Nightmare Install, Sony XAV-AV100, 2012 Chevrolet Tahoe

The only 2 ways the radio will show the camera display is when there is 12 volts on the radio's reverse wire or when you press the icon. The radio has no way to tell if the camera is powered up. As long as there is not 12 volts on the reverse wire it will not switch to the camera at power up.

Not in my experience. What I was observing with this radio was that if you have a camera that has 12v going to it at all times the car is running, this sony radio will go straight to displaying the image when the car is started, irregardless of gear or pressing the icon. It was like the radio sensed the camera was powered on and putting out a video signal and it automatically switched to it. The only way for me to prove or disprove this would be to yet again, pull off the trim panel and mess around with the wires, which have all been taped up. I may do it sometime in the future.