Chevrolet 2007 HH7 Owner's Manual page 118

Column Lock Release
For vehicles with an automatic transaxle, the
following procedure allows the ignition to be turned
to LOCK and ignition key removal in case of a
dead battery or low voltage battery.
1. Make sure the shift lever is in PARK (P).
2. Remove the cover from the bottom of the
steering column.
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3. Locate the plunger.
4. Press and hold the plunger toward the driver's
door while turning the ignition key to LOCK.
Remove the key.
Have your vehicle serviced at your GM dealer as
soon as possible.