Service brake GMC SIERRA 2020 Owner's Guide

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 253
Curves in the Road
{Warning
On curves, ACC may not detect a
vehicle ahead in your lane. You
could be startled if the vehicle
accelerates up to the set speed,
especially when following a
vehicle exiting or entering exit
ramps. You could lose control of
the vehicle or crash. Do not use
ACC while driving on an entrance
or exit ramp. Always be ready to
use the brakes if necessary.
{Warning
On curves, ACC may respond to
a vehicle in another lane, or may
not have time to react to a vehicle
in your lane. You could crash into
a vehicle ahead of you, or lose
control of your vehicle. Give extra
attention in curves and be ready(Continued)
Warning (Continued)
to use the brakes if necessary.
Select an appropriate speed while
driving in curves.
ACC may operate differently in a
sharp curve. It may reduce the
vehicle speed if the curve is too
sharp.
When following a vehicle and
entering a curve, ACC may not
detect the vehicle ahead and
accelerate to the set speed. When
this happens, the vehicle ahead
indicator will not appear.
ACC may detect a vehicle that is
not in your lane and apply the
brakes.
ACC may occasionally provide an
alert and/or braking that is
considered unnecessary. It could
respond to vehicles in different
lanes or stationary objects when
entering or exiting a curve. This is
normal operation. The vehicle does
not need service.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
270 Driving and Operating
Tailgating Alert
The vehicle ahead indicator will
display amber when you are
following a vehicle ahead much too
closely.
Selecting the Alert Timing
The Collision Alert control is on the
steering wheel. Press
[to set the
FCA timing to Far, Medium, or Near.
The first button press shows the
current setting on the DIC.
Additional button presses will
change this setting. The chosen
setting will remain until it is changed
and will affect the timing of both the
Collision Alert and the Tailgating
Alert features. The timing of both
alerts will vary based on vehicle
speed. The faster the vehicle speed,
the farther away the alert will occur.
Consider traffic and weather
conditions when selecting the alert timing. The range of selectable alert
timings may not be appropriate for
all drivers and driving conditions.
If your vehicle is equipped with
Adaptive Cruise Control (ACC),
changing the FCA timing setting
automatically changes the following
gap setting (Far, Medium, or Near).
Following Distance Indicator
The following distance to a moving
vehicle ahead in your path is
indicated in following time in
seconds on the Driver Information
Center (DIC). The minimum
following time is 0.5 seconds away.
If there is no vehicle detected
ahead, or the vehicle ahead is out of
sensor range, dashes will be
displayed.
Unnecessary Alerts
FCA may provide unnecessary
alerts for turning vehicles, vehicles
in other lanes, objects that are not
vehicles, or shadows. These alerts
are normal operation and the
vehicle does not need service.
Cleaning the System
If the FCA system does not seem to
operate properly, this may correct
the issue:
.
Clean the outside of the
windshield in front of the
rearview mirror.
. Clean the entire front of the
vehicle.
. Clean the headlamps.
Automatic Emergency
Braking (AEB)
If the vehicle has Forward Collision
Alert (FCA), it also has AEB (1500
series only), which includes
Intelligent Brake Assist (IBA). When
the system detects a vehicle ahead
in your path that is traveling in the
same direction that you may be
about to crash into, it can provide a
boost to braking or automatically
brake the vehicle. This can help
avoid or lessen the severity of
crashes when driving in a forward
gear. Depending on the situation,
the vehicle may automatically brake

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
272 Driving and Operating
{Warning
IBA may increase vehicle braking
in situations when it may not be
necessary. You could block the
flow of traffic. If this occurs, take
your foot off the brake pedal and
then apply the brakes as needed.
AEB and IBA can be disabled. See
“Collision/Detection Systems” under
Vehicle Personalization 0157.
{Warning
Using AEB or IBA while towing a
trailer could cause you to lose
control of the vehicle and crash.
Turn the system to Alert or Off
when towing a trailer.
A system unavailable message may
display if:
. The front of the vehicle or
windshield is not clean.
. Heavy rain or snow is interfering
with object detection. .
There is a problem with the
StabiliTrak/Electronic Stability
Control (ESC) system.
The AEB system does not need
service.
