It is attached to the liftgate latch assembly.

Have you checked your liftgate fuse? In my 2006 Yukon, when the liftgate fuse went out the rear ac wouldn't work nor would the electric locks for the liftgate itself.

Remove the liftgate inner trim panel.

Remove the liftgate inner trim panel.

(1) Open the liftgate. (2) Remove the trim cover and latch mounting screws. (3) disconnect the actuating rod - detach electrical connectors (if any) - then remove latch from liftgate. Installation is the reverse of removal.

fuse for the liftgate glass is in the fuse box at the passengerside kick panel