GMC SIERRA 2021 Owner's Manual

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
250 Driving and Operating
Caution
Do not repeatedly brake or accelerate
heavily when TCS is off. The vehicle
driveline could be damaged.
To turn off only TCS, press and release
g.
The traction off light
idisplays in the
instrument cluster. The appropriate message
will display in the DIC. To turn TCS on again,
press and release
g. The traction off light
idisplayed in the instrument cluster will
turn off.
If TCS is limiting wheel spin when
gis
pressed, the system will not turn off until
the wheels stop spinning.
To turn off both TCS and StabiliTrak/ESC,
press and hold
guntil the traction off light
iand the StabiliTrak/ESC OFF lightgcome on and stay on in the instrument
cluster, then release. The appropriate
message will display in the DIC.
To turn TCS and StabiliTrak/ESC on again,
press and release
g. The traction off light
iand the StabiliTrak/ESC OFF lightgin
the instrument cluster turn off. StabiliTrak/ESC will automatically turn on if
the vehicle exceeds 56 km/h (35 mph).
Traction control will remain off.
The vehicle has a Trailer Sway Control (TSC)
feature and a Hill Start Assist (HSA) feature.
See
Trailer Sway Control (TSC) 0306 or
Hill Start Assist (HSA) 0248.
Adding accessories can affect the vehicle
performance. See Accessories and
Modifications 0323.
Hill Descent Control (HDC)
If equipped, Hill Descent Control (HDC) sets
and maintains vehicle speed while driving
down steep grades in a forward or reverse
gear. The HDC switch is on the center stack,
below the climate controls.
Press
5to enable or disable HDC. Vehicle
speed must be below 50 km/h (31 mph).
When enabled, the HDC light displays on
the instrument cluster. A blinking HDC light indicates the system is
actively applying the brakes to maintain
vehicle speed. HDC can maintain vehicle
speeds between 1 and 22 km/h (1 and
14 mph) on grades greater than or equal
to 10%.
If HDC is to be used for more than
three minutes or on grades steeper than
25%, the transfer case should be put into
Four-Wheel Drive Low (4
n) to reduce the
possibility of brake overheating.
Noise from the Electronic Brake Control
Module (EBCM) is normal when HDC is
active.
When HDC is activated, the initial HDC
speed is set to the current driving speed.
It can be increased or decreased by pressing
+RES or SET- on the steering wheel, or by
applying the accelerator or brake pedal. This
adjusted speed becomes the new set speed.
HDC will remain enabled between 30 and
60 km/h (19 and 37 mph); however, vehicle
speed cannot be set or maintained in this
range. HDC will automatically disable if the
vehicle speed is above 80 km/h (50 mph) or
above 60 km/h (37 mph) for at least
30 seconds.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Driving and Operating 251
5must be pressed again to re-enable HDC.
HDC may disable after an extended period
of use. If this happens, HDC will require
time to cool down. The length of time HDC
remains active depends on road conditions,
grade, set speed, vehicle loading, and
outside temperature.
When enabled, if the vehicle speed is above
30 km/h (19 mph) and below 60 km/h
(37 mph), a DIC message will display.
Driver Mode Control
Driver Mode Control (DMC) allows the driver
to adjust the overall driving experience to
better suit preference by adjusting multiple
systems to fit specific driving needs. Drive
mode availability and affected vehicle
subsystems are dependent upon vehicle trim
level, region, and optional features.
Mode Activation
To activate Tow/Haul Mode turn the knob
counterclockwise. To activate other drive
modes turn the knob clockwise.
If equipped, select Terrain Mode by
pressing the
gbelow the 4mtransfer
case button.
Modes:
Normal Mode : Use for normal city and
highway driving to provide a smooth ride.
This setting provides balance between
comfort and handling. This is the standard/
default mode. There is no persistent
indicator in the instrument cluster for
this mode.
