Chevrolet Malibu 2007 Owner's Manual page 339

Parking on Hills
CAUTION:
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You really should not park your vehicle,
with a trailer attached, on a hill. If
something goes wrong, your rig could
start to move. People can be injured,
and both your vehicle and the trailer
can be damaged.
But if you ever have to park your rig on a hill,
here's how to do it:
1. Apply your regular brakes, but don't shift
into PARK (P) yet.
2. Have someone place chocks under the
trailer wheels.
3. When the wheel chocks are in place,
release the regular brakes until the chocks
absorb the load.
4. Reapply the regular brakes. Then apply
your parking brake and shift into PARK (P).
5. Release the regular brakes.
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