GMC Sierra 2010 Owner's Manual page 541

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.
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 spare tire does not lower to the ground, the
secondary latch, if the vehicle has one, may be
engaged causing the tire not to lower. See
Secondary Latch System on page 6 103.
5. Use the wheel wrench
hook which allows you
to pull the hoist cable
towards you to assist in
reaching the spare tire.
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