GMC 2015 Sierra Denali Owner's Manual page 220

turned on, and one will stay on.
If the lights display momentarily
when the ignition is in ON/RUN, but
none stay on, the knob may have
been turned while the vehicle was
off. To see the indicator, turn the
knob to another position so that it
matches the actual transfer case
setting. If no lights display, take the
vehicle to your dealer for service.
An indicator light flashes while
shifting and until the shift is
complete.
If the transfer case cannot complete
a requested shift, it will return to the
last chosen setting. Turn the control
back to the previous setting to see
the indicator light.
Caution
Shifting the transmission into gear
before the requested mode
indicator light has stopped
flashing could damage the
transfer case.
The settings are:
N (Neutral): Shift the transfer case
to N (Neutral) only when towing the
vehicle. See Recreational Vehicle
Towing on page 10-91 or Towing the
Vehicle on page 10-91.
2 (Two-Wheel Drive High): Use
for driving on most streets and
highways. The front axle is not
engaged. This setting provides the
best fuel economy.
4 (Four-Wheel Drive Low): This
setting engages the front axle and
delivers extra torque. Choose 4 if
driving off-road in deep sand, deep
mud, or deep snow, and while
climbing or descending steep hills.
When engaged, keep vehicle speed
below 72 km/h (45 mph).
Shifting into 4 will turn Traction
Control and StabiliTrak off. See
Traction Control/Electronic Stability
Control on page 9-49.
Driving and Operating
4 (Four-Wheel Drive High): Use
when extra traction is needed. The
front axle engages and helps when
driving on snowy or icy roads, when
off-roading, or when plowing snow.
The vehicle can be shifted from 2
to 4 while the vehicle is moving.
Shifting Into 4
Turn the knob to 4 at any speed
up to 121 km/h (75 mph), except
from 4 . The indicator light will flash
while shifting and will remain on the
selected setting.
Shifting Into 2
Turn the knob to 2 at any speed,
except when shifting from 4 .
9-41