GMC 2010 GMC Sierra, Owner'S Manual, Page: 187 / 660

Automatic Transfer Case
The transfer case knob is
located next to the
steering column.
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.
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.
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