OMG you guys are making this way too difficult. Buy some extra pulse timer bologne? No wai! The unit is looking for the parking brake to be on, then off, then on again. So you need a signal you can control. I believe the AVH-P4000DVD has a USB cable that you can use to play music from a player or flash drive. And doesn't that cable have a small electrical signal associated with it? Try taking that "parking brake" wire and sticking it into the USB extension cable. Guess what? The unit now sees a signal (it doesn't know or care what it is) and will allow the screen to play. No extra part