Front Pedestrian Braking
(FPB) System (1500
Series)
If equipped, the FPB system may
help avoid or reduce the harm
caused by front-end crashes with
nearby pedestrians when driving in
a forward gear. FPB displays an
amber indicator,
~, when a nearby
pedestrian is detected ahead. When
approaching a detected pedestrian
too quickly, FPB provides a red
flashing alert on the windshield and
rapidly beeps or pulses the driver
seat. FPB can provide a boost to
braking or automatically brake the
vehicle. This system includes
Intelligent Brake Assist (IBA), and
the Automatic Emergency Braking
(AEB) system may also respond to
pedestrians. See Automatic
Emergency Braking (AEB) 0270. The FPB system can detect and
alert to pedestrians in a forward
gear at speeds between 8 km/h
(5 mph) and 80 km/h (50 mph).
During daytime driving, the system
detects pedestrians up to a distance
of approximately 40 m (131 ft).
During nighttime driving, system
performance is very limited.
{Warning
FPB does not provide an alert or
automatically brake the vehicle,
unless it detects a pedestrian.
FPB may not detect pedestrians,
including children:
. When the pedestrian is not
directly ahead, fully visible,
or standing upright, or when
part of a group.
. Due to poor visibility,
including nighttime
conditions, fog, rain,
or snow.
. If the FPB sensor is blocked
by dirt, snow, or ice.
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
274 Driving and Operating
of the accelerator pedal will also
release Automatic Braking and
the EPB.
{Warning
FPB may alert or automatically
brake the vehicle suddenly in
situations where it is unexpected
and undesired. It could falsely
alert or brake for objects similar in
shape or size to pedestrians,
including shadows. This is normal
operation and the vehicle does
not need service. To override
Automatic Braking, firmly press
the accelerator pedal, if it is safe
to do so.
Automatic Braking can be disabled
through vehicle personalization. See
“Front Pedestrian Detection” in
“Collision/Detection Systems” under
Vehicle Personalization 0157.
{Warning
Using the Front Pedestrian
Braking system while towing a
trailer could cause you to lose
control of the vehicle and crash.
Turn the system to Alert or Off
when towing a trailer.
Cleaning the System
If FPB does not seem to operate
properly, cleaning the outside of the
windshield in front of the rearview
mirror may correct the issue.
Side Blind Zone
Alert (SBZA)
If equipped, the SBZA system is a
lane-changing aid that assists
drivers with avoiding crashes that
occur with moving vehicles in the
side blind zone (or spot) areas.
When the vehicle is in a forward
gear, the left or right side mirror
display will light up if a moving
vehicle is detected in that blind
zone. If the turn signal is activated and a vehicle is also detected on
the same side, the display will flash
as an extra warning not to change
lanes. Since this system is part of
the Lane Change Alert (LCA)
system, read the entire LCA section
before using this feature.
Lane Change Alert (LCA)
If equipped, the LCA system is a
lane-changing aid that assists
drivers with avoiding lane change
crashes that occur with moving
vehicles in the side blind zone (or
spot) areas or with vehicles rapidly
approaching these areas from
behind. The LCA warning display
will light up in the corresponding
outside side mirror and will flash if
the turn signal is on.
{Warning
LCA does not alert the driver to
vehicles outside of the system
detection zones, pedestrians,
bicyclists, or animals. It may not
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
292 Driving and Operating
the drive mode that is
appropriate for the road
conditions.
Caution
If the vehicle tires begin to spin
and the vehicle begins to slide
toward the water, remove your
foot from the accelerator pedal
and apply the brake pedal. Seek
help to have the vehicle towed up
the ramp.
Maintenance when Trailer
Towing
The vehicle needs service more
often when used to tow trailers. See
Maintenance Schedule0442. It is
especially important to check the
engine oil, axle lubricant, belts,
cooling system, and brake system
before and during each trip.
Check periodically to see that all
nuts and bolts on the trailer hitch
are tight.
Engine Cooling When Trailer
Towing
The cooling system may temporarily
overheat during severe operating
conditions. See Engine Overheating
0 351.
Trailer Towing
If equipped with a diesel engine,
see the Duramax diesel
supplement.
Caution
Towing a trailer improperly can
damage the vehicle and result in
costly repairs not covered by the
vehicle warranty. To tow a trailer
correctly, follow the directions in
this section and see your dealer
for important information about
towing a trailer with the vehicle.