8Sport Mode : Use where road conditions
or personal preference demand a more
controlled response.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
252 Driving and Operating
When you enter this mode, you will
immediately feel a down shift. In this mode
the vehicle also monitors driving behaviors
and automatically enables Performance Shift
Features when spirited driving is detected.
These features maintain lower transmission
gears to increase available engine braking
and improve acceleration response. The
vehicle will exit these features and return to
normal operation after a short period when
spirited driving is no longer detected. If the
vehicle has Magnetic Ride Control, the
suspension will change to provide better
cornering performance.
6Snow/Ice Mode :Snow/Ice Mode
improves vehicle acceleration on snow and
ice covered roads. When active, Snow/Ice
Mode will adjust acceleration to optimize
traction on slippery surfaces. This can
compromise the acceleration on dry asphalt.
This feature is not intended for use when
the vehicle is stuck in sand, mud, ice, snow,
or gravel. If the vehicle becomes stuck, see If
the Vehicle Is Stuck 0221.
7Off-Road Mode : Use this mode for
off-road recreational driving. Off-Road Mode
should be used to improve driving at
moderate speeds, on grass, gravel, dirt,
unpaved roads, or snow-covered roads. The accelerator pedal is tuned for off-road use.
This mode modifies pedal mapping,
All-Wheel Drive (AWD), ride height, Antilock
Brake System (ABS), StabiliTrak/Electronic
Stability Control (ESC), and Traction Control
System (TCS) performance.
For more information on off-road driving see
Off-Road Driving
0215.
_Tow/Haul Mode : Use this mode
when hauling heavy loads to provide
increased performance and vehicle control.
Tow/Haul Mode adjusts the transmission
shift pattern, AWD, and ESC performance.
If the vehicle is turned off with Tow/Haul
Mode active and then restarted within four
hours or less, Tow/Haul will remain active.
Otherwise, the vehicle will start in
Normal Mode.
If the vehicle has a diesel engine, exhaust
braking is automatically activated when
Tow/Haul Mode is selected. It maintains
vehicle speed by automatically
implementing a shift pattern that uses the
engine and the transmission to slow the
vehicle. The system will command
downshifts and use the turbocharger on the
engine to reduce vehicle speed when the
brake is applied. The normal tow/haul shift pattern will return once the vehicle is on a
low grade or when the accelerator pedal is
pressed.
While in the Electronic Range Select (ERS)
Mode (see
“manual mode”), grade breaking
is deactivated, allowing the driver to select a
range and limiting the highest gear
available.
For more information on trailer weight
specifications, see Towing Equipment 0296.
gTerrain Mode : Use for finer control
during low speed, off-road driving. When
using this mode it will mimic the
characteristics of four-wheel-drive low (4
n)
without the torque capabilities.
Use when:
.Traveling on very rough roads at very low
speeds, such as a two-track or heavily
rutted road.
.Traveling slowly in grassy fields.
.Pulling a boat out of the water on a
trailer.
.Using the vehicle for public off-road
recreational driving. See Off-Road Driving
0 215 and
Hill and Mountain Roads 0219.

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Driving and Operating 253
When in Terrain Mode, the vehicle will shift
automatically but may hold a lower gear
longer to maximize engine torque. The
steering will change to provide more precise
control. A unique pedal map, transmission
shift pattern, and rpm control are utilized to
give better control at lower speeds and over
rough terrain. When the vehicle comes to a
stop, Vehicle Hold is engaged. TCS will be
optimized for maximum torque transfer
across axles, and Active Braking During Lift
Throttle will be engaged.
Active Braking During Lift Throttle:
.Automatically applies light braking,
similar to heavy engine braking of
four-wheel-drive low.
.Applies light braking in D (Drive) until the
vehicle is at idle speeds. In Manual L1 and
Manual L2, moderate braking may stop
the vehicle.
