index GMC SIERRA 2021 Owner's Manual

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 2/18/21
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Keys, Doors, and Windows . . . . . . . . . . . . . . . 7
Seats and Restraints . . . . . . . . . . . . . . . . . . . . . 45
Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Instruments and Controls . . . . . . . . . . . . . . . 99
Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Infotainment System . . . . . . . . . . . . . . . . . . . 148
Climate Controls . . . . . . . . . . . . . . . . . . . . . . . 204
Driving and Operating . . . . . . . . . . . . . . . . . . 211
Vehicle Care . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
Service and Maintenance . . . . . . . . . . . . . . 408
Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . 423
Customer Information . . . . . . . . . . . . . . . . . . 428
Reporting Safety Defects . . . . . . . . . . . . . . . 436
OnStar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440
Connected Services . . . . . . . . . . . . . . . . . . . . . 445
Index . . . . . . . . . . . . . . . . . . . . . . . . . . 448
Introduction
The names, logos, emblems, slogans, vehicle
model names, and vehicle body designs
appearing in this manual including, but not
limited to, GM, the GM logo, GMC, the GMC
Truck Emblem, SIERRA, and DENALI are
trademarks and/or service marks of General
Motors LLC, its subsidiaries, affiliates,
or licensors.
For vehicles first sold in Canada, substitute
the name“General Motors of Canada
Company” for GMC Division wherever it
appears in this manual. This manual describes features that may or
may not be on the vehicle because of
optional equipment that was not purchased
on the vehicle, model variants, country
specifications, features/applications that may
not be available in your region, or changes
subsequent to the printing of this owner’s
manual.
If the vehicle has the Duramax diesel
engine, see the Duramax diesel supplement
for additional and specific information on
this engine.
Refer to the purchase documentation
relating to your specific vehicle to confirm
the features.
Keep this manual in the vehicle for quick
reference.
Litho in U.S.A.
Part No. 84550392 C Third Printing©2021 General Motors LLC. All Rights Reserved.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
2 Introduction
Canadian Vehicle Owners
A French language manual can be obtained
from your dealer, at www.helminc.com,
or from:
Propriétaires Canadiens
On peut obtenir un exemplaire de ce guide
en français auprès du concessionnaire ou à
l'adresse suivante:
Helm, Incorporated
Attention: Customer Service
47911 Halyard Drive
Plymouth, MI 48170
USA
Using this Manual
To quickly locate information about the
vehicle, use the Index in the back of the
manual. It is an alphabetical list of what is
in the manual and the page number where
it can be found.
Danger, Warning, and Caution
Warning messages found on vehicle labels
and in this manual describe hazards and
what to do to avoid or reduce them.
{Danger
Danger indicates a hazard with a high
level of risk which will result in serious
injury or death.
{Warning
Warning indicates a hazard that could
result in injury or death.
Caution
Caution indicates a hazard that could
result in property or vehicle damage.
A circle with a slash through it is a safety
symbol which means“Do not,” “Do not do
this,” or“Do not let this happen.”
Symbols
The vehicle has components and labels that
use symbols instead of text. Symbols are
shown along with the text describing the
operation or information relating to a
specific component, control, message, gauge,
or indicator.
M:Shown when the owner’s manual has
additional instructions or information.
*: Shown when the service manual has
additional instructions or information.
0: Shown when there is more information
on another page — “see page.”
Vehicle Symbol Chart
Here are some additional symbols that may
be found on the vehicle and what they
mean. See the features in this manual for
information.
u: Air Conditioning System
G:Air Conditioning Refrigerant Oil
9:Airbag Readiness Light
!:Antilock Brake System (ABS)
$:Brake System Warning Light

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 57
Always use the correct buckle for your
seating position.
Never route the lap or shoulder belt over an
armrest.
{Warning
The seat belt can be pinched if it is
routed under plastic trim on the seat,
such as trim around the rear seatback
folding handle or side airbag. In a crash,
pinched seat belts might not be able to
provide adequate protection. Never allow
seat belts to be routed under plastic trim
pieces.
Lap-Shoulder Belt
All seating positions in the vehicle have a
lap-shoulder belt.
