GMC 2012 Sierra Denali Owner's Manual page 298

The rear vision camera must be
disconnected if the tailgate needs to
be removed.
To disconnect the camera:
1. Remove the license plate.
2. Disconnect the camera
connectors from the chassis
harness, located behind the
license plate, by pressing on the
release tab on each connector.
A. Chassis harness connector
B. Release tab
C. Camera connector
3. Plug the two exposed chassis
harness connectors together to
prevent contamination.
A. Chassis harness connector
B. Release tab
4. Feed the wiring harness through
the pickup box, then plug the
camera connectors together to
prevent contamination.
5. Remove the tailgate. See
information.
6. Reinstall the license plate.
Reverse this procedure to reinstall
the RVC and make sure the
grommet and connection are
secure.
for more