.Reduces trailer braking.Terrain Mode Drive
Select Expected Vehicle Behavior Ideal Terrain
Drive (L3-Lx) Minor deceleration when off
throttle and mild ability to
modulate throttle; mimics
performance of 4
nwithout torque
multiplication. Grassy fields,
mild two tracks,
rutted roads,
large rolling hills,
L2 Moderate deceleration when off
throttle and moderate ability to
modulate throttle; will bring vehicle
to a stop in most cases. Mild rock crawling,
heavy ruts,
short, steeper grades,
L1 Significant deceleration when off
throttle and significant ability to
modulate throttle; will bring vehicle
to a stop in most cases. Rock crawling downhill
Active Braking During Lift Throttle will
reduce the back and forth between the
accelerator and brake pedals.
Vehicle Hold Features:
.When the vehicle comes to a stop on an
incline grade in forward gear or on a
decline grade in reverse gear, Vehicle
Hold is engaged until the accelerator
pedal is pressed.
.When the vehicle is in forward gear on a
decline, the vehicle is allowed to creep
down the hill when the brake pedal is
released without pressing the accelerator
pedal. The vehicle will also creep forward
on flat ground.
.If the driver seat belt is removed and the
driver door is opened while the vehicle is
being held, EPB will be engaged.
.EPB will engage if the vehicle is held for
an extended period.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
254 Driving and Operating
Terrain Mode is only available on vehicles
equipped with the single speed
transfer case.
Terrain Mode can only be active when:
.Vehicle speed is less than 80 km/h
(50 mph).
.The transfer case is in 4m.
Frequent use of this mode may cause brake
wear due to the light braking.
The vehicle will automatically exit the mode
if the brakes get too hot. Terrain Mode can
be turned back on after the brakes have
cooled.
When Terrain Mode is selected:
.Auto Engine Start/Stop will be disabled.
.The Terrain Mode indicator displays on
the instrument cluster.
Limited-Slip Differential
If equipped, the limited-slip differential can
give more traction on snow, mud, ice, sand,
or gravel. It works like a standard axle most
of the time, but when traction is low, this
feature allows the drive wheel with the
most traction to move the vehicle. For
vehicles with the limited-slip differential, driven under severe conditions, the rear axle
fluid should be changed. See
Maintenance
Schedule 0409.
Locking Rear Axle
Vehicles with a locking rear axle can give
more traction on snow, mud, ice, sand,
or gravel. It works like a standard axle most
of the time, but when traction is low, this
feature will allow the rear wheel with the
most traction to move the vehicle.
Cruise Control
{
Warning
Cruise control can be dangerous where
you cannot drive safely at a steady
speed. Do not use cruise control on
winding roads or in heavy traffic.
Cruise control can be dangerous on
slippery roads. On such roads, fast
changes in tire traction can cause
excessive wheel slip, and you could lose
control. Do not use cruise control on
slippery roads. If equipped with cruise control, a speed of
about 40 km/h (25 mph) or more can be
maintained without keeping your foot on
the accelerator. Cruise control does not work
at speeds below about 40 km/h (25 mph).
If the cruise control is being used and the
Traction Control System (TCS) or StabiliTrak/
Electronic Stability Control (ESC) begins to
limit wheel spin, the cruise control will
automatically disengage. See
Traction
Control/Electronic Stability Control 0248.
If a collision alert occurs when cruise control
is activated, cruise control is disengaged. See
Forward Collision Alert (FCA) System 0275.
When road conditions allow you to safely
use it again, cruise control can be turned
back on.
Turning off the TCS or StabiliTrak/ESC
system will disengage the cruise control.
If the brakes are applied, cruise control
disengages.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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Driving and Operating 255
5:Press to turn cruise control on or off.
A white indicator comes on or off in the
instrument cluster.
+RES : If there is a set speed in memory,
press the control up briefly to resume to
that speed or press and hold to accelerate.
If cruise control is already engaged, use to
increase vehicle speed.
SET− :Press the control down briefly to set
the speed and activate cruise control.
If cruise control is already engaged, use to
decrease vehicle speed.