The following instructions explain how to
wear a lap-shoulder belt properly.1. Adjust the seat, if the seat is adjustable, so you can sit up straight. To see how,
see “Seats” in the Index.2. Pick up the latch plate and pull the belt
across you. Do not let it get twisted.
The lap-shoulder belt may lock if you
pull the belt across you very quickly.
If this happens, let the belt go back
slightly to unlock it. Then pull the belt
across you more slowly.
If the shoulder portion of a passenger
belt is pulled out all the way, the child
restraint locking feature may be
engaged. See Child Restraint Systems
0 74. If this occurs, let the belt go back
all the way and start again. If the
locking feature stays engaged after
letting the belt go back to stowed

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 69
{Warning
If the front outboard passenger airbag is
turned off for an adult-sized occupant,
the airbag will not be able to inflate and
help protect that person in a crash,
resulting in an increased risk of serious
injury or even death. An adult-sized
occupant should not ride in the front
outboard passenger seat, if the passenger
airbag OFF indicator is lit.
Additional Factors Affecting System
Operation
Seat belts help keep the passenger in
position on the seat during vehicle
maneuvers and braking, which helps the
passenger sensing system maintain the
passenger airbag status. See“Seat Belts”
and “Child Restraints” in the Index for
additional information about the importance
of proper restraint use.
A thick layer of additional material, such as
a blanket or cushion, or aftermarket
equipment such as seat covers, seat heaters,
and seat massagers can affect how well the
passenger sensing system operates. We
recommend that you not use seat covers or
other aftermarket equipment except when approved by GM for your specific vehicle.
See
Adding Equipment to the
Airbag-Equipped Vehicle 069 for more
information about modifications that can
affect how the system operates.
The ON indicator may be lit if an object,
such as a briefcase, handbag, grocery bag,
laptop, or other electronic device, is put on
an unoccupied seat. If this is not desired,
remove the object from the seat.
{Warning
Stowing articles under the passenger seat
or between the passenger seat cushion
and seatback may interfere with the
proper operation of the passenger
sensing system.
Servicing the Airbag-Equipped
Vehicle
Airbags affect how the vehicle should be
serviced. There are parts of the airbag
system in several places around the vehicle.
Your dealer and the service manual have
information about servicing the vehicle and
the airbag system. To purchase a service
manual, see Publication Ordering
Information 0435.
{Warning
For up to 10 seconds after the vehicle is
turned off and the battery is
disconnected, an airbag can still inflate
during improper service. You can be
injured if you are close to an airbag
when it inflates. Avoid yellow connectors.
They are probably part of the airbag
system. Be sure to follow proper service
procedures, and make sure the person
performing work for you is qualified to
do so.
Adding Equipment to the
Airbag-Equipped Vehicle
Adding accessories that change the vehicle's
frame, bumper system, height, front end,
or side sheet metal, may keep the airbag
system from working properly.
The operation of the airbag system can also
be affected by changing, including
improperly repairing or replacing, any parts
of the following:
.Airbag system, including airbag modules,
front or side impact sensors, sensing and
diagnostic module, or airbag wiring

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Instruments and Controls 109
.Home
.Info App. This is where the selected Driver
Information Center (DIC) displays can be
viewed. See“Driver Information Center
(DIC) (Uplevel)” in the Index.
.Audio
.Navigation
.Phone
.Options
Home
Information displayed here can be
customized from the Options menu.
Speedometer : Displays how fast the vehicle
is moving in either kilometers per hour
(km/h) or miles per hour (mph).
Speed Sign : Shows sign information, which
comes from a roadway database in the
onboard navigation, if equipped.
Time : Displays the current time.
Fuel Range : Displays the approximate
distance the vehicle can be driven without
refueling. The fuel range estimate is based
on an average of the vehicle’s fuel economy
over recent driving history and the amount
of fuel remaining in the fuel tank. Fuel
range cannot be reset. Audio
In the Audio menu, use the thumbwheel to
scroll through options, browse for music,
select from favorites, or change the audio
source. In the main view, scroll to change
the station or go to the next or previous
track.
Navigation
In the Navigation menu, if there is no active
route, a compass will be displayed. If there
is an active route, press the thumbwheel to
cancel or resume route guidance, mute or
unmute voice guidance, or access Recents or
Favorites.
