Basicly what I am talking about for Auto Reverse cam is controlling it by
My solution to Auto Power ON Lilliput screen
Instead of running the relay from power on off the PSU running it from the Reverse Light on the car. And then when that power is gone having it switch to the VGA button.
Now if there isn't a VGA button and its a video selector I would have make it pulse somehow a couple times but I know this can be done. I am suprised I haven't seen anyone do this yet actually...