1997 GMC Suburban Owner's Manual - Page 236

When You Are Ready to Leave After Parking on a Hill I . Apply your regular brakes and hold the pedal down while you: 0 Trailer Wiring Harness A seven-wire harness is stored under the rear of your vehicle, between the frame rails. An electrical connector will need to be added at the trailer end of the harness, by a qualified electrical technician. For additional trailer wiring and towing information, please consult your dealer. Securely attach the harness to the trailer, then tape or strap it to your vehicle's frame rail. Be sure you leave it loose enough so the wiring won't bind or break when turning with the trailer, but not so loose that it drags on the ground. Store the harness in its original position. Wrap the harness together and tie it neatly so it won't be damaged. If you tow a trailer, your Center High-Mounted Stoplamp (CHMSL) may not be properly visible from behind. You should select a trailer with a CHMSL on it or, if one is not available, have one installed. See your GM dealer about how to connect your vehicle's wiring to a trailer CHMSL. Start your 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. Maintenance When Trailer Towing Your vehicle will need service more often when you're pulling a trailer. See the Maintenance Schedule 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 adjustment. 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.