Not needed for a reverse camera. connect camera power to blue/red wire and negative to black/white wire on your tail/stop/reverse/signal wire harness.
Should be a setting in the radio that you need to turn on for display to automatically switch to the reverse camera. However, did you hook up the reverse camera lead wire to a reverse gear signal?

 

I have an '06 GS300 that had the multiplex "forcibly removed" and I am in need of a comprehensive wiring diagram for everything that plugged into the multiplex AND the amp. No Mark Levinson, just pioneer. I figured since the wiring was shredded, now would be the time to upgrade to an android screen... and i am lost now I finally got the new screen to power on. No, integrated functionality whatso ever apart from functioning hazard lights. (....whoo hoo...) I'm freaking desperate at this point, to be frank. It's COLD out and my old lady is... not happy about it to say the least. so, I'm here, swallowing my pride, asking for help. Anybody?

 

I'm not sure if this is what you're looking for but here's some wiring for the audio for the multiplex on the 2006 GS.

 

Wow Nap2Gap,
Wish I would have come here sooner. That info was crazy helpful, thank you. To be clear though I am also looking for some color diagrams of what goes where for the climate controls.
You have all probably heard this before, but I am just trying to put a Tesla-style head unit in the car. That's a 2006 GS300, nothing special, plain-jane Lexus. I have average skills, and never thought replacing a head unit could be so complicated. Since this car did not come with the OEM unit (it came with a hole where it used to be), I, of course, went for an inexpensive (cheap) unit. We have traced out with a toner the wires for the radio as there are no factory connectors for the back of that unit. It has been a challenge. Between the climate control (which did have the connectors) and the radio with an amp from hell (also had connectors cut), it has made this install… well, interesting. Always looking to learn something new, but this car is making me more careful what I ask for in life. Any and all info is welcome.

 

let me see what i can find and i apologize in advance if it may take a while