2020 GMC SIERRA brakes

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
226 Driving and Operating
10-Speed Automatic TransmissionGear before shifting from D (Drive) to
L (Manual Mode) 10th 9th 8th 7th 6th 5th 4th 3rd 2nd 1st
Range after shifting from D (Drive) to
L (Manual Mode) - Tow/Haul not engaged L7 L7 L7 L6 L5 L4 L3 L3 L2 L1
Range after shifting from D (Drive) to
L (Manual Mode) - Tow/Haul engaged L7 L7 L6 L5 L4 L3 L3 L3 L2 L1
Grade Braking is not available when
Range Selection Mode is active.
See Tow/Haul Mode 0226.
While using Range Selection Mode,
cruise control and the Tow/Haul
Mode can be used.
If the vehicle has an exhaust brake,
it can also be used, but will not
automatically downshift the
transmission. See “Exhaust Brake”
in the Duramax diesel supplement.
Caution
Spinning the tires or holding the
vehicle in one place on a hill
using only the accelerator pedal
may damage the transmission.
The repair will not be covered by
the vehicle warranty. If the vehicle
is stuck, do not spin the tires.
When stopping on a hill, use the
brakes to hold the vehicle in
place.
Low Traction Mode
If equipped, Low Traction Mode
assists in vehicle acceleration when
road conditions are slippery, such as with ice or snow. While the
vehicle is at a stop, select L2 using
Range Selection Mode. This will
limit torque to the wheels and help
prevent the tires from spinning.
Tow/Haul Mode
The Tow/Haul Mode adjusts the
transmission shift pattern to reduce
shift cycling. This provides
increased performance, vehicle
control, and enhanced transmission
and engine cooling when driving
down steep hills or mountain
grades, when towing, or when
hauling heavy loads. See
Driver
Mode Control 0238 to activate Tow/
Haul Mode.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
232 Driving and Operating
cannot complete a shift request, it
will go back to its last chosen
setting.
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, 4m, 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
Electric Brake Boost
Vehicles equipped with electric
brake boost have hydraulic brake
circuits that are electronically
controlled when the brake pedal is
applied during normal operation.
The system performs routine tests
and turns off within a few minutes
after the vehicle is shutdown. Noise
may be heard during this time. If the
brake pedal is pressed during the
tests or when the electric brake
boost system is off, a noticeable
change in pedal force and travel
may be felt. This is normal.
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

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 233
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. SeeAntilock
Brake System (ABS) Warning Light
0 141.
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.
Electric Parking Brake
The vehicle has an Electric Parking
Brake (EPB). The EPB can always
be activated, even if the ignition is off. To prevent draining the battery,
avoid repeated cycles of the EPB
when the engine is not running.
The system has a
Yor PARK
Electric Parking Brake light, and a
8
Service Parking Brake light. See
Electric Parking Brake Light 0141
and
Service Electric Parking Brake Light
0 141. There are also parking
brake-related Driver Information
Center (DIC) messages.
Before leaving the vehicle, check for
the
Yor PARK light to ensure that
the parking brake is applied.
EPB Apply
To apply the EPB:
1. Be sure the vehicle is at a complete stop.
2. Press the EPB switch momentarily.
The
Yor PARK light will flash and
then stay on once the EPB is fully
applied. If the
Yor PARK light
flashes continuously, then the EPB

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 235
pedal pulsation, and/or pedal
movement during this time may
occur. Continue to apply the brake
pedal as the driving situation
dictates. Brake Assist disengages
when the brake pedal is released.
Hill Start Assist (HSA)
{Warning
Do not rely on the HSA feature.
HSA does not replace the need to
pay attention and drive safely.
You may not hear or feel alerts or
warnings provided by this system.
Failure to use proper care when
driving may result in injury, death,
or vehicle damage. See
Defensive Driving0187.
When the vehicle is stopped on a
grade, Hill Start Assist (HSA)
prevents the vehicle from rolling in
an unintended direction during the
transition from brake pedal release
to accelerator pedal apply. The
brakes release when the accelerator
pedal is applied. If the accelerator pedal is not applied within a few
minutes, the Electric Parking Brake
will apply. The brakes may also
release under other conditions. Do
not rely on HSA to hold the vehicle.
HSA is available when the vehicle is
facing uphill in a forward gear,
or when facing downhill in
R (Reverse). The vehicle must
come to a complete stop on a grade
for HSA to activate.
Ride Control Systems
Traction Control/
Electronic Stability
Control
System Operation
The vehicle has a Traction Control
System (TCS) and StabiliTrak/
Electronic Stability Control (ESC)
system. These systems help limit
wheel spin and assist the driver in
maintaining control, especially on
slippery road conditions.
TCS activates if it senses any of the
drive wheels are spinning or
beginning to lose traction. When this
happens, TCS applies the brakes to
the spinning wheels and reduces
engine power to limit wheel spin.
StabiliTrak/ESC activates when the
vehicle senses a difference between
the intended path and the direction
the vehicle is actually traveling.
StabiliTrak/ESC selectively applies
braking pressure to any one of the
vehicle wheel brakes to assist the
driver in keeping the vehicle on the

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 237
The button for TCS and StabiliTrak/
ESC is on the center stack.
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 lighti
displays 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
g
is 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 light
gcome
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 light
gin 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) 0308 or
Hill Start Assist (HSA) 0235.
Adding accessories can affect the
vehicle performance. See
Accessories and Modifications
0 329.
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%.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
242 Driving and Operating
Terrain ModeDrive Select Expected Vehicle Behavior Ideal Terrain
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.
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 4
m. 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 0442.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 243
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
0235. If a collision alert
occurs when cruise control is
activated, cruise control is
disengaged. See Forward Collision
Alert (FCA) System 0268. 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 Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
244 Driving and Operating
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
5
off 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 0127.
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 0127.
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 0127.
The increment value used depends
on the units displayed.