GMC 2007 Sierra 1500 Pickup Owner's Manual page 158

Recommended Transfer Case Settings
Driving
Conditions m
2
Normal YES
Variable
Severe
Extreme
Vehicle in
Tow*
*See Recreational Vehicle Towing on page 424 for
further information.
You can choose among five driving settings:
Notice: Driving on clean, dry pavement in
Four-Wheel-Drive High or Four-Wheel-Drive
Low for an extended period of time may cause
premature wear on your vehicle's powertrain.
Do not drive on clean, dry pavement in
Four-Wheel-Drive High or Four-Wheel-Drive
Low for extended periods of time.
158
Transfer Case Settings
AUTO
m n
4 4
4WD
YES
YES
YES
Indicator lights in the switches show the current
setting. The indicator lights will come on briefly
when you turn on the ignition and the last chosen
setting will stay on. If the lights do not come
N
on, you should take your vehicle to your dealer for
service. An indicator light will flash while shifting.
Fast flashing means the conditions are not
being met to make the desired shift, typically the
vehicle is going too fast, the automatic
transmission is not in NEUTRAL, or the clutch
pedal is not fully pressed. Slow flashing means the
YES
shift is in progress. It will stay on when the shift
is completed. If for some reason the transfer case
cannot make a requested shift, it will return to
the last chosen setting.
AUTO 4WD (Automatic Four-Wheel Drive): This
setting is ideal for use when road surface
traction conditions are variable. When driving your
vehicle in AUTO 4WD, the front axle is engaged,
but the vehicle's power is primarily sent to the rear
wheels. When the vehicle's software determines
a need for more traction, the system will
transfer more power to the front wheels. Driving in
this mode results in slightly lower fuel economy
than Two-Wheel Drive High.