GMC Sierra Classic 2007 Owner's Manual page 157

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
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
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.
m
2 (Two-Wheel Drive High): This setting is
used for driving in most street and highway
situations. Your front axle is not engaged in
two-wheel drive. This setting also provides the best
fuel economy.
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 168.
N (NEUTRAL): Shift the vehicle's transfer case to
N (NEUTRAL) only when towing your vehicle.
See Recreational Vehicle Towing on page 418 or
Towing Your Vehicle on page 417 for more
information.
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