GMC 2009 Sierra 1500 Crew Cab Owner's Manual page 508

Be sure the hoist end of the extension (F) connects
to the hoist shaft (E). The ribbed square end of
the extension is used to lower the spare tire.
5-98
3. Insert the hoist end
(open end) (F) of the
extension through the
hole (G) in the rear
bumper.
Do not use the chiseled
end of the wheel
wrench.
4. Turn the wheel wrench (H) counterclockwise to
lower the spare tire to the ground. Continue to
turn the wheel wrench until the spare tire can
be pulled out from under the vehicle.
If the spare tire does not lower to the ground,
the secondary latch is engaged causing the tire
not to lower. See Secondary Latch System
on page 5-107.
5. Use the wheel wrench
hook which allows you
to pull the hoist cable
towards you to assist in
reaching the spare tire.