Need help triggering rear view camera (2012 Mazda5)

Looking for some help from the folks on the forum. Recently bought a 2012 Mazda 5 for my younger brother and installed BOSS Audio BE62CP-C head unit with reverse camera. I installed the unit with Crux SWRMZ-64C Wiring Interface and everything seems to work just great EXCEPT for the rear view camera. The camera works only if I select the Camera option on the Boss unit, but I'd like the rear camera show up on the Boss unit when I put the gear in Reverse instead of having to manually select the Camera option on the Boss unit. So I'm trying to figure out how to trigger that reverse camera. Which wire can I tap into to trigger the reverse camera? Any help will be greatly appreciate.
 
I had to wire up a new backup camera in my Ford Focus and tied the input trigger wire on my display into the reverse tail light wire. When those lights come on, it flips the media display over to the backup camera automatically.

If that Boss radio comes with a backup camera, I feel like the unit itself should have a reverse trigger wire on it, but I don't have that unit.
 
Yup Molarcraft, that sounds about right. I installed a pioneer double din radio and got a backup camera from Bestbuy. I think I did the same thing. I did ghetto splice it and just used some wire nuts and black electrical tape but it's working . LOLL
 
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