2010 GMC Acadia Owner's Manual - Page 308

9-52 Driving and Operating If parking the rig on a hill: 1. Press the brake pedal, but do not shift into P (Park) yet. 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). 5. Release the brake pedal. Parking on Hills Leaving After Parking on a Hill 1. Apply and hold the brake pedal while you: ... { WARNING Parking the vehicle on a hill with the trailer attached can be dangerous. If something goes wrong, the rig could start to move. People can be injured, and both the vehicle and the trailer can be damaged. When possible, always park the rig on a flat surface. 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.