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GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada/Mexico-14632286) - 2021 - CRC - 11/19/20
246
Driving and Operating
The settings are:
2
m
(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.
4
m
(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.
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
m
.
Shifts between 2
m
, 4
m
, 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.
Once the 4x4 shift has completed, the DIC
message disappears, the 4x4 graphic stops
flashing, and the current setting is indicated.
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. Once the 4x4 shift
has completed, the DIC message disappears,
the 4x4 graphic stops flashing, and the
current setting is indicated.
Brakes
Antilock Brake System (ABS)
The Antilock Brake System (ABS) helps
prevent a braking skid and maintain steering
while braking hard.
ABS performs a system check when the
vehicle is first driven. A momentary motor
or clicking noise may be heard while this
test is going on, and the brake pedal may
move slightly. This is normal.
If there is a problem with ABS, this warning
light stays on. See
ABS does not change the time needed to
get a foot on the brake pedal and does not
always decrease stopping distance. If you
get too close to the vehicle ahead, there will
not be enough time to apply the brakes if
that vehicle suddenly slows or stops. Always
leave enough room ahead to stop, even
with ABS.
Using ABS
Do not pump the brakes. Just hold the brake
pedal down firmly. Hearing or feeling ABS
operate is normal.
Braking in Emergencies
ABS allows steering and braking at the same
time. In many emergencies, steering can
help even more than braking.