Chevrolet 2009 Suburban Owner's Manual page 147

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2 (Two-Wheel Drive High): This setting is used
for driving in most street and highway situations.
The front axle is not engaged in two-wheel drive.
This setting also provides the best fuel economy.
AUTO (Automatic Four-Wheel Drive): This setting is
ideal for use when road surface traction conditions are
variable. When driving your vehicle in AUTO, 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.
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4 (Four-Wheel Drive High): Use the four-wheel high
position when you need extra traction, such as on snowy
or icy roads or in most off-road situations. This setting
also engages your front axle to help drive the vehicle.
This is the best setting to use when plowing snow.
n
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 if you
are driving off-road in deep sand, deep mud, deep snow,
and while climbing or descending steep hills.
The vehicle has StabiliTrak
Four-Wheel-Drive Low will turn Traction Control and
®
StabiliTrak off. See StabiliTrak
CAUTION:
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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 2-45.
N (Neutral): Shift the vehicle's transfer case
to N (Neutral) only when towing the vehicle.
See Recreational Vehicle Towing on page 4-43
or Towing Your Vehicle on page 4-43 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 3-64.
®
. Shifting into
®
System on page 4-6.
2-41