Reverse signal wire

I have my new radio all connected but need a reverse signal so that the screen swaps to the backup camera automatically when going into reverse. I have the camera power connected to a switched 12v so that I can use it anytime.

The PAC harness has a connection for the reverse signal but that harness isn’t used. What I would like to do is connect a pin to the pin on the unused harness for the reverse signal and connect that wire to whatever the reverse signal is from the factory.

Is a reverse signal on any one of these connectors or harnesses?

 

I gave up trying to find a trigger wire in that area and ended up running a wire to the passenger side kick panel. There's a blue wire in the lower white plug that gets 12v when the vehicle is put in reverse.

 

I was able to find a reverse signal behind the radio. The light gray/dirty white wire harness has the same blue wire from the passenger kick panel I believe, and opening it up there is a series of 5 and a series of 3 metal "pads". The group of 3 are energized when the gear shifter goes into reverse.

 

My backup camera stopped functioning after installing the ARB twin compressor under the driver seat. I had removed the positive battery terminal prior to the install and after placing back on the battery post I started the truck and it almost immediately shut down without any indicators as to why. A subsequent attempt to start the truck was successful, but alas, the backup camera functions did not work when placing the gear shift in reverse. I am presently looking for wiring diagrams to assist in troubleshooting.
There are no printed manuals available and I was given a keycode from the dealer parts department to have access to the electrical service manual for 1 year, but that effort is not panning out, and I am running into roadblocks with the web page available (Techinfo.Toyota.com & NASTF registry). There may be a simple answer or some test techniques for me to use for troubleshooting, so if anyone can lend some ideas or any valuable information I would be very grateful.
Thanks,
Dan
P.S., the dealer had tried to diagnose the problem, but the technician was not able to help. I will be taking the head unit out to see if the connectors in the photo above are available. BTW, 2019 Tundra Sport package all upgraded to PRO.
New edit:
Also, I will be contacting Beat-Sonic, the front camera supplier who are experts on the toyota backup camera and head unit system. I suspect their control module died when I removed the positive battery terminal causing an inductive voltage spike.
Will see if they concur and are willing to send me a free replacement.

2022-04-13 New edit: The camera system fixed itself after I used cruise control.
Beat-Sonic new about the camera anomaly that was commonplace when the battery was disconnected and reconnected and have a video on troubleshooting these issues. Their solution is to remove the head unit to get to their control module and replace the video connectors back to factory configuration wait for the camera function to return and then rewire as before to get the front camera operation restored. I was prepared to do this but because of my work schedule had no time and had to put it off, but was encouraged that the camera function would return. After using cruise control on a stretch of freeway, the camera function was restored. I don't know if this can be relied on as a solution but it worked in my case. I reported the findings to the camera and truck dealers. They were amazed and Toyota was not ever aware of the problem where the head unit loses its memory when the battery is disconnected, the Beat-sonic company are true experts and Toyota hacks. I think they are Japanese Americans with inside knowledge. I highly recommend their camera product!