GMC Sierra 2010 Owner's Manual page 178

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, deep snow,
and while climbing or descending steep hills.
If the vehicle has StabiliTrak
Four-Wheel-Drive Low will turn Traction Control and
®
StabiliTrak off. See StabiliTrak
3-42
®
, shifting into
®
System on page 5 6.
WARNING:
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 3 50.
N (Neutral) : Shift the vehicle's transfer case to
N (Neutral) only when towing the vehicle. See
Recreational Vehicle Towing on page 5 43 or Towing
Your Vehicle on page 5 43 for more information.
If the SERVICE 4 WHEEL DRIVE message stays on,
you should take the vehicle to your dealer/retailer for
service. See Service 4 Wheel Drive message under
DIC Warnings and Messages on page 4 65.