GMC Chevrolet Silverado 2500HD 2021 Owner's Manual page 238

If equipped, the transfer case controls are
used to shift into and out of four-wheel
drive.
To shift the transfer case, press the desired
button. The graphic in the instrument
cluster will flash while a shift is in progress.
The graphic displayed will change to indicate
the setting requested.
When the shift is complete the graphic will
stop flashing. The DIC message turns off
once the shift is complete. If the transfer
case cannot complete a shift request, it will
go back to its last chosen setting.
The settings are:
N (Neutral) : Use only when the vehicle
needs to be towed. See Recreational Vehicle
Towing 0 370 or
Towing the Vehicle 0 369.
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.
AUTO (Automatic Four-Wheel Drive) : Use
when road surface conditions are variable.
When driving in AUTO, the front axle is
engaged, and the vehicle's power is sent to
the front and rear wheels automatically
based on driving conditions. This setting
provides slightly lower fuel economy
than 2 .
4 (Four-Wheel Drive High) : Use this
setting when extra traction is needed, such
as when driving on snowy or icy roads,
when off-roading, or when plowing snow.
4 (Four-Wheel Drive Low) : This setting
engages the front axle and delivers extra
torque. Choose 4 when driving off-road in
deep sand, deep mud, or deep snow, and
while climbing or descending steep hills.
While driving in 4 , keep vehicle speed
below 72 km/h (45 mph).
Shifting into 4 will turn Traction Control
and StabiliTrak/ESC off. See Traction Control/
Electronic Stability Control 0 242.
Shifts between 2 , 4 , and AUTO
Any of these shifts can be made at normal
driving speed.
The actual 4x4 shift request is only made
after the button is released. The 4x4 graphic
will remain flashing until the shift request
has completed. A DIC message displays to
indicate that the 4x4 transfer case has been
requested to shift to the new desired state.
Driving and Operating
Once the 4x4 shift has completed, the DIC
message disappears, the 4x4 graphic stops
flashing, and the current setting is indicated.
When a shift to 2 is completed successfully
while in P (Park), the parking brake will
engage. To resume driving, shift the
transmission to the desired gear and
manually release the parking brake or press
the accelerator pedal to begin driving. See
Electric Parking Brake 0 240.
If equipped, use 4 , AUTO, or 4 to provide
additional traction when parking on a steep
grade with poor traction such as ice, snow,
mud, or gravel.
Shifting Into 4
1. The ignition must be on and the vehicle
must be stopped or moving less than
5 km/h (3 mph) with the transmission in
N (Neutral). It is best for the vehicle to
be moving 1.6 to 3.2 km/h (1 to 2 mph).
2. Press 4 . The actual 4x4 shift request is
only made after the button is released.
The 4x4 graphic will remain flashing
until the shift request has completed.
A DIC message displays to indicate that
the 4x4 transfer case has been requested
to shift to the new desired state.
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