warning GMC SIERRA 2021 Service Manual

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 75
Forward-Facing Child Restraint
A forward-facing child restraint provides
restraint for the child's body with the
harness.Booster Seats
A belt-positioning booster seat is used for
children who have outgrown their
forward-facing child restraint. Boosters are
designed to improve the fit of the vehicle's
seat belt system until the child is large
enough for the vehicle seat belts to fit
properly without a booster seat. See the
seat belt fit test in Older Children071.
Securing an Add-On Child Restraint in
the Vehicle
{Warning
A child can be seriously injured or killed
in a crash if the child restraint is not
properly secured in the vehicle. Secure
the child restraint properly in the vehicle
using the vehicle seat belt or LATCH
system, following the instructions that
came with that child restraint and the
instructions in this manual.
To help reduce the chance of injury, the
child restraint must be secured in the
vehicle. Child restraints must be secured in
vehicle seats by lap belts or the lap belt
portion of a lap-shoulder belt, or by the
LATCH system. See Lower Anchors and
Tethers for Children (LATCH System) 077 for
more information. Children can be
endangered in a crash if the child restraint is
not properly secured in the vehicle.
When securing an add-on child restraint,
refer to the following:
1. Instruction labels provided on the child restraint

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
76 Seats and Restraints
2. Instruction manual provided with thechild restraint
3. This vehicle owner's manual
The child restraint instructions are
important, so if they are not available,
obtain a replacement copy from the
manufacturer.
Keep in mind that an unsecured child
restraint can move around in a collision or
sudden stop and injure people in the vehicle.
Be sure to properly secure any child
restraint in the vehicle —even when no
child is in it.
In some areas Certified Child Passenger
Safety Technicians (CPSTs) are available to
inspect and demonstrate how to correctly
use and install child restraints. In the U.S.,
refer to the National Highway Traffic Safety
Administration (NHTSA) website to locate
the nearest child safety seat inspection
station. For CPST availability in Canada,
check with Transport Canada or the
Provincial Ministry of Transportation office.Securing the Child Within the Child
Restraint
{Warning
A child can be seriously injured or killed
in a crash if the child is not properly
secured in the child restraint. Secure the
child properly following the instructions
that came with that child restraint.
Where to Put the Restraint
According to accident statistics, children and
infants are safer when properly restrained in
an appropriate child restraint secured in a
rear seating position.
Whenever possible, children aged 12 and
under should be secured in a rear seating
position.
Never put a rear-facing child restraint in the
front. This is because the risk to the
rear-facing child is so great if the airbag
deploys.
{Warning
A child in a rear-facing child restraint can
be seriously injured or killed if the front
passenger airbag inflates. This is because
the back of the rear-facing child restraint
would be very close to the inflating
airbag. A child in a forward-facing child
restraint can be seriously injured or killed
if the front passenger airbag inflates and
the passenger seat is in a forward
position.
Even if the passenger sensing system has
turned off the front passenger frontal
airbag, no system is fail-safe. No one can
guarantee that an airbag will not deploy
under some unusual circumstance, even
though it is turned off.
Secure rear-facing child restraints in a
rear seat, even if the airbag is off. If you
secure a forward-facing child restraint in
the front seat, always move the front
passenger seat as far back as it will go.
It is better to secure the child restraint in
a rear seat.
See Passenger Sensing System 066 for
additional information.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 77
{Warning
A child in a child restraint in the center
front seat can be badly injured or killed
by the frontal airbags if they inflate.
Never secure a child restraint in the
center front seat. It is always better to
secure a child restraint in a rear seat.
Do not use child restraints in the center
front seat position.
If the vehicle does not have a rear seat that
will accommodate a rear-facing child
restraint, a rear-facing child restraint should
not be installed in the vehicle, even if the
airbag is off.
When securing a child restraint with the
seat belts in a rear seat position, study the
instructions that came with the child
restraint to make sure it is compatible with
this vehicle.
Child restraints and booster seats vary
considerably in size, and some may fit in
certain seating positions better than others.