Phone
In the Phone menu, if there is no active
phone call, view recent calls, scroll through
contacts, select from the favorites, or change
the phone source. If there is an active call,
mute the phone or switch to handset
operation.
Options
Use the thumbwheel to scroll through items
in the Options menu.
Head-up Display (HUD) :
If equipped, this
feature allows for adjusting the angle of the
HUD image and changing or turning off the
Speed Limit Sign.
HUD Rotation: Press the thumbwheel while
Adjust Rotation is highlighted to enter
Adjust Mode. Scroll to adjust the angle of
the HUD display. Press the thumbwheel to
confirm and save the setting. This feature
may only be available in P (Park).
Speed Limit Style: Press the thumbwheel
while Speed Limit Style is highlighted to
change the speed sign style or to turn it off.
Units : Press the thumbwheel while Units is
displayed to enter the Units menu. Choose
US or metric units by pressing the
thumbwheel while the desired item is
highlighted. A selected mark will be
displayed next to the selected item.
Info Page Options : Press the thumbwheel
while Info Page Options is displayed to
enter and select the items to be displayed
in the Info app. A selected mark will be
displayed next to the selected item.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Infotainment System 159
Caution
To avoid vehicle damage, unplug all
accessories and disconnect all accessory
cables from the vehicle when not in use.
Accessory cables left plugged into the
vehicle, unconnected to a device, could be
damaged or cause an electrical short if
the unconnected end comes in contact
with liquids or another power source such
as the accessory power outlet.
Playing from a USB
A USB mass storage device can be connected
to the USB port.
Gracenote
When plugging in a USB device, Gracenote
service builds voice tags for music. Voice
tags allow artists, albums with hard to
pronounce names, and nicknames to be used
to play music through voice recognition.
While indexing, infotainment features are
available.My Media Library
MyMedia is only available when more than
one indexed device is connected. It allows
access to content from all indexed media
sources. MyMedia will show as an available
source in the Source page.
USB MP3 Player and USB Devices
The USB MP3 players and USB devices
connected must comply with the USB Mass
Storage Class specification (USB MSC).
to play a USB device:
1. Connect the USB.
2. Press MEDIA on the center stack until the connected device is shown.
Use the following when playing an active
USB source:
r: Touch to play the current media source.
j: Touch to pause playback of the current
media source.
g:
.Press to seek to the beginning of the
current or previous track.
.Press and hold to reverse quickly through
playback. Release to return to playing
speed. Elapsed time displays.
d:
.Press to seek to the next track.
.Press and hold to advance quickly
through playback. Release to return to
playing speed. Elapsed time displays.
Shuffle : Touch the shuffle icon to play
music in random order.
USB Menu
Touch the Menu icon to display the USB
menu. The following may be available:
Shuffle : Touch to play the tracks randomly.
Touch again to stop shuffle.
Tone : Touch + or –to adjust the tone
settings. See AM-FM Radio 0155.
Auto Volume (If Equipped) : This feature
adjusts the volume based on the vehicle
speed. See AM-FM Radio 0155.
Bose AudioPilot Noise Compensation
Technology (If Equipped : This feature
adjusts the volume based on the noise in
the vehicle and speed. See AM-FM Radio
0 155.
USB Browse Menu
When a list of songs, albums, artists,
or other types of media displays, the up and
down arrows and A-Z appear on the left

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Infotainment System 169
.Use the index finger and thumb to zoom
out by pinching and then zoom in by
spreading those two fingers on the map.
Map Gestures and Map Scale
Use the following gestures on the
infotainment display to adjust the map scale
and display options.
.Pinch to zoom in or out.
.Pan the map.
.Use two fingers to tilt down and change
from 2D to 3D. Tilt up to change back
to 2D.
.Rotate the map.
See Using the System 0152.
Mute
When in active guidance, the audio prompts
while using navigation can be muted. Touch
the speaker icon on the right side of the
upper bar. A slash will appear on the
speaker to indicate voice guidance is muted.
Active Guidance View
When a destination is chosen and a
navigation session is active, the navigation
system enters into an Active Guidance
View (AGV). Map Orientation
Touch
Aon the map to access map
orientation settings. Map orientation is 3D
Heading Up by default.
