2021 GMC SIERRA roof

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Seats and Restraints 65
What Will You See after an
Airbag Inflates?
After frontal and seat-mounted side impact
airbags inflate, they quickly deflate, so
quickly that some people may not even
realize the airbags inflated. Roof-rail airbags
may still be at least partially inflated for
some time after they inflate. Some
components of the airbag module may be
hot for several minutes. For location of the
airbags, seeWhere Are the Airbags? 062.
The parts of the airbag that come into
contact with you may be warm, but not too
hot to touch. There may be some smoke
and dust coming from the vents in the
deflated airbags. Airbag inflation does not
prevent the driver from seeing out of the
windshield or being able to steer the
vehicle, nor does it prevent people from
leaving the vehicle.
{Warning
When an airbag inflates, there may be
dust in the air. This dust could cause
breathing problems for people with a
history of asthma or other breathing
trouble. To avoid this, everyone in the (Continued)
Warning (Continued)
vehicle should get out as soon as it is
safe to do so. If you have breathing
problems but cannot get out of the
vehicle after an airbag inflates, then get
fresh air by opening a window or a door.
If you experience breathing problems
following an airbag deployment, you
should seek medical attention.
The vehicle has a feature that may
automatically unlock the doors, turn on the
interior lamps and hazard warning flashers,
and shut off the fuel system after the
airbags inflate. The feature may also
activate, without airbag inflation, after an
event that exceeds a predetermined
threshold. After turning the ignition off and
then on again, the fuel system will return to
normal operation; the doors can be locked,
the interior lamps can be turned off, and
the hazard warning flashers can be turned
off using the controls for those features.
If any of these systems are damaged in the
crash they may not operate as normal.
{Warning
A crash severe enough to inflate the
airbags may have also damaged
important functions in the vehicle, such
as the fuel system, brake and steering
systems, etc. Even if the vehicle appears
to be drivable after a moderate crash,
there may be concealed damage that
could make it difficult to safely operate
the vehicle.
Use caution if you should attempt to
restart the engine after a crash has
occurred.
In many crashes severe enough to inflate
the airbag, windshields are broken by
vehicle deformation. Additional windshield
breakage may also occur from the front
outboard passenger airbag.
.Airbags are designed to inflate only once.
After an airbag inflates, you will need
some new parts for the airbag system.
If you do not get them, the airbag
system will not be there to help protect
you in another crash. A new system will
include airbag modules and possibly other
parts. The service manual for the vehicle
covers the need to replace other parts.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
70 Seats and Restraints
.Front seats, including stitching, seams,
or zippers
.Seat belts
.Steering wheel, instrument panel,
overhead console, ceiling trim, or pillar
garnish trim
.Inner door seals, including speakers
Your dealer and the service manual have
information about the location of the airbag
modules and sensors, sensing and diagnostic
module, and airbag wiring along with the
proper replacement procedures.
In addition, the vehicle has a passenger
sensing system for the front outboard
passenger position, which includes sensors
that are part of the passenger seat. The
passenger sensing system may not operate
properly if the original seat trim is replaced
with non-GM covers, upholstery, or trim; or
with GM covers, upholstery, or trim
designed for a different vehicle. Any object,
such as an aftermarket seat heater or a
comfort-enhancing pad or device, installed
under or on top of the seat fabric, could
also interfere with the operation of the
passenger sensing system. This could either
prevent proper deployment of the passenger
airbag(s) or prevent the passenger sensing system from properly turning off the
passenger airbag(s). See
Passenger Sensing
System 066.
If the vehicle has rollover roof-rail airbags,
see Different Size Tires and Wheels 0377 for
additional important information.
If a snow plow is added to the vehicle, the
airbags should still work properly. The
airbag systems were designed to work
properly under a wide range of conditions,
including snow plowing with vehicles that
have the optional snow plow prep package
(RPO VYU). Do not change or defeat the
snow plow's “tripping mechanism.” If you
do, it can damage the snow plow and the
vehicle, and may cause an airbag
deployment.
