GMC 2012 Sierra Denali Owner's Manual page 291

4 (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.
4 (Four-Wheel Drive Low): This
setting also engages the front axle
and delivers extra torque. You may
never need this setting. It sends
maximum power to all four wheels.
You might choose Four-Wheel Drive
Low while driving off-road in deep
sand, deep mud, or deep snow, and
while climbing or descending steep
hills.
If the vehicle has StabiliTrak
shifting into Four-Wheel Drive Low
will turn Traction Control and
®
StabiliTrak off. See StabiliTrak
System on page 9 47.
Shifting the transfer case to
N (Neutral) can cause the vehicle
to roll even if the transmission is
in P (Park). You or someone else
could be seriously injured. Be
sure to set the parking brake
before placing the transfer case in
N (Neutral). See Parking Brake on
page 9 45.
N (Neutral): Shift the vehicle's
transfer case to N (Neutral) only
when towing the vehicle. See
Recreational Vehicle Towing on
page 10 88 or Towing the Vehicle
on page 10 87 for more information.
®
,
If the SERVICE 4 WHEEL DRIVE
message stays on, you should take
the vehicle to your dealer for
®
service. See SERVICE 4 WHEEL
DRIVE under Transmission
Messages on page 5 46.
Driving and Operating
WARNING
Shifting Into Two-Wheel
Drive High
Turn the knob to the Two-Wheel
Drive High position. This can be
done at any speed, except when
shifting from Four-Wheel Drive Low.
See Shifting Out of Four-Wheel
Drive Low for more information.
Shifting Into Four-Wheel
Drive Low
When Four-Wheel Drive Low is
engaged, vehicle speed should be
kept below 72 km/h (45 mph).
Extended high-speed operation in
Four-Wheel Drive Low may damage
or shorten the life of the drivetrain.
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