Do not install a child restraint in any rear
seating position where it cannot be installed
securely. Depending on where you place the child
restraint and the size of the child restraint,
you may not be able to access adjacent seat
belts or LATCH anchors for additional
passengers or child restraints. Adjacent
seating positions should not be used if the
child restraint prevents access to or
interferes with the routing of the seat belt.
The seat in front of an installed child
restraint should be adjusted to ensure
proper installation according to the child
restraint manual.
Wherever a child restraint is installed, be
sure to follow the instructions that came
with the child restraint and secure the child
restraint properly.
Keep in mind that an unsecured child
restraint can move around in a collision or
sudden stop and injure people in the vehicle.
Be sure to properly secure any child
restraint in the vehicle
—even when no
child is in it.
Lower Anchors and Tethers for
Children (LATCH System)
The LATCH system secures a child restraint
during driving or in a crash. LATCH
attachments on the child restraint are used
to attach the child restraint to the anchors
in the vehicle. This system is designed to
make installation of a child restraint easier.
In order to use the LATCH system in your
vehicle, you need a child restraint that has
LATCH attachments. LATCH-compatible
rear-facing and forward-facing child seats can
be properly installed using either the LATCH
anchors or the vehicle’s seat belts. Do not
use both the seat belts and the LATCH
anchorage system to secure a rear-facing or
forward-facing child seat.
Booster seats use the vehicle’s seat belts to
secure the child and the booster seat. If the
manufacturer recommends that the booster
seat be secured with the LATCH system, this
can be done as long as the booster seat can
be positioned properly and there is no
interference with the proper positioning of
the lap-shoulder belt on the child.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 83
According to accident statistics, children and
infants are safer when properly restrained in
a child restraint system or infant restraint
system secured in a rear seating position.
SeeWhere to Put the Restraint 076 for
additional information.
Securing a Child Restraint Designed for
the LATCH System
{Warning
A child could be seriously injured or killed
in a crash if the child restraint is not
properly attached to the vehicle using
either the LATCH anchors or the vehicle
seat belt. Follow the instructions that
came with the child restraint and the
instructions in this manual.
{Warning
Do not attach more than one child
restraint to a single anchor, except for
the center top tether anchors in the crew
cab models. Attaching more than one
child restraint to a single anchor could
cause the anchor or attachment to come
loose or even break during a crash.
(Continued)
Warning (Continued)
A child or others could be injured. To
reduce the risk of serious or fatal injuries
during a crash, attach only one child
restraint per anchor.
{Warning
Children can be seriously injured or
strangled if a shoulder belt is wrapped
around their neck. The shoulder belt can
tighten but cannot be loosened if it is
locked. The shoulder belt locks when it is
pulled all the way out of the retractor.
It unlocks when the shoulder belt is
allowed to go all the way back into the
retractor, but it cannot do this if it is
wrapped around a child’s neck. If the
shoulder belt is locked and tightened
around a child’s neck, the only way to
loosen the belt is to cut it.
Buckle any unused seat belts behind the
child restraint so children cannot reach
them. Pull the shoulder belt all the way
out of the retractor to set the lock, and(Continued)
Warning (Continued)
tighten the belt behind the child restraint
after the child restraint has been
installed.
Caution
Do not let the LATCH attachments rub
against the vehicle’s seat belts. This may
damage these parts. If necessary, move
buckled seat belts to avoid rubbing the
LATCH attachments.
Do not fold the rear seat cushion when
the seat is occupied. Do not fold the
empty rear seat with a seat belt buckled.
This could damage the seat belt or the
seat. Unbuckle and return the seat belt to
its stowed position, before folding
the seat.
If you need to secure more than one child
restraint in the rear seat, see Where to Put
the Restraint 076.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
88 Seats and Restraints
{Warning
With head restraints that are not
installed and adjusted properly, there is a
greater chance that occupants will suffer
a neck/spinal injury in a crash. Do not
drive until the head restraints for all
occupants are installed and adjusted
properly.
To reinstall the head restraint or headrest:
1. Insert the head restraint or headrest posts into the holes in the top of the
seatback. The notches on the posts must
face the driver side of the vehicle. 2. Push the head restraint or
headrest down.