Trailering is different than just
driving the vehicle by itself.
Trailering means changes in
handling, acceleration, braking,
durability, and fuel economy. Successful, safe trailering takes
correct equipment, and it has to be
used properly.
The following information has many
time-tested, important trailering tips
and safety rules. Many of these are
important for your safety and that of
your passengers. Read this section
carefully before pulling a trailer.
Trailer Weight
{Warning
Never exceed the towing capacity
for your vehicle.
Safe trailering requires monitoring
the weight, speed, altitude, road
grades, outside temperature, and
how frequently the vehicle is used to
tow a trailer.
Trailer Weight Ratings
When towing a trailer, the combined
weight of the vehicle, vehicle
contents, trailer, and trailer contents

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
306 Driving and Operating
Trailer Brake DIC Display Page
The ITBC display page indicates:
.Trailer Gain setting
. Output to the trailer brakes
. Trailer connection
. System operational status
To display:
. Scroll through the DIC menu
pages
. Press a Trailer Gain (+) or (−)
button
. Activate the Manual Trailer
Brake Apply Lever
TRAILER GAIN: Press a Trailer
Gain button to recall the current
Trailer Gain setting. Each press and
release of the gain buttons will then
change the Trailer Gain setting.
Press the Trailer Gain (+) or (-) to
adjust. Press and hold to
continuously adjust the Trailer Gain.
To turn the output to the trailer off,
adjust the Trailer Gain setting to 0.0.
This setting can be adjusted from
0.0 to 10.0 with a trailer connected
or disconnected. TRAILER OUTPUT: This displays
anytime a trailer with electric brakes
is connected. Output to the trailer
brakes is based on the amount of
vehicle braking present and relative
to the Trailer Gain setting. Output is
displayed from 0 to 100% for each
gain setting.
The Trailer Output will indicate
“- - -
- - -” on the Trailer Brake Display
Page whenever the following occur:
. No trailer is connected.
. A trailer without electric brakes
is connected. No DIC message
displays.
. A trailer with electric brakes has
become disconnected.
A CHECK TRAILER WIRING
message displays on the DIC.
. There is a fault present in the
wiring to the trailer brakes.
A CHECK TRAILER WIRING
message displays on the DIC.
. The ITBC system is not working
due to a fault. A SERVICE
TRAILER BRAKE SYSTEM
message displays in the DIC.
Manual Trailer Brake Apply
Lever
Slide this lever right to apply the
trailer ’s electric brakes independent
of the vehicle’s brakes. Use this
lever to adjust the Trailer Gain to
achieve proper power output to the
trailer brakes. Under certain
circumstances, this lever can also
be used to apply additional trailer
braking. The trailer and vehicle
brake lamps will come on when
either the vehicle brakes or trailer
brakes are applied and properly
connected.
Trailer Gain Adjustment
Procedure
Trailer Gain should be set for a
specific trailering condition and it
must be readjusted anytime vehicle
loading, trailer loading, or road
surface conditions change.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
308 Driving and Operating
To determine whether the electrical
fault is on the vehicle side or trailer
side of the trailer wiring harness
connection:1. Disconnect the trailer wiring harness from the vehicle.
2. Turn the ignition off.
3. Wait 10 seconds, then turn the ignition back to RUN.
4. If the CHECK TRAILER WIRING message reappears,
the electrical fault is on the
vehicle side.
If the CHECK TRAILER WIRING
message only reappears when
connecting the trailer wiring harness
to the vehicle, the electrical fault is
on the trailer side.
SERVICE TRAILER BRAKE
SYSTEM: This message will display
when there is a problem with the
ITBC system. If this message
continues over multiple ignition
cycles, have the vehicle serviced.
If either the CHECK TRAILER
WIRING or SERVICE TRAILER
BRAKE SYSTEM message displays while driving, the ITBC system may
not be fully functional or may not
function at all. When traffic
conditions allow, carefully pull the
vehicle over to the side of the road
and turn the ignition off. Check the
wiring connection to the trailer and
turn the ignition back on. If either of
these messages continues, either
the vehicle or trailer needs service.
A GM dealer may be able to
diagnose and repair problems with
the trailer. However, any diagnosis
and repair of the trailer is not
covered under the vehicle warranty.
Contact your trailer dealer for
assistance with trailer repairs and
trailer warranty information.
