Service GMC SIERRA 2020 Owner's Manual

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . 2
Keys, Doors, and Windows . . . . . . 9
Seats and Restraints . . . . . . . . . . . 53
Storage . . . . . . . . . . . . . . . . . . . . . . . 113
Instruments and Controls . . . . . . 118
Lighting . . . . . . . . . . . . . . . . . . . . . . . 165
Infotainment System . . . . . . . . . . 176
Climate Controls . . . . . . . . . . . . . . 177
Driving and Operating . . . . . . . . . 185
Vehicle Care . . . . . . . . . . . . . . . . . . 327
Service and Maintenance . . . . . 440
Technical Data . . . . . . . . . . . . . . . . 458
Customer Information . . . . . . . . . 463
Reporting Safety Defects . . . . . . 473
OnStar . . . . . . . . . . . . . . . . . . . . . . . . 477
Connected Services . . . . . . . . . . . 485
Index . . . . . . . . . . . . . . . . . . . . 488

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
2 Introduction
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.
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.
Litho in U.S.A.
Part No. 84186890 A First Printing©2019 General Motors LLC. All Rights Reserved.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
Introduction 3
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
9:Dispose of Used Components
Properly
P: Do Not Apply High Pressure
Water
B: Engine Coolant Temperature
_: Flame/Fire Prohibited
H:Flammable
[:Forward Collision Alert
R: Fuse Block Cover Lock
Location
+: Fuses
j:ISOFIX/LATCH System Child
Restraints

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
12 Keys, Doors, and Windows
learned and all previously
known keys will no longer work
with the vehicle.
6. To learn a second key, turn the ignition off, insert the second
key to be learned, and turn the
ignition on.
After two keys are learned, the
remaining keys can be learned by
following the procedure in
“Programming with Two
Recognized Keys.”
The key has a bar-coded key tag
that the dealer or qualified locksmith
can use to make new keys. Store
this information in a safe place, not
in the vehicle.
See your dealer if a replacement
key or additional key is needed.
If it becomes difficult to turn a key,
inspect the key blade for debris.
Periodically clean with a brush
or pick.
If locked out of the vehicle, see
Roadside Assistance Program
0 467. With an active OnStar or connected
service plan, an OnStar Advisor
may remotely unlock the vehicle.
See
OnStar Overview 0477.
Keys (Keyless Access)
{Warning
Leaving children in a vehicle with
an ignition key or Remote
Keyless Entry (RKE) transmitter is
dangerous and children or others
could be seriously injured or
killed. They could operate the
power window or other controls or
make the vehicle move. The
windows will function with the key
in the ignition or with the RKE
transmitter in the vehicle, and
children or others could be caught
in the path of a closing window.
Do not leave children in a vehicle
with the ignition key or an RKE
transmitter.
If the vehicle has the Keyless
Access system, the transmitter has
a button on the side of the
transmitter used to remove the key.
This key is used for the driver door
and glove box.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Keys, Doors, and Windows 13
Press the button to remove the key.
Never pull the key out without
pressing the button.
See your dealer if a replacement
key or additional key is needed.
If it becomes difficult to turn a key,
inspect the key blade for debris.
Periodically clean with a brush
or pick.
With an active OnStar or connected
service plan, an OnStar Advisor
may remotely unlock the vehicle.
SeeOnStar Overview 0477.
If locked out of the vehicle, see
Roadside Assistance Program
0 467. If equipped with memory seats, RKE
transmitters 1 and 2 are linked to
seating positions of memory 1 or 2.
See
Memory Seats 059.
Remote Keyless Entry
(RKE) System
See Radio Frequency Statement
0 472.
If there is a decrease in the Remote
Keyless Entry (RKE) operating
range:
. Check the distance. The
transmitter may be too far from
the vehicle.
. Check the location. Other
vehicles or objects may be
blocking the signal.
. Check the transmitter's battery.
See “Battery Replacement” later
in this section.
. If the transmitter is still not
working correctly, see your
dealer or a qualified technician
for service.
Remote Keyless Entry
(RKE) System Operation
(Key Access)
The RKE transmitter functions may
work up to 60 m (197 ft) away from
the vehicle.
Other conditions can affect the
performance of the transmitter. See
Remote Keyless Entry (RKE)
System 013.
/:Press and releaseQ, then
immediately press and hold
/until
the turn signal lamps flash or for at