Available settings are:
.3D Heading Up (Default): 3D map with
the vehicle pointing up. In this mode, the
current location icon will always head up
and the map will rotate around it.
.2D Heading Up: 2D map with the vehicle
pointing up. In this mode, the current
location icon will always head up and the
map will rotate around it.
.2D North Up: 2D map with North pointing
up. In this mode, the current location icon
will shift as the vehicle turns left and
right.
Touch the icon to change the map type. The
icon and label will also update accordingly.
Depending on the zoom level of the 2D
Heading Up and 3D Heading Up maps, the
system may automatically switch to the 2D
North Up map.
When in AGV, the entire route can be
viewed in 2D North Up by touching the
traffic bar. The map will zoom out and
readjust to display the full route. When in 2D North Up Route View, the Recenter icon
will appear in the middle of the display.
Touch either the Recenter icon or the traffic
bar again to return to the previous view,
either 2D or 3D.
Lane Guidance
The map will display the lane information
for the upcoming maneuver if it is available.
Junction View
When a vehicle is on the highway and
approaching the exit, an image displays the
lane that the vehicle must stay in to
complete the next maneuver.
Quick-Turn View

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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Infotainment System 191
.Set Number of Audio Favorites: Touch to
select how many favorites pages can be
viewed from the audio application. The
Auto setting will automatically adjust this
number based on the number of favorites
you have saved. Touch Auto, 5, 10, 15, 20,
25, 30, 35, or 40.
.RDS: This allows the Radio Data System
(RDS) to be turned on or off.
Touch the controls on the infotainment
display to disable or enable.
.HD Radio: This allows HD Radio reception
to be turned on or off.
Touch the controls on the infotainment
display to disable or enable.
.Explicit Content Filter: This setting allows
access to explicit content SiriusXM
channels.
Touch Off or On.
.Manage Phones: Select to connect to a
different phone source, disconnect a
phone, or delete a phone.
.Reset Music Index: This allows the music
index to be reset if you are having
difficulty accessing all of the media
content on your device.
Touch Yes or No.Climate
Touch and the following may display:
.Auto Fan Speed: This setting specifies the
amount of airflow when the climate
control fan setting is Auto Fan.
Touch Low, Medium, or High.
.Air Quality Sensor: This setting switches
the system into Recirculation Mode based
on the quality of the outside air.
Touch Off, Low Sensitivity, or High
Sensitivity.
.Auto Cooled Seats: This setting
automatically turns on and regulates the
ventilated seats when the cabin
temperature is warm.
Touch the controls on the infotainment
display to disable or enable.
.Auto Heated Seats: This setting
automatically turns on and regulates the
heated seats when the cabin temperature
is cool. The auto heated seats can be
turned off by using the heated seat
controls on the center stack.
Touch the controls on the infotainment
display to disable or enable.
.Auto Defog: This setting automatically
turns the front defogger on when the
vehicle engine is started. Touch the controls on the infotainment
display to disable or enable.
.Auto Rear Defog: This setting
automatically turns the rear window
defogger on when the vehicle engine is
started.
Touch the controls on the infotainment
display to disable or enable.
Navigation
Touch and the following may display:
.Set Up My Places
.Map Preferences
.Route Preferences
.Navigation Voice Control
.Traffic Preferences
.Alert Preferences
.Manage History
.Predictive Navigation
.About
See Using the Navigation System 0163.
Phone
Touch and the following may display:
.My Number: Displays the cell phone
number of the Bluetooth connected
device.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
284 Driving and Operating
Recommended Fuel (6.2L
V8 Engine)
Premium unleaded gasoline meeting ASTM
specification D4814 with a posted octane
rating of 93—(R+M)/2 —is highly
recommended for best performance and fuel
economy. Unleaded gasoline with an octane
rated as low as 87 can be used. Using
unleaded gasoline rated below 93 octane,
however, will lead to reduced acceleration
and fuel economy. If knocking occurs, use a
gasoline rated at 93 octane as soon as
possible, otherwise, the engine could be
damaged. If heavy knocking is heard when
using gasoline with a 93 octane rating, the
engine needs service.
Do not use any fuel labeled E85 or FlexFuel.
Do not use gasoline with ethanol levels
greater than 15% by volume.