3. Try to move the head restraint or headrest to make sure that it is locked in
place.
Replacing LATCH System Parts
After a Crash
{Warning
A crash can damage the LATCH system in
the vehicle. A damaged LATCH system
may not properly secure the child
restraint, resulting in serious injury or
even death in a crash. To help make sure
the LATCH system is working properly
after a crash, see your dealer to have the
system inspected and any necessary
replacements made as soon as possible.
If the vehicle has the LATCH system and it
was being used during a crash, new LATCH
system parts may be needed.
New parts and repairs may be necessary
even if the LATCH system was not being
used at the time of the crash.
Securing Child Restraints (With
the Seat Belt in the Rear Seat)
When securing a child restraint with the
seat belts in a rear seat position, study the
instructions that came with the child
restraint to make sure it is compatible with
this vehicle.
If the child restraint has the LATCH system,
see Lower Anchors and Tethers for Children
(LATCH System) 077 for how and where to
install the child restraint using LATCH. If a
child restraint is secured in the vehicle using
a seat belt and it uses a top tether, see
Lower Anchors and Tethers for Children
(LATCH System) 077 for top tether anchor
locations.
Do not secure a child seat in a position
without a top tether anchor if a national or
local law requires that the top tether be
anchored, or if the instructions that come
with the child restraint say that the top
tether must be anchored.
In Canada, the law requires that
forward-facing child restraints have a top
tether, and that the tether be attached.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
92 Seats and Restraints
Securing Child Restraints (With
the Seat Belt in the Center
Front Seat)
{Warning
A child in a child restraint in the center
front seat can be badly injured or killed
by the frontal airbags if they inflate.
Never secure a child restraint in the
center front seat. It is always better to
secure a child restraint in a rear seat.
Do not use child restraints in the center
front seat position.
Securing Child Restraints (With
the Seat Belt in the Front
Passenger Seat)
This vehicle has airbags. A rear seat is a
safer place to secure a forward-facing child
restraint. See Where to Put the Restraint
0 76. In addition, the vehicle has a passenger
sensing system which is designed to turn off
the front outboard passenger frontal airbag
under certain conditions. See
Passenger
Sensing System 066 and
Passenger Airbag Status Indicator 0114 for
more information, including important
safety information.
Never put a rear-facing child restraint in the
front. This is because the risk to the
rear-facing child is so great, if the airbag
deploys.
{Warning
A child in a rear-facing child restraint can
be seriously injured or killed if the front
outboard passenger frontal airbag
inflates. This is because the back of the
rear-facing child restraint would be very
close to the inflating airbag. A child in a
forward-facing child restraint can be
seriously injured or killed if the front
outboard passenger frontal airbag inflates
and the passenger seat is in a forward
position.
(Continued)
Warning (Continued)
Even if the passenger sensing system has
turned off the front outboard passenger
frontal airbag, no system is fail-safe. No
one can guarantee that an airbag will not
deploy under some unusual circumstance,
even though it is turned off.
Secure rear-facing child restraints in a
rear seat, even if the airbag is off. If you
secure a forward-facing child restraint in
the front outboard passenger seat,
always move the seat as far back as it
will go. It is better to secure the child
restraint in a rear seat.
SeePassenger Sensing System 066 for
additional information.
If the vehicle does not have a rear seat that
will accommodate a rear-facing child
restraint, a rear-facing child restraint should
not be installed in the vehicle, even if the
airbag is off.
If the child restraint uses a top tether, see
Lower Anchors and Tethers for Children
(LATCH System) 077 for top tether anchor
locations.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Storage 95
Storage
Storage Compartments
Storage Compartments . . . . . . . . . . . . . . . . . 95
Glove Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Cupholders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Underseat Storage . . . . . . . . . . . . . . . . . . . . . 96
Rear Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Center Console Storage . . . . . . . . . . . . . . . . 96
Floor Console Storage . . . . . . . . . . . . . . . . . . 97
Additional Storage Features
Cargo Tie-Downs . . . . . . . . . . . . . . . . . . . . . . . 97
Storage Compartments{
Warning
Do not store heavy or sharp objects in
storage compartments. In a crash, these
objects may cause the cover to open and
could result in injury.