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Keys, Doors, and Windows 31
power close. Power opening is still
enabled. See your dealer for
service.
The power tailgate may be
temporarily disabled after repeated
power cycling over a short period of
time. If this occurs, the tailgate can
still be operated manually.
The vehicle must be in P (Park) to
operate the power tailgate. If the
vehicle is shifted out of P (Park)
while the power function is in
progress, the tailgate will continue
to completion. If the vehicle is
accelerated while the tailgate is still
closing, the tailgate may stop and
reverse direction. Make sure the
tailgate is closed and latched before
driving.Lift-to-Close Operation
To close the tailgate using the
lift-to-close feature, lift the tailgate
from the full-open position to at least
10 cm (4 in) and hold it momentarily.
Then, the tailgate will start closing
automatically. If the tailgate is lifted
more than halfway between open
and close, then it will not close
automatically.
Obstacle Detection
If the tailgate encounters an
obstacle during a power open cycle,
it will stop on the obstacle. After
removing the obstruction, the
tailgate can be allowed to open.If the tailgate encounters an
obstacle during the closing cycle, it
will stop and reverse to full open.
If the tailgate encounters multiple
obstacles, the power function will
deactivate. After removing the
obstructions, manually close the
tailgate to resume normal power
operation.
Manual Operation
The tailgate can be manually closed
from the full-open position when the
tailgate is lifted in a continuous
motion. If the tailgate motion is
stopped between the full-open and
half-closed positions, the lift-to-close
feature can engage and power
close the tailgate. If the touch pad is
pressed during power operation, the
tailgate will stop and allow manual
operation. The tailgate must be held
after stopping, or it will continue
to open.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
38 Keys, Doors, and Windows
the lights will flash to indicate
pre-alarm. If the vehicle is not
started, or the door is not unlocked
by pressing
Kon the RKE
transmitter during the 10-second
pre-alarm, the alarm will be
activated.
The alarm will also be activated if a
passenger door or the hood is
opened without first disarming the
system. When the alarm is
activated, the turn signals flash and
the horn sounds for about
30 seconds. The alarm system will
then re-arm to monitor for the next
unauthorized event.
Disarming the Alarm System
To disarm the alarm system or turn
off the alarm if it has been activated:
. Press
Kon the RKE transmitter.
. Start the vehicle.
To avoid setting off the alarm by
mistake:
. Lock the vehicle after all
occupants have exited. .
Always unlock a door with the
RKE transmitter.
Unlocking the driver door with
the key will not disarm the
system or turn off the alarm.
How to Detect a Tamper
Condition
IfKis pressed on the RKE
transmitter and the horn chirps three
times, an alarm occurred previously
while the alarm system was armed.
If the alarm has been activated, a
message will appear on the DIC.
Steering Column Lock
If equipped, the steering column
lock is a theft-deterrent device. This
feature locks the steering column
when the vehicle is turned off and
the driver door is opened, or when
the driver door is opened and then
the vehicle is turned off. The
steering column unlocks when the
vehicle is turned on.
The Driver Information Center (DIC)
may display one of these
messages: .
A message to service the
steering column lock indicates
that an issue has been detected
with the column lock feature and
the vehicle should be serviced.
. A message that the steering
column is locked indicates that
the engine is running, but the
steering column is still locked.
It is normal for the column to be
locked during a remote start, but
the column should unlock after
the brake pedal is pressed and
the vehicle is started. No
message will display during a
remote start.
. A message that the steering
wheel must be turned and the
vehicle must be started again
indicates that the column lock
mechanism is bound, the column
locking device was unable to
unlock the steering column, and
the vehicle did not start. If this
happens, immediately turn the
steering wheel from side to side
to unbind the column lock. If this
does not unlock the steering
column, turn the vehicle off and