Prohibited Fuels
Caution
Do not use fuels with any of the
following conditions; doing so may
damage the vehicle and void its
warranty:
.For vehicles that are not FlexFuel, fuel
labeled greater than 15% ethanol by
volume, such as mid-level ethanol
blends (16–50% ethanol), E85,
or FlexFuel.
.Fuel with any amount of methanol,
methylal, ferrocene, and aniline. These
fuels can corrode metal fuel system
parts or damage plastic and rubber
parts.
.Fuel containing metals such as
methylcyclopentadienyl manganese
tricarbonyl (MMT), which can damage
the emissions control system and
spark plugs.
.Fuel with a posted octane rating of
less than the recommended fuel. Using
this fuel will lower fuel economy and
performance, and may decrease the
life of the emissions catalyst.
Fuels in Foreign Countries
The U.S., Canada, and Mexico post fuel
octane ratings in anti-knock index (AKI). For
fuel not to use in a foreign country, see
Prohibited Fuels 0284.
Fuel Additives
TOP TIER Detergent Gasoline is highly
recommended for use with your vehicle.
If your country does not have TOP TIER
Detergent Gasoline, add ACDelco Fuel
System Treatment Plus−Gasoline to the
vehicle’s gasoline fuel tank at every oil
change or 15 000 km (9,000 mi), whichever
occurs first. TOP TIER Detergent Gasoline and
ACDelco Fuel System Treatment Plus
−Gasoline will help keep your vehicle’s
engine fuel deposit free and performing
optimally.
E85 or FlexFuel
Vehicles with a yellow fuel sticker on the
fuel door can use either unleaded gasoline
or fuel containing up to 85% ethanol (E85).
All other vehicles should use only the
unleaded gasoline as described in
Recommended Fuel (Except 6.2L V8 Engine)
0283 or
Recommended Fuel (6.2L V8 Engine) 0284.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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290 Driving and Operating
{Warning
To prevent serious injury or death from
carbon monoxide (CO), when towing a
trailer:
.Do not drive with the liftgate, trunk/
hatch, or rear-most window open.
.Fully open the air outlets on or under
the instrument panel.
.Adjust the climate control system to a
setting that brings in only outside air.
See“Climate Control Systems” in the
Index.
For more information about carbon
monoxide, see Engine Exhaust 0238.
Towing a trailer requires experience. The
combination of the vehicle and trailer is
longer and not as responsive as the vehicle
itself. Get used to the handling and braking
of the combination by driving on a level
road surface before driving on public roads.
The trailer structure, the tires, and the
brakes must all be rated to carry the
intended cargo. Inadequate trailer
equipment can cause the combination to
operate in an unexpected or unsafe manner.
Before driving, inspect all trailer hitch parts and attachments, safety chains, electrical
connectors, lamps, tires, and mirrors. See
Towing Equipment
0296. If the trailer has
electric brakes, start the combination
moving and then manually apply the trailer
brake controller to check that the trailer
brakes work. During the trip, occasionally
check that the cargo and trailer are secure
and that the lamps and any trailer brakes
are working.Towing with a Stability Control System
When towing, the stability control system
might be heard. The system reacts to
vehicle movement caused by the trailer,
which mainly occurs during cornering. This is
normal when towing heavier trailers.
Following Distance
Stay at least twice as far behind the vehicle
ahead as you would when driving without a
trailer. This can help to avoid heavy braking
and sudden turns.
Passing
More passing distance is needed when
towing a trailer. The combination of the
vehicle and trailer will not accelerate as
quickly and is much longer than the vehicle
alone. It is necessary to go much farther beyond the passed vehicle before returning
to the lane. Pass on level roadways. Avoid
passing on hills if possible.
Backing Up
Hold the bottom of the steering wheel with
one hand. To move the trailer to the left,
move that hand to the left. To move the
trailer to the right, move that hand to the
right. Always back up slowly and, if possible,
have someone guide you.
Making Turns
Caution
Turn more slowly and make wider arcs
when towing a trailer to prevent damage
to your vehicle. Making very sharp turns
could cause the trailer to contact the
vehicle.
Make wider turns than normal when towing,
so the trailer will not go over soft shoulders,
over curbs, or strike road signs, trees,
or other objects. Always signal turns well in
advance. Do not steer or brake suddenly.