Need help with Pibus and RPi3B+

[TooEasyL2P]

gpio23 is for relay control. if the screen switches from pi or bmw screen to black screen, so the relay is working. but the rearcam signal has a problem.
option 1: power for rearcam is bad
option 2: rearcam video signal is bad

It doesn't switch.

So wait... what is GPIO27?

I tested GPIO23 and you said that GPIO27 should be tested. And GPIO27 reacts to gears.