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Keys, Doors, and Windows 39
open the driver door to reset the
system. Then turn the vehicle on
and immediately turn the
steering wheel side to side for
about 15 seconds. In some
cases, it may take significant
force to unbind the column.
To keep the steering column from
binding, straighten the front wheels
before turning off the vehicle.
Immobilizer
See Radio Frequency Statement
0 472.
Immobilizer Operation
This vehicle has a passive
theft-deterrent system.
The system does not have to be
manually armed or disarmed. The vehicle is automatically
immobilized when the vehicle is
turned off.
The system is automatically
disarmed when the ignition is turned
from off to on.
The security light, in the instrument
cluster, comes on if there is a
problem with arming or disarming
the theft-deterrent system.
The system has one or more RKE
transmitters matched to an
immobilizer control unit in your
vehicle. Only a correctly matched
RKE transmitter will start the
vehicle. If the transmitter is ever
damaged, you may not be able to
start your vehicle.
When trying to start the vehicle, the
security light may come on briefly
when the ignition is turned on. If the
engine does not start and the
security light stays on, there is a
problem with the system. Turn the
ignition off and try again.
If the vehicle will not change ignition
modes (ACC/ACCESSORY, on, off),
and the RKE transmitter appears tobe undamaged, try another
transmitter. Or, you may try placing
the transmitter in the transmitter
pocket located in the center
console. See
Remote Keyless Entry
(RKE) System Operation (Key
Access) 013 or
Remote Keyless Entry (RKE)
System Operation (Keyless Access)
0 15.
If the ignition mode will not change
with the other transmitter or with the
transmitter in the transmitter pocket,
your vehicle needs service. If the
ignition does change modes, the
first transmitter may be faulty. See
your dealer who can service the
theft-deterrent system and have a
new RKE transmitter programmed to
the vehicle.
It is possible for the immobilizer
system to learn new or replacement
RKE transmitters. Up to eight
transmitters can be programmed for
the vehicle. To program additional
transmitters, see "Programming

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
40 Keys, Doors, and Windows
Transmitters to the Vehicle" under
Remote Keyless Entry (RKE)
System Operation (Key Access)
013 or
Remote Keyless Entry (RKE)
System Operation (Keyless Access)
0 15
Do not leave the transmitter or
device that disarms or deactivates
the vehicle theft system in the
vehicle.
When equipped with a key, if the
engine still does not start, and the
key appears to be undamaged, try
another ignition key. It may be
necessary to check the fuse. See
Fuses and Circuit Breakers 0370.
If the engine still does not start with
the other key, the vehicle needs
service. If the vehicle does start, the
first key may be faulty. See your
dealer. It is possible for the
immobilizer system to learn new or
replacement keys. Up to eight keys
can be programmed for the vehicle.
To program additional keys, see
Keys (Key Access) 09or
Keys (Keyless Access) 012. Do not leave the key or device that disarms
or deactivates the vehicle theft
system in the vehicle.
See your dealer to get a new key
blank cut exactly as the ignition key
that operates the system.Exterior Mirrors
Convex Mirrors
{Warning
A convex mirror can make things,
like other vehicles, look farther
away than they really are. If you
cut too sharply into the right lane,
you could hit a vehicle on the
right. Check the inside mirror or
glance over your shoulder before
changing lanes.
Standard Mirrors
The passenger side mirror is convex
shaped. A convex mirror's surface is
curved so more can be seen from
the driver seat.
Trailer-Tow Mirrors
The upper portion of both the driver
and passenger mirrors is flat.
The lower portion of both the driver
and passenger mirrors is convex.
A convex mirror ’s surface is curved

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
48 Keys, Doors, and Windows
Troubleshooting
See your dealer for service if a blue
screen and
3are displayed in
the mirror, and the display shuts off.
Also, push the tab as indicated to
return to the automatic
dimming mode.
The Rear Camera Mirror may not
work properly or display a clear
image if:
. There is glare from the sun or
headlamps. This may obstruct
objects from view. If needed,
push the tab to turn off the
display. .
Dirt, snow, or other debris blocks
the camera lens. Clean the lens
with a soft damp cloth.
. The camera’s mounting on the
vehicle has been damaged, and/
or the position or the mounting
angle of the camera has
changed.
Windows
{Warning
Never leave a child, a helpless
adult, or a pet alone in a vehicle,
especially with the windows
closed in warm or hot weather.
They can be overcome by the
extreme heat and suffer
permanent injuries or even death
from heat stroke.