2003 GMC Yukon Owner's Manual - Page 120

When tow/haul mode is selected the tow/haul indicator light will illuminate. Front Axle Locking Feature The front axle locks and unlocks automatically when you shift the transfer case. Some delay for the axle to lock or unlock is normal. Automatic Transfer Case The tow/haul mode also interacts with the Autoride™ feature, if your vehicle is so equipped, to enhance the ride when trailering or with a loaded vehicle. See Autoride™ on page 4-60. {CAUTION: Shifting the transfer case to NEUTRAL can cause your vehicle to roll even if the transmission is in PARK (P). You or someone else could be seriously injured. Be sure to set the parking brake before placing the transfer case in NEUTRAL. See Parking Brake on page 2-34. Four-Wheel Drive If your vehicle has four-wheel drive, you can send your engine's driving power to all four wheels for extra traction. To get the most satisfaction out of four-wheel drive, you must be familiar with its operation. Read the part that follows before using four-wheel drive. See the appropriate text for the transfer case in your vehicle. Notice: Driving on pavement in four-wheel drive for an extended period of time may cause premature wear on your vehicle's powertrain. Do not drive in four-wheel drive on pavement for extended periods of time. 2-26