2003 GMC Sonoma Owner's Manual - Page 263

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, or into gear for a manual transmission. When parking uphill, turn your wheels away from the curb. When parking downhill, turn your wheels into the curb. 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 then shift into PARK (P), or REVERSE (R) for a manual transmission. 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. Maintenance When Trailer Towing Your vehicle will need service more often when you're pulling a trailer. See Part A: Scheduled Maintenance Services on page 6-4 for more on this. Things that are especially important in trailer operation are automatic transmission fluid (don't overfill), engine oil, axle lubricant, belt, cooling system and brake system. Each of these is covered in this manual, and the Index will help you find them quickly. If you're trailering, it's a good idea to review these sections before you start your trip. Check periodically to see that all hitch nuts and bolts are tight. 5. If you have a four-wheel-drive vehicle with an automatic transfer case, be sure the transfer case is in a drive gear-not in NEUTRAL. 6. Release the regular brakes. When You Are Ready to Leave After Parking on a Hill 1. Apply your regular brakes and hold the pedal down while you: start your engine, shift into a gear, and release the parking brake. 4-62