GMC 2006 Sierra - Manual (Page 137)

When the vehicle detects a loss of traction, the system
will automatically engage four-wheel drive. Driving in
this mode results in slightly lower fuel economy than
Two-Wheel High.
2
m
(Two-Wheel 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 2-52.
N (NEUTRAL): Shift the vehicle’s transfer case to
N (NEUTRAL) only when towing your vehicle. See
Recreational Vehicle Towing on page 4-62 or Towing
Your Vehicle on page 4-62 for more information.
4
m
(Four-Wheel High): Use this setting when you
need extra traction, such a on snowy or icy roads or in
most off-road situations. This setting also engages your
front axle to help drive your vehicle. This is the best
setting to use when plowing snow.
4
n
(Four-Wheel Low): This setting also engages
your front axle and delivers extra torque. You may never
need Four-Wheel Low. It sends maximum power to all
four wheels. You might choose Four-Wheel Low if you
are driving off-road in deep sand, deep mud, deep snow,
and while climbing or descending steep hills. When
operating in Four-Wheel Low, the gear ratio provides
additional torque when compared to four-wheel high.
The transmission gear shift feel will be exaggerated.
Indicator lights in the switches show which setting your
transfer case is in. The indicator lights will come on briefly
when you turn on the ignition and one 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
the transfer case is being shifted. It will stay on when the
shift is complete. If for some reason the transfer case
cannot make a requested shift, it will return to the last
chosen setting.
If the SERVICE 4WD message stays on, you should take
your vehicle to your dealer for service. See DIC Warnings
and Messages on page 3-55 for further information.
2-43