2004 GMC Yukon Owner's Manual - Page 123

You can choose among four driving settings: h (2HI): This setting is used for driving in most street and highway situations. Your front axle is not engaged in two-wheel drive. This setting also provides the best fuel economy. AUTO 4WD: This setting is ideal for use when road conditions are variable. When driving your vehicle in AUTO 4WD, the front axle is engaged, but the vehicle's power is sent only to the rear wheels. When the vehicle senses a loss of traction, the system will automatically engage four-wheel drive. Driving in this mode results in slightly lower fuel economy than 2HI. {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 2-36. NEUTRAL (N): Shift the vehicle's transfer case to NEUTRAL only when towing your vehicle. See Recreational Vehicle Towing on page 4-53 or Towing Your Vehicle on page 4-53 for more information. Indicator lights in the button show which setting you are in. The indicator lights will come on briefly when you turn on the ignition and one will stay on. If the lights do not come on, you should take your vehicle to your dealer for service. An indicator light will flash while shifting the transfer case. It will remain illuminated when the shift is complete. If for some reason the transfer case cannot make a requested shift, it will return to the last chosen setting. G (4HI): Use the 4HI position when you need extra traction, such as on snowy or icy roads or in most off-road situations. This setting also engages your front axle to help drive your vehicle. This is the best setting to use when plowing snow. 5(4LO): This setting also engages your front axle and delivers extra torque. You may never need this setting. It sends maximum power to all four wheels. You might choose 4LO if you are driving off-road in deep sand, deep mud, deep snow and climbing or descending steep hills. 2-29