I have the 2 wire bypass in place but 2nd video input is grey. Ive tried several video sources but the button stays grey? Ive also gone through every aux. screen to try and activate the input. does this input solely rely on the parking brake? Any help will be appreciated.

you need chek the wires in some times is not all the way in , if is o.k. reset the z-1 and check o.k.

What have you connected to the 2nd video input?