Right rear door wiring:
Dark blue wire in door harness = Main power to all door switches feeds from the drivers master switch lockout button.
Black wire = Ground for rear door attaches to B pillar under the trim.
Light green out of master switch splices to dark green at the door = Window up control feed.
Purple wire = Window down control feed.
Brown and dark blue inside door feed the window motor.
My bet is that the dark green wire is broken in the harness to the rear door or the light green wire from the master switch through the door flex harness in the driver's door has broken.
GM has altered the wiring in the newer trucks, each door now gets a power line to it and the switches trigger relays in the switches to control them. They no longer use the older reverse polarity feed from the main switches to the way they used to. Supposed to be "more reliable" that way.
Saturday, December 31st, 2016 AT 7:05 PM