Trailer Sway
Control (TSC)
Vehicles with StabiliTrak/Electronic
Stability Control (ESC) have a
Trailer Sway Control (TSC) feature.
Trailer sway is unintended
side-to-side motion of a trailer while
towing. If the vehicle is towing a
trailer and the TSC detects that
sway is increasing, the vehiclebrakes are selectively applied at
each wheel, to help reduce
excessive trailer sway. If equipped
with the Integrated Trailer Brake
Control (ITBC) system, and the
trailer has an electric brake system,
StabiliTrak/ESC may also apply the
trailer brakes.If TSC is enabled, the Traction
Control System (TCS)/StabiliTrak/
ESC warning light will flash on the
instrument cluster. Reduce vehicle
speed by gradually removing your
foot from the accelerator. If trailer
sway continues, StabiliTrak/ESC
can reduce engine torque to help

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
312 Driving and Operating
3. Touch IMPORT.
A pop-up will indicate the import
was successful. Touch OK to return
to the trailer list and select the trailer
profile. The Tow/Haul Mode
reminder, Brake Gain Setting and
Trailer Tire Pressure sensor
learning, if equipped, do not import.
Trailer Feature Setup
Tow/Haul Mode Reminder
To turn the Tow/Haul Mode
Reminder setting on, touch Yes. To
turn it off, touch No.
Trailer Tire Pressure Setup
If the Trailer Tire Pressure
Monitoring System (TTPMS) is
detected, touch the Tire Pressure
Monitoring icon to set up tire
pressure monitoring.Touch Yes to
set up the sensors or touch No to
return to the previous screen.
A trailer must be electrically
connected to the vehicle before
starting the sensor-to-vehicle learn
process. After selecting Start from the Learn
Sensors screen, use the Tool
Method or the Manual Method
(described below) to learn each tire
sensor, during which the current tire
number will be highlighted.
Each sensor has a minimum of
two minutes to learn, shown by a
timer. After a sensor is learned, a
checkmark appears next to the tire,
the vehicle horn will sound, the
vehicle’s brake lamps will flash, and
all working trailer lamps will flash.
It then moves to the next sensor.
To cancel the process touch Stop.
The recommended tire pressure
must be entered for the trailer tires.
This allows the vehicle to alert when
the tire pressure is high or low.
TTPMS must learn the location of
the installed tire sensors to show
correct air pressure and
temperature for each tire. To set up,
use one of the following options or
see a tire or trailer dealer for
service. The learning process must
be repeated when the trailer tires
are rotated or replaced. See
“Editinga Trailer Profile”
later in this section
for tire pressure sensor relearn
information.
Tool Method: A TTPMS activation
tool can be purchased separately to
learn the sensor locations.
Manual Method: Without the tool,
the air pressure can be increased or
decreased in each tire for
10 seconds. Do not exceed the
maximum inflation pressure found
on the tire sidewalls. Make sure to
re-adjust tire pressure to the
recommended level when the
process is complete.
Sensor Learning Steps
To complete the sensor-to-vehicle
learn process:
1. Touch Start on the Learn Sensors screen. The horn
chirps twice and the Learning
Active screen appears on the
infotainment display.
