I recently bought an android aftermarket Head unit and came across this problem as well when trying to connect the stock reverse camera to the after market HU.
Below is my 20 pin connector from my 2010 Camry hybrid. Looks identical to Peter Yeh's. I'm using his wire identification above.
It didn't work after 2 tries, I haven't soldered it into place yet as I'm not sure it's right. I have a 12v to 6v converter from Jaycar as well. Here's my connection:
pin 5 (red) reverse signal -> 12v in
pin 11 Video+ (red) -> RCA+ (middle lead)
pin 12 Video- (white) -> RCA- (outside lead)
pin13 Camera+ (black) -> 6v out
pin 14 Camera- (black) -> short to ground with main connector (brown) from the large bunch of wires from the other connector head.
I short the 12v-in ground with the 6v-out ground with pin 14 and the brown ground wire from another connector.
Is this right? With the RCA plugged into the HU, nothing happened when I shifted into reverse gear.
I know this thread is old, but any experts still around?