Oldsmobile 2001 Silhouette Owner's Manual page 118

To close the liftgate, pull down on the handle, then
firmly shut the liftgate. Don't drive with the liftgate
open, even slightly. See "Engine Exhaust" in the Index.
A message in your message center will warn you if the
liftgate is not completely closed. See "Rear Hatch Ajar
Warning Message" in the Index.
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Theft
Vehicle theft is big business, especially in some cities.
Although your vehicle has a number of theft
features, we know that nothing we put on it can make
it impossible to steal. However, there are ways you
can help.
Key in the Ignition
If you leave your vehicle with the keys inside, it's an
easy target for joy riders or professional thieves
don't do it.
When you park your vehicle and open the driver's door,
you'll hear a chime reminding you to remove your key
from the ignition and take it with you. Always do this.
Your steering wheel will be locked, and so will your
ignition and transaxle. Also remember to lock the doors.
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deterrent
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so