*: Press to disengage cruise control
without erasing the set speed from memory. Setting Cruise Control
If
5is on when not in use, SET−
or +RES
could get pressed and go into cruise when
not desired. Keep
5off when cruise is not
being used.
1. Press
5to turn the cruise system on.
2. Get up to the desired speed.
3. Press and release SET−.
4. Remove your foot from the accelerator.
The cruise control indicator on the
instrument cluster turns green after cruise
control has been set to the desired speed.
See Instrument Cluster 0106.
Resuming a Set Speed
If the cruise control is set at a desired speed
and then the brakes are applied or
*is
pressed, the cruise control is disengaged
without erasing the set speed from memory.
Once the vehicle reaches about 40 km/h
(25 mph) or more, press RES+ up briefly. The
vehicle returns to the previously set speed.
Increasing Speed While Using Cruise Control
Do one of the following:
.Press and hold +RES up until the desired
speed is reached, then release it.
.To increase vehicle speed in small
increments, press +RES up briefly. For
each press, the vehicle goes about 1 km/h
(1 mph) faster.
The speedometer reading can be displayed
in either English or metric units. See
Instrument Cluster 0106. The increment
value used depends on the units displayed.
Reducing Speed While Using Cruise Control
Do one of the following:
.Press and hold SET– down until the
desired lower speed is reached, then
release it.
.To slow down in small increments, press
SET– down briefly. For each press, the
vehicle goes about 1 km/h (1 mph) slower.
The speedometer reading can be displayed
in either English or metric units. See
Instrument Cluster 0106. The increment
value used depends on the units displayed.
Passing Another Vehicle While Using Cruise
Control
Use the accelerator pedal to increase the
vehicle speed. When you take your foot off
the pedal, the vehicle will slow down to the
previously set cruise speed. While pressing
the accelerator pedal or shortly following

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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256 Driving and Operating
the release to override cruise control, briefly
pressing SET–will result in cruise control set
to the current vehicle speed.
Using Cruise Control on Hills
How well the cruise control works on hills
depends on the vehicle speed, the load, and
the steepness of the hills. When going up
steep hills, pressing the accelerator pedal
may be necessary to maintain vehicle speed.
While going downhill, cruise braking helps
maintain driver selected speed.
Cruise Grade Braking is enabled when the
vehicle is started and cruise control is active.
It is not enabled in Range Selection Mode.
It assists in maintaining driver selected
speed when driving on downhill grades by
using the engine and transmission to slow
the vehicle.
For other forms of descent control, see Hill
Descent Control (HDC) 0250, Automatic
Transmission 0239, and Tow/Haul Mode
0 242.
Ending Cruise Control
There are four ways to end cruise control:
.Step lightly on the brake pedal.
.Press*.
.Shift the transmission to N (Neutral).
.To turn off cruise control, press5.
Erasing Speed Memory
The cruise control set speed is erased from
memory if
5is pressed or the ignition is
turned off.
Adaptive Cruise Control (Camera)
If equipped, Adaptive Cruise Control (ACC)
allows the cruise control set speed and
following gap to be selected. Read this
entire section before using this system. The
following gap is the following time between
your vehicle and a vehicle detected directly
ahead in your path, moving in the same
direction. If no vehicle is detected in your
path, ACC works like regular cruise control.
ACC uses a windshield mounted front
camera sensor.
If a vehicle is detected in your path, ACC can
apply acceleration or limited, moderate
braking to maintain the selected following
gap. To disengage ACC, apply the brake.
If ACC is controlling the vehicle speed when
the Traction Control System (TCS) or
StabiliTrak/Electronic Stability Control (ESC)
system activates, ACC may automatically disengage. See
Traction Control/Electronic
Stability Control 0248. When road
conditions allow ACC to be safely used, ACC
can be turned back on. Disabling the TCS or
StabiliTrak/ESC system will disengage and
prevent engagement of ACC.