Glove Box
To access the upper glove box, pull up on
the handle.
To access the lower glove box, unlock with
the key and pull down on the handle.
Cupholders
Front
There may be cupholders on the center
front seat console armrest.
Rear
If equipped, pull the rear seat armrest down
to access the cupholders.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Instruments and Controls 99
Instruments and Controls
Controls
Steering Wheel Adjustment . . . . . . . . . . . 100
Steering Wheel Controls . . . . . . . . . . . . . . 100
Heated Steering Wheel . . . . . . . . . . . . . . . . 100
Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Windshield Wiper/Washer . . . . . . . . . . . . . 101
Compass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Power Outlets . . . . . . . . . . . . . . . . . . . . . . . . . 102
Wireless Charging . . . . . . . . . . . . . . . . . . . . . 103
Warning Lights, Gauges, and Indicators
Warning Lights, Gauges, andIndicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Instrument Cluster . . . . . . . . . . . . . . . . . . . . 106
Speedometer . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Odometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Trip Odometer . . . . . . . . . . . . . . . . . . . . . . . . . 110
Tachometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Fuel Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Engine Oil Pressure Gauge . . . . . . . . . . . . . 111
Engine Coolant Temperature Gauge . . . . 112
Voltmeter Gauge . . . . . . . . . . . . . . . . . . . . . . . 113
Seat Belt Reminders . . . . . . . . . . . . . . . . . . . . 113
Airbag Readiness Light . . . . . . . . . . . . . . . . . 114
Passenger Airbag Status Indicator . . . . . . 114
Charging System Light . . . . . . . . . . . . . . . . . 115 Malfunction Indicator Lamp (Check
Engine Light) . . . . . . . . . . . . . . . . . . . . . . . . . 115
Brake System Warning Light . . . . . . . . . . . 117
Electric Parking Brake Light . . . . . . . . . . . . 117
Service Electric Parking Brake Light . . . . 118
Antilock Brake System (ABS) Warning Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Four-Wheel-Drive Light . . . . . . . . . . . . . . . . . 118
Tow/Haul Mode Light . . . . . . . . . . . . . . . . . 119
Hill Descent Control Light . . . . . . . . . . . . . . 119
Lane Keep Assist (LKA) Light . . . . . . . . . . . 119
Vehicle Ahead Indicator . . . . . . . . . . . . . . . . 119
Pedestrian Ahead Indicator . . . . . . . . . . . . 119
Traction Off Light . . . . . . . . . . . . . . . . . . . . . . 120
Traction Control System (TCS)/Electronic Stability Control Light . . . . . . . . . . . . . . . 120
Electronic Stability Control (ESC) Off Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Engine Coolant Temperature Warning Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Driver Mode Control Light . . . . . . . . . . . . . 121
Tire Pressure Light . . . . . . . . . . . . . . . . . . . . . 122
Engine Oil Pressure Light (Uplevel Cluster) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Low Fuel Warning Light . . . . . . . . . . . . . . . . 122
Security Light . . . . . . . . . . . . . . . . . . . . . . . . . . 122
High-Beam On Light . . . . . . . . . . . . . . . . . . . 123
Front Fog Lamp Light . . . . . . . . . . . . . . . . . . 123
Lamps On Reminder . . . . . . . . . . . . . . . . . . . 123
Cruise Control Light . . . . . . . . . . . . . . . . . . . . 123 Door Ajar Light . . . . . . . . . . . . . . . . . . . . . . . . 124
Information Displays
Driver Information Center (DIC) (Base
Level) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Driver Information Center (DIC) (Midlevel and Uplevel) . . . . . . . . . . . . . . . 125
Head-Up Display (HUD) . . . . . . . . . . . . . . . . 128
Vehicle Messages
Vehicle Messages . . . . . . . . . . . . . . . . . . . . . . 130
Engine Power Messages . . . . . . . . . . . . . . . . 131
Vehicle Speed Messages . . . . . . . . . . . . . . . 131
Vehicle Personalization
Vehicle Personalization . . . . . . . . . . . . . . . . . 131
Universal Remote System
Universal Remote System . . . . . . . . . . . . . 136
Universal Remote System Programming . . . . . . . . . . . . . . . . . . . . . . . . 136
Universal Remote System Operation . . . 138

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Instruments and Controls 101
seats when it is cold outside. The heated
steering wheel indicator light may not
come on.
