radio stereo head unit jbl dvd

has anyone pulled apart their stereo/nav head unit and disabled ONLY THE navigation and dvd portion?
supposedly i can send it to some service but that is big $ and the last time i did that with a dash cluster on my old caddy, the dang business just kept it and went out of business.
does anyone know where to find a serious wiring diagram for the head unit.
my darn head unit kind of went out finally at 250K miles. the nav screen wouldn't shut off and the unit would not shut off when key was out and doors closed. it was creating a parasitic drain of about 1.7 amps. the only fix i could do short term was unplug the main wiring harness which effectly shuts the entire thing down. however,, i suspect it is just the nav part, or dvd part, all of which i could live with out. i do like the back up screen and the radio.

this is what mine looks like exactly