I have the exact same problem. I just wired it as described. The previous owner mentioned he had it working with this method and then it stoped. I figured the connection had come loose on the ground pin. You never know with a used unit...
I ended up taking the "guide on" wire (since I don't have a external sound processor) and using it to make sure I had a good ground like in the above diagram.
Same symptoms. I can play a movie, it works for a few, gives me the parking break connection error, and then it will only play when I'm at stop lights. I have audio but no video when the car is
