GMC Sierra Classic 2007 Owner's Manual page 578

9. Position the center lift point of the jack under
the center of the spare tire.
10. Turn the wheel wrench clockwise to raise the
jack until it lifts the end fitting.
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11. Continue raising the jack until the spare tire
stops moving upward and is held firmly in
place. The secondary latch has released and
the spare tire is balancing on the jack.
12. Lower the jack by turning the wheel wrench
counterclockwise. Keep lowering the jack
until the spare tire slides off the jack or
is hanging by the cable.
CAUTION:
{
Someone standing too close during the
procedure could be injured by the jack. If
the spare tire does not slide off the jack
completely, make sure no one is behind
you or on either side of you as you pull
the jack out from under the spare.
13. Disconnect the jack handle from the jack.
Carefully remove the jack from underneath
the vehicle.