r207,
check your connections:
the OEM TV tuner is supposed to handle the camera and the AV input without the need for additional video switchers - here is the pinout on the tuner's plugs:
camera video goes to white plug (X18806)
(+) - pin 13
(-) - pin 14
when ground is applied to pin 17 of the blue plug (X18804), it activates the pins 13 and 14 and the front screen is showing the reverse image (or goes blank, if the 13 and 14 are not connected to anything).
for the AV input the pinout on the white plug (X18806) is:
audio out (+) - pin 1
audio out (-) - pin 10
video out (+) - pin 2
video out (-) - pin 11
audio in (+) - pin 4
audio in (-) - pin 5
video in (+) - pin 6
video in (-) - pin 15
"AV out" is a full time image/sound that is the same as on the main screen.
"AV in" brings whatever source is connected to it on the main screen and also on the AV out.
Bear in mind that the audio portion of the OEM tuner is only mono.
Have fun,