SeeHeated and Ventilated Front Seats 052.
Horn
To sound the horn, pressaon the
steering wheel.
Windshield Wiper/Washer
The windshield wiper control is on the turn
signal lever.
The windshield wipers are controlled by
turning the band with
Non it.
With the ignition on or in ACC/ACCESSORY,
turn the
Nband to select the wiper speed.
HI : Use for fast wipes. LO :
Use for slow wipes.
3:Turn the band up for more frequent
intermittent wipes or down for less frequent
intermittent wipes.
OFF : Use to turn the wipers off.
1x : For a single wipe, briefly turn the
N
band down. For several wipes, hold the
band down.
L:PressLon the windshield wiper
control to spray windshield washer fluid and
activate the wipers. The wipers will continue
until
Lis released or the maximum wash
time is reached. When
Lis released,
additional wipes may occur depending on
how long the windshield washer had been
activated. See Washer Fluid0340 for
information on filling the windshield washer
fluid reservoir.
Clear snow and ice from the wiper blades
before using them. If frozen to the
windshield, carefully loosen or thaw them.
Damaged blades should be replaced. See
Wiper Blade Replacement 0348.
Heavy snow or ice can overload the wiper
motor.
{Warning
In freezing weather, do not use the
washer until the windshield is warmed.
Otherwise the washer fluid can form ice
on the windshield, blocking your vision.
{Warning
Before driving the vehicle, always clear
snow and ice from the hood, windshield,
roof, and rear of the vehicle, including all
lamps and windows. Reduced visibility
from snow and ice buildup could lead to
a crash.
Wipe Parking
If the ignition is turned off while the wipers
are on LO, HI, or
3, they will
immediately stop.
If the windshield wiper control is ON then
moved to OFF before the driver door is
opened or within 10 minutes, the wipers will
restart and move to the base of the
windshield.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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102 Instruments and Controls
If the ignition is turned off while the wipers
are performing wipes due to windshield
washing, the wipers continue to run until
they reach the base of the windshield.
Compass
The vehicle may have a compass display on
the Driver Information Center (DIC). The
compass receives its heading and other
information from the Global Positioning
System (GPS) antenna, Electronic Stability
Control (ESC), and vehicle speed information.
The compass system is designed to operate
for a certain number of miles or degrees of
turn before needing a signal from the GPS
satellites. When the compass display shows
CAL, drive the vehicle for a short distance in
an open area where it can receive a GPS
signal. The compass system will
automatically determine when a GPS signal
is restored and provide a heading again.
Clock
Set the time and date using the
infotainment system. See "Time / Date"
underSettings 0186.
Power Outlets
Accessory power outlets can be used to plug
in electrical equipment, such as a cell phone
or MP3 player.
Rear of Front Center Console
The vehicle has one accessory power outlet
under the climate control system and one
accessory power outlet on the rear of the
center console, if equipped, or on the rear of
the bench seat, if equipped.
Lift the cover to access and replace when
not in use.
{Warning
Power is always supplied to the outlets.
Do not leave electrical equipment
plugged in when the vehicle is not in use
because the vehicle could catch fire and
cause injury or death.
Caution
Leaving electrical equipment plugged in
for an extended period of time while the
vehicle is off will drain the battery.
Always unplug electrical equipment when
not in use and do not plug in equipment
that exceeds the maximum 15 amp
rating.
Certain power accessory plugs may not be
compatible with the accessory power outlet
and could overload vehicle or adapter fuses.
If a problem is experienced, see your dealer.
When adding electrical equipment, be sure
to follow the proper installation instructions
included with the equipment. See Add-On
Electrical Equipment 0318.