Chevrolet 2009 Suburban Owner's Manual page 490

Be sure the hoist end (J) of the extension (D)
connects to the hoist shaft (B). The ribbed square
end of the extension is used to lower the spare tire.
5. Turn the wheel wrench (E) counterclockwise to
lower the spare tire (H) to the ground. Continue
to turn the wheel wrench until the spare tire can be
pulled out from under the vehicle.
5-90
4. Insert the open end
of the extension (J)
through the hole in the
rear bumper (I) (hoist
shaft access hole).
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 5-99 for more information.
6. Use the wheel wrench
hook that allows you to
pull the hoist cable
towards you, to assist
in reaching the
spare tire.