Not sure on your car, but as far as I know on the imported ALTEZZA with japaneese sat nav and japaneese TV tuner this is how it works.
Head unit controls TV tuner option, audio/video.
TV unit wires via SAT NAV box (TV tuner selections must control via sat nav box, with sat nav box removed and interchanged with UK sat nav box, TV tuner button fails to work on oem radio.
The sat nav therefore is probally the heart of the system, as it is the main feature of the monitor (primary) you should really tag your connections from there.
You will find the colours easily as all you need to know is the Red Green Blue and sync.
There is normally a shileded cable with about 5 cables inside.
I know this may sound a little silly, but if you were to have the system on and cut onyou will start to loose the colours on the monitor one by one when you find the correct ones... i.e cut the wire that transmits your Blue (in RGB) and the blue colour will go from your display leaving it a little pinky/green.. you can do the same for the other colours, once you find the SYNC colour the picture should be line'e and flicker.
If I were you I would follow the colours that refer to your YEAR of car being simular model, as the colours from DVD NAV and CD rom nav are different colours slightly.