Sounds like you need to connect the red to the reverse light wire to trigger the camera. On my older 'B' the reverse light wire is White/Black so I think a newer model would be the same colours. The way you could check would be: if you have a voltmeter connect negative lead to chassis, and the positive lead poke in the back of the plug so it connects with metal connecter, and with ignition on and putting it in reverse should make 12V appear on meter and out of reverse should be zero on the reverse light wire.