If the vehicle must be modified because you
have a disability and have questions about
whether the modifications will affect the
vehicle's airbag system, or if you have
questions about whether the airbag system
will be affected if the vehicle is modified for
any other reason, call Customer Assistance.
See Customer Assistance Offices 0430.
Airbag System Check
The airbag system does not need regularly
scheduled maintenance or replacement.
Make sure the airbag readiness light is
working. See Airbag Readiness Light 0114.
Caution
If an airbag covering is damaged, opened,
or broken, the airbag may not work
properly. Do not open or break the airbag
coverings. If there are any opened or
broken airbag coverings, have the airbag
covering and/or airbag module replaced.
For the location of the airbags, see Where
Are the Airbags? 062. See your dealer
for service.

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./
Canada/Mexico-14632426) - 2021 - CRC - 11/6/20
Lighting 139
Lighting
Exterior Lighting
Exterior Lamp Controls . . . . . . . . . . . . . . . . 139
Exterior Lamps Off Reminder . . . . . . . . . . . 141
Headlamp High/Low-Beam Changer . . . . 141
Flash-to-Pass . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Daytime Running Lamps (DRL) . . . . . . . . . 141
Automatic Headlamp System . . . . . . . . . . 142
Hazard Warning Flashers . . . . . . . . . . . . . . 142
Turn and Lane-Change Signals . . . . . . . . . 143
Fog Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Task Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Auxiliary Roof-Mounted Lamp . . . . . . . . . 144
Exterior Cargo Lamps . . . . . . . . . . . . . . . . . . 144
Interior Lighting
Instrument Panel IlluminationControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Dome Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Reading Lamps . . . . . . . . . . . . . . . . . . . . . . . . 146
Lighting Features
Entry Lighting . . . . . . . . . . . . . . . . . . . . . . . . . 146
Exit Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Battery Load Management . . . . . . . . . . . . 146
Battery Power Protection . . . . . . . . . . . . . . 147
Exterior Lighting Battery Saver . . . . . . . . 147
Exterior Lighting
Exterior Lamp Controls
The exterior lamp control is on the
instrument panel to the left of the steering
wheel.
O: Turns off the automatic headlamps and
Daytime Running Lamps (DRL). Turn the
headlamp control to
Oagain to turn the
automatic headlamps or DRL back on.
For vehicles first sold in Canada, off will only
work when the vehicle is in P (Park). AUTO :
Automatically turns on the
headlamps, parking lamps, taillamps,
instrument panel lights, roof marker lamps
(if equipped), front/rear sidemarker lamps,
and license plate lamps.
;: Turns on the parking lamps including
all lamps, except the headlamps and fog
lamps, if equipped.
For some trim levels and series of trucks
first sold in Canada, the headlamps may
turn on with the parking lamps.
2: Turns on the headlamps together with
the parking lamps, taillamps, instrument
panel lights, roof marker lamps (if
equipped), front/rear sidemarker lamps, and
license plate lamps.
When the headlamps are turned on while
the vehicle is on, the headlamps turn off
automatically 10 minutes after the ignition
is turned off. When the headlamps are
turned on while the vehicle is off, the
headlamps will stay on for 10 minutes
before turning off to prevent the battery
from being drained. Turn the headlamp
control off and then back to the headlamp
on position to make the headlamps stay on

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/6/20
144 Lighting
Some localities have laws that require the
headlamps to be on with the fog lamps.
Task Lighting
If equipped, task lighting projects light from
the outside mirrors away from the vehicle.
While the vehicle is parked, press
Kto
select one of the following options:
.Left and Right Task Lights Illuminated
.Left Task Light Illuminated
.Right Task Light Illuminated
.Left and Right Task Lights Off
If the vehicle leaves a parked position, the
lights will immediately turn off. If the vehicle is off, the lights will stay on
for approximately 10 minutes.
If any Task lights are on, if the button has
not been pressed after approximately
5 seconds, pressing it again will turn off all
Task Lights.
Auxiliary Roof-Mounted Lamp
If equipped, this button includes wiring
provisions for a dealer or a qualified service
center to install an auxiliary roof lamp.
