GMC 2010 Canyon Crew Cab Owner's Manual page 275

If parking the rig on a hill:
1. Press the brake pedal, but do not shift into P (Park)
yet for vehicles with an automatic transmission, or
into gear for vehicles with a manual transmission.
Turn the wheels into the curb if facing downhill
or into traffic if facing uphill.
2. Have someone place chocks under the trailer
wheels.
3. When the wheel chocks are in place, release the
brake pedal until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking
brake and shift into P (Park) for vehicles with an
automatic transmission or into gear for vehicles with
a manual transmission.
5. If the vehicle has four-wheel-drive, be sure
the transfer case is in a drive gear and not in
N (Neutral). See Four-Wheel Drive on page 3-25
for more information.
6. Release the brake pedal.
Leaving After Parking on a Hill
1. Apply and hold the brake pedal while you:
•
Start the engine
•
Shift into a gear
•
Release the parking brake
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the
chocks.
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