2009 GMC Acadia Owner's Manual - Page 284

4-32 Driving Your Vehicle 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 the transmission into P (Park). 5. Release the brake pedal. Parking on Hills Maintenance When Trailer Towing The vehicle needs service more often when pulling a trailer. See Scheduled Maintenance on page 6-3 for more information. Things that are especially important in trailer operation are automatic transmission fluid, engine oil, axle lubricant, belts, cooling system and brake system. It is a good idea to inspect these before and during the trip. Check periodically to see that all hitch nuts and bolts are tight. { CAUTION 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. 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. Leaving After Parking on a Hill 1. Apply and hold the brake pedal while you: • start the engine, • shift into a gear, and • 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. Trailer Wiring Harness The vehicle is equipped with the following wiring harness for towing a trailer. Basic Trailer Wiring The trailer wiring harness, with a seven-pin connector, is located at the rear of the vehicle and is tied to the vehicle's frame.