2004 GMC Yukon Owner's Manual - Page 127

You can choose among three driving settings: This button is used with the Stabilitrak® system and is also used to shift the transfer case into Neutral (N). For more information on using Stabilitrak® see Stabilitrak® System on page 4-11. d (Stabilitrak®): NEUTRAL: 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 buttons 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. If the SERVICE 4WD message stays on, you should take your vehicle to your dealer for service. See SERVICE 4WD under Driver Information Center (DIC) on page 3-56. f (All-Wheel Drive): g (4LO): This setting delivers power to all four wheels as needed depending on road and driving conditions. This setting 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. {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. 2-33