2. Start with the driver side front trailer tire.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
Vehicle Care 327
Vehicle Care
General Information
General Information . . . . . . . . . . 328
California Proposition65 Warning . . . . . . . . . . . . . . . . . 329
California Perchlorate Materials Requirements . . . . . 329
Accessories and Modifications . . . . . . . . . . . . . . . . 329
Vehicle Checks
Doing Your OwnService Work . . . . . . . . . . . . . . . 330
Hood . . . . . . . . . . . . . . . . . . . . . . . . . 330
Engine Compartment Overview . . . . . . . . . . . . . . . . . . . . 332
Engine Oil . . . . . . . . . . . . . . . . . . . . 339
Engine Oil Life System . . . . . . . 341
Automatic Transmission Fluid . . . . . . . . . . . . . . . . . . . . . . . . 343
Engine Air Filter Life System . . . . . . . . . . . . . . . . . . . . . . 343
Engine Air Cleaner/Filter . . . . . . 344
Cooling System . . . . . . . . . . . . . . 346
Engine Overheating . . . . . . . . . . 351
Overheated Engine Protection Operating Mode . . . . . . . . . . . . . 352
Engine Fan . . . . . . . . . . . . . . . . . . . 353 Power Steering Fluid . . . . . . . . . 354
Washer Fluid . . . . . . . . . . . . . . . . . 354
Brakes . . . . . . . . . . . . . . . . . . . . . . . 355
Brake Pad Life System . . . . . . . 356
Brake Fluid . . . . . . . . . . . . . . . . . . . 357
Battery - North America . . . . . . 358
Four-Wheel Drive . . . . . . . . . . . . . 361
Front Axle . . . . . . . . . . . . . . . . . . . . 361
Rear Axle . . . . . . . . . . . . . . . . . . . . 362
Noise Control System . . . . . . . . 362
Starter Switch Check . . . . . . . . . 363
Automatic Transmission Shift
Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . . . 363
Ignition Transmission Lock Check . . . . . . . . . . . . . . . . . . . . . . . 363
Park Brake and P (Park) Mechanism Check . . . . . . . . . . 364
Wiper Blade Replacement . . . . 364
Windshield Replacement . . . . . 365
Gas Strut(s) . . . . . . . . . . . . . . . . . . 365
Headlamp Aiming
Headlamp Aiming . . . . . . . . . . . . 366
Bulb Replacement
Bulb Replacement . . . . . . . . . . . . 367
Halogen Bulbs . . . . . . . . . . . . . . . . 367
LED Lighting . . . . . . . . . . . . . . . . . 367 Headlamps, Front Turn Signal,
Sidemarker, and Parking
Lamps . . . . . . . . . . . . . . . . . . . . . . 367
Taillamps, Turn Signal, Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . . . 368
Center High-Mounted Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . . . 369
License Plate Lamp . . . . . . . . . . 369
Electrical System
Electrical System Overload . . . 370
Fuses and Circuit Breakers . . . 370
Engine Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . . . . 371
Instrument Panel Fuse
Block (Left) . . . . . . . . . . . . . . . . . 374
Instrument Panel Fuse Block (Right) . . . . . . . . . . . . . . . . . . . . . . 376
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . 379
All-Season Tires . . . . . . . . . . . . . . 379
Winter Tires . . . . . . . . . . . . . . . . . . 380
Low-Profile Tires . . . . . . . . . . . . . 380
All-Terrain Tires . . . . . . . . . . . . . . . 381
Tire Sidewall Labeling . . . . . . . . 381
Tire Designations . . . . . . . . . . . . . 383
Tire Terminology andDefinitions . . . . . . . . . . . . . . . . . . 385

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
Vehicle Care 329
California Proposition
65 Warning
{Warning
Most motor vehicles, including
this one, as well as many of its
service parts and fluids, contain
and/or emit chemicals known to
the State of California to cause
cancer and birth defects or other
reproductive harm. Engine
exhaust, many parts and
systems, many fluids, and some
component wear by-products
contain and/or emit these
chemicals. For more information
go to www.P65Warnings.ca.gov/
passenger-vehicle.
See Battery - North America 0358
and
Jump Starting - North America
0 419 and the back cover.
California Perchlorate
Materials Requirements
Certain types of automotive
applications, such as airbag
initiators, seat belt pretensioners,
and lithium batteries contained in
electronic keys, may contain
perchlorate materials. Perchlorate
Material –special handling may
apply. See www.dtsc.ca.gov/
hazardouswaste/perchlorate.
Accessories and
Modifications
Adding non-dealer accessories or
making modifications to the vehicle
can affect vehicle performance and
safety, including such things as
airbags, braking, stability, ride and
handling, emissions systems,
aerodynamics, durability, and
electronic systems like antilock
brakes, traction control, and stability
control. These accessories or
modifications could even cause
malfunction or damage not covered
by the vehicle warranty. Damage to suspension components
caused by modifying vehicle height
outside of factory settings will not be
covered by the vehicle warranty.
Damage to vehicle components
resulting from modifications or the
installation or use of non-GM
certified parts, including control
module or software modifications, is
not covered under the terms of the
vehicle warranty and may affect
remaining warranty coverage for
affected parts.
GM Accessories are designed to
complement and function with other
systems on the vehicle. See your
dealer to accessorize the vehicle
using genuine GM Accessories
installed by a dealer technician.
Also, see
Adding Equipment to the
Airbag-Equipped Vehicle 083.