2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 187

Automatic Transfer Case The transfer case knob is located next to the steering column. 2 m (Two-Wheel-Drive High): This setting is used for driving in most street and highway situations. The front axle is not engaged in Two-Wheel Drive. This setting also provides the best fuel economy. AUTO (Automatic Four-Wheel Drive): This setting is ideal for use when road surface traction conditions are variable. When driving the vehicle in AUTO, the front axle is engaged, but the vehicle's power is sent only to the front and rear wheels automatically based on driving conditions. Driving in this mode results in slightly lower fuel economy than Two-Wheel-Drive High. 4 m (Four-Wheel-Drive High): Use the Four-Wheel-Drive High position when extra traction is needed, such as on snowy or icy roads or in most off-road situations. This setting also engages the front axle to help drive the vehicle. This is the best setting to use when plowing snow. Use the dial to shift into and out of Four-Wheel Drive. You can choose among five driving settings: Indicator lights in the dial 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 the 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. 3-49