I know there are a few threads about this already, but this is a bit different. As far as I can tell, there are two things that cause the Video Screen to grey out

1. parking brake is not on
2. detects the car is in motion.

I read that #1 can be bypass bying tapping into the wire and grounding it. For #2, I would assume that the only way it can detect motion is through the GPS for the navigation system. Now if you don't have Nav, how can it detect motion. Is there a third saftey measure??? I'm hoping someone without Nav would try the parking brake bypass and report if it works.

 

Uh... maybe by wheel speed, vehicle speed, etc. Speedometers work in non Nav cars, so it ain't too difficult.