it could be the reverse signal power is not working or is not providing enough voltage to make the radio show video.I honestly really do appreciate your help and suggestions. The fact that both my pioneer units are not displaying an imagine in reverse in my escalade yet they both work with after market cameras just tells me that the radios are ok. I will focus on wiring even though Ive checked and checked and checked some more and nothing helped.
Is there a way to by pass pac module and run a wire directly to reverse light under dash? If so, which wire and harness? I believe some where in the bcm?
there should be a reverse signal wire at the bcm or at the lower left kickpanel.
check the gm upfitter guide they have halfway decent wiring diagrams and should show the reverse signal wire location
you could also use a meter and see what the voltage shows from the pac module when you put it in reverse, not sure what the minimum requirement is for the radio
but.. I thought you posted above>>"Plug in the OEM radio again and back up camera works."