N2 backup camera question.

[Baker1082]

Hello, I purchased a n2 off ebay and it did not come with the manuals. I am hooking up a backup camera. I know I need to hook up the reverse sense wire to make the screen switch when I go into reverse. My question is what reverse wire do I hook into? There is a reverse input on the main unit and the hideaway unit. Do I need to hook into both of them? Thanks for your time!