

HELP! I am now in the process of preparing to button everything up, but a run through test first. In doing so, here's my problem: The Carplay is via usb to iPhone. The extending/retracting of the flip screen is normal with usb cord plugged in. When I plug the usb cord into the iPhone the screen will retract. If a hook phone up and then push button to open screen, it goes short of full open, I can see something on the screen before it starts retracting. I did notice that the HVAC back lighting bulb would glow at different levels as the flip screen was operating.
 
New question. All buttoned up except for rear camera. Wiring diagram says the backup lights are a light green wire that comes into the right backup light and over to the left. Can't locate it; I need help.
 
Update: Found the wire. A PO had remodeled the bedroom and covered up the back access panels to the lights. Had to remove cabinet and bed flooring just to get to wire, but I'm A HAPPY CAMPER again.