GMC 2010 Sierra Owner's Manual page 564

1. Open the spare tire lock cover on the bumper and
use the ignition key to remove the spare tire
lock (J). To remove the spare tire lock, insert the
ignition key turn and pull straight out.
2. Assemble the wheel wrench (H) and the two jack
handle extensions (I) as shown.
6-104
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.
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 6 113.
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.