Ok so i just bought the Kenwood KNA-G510 navigation unit brand new and i believe i have all the wiring right but it doesnt seem to work. Here is how i have it wired. I have a 98 jeep grand cherokee

So i have the little navigation box underneath the back seat where the factory amp is. There is 4 wires coming from the little box, yellow battery wire, red 12 volt acc. wire, black ground wire, and a green parking brake wire.

I have the ground wire and the battery wire cut short and then spliced into the battery and ground wires coming from the box that all the connections go to i.e ipod, navigation, video cable going to HU etc.

I then have the parking brake wire and the 12 volt acc. wire running up to where the HU is. I then spliced into the wiring harness and attached the red 12 volt acc. wire and then i attached the ground wire to the factory ground cable.

On the back of the HU i have tried connecting the parking brake wire to the ground but that doesnt seem to work because i get no video. I also have the ground wire that comes from the HU connected to the factory ground and that works.

Basically my problem is that when i turn on the HU and go to menu I cannot select NAVIGATION, and when i insert a DVD it will read it and start to play but i get no picture.

Is there anything i spaced out about or does anybody have any suggestions. At this point i will try just about anything.