2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 178

A Four-Wheel Drive indicator light comes on when you shift into four-wheel drive and the front axle engages. See Four-Wheel-Drive Light on page 4‑48. Some delay between shifting and when the indicator light comes on is normal. Notice: Driving on clean, dry pavement in four-wheel drive for an extended period of time can cause premature wear on the vehicle's powertrain. Do not drive on clean, dry pavement in Four-Wheel Drive for extended periods of time. 4 n (Four-Wheel-Drive Low): This setting also engages the front axle and delivers extra torque. You may never need Four-Wheel-Drive Low. It sends maximum power to all four wheels. You might choose Four-Wheel-Drive Low if you are driving off-road in deep sand, deep mud, deep snow, and while climbing or descending steep hills. If the vehicle has StabiliTrak®, shifting into Four-Wheel-Drive Low will turn Traction Control and StabiliTrak® off. See StabiliTrak® System on page 5‑6. Recommended Transfer Case Settings Transfer Case Settings 2m 4m 4n N Normal YES Severe YES Extreme YES Vehicle in Tow* YES *See Recreational Vehicle Towing on page 5‑49 or Towing Your Vehicle on page 5‑48 Driving Conditions 3-40