ACC can reduce the need for you to
frequently brake and accelerate, especially
when used on expressways, freeways, and
interstate highways. When used on other
roads, you may need to take over the
control of braking or acceleration more
often.
{Warning
ACC has limited braking ability and may
not have time to slow the vehicle down
enough to avoid a collision with another
vehicle you are following. This can occur
when vehicles suddenly slow or stop
ahead, or enter your lane. Also see
“Alerting the Driver” later in this section.
Complete attention is always required
while driving and you should be ready to
take action and apply the brakes. See
Defensive Driving 0213.

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Driving and Operating 257
{Warning
ACC will not detect or brake for children,
pedestrians, animals, or other objects.
Do not use ACC when:
.On winding and hilly roads or when
the camera sensor is blocked by snow,
ice, or dirt. The system may not
detect a vehicle ahead. Keep the
windshield and headlamps clean.
.When visibility is poor due to rain,
snow, fog, dirt, insect residue, or dust;
when other foreign objects obscure
the camera’s view; or when the
vehicle in front or oncoming traffic
causes additional environmental
obstructions, such as road spray. ACC
performance is limited under these
conditions.
.On slippery roads where fast changes
in tire traction can cause excessive
wheel slip
.With extremely heavy cargo loaded in
the cargo area or rear seat
.When towing a trailer
J:Press to turn the system on or off. The
indicator turns white on the instrument
cluster when ACC is turned on.
RES+ : Press briefly to resume the previous
set speed or to increase vehicle speed if ACC
is already activated. To increase speed by
about 1 km/h (1 mph), press RES+ briefly. To
increase speed to the next 5 km/h (5 mph)
mark on the speedometer, hold RES+.
SET– :Press briefly to set the speed and
activate ACC or to decrease vehicle speed if
ACC is already activated. To decrease speed
by about 1 km/h (1 mph), press SET– briefly.
To decrease speed to the next 5 km/h
(5 mph) mark on the speedometer,
hold SET–.
*: Press to disengage ACC without erasing
the selected set speed.
[: Press to select a following gap setting
for ACC of Far, Medium, or Near.
The speedometer reading can be displayed
in either English or metric units. See
Instrument Cluster 0106. The increment
value used depends on the units displayed.
Switching Between ACC and Regular Cruise
Control
To switch between ACC and regular cruise
control, press and hold
*. A Driver
Information Display (DIC) message displays.
See Vehicle Messages 0130.
ACC IndicatorRegular Cruise Control
Indicator
When ACC is engaged, a green
oindicator
will be lit on the instrument cluster and the
following gap will be displayed. When the

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
258 Driving and Operating
regular cruise control is engaged, a green
Jindicator will be lit on the instrument
cluster; the following gap will not display.
When the vehicle is turned on, the cruise
control mode will be set to the last mode
used before the vehicle was turned off.
{Warning
Always check the cruise control indicator
on the instrument cluster to determine
which mode cruise control is in before
using the feature. If ACC is not active, the
vehicle will not automatically brake for
other vehicles, which could cause a crash
if the brakes are not applied manually.
You and others could be seriously injured
or killed.
Setting Adaptive Cruise Control
If
Jis on when not in use, SET–/RES+
could be pressed by mistake and engage
ACC when not desired. Keep
Joff when
cruise is not being used.
Select the set speed desired for ACC. This is
the vehicle speed when no vehicle is
detected in your path. While the vehicle is moving, ACC will not set
at a speed less than 5 km/h (3 mph),
although it can be resumed. The minimum
allowable set speed is 25 km/h (15 mph).
To set ACC while moving:
1. Press
J.
2. Get up to the desired speed.
3. Press and release SET–.
4. Remove foot from the accelerator.
After ACC is set, it may immediately apply
the brakes if a vehicle ahead is detected
closer than the selected following gap.
ACC can also be set while the vehicle is
stopped if ACC is on and the brake pedal is
applied.
The ACC indicator displays in the instrument
cluster and Head-Up Display (HUD),
if equipped. When ACC is turned on, the
indicator will be lit white. When the ACC is
active, the indicator turns green. Be mindful of speed limits, surrounding
traffic speeds, and weather conditions when
selecting the set speed.
Resuming a Set Speed
If the ACC is set at a desired speed and then
the brakes are applied, ACC is disengaged
without erasing the set speed from memory.
To begin using ACC again, press RES+ up
briefly.
.If the vehicle is moving more than 5 km/h
(3 mph), it returns to the previous set
speed.
.If the vehicle is stopped with the brake
pedal applied, press RES+ and release the
brake pedal. ACC will hold the vehicle
until RES+ or the accelerator pedal is
pressed.
A green ACC indicator and the set speed
display on the instrument cluster. The
vehicle ahead indicator may be flashing if a
vehicle ahead was present and moved. See
“Approaching and Following a Vehicle” later
in this section.
Once ACC has resumed, if there is no vehicle
ahead, if the vehicle ahead is beyond the
selected following gap, or if the vehicle has
exited a sharp curve, then the vehicle speed
will increase to the set speed.

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Driving and Operating 259
Increasing Speed While ACC Is at a Set Speed
If ACC is already activated, do one of the
following:
.Use the accelerator to get to the higher
speed. Press SET–. Release SET–and the
accelerator pedal. The vehicle will now
cruise at the higher speed.
When the accelerator pedal is pressed,
ACC will not brake because it is
overridden. The ACC indicator will turn
blue on the instrument cluster and HUD,
if equipped.
.Press and hold RES+ until the desired set
speed is displayed, then release it.
.To increase vehicle speed in smaller
increments, press RES+ briefly. For each
press, the vehicle goes about 1 km/h
(1 mph) faster.
.To increase vehicle speed in larger
increments, hold RES+. While holding RES
+, the vehicle speed increases to the next
5 km/h (5 mph) step, then continues to
increase by 5 km/h (5 mph) at a time.
The set speed can also be increased while
the vehicle is stopped.
.If stopped with the brake pedal applied,
press RES+ until the desired set speed is
displayed.
.If ACC is holding the vehicle at a stop and
there is another vehicle directly ahead,
pressing RES+ will increase the set speed.
.Pressing RES+ when there is no longer a
vehicle ahead or the vehicle ahead is
pulling away and the brake is not applied
with cause the ACC to resume.
When it is determined that there is no
vehicle ahead or the vehicle ahead is beyond
the selected following gap, then the vehicle
speed will increase to the set speed.
Reducing Speed While ACC Is at a Set Speed
If ACC is already activated, do one of the
following:
.Use the brake to get to the desired lower
speed. Release the brake and press SET–.
The vehicle will now cruise at the lower
speed.
.Press and hold SET– until the desired
lower speed is reached, then release it.
.To decrease the vehicle speed in smaller
increments, press SET− briefly. For each
press, the vehicle goes about 1 km/h
(1 mph) slower.
.To decrease the vehicle speed in larger
increments, hold SET−. While holding
SET−, the vehicle speed decreases to the
next 5 km/h (5 mph) step, then continues
to decrease by 5 km/h (5 mph) at a time.
The set speed can also be decreased while
the vehicle is stopped.
.If stopped with the brake applied, press
or hold SET− until the desired set speed is
displayed.
Selecting the Follow Distance Gap
When a slower moving vehicle is detected
ahead within the selected following gap,
ACC will adjust the vehicle's speed and
attempt to maintain the follow distance gap
selected.
Press
[on the steering wheel to adjust
the following gap. Each press cycles the gap
button through three settings: Far, Medium,
or Near.
When pressed, the current gap setting
displays briefly on the instrument cluster
and HUD, if equipped. The gap setting will
be maintained until it is changed.
Since each gap setting corresponds to a
following time (Far, Medium, or Near), the
following distance will vary based on vehicle