For information on roof-mounted emergency
lamp installation, see www.gmupfitter.com
or contact your dealer.
If the vehicle has this button, the vehicle
may have the snow plow prep package. See
Add-On Electrical Equipment
0318.
Exterior Cargo Lamps
The cargo lamps provide more light in the
cargo area or on the sides of the vehicle,
if needed. The lamps inside the pickup box,
in the tailgate handle, for the hitch, and/or
the cargo mirror lamps also turn on,
if equipped.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
158 Infotainment System
by model and require a complete working
electrical system, cell reception, and GPS
signal. An active connected plan is required.
Reference the SiriusXM user guide for use
and subscription information.
Radio Reception
Unplug electronic devices from the accessory
power outlets if there is interference or
static in the radio.
FM
FM signals only reach about 16 to 65 km (10
to 40 mi). Although the radio has a built-in
electronic circuit that automatically works to
reduce interference, some static can occur,
especially around tall buildings or hills,
causing the sound to fade in and out.
AM
The range for most AM stations is greater
than for FM, especially at night. The longer
range can cause station frequencies to
interfere with each other. Static can also
occur when things like storms and power
lines interfere with radio reception. When
this happens, try reducing the treble on the
radio.
SiriusXM Satellite Radio Service
If equipped, SiriusXM Satellite Radio Service
provides digital radio reception. Tall
buildings or hills can interfere with satellite
radio signals, causing the sound to fade in
and out. In addition, traveling or standing
under heavy foliage, bridges, garages,
or tunnels may cause loss of the SiriusXM
signal for a period of time. Some cellular
services may interfere with SXM reception
causing loss of signal.
Mobile Device Usage
Mobile device usage, such as making or
receiving calls, charging, or just having the
mobile device on may cause static
interference in the radio. Unplug the mobile
device or turn it off if this happens.
Fixed Mast Antenna
The fixed mast antenna will go through
most car washes as long as it is securely
attached. If the antenna becomes slightly
bent, straighten it out by hand. If it is badly
bent, replace it.
Occasionally check that the antenna is tight
at the base. If tightening is required, protect
the paint from damage.
Multi-Band Antenna
The roof antenna is for SiriusXM Satellite
Radio, OnStar, and GPS (Global Positioning
System), depending on the equipped
options. Keep clear of obstructions for clear
reception. If the vehicle has a sunroof, and it
is open, reception can also be affected.
Audio Players
Avoiding Untrusted Media Devices
When using media devices such as SD cards,
USB devices, and mobile devices, consider
the source. Untrusted media devices could
contain files that affect system operation or
performance. Avoid use if the content or
origin cannot be trusted.
USB Port
This vehicle is equipped with two USB ports
in the center console under the armrest and
another two in the center stack. These ports
are for data and charging.
There may also be two USB ports for
charging only at the rear of the center
console.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
174 Infotainment System
This system might not be available or
interference can occur if any of the
following are true:
.Signals are obstructed by tall buildings,
trees, large trucks, or a tunnel.
.Satellites are being repaired or improved.
For more information if the GPS is not
functioning properly, see Problems with
Route Guidance 0174 and
If the System Needs Service 0175.
Vehicle Positioning
At times, the position of the vehicle on the
map could be inaccurate due to one or more
of the following reasons:
.The road system has changed.
.The vehicle is driving on slippery road
surfaces such as sand, gravel, or snow.
.The vehicle is traveling on winding roads
or long, straight roads.
.The vehicle is approaching a tall building
or a large vehicle.
.The surface streets run parallel to a
freeway.
.The vehicle has been transferred by a
vehicle carrier or a ferry.
.The current position calibration is set
incorrectly.
.The vehicle is traveling at high speed.
.The vehicle changes directions more than
once, or the vehicle is turning on a turn
table in a parking lot.
.The vehicle is entering and/or exiting a
parking lot, garage, or a lot with a roof.
.The GPS signal is not received.
.A roof carrier is installed on the vehicle.
.Tire chains are installed on the vehicle.
.The tires are replaced or worn.
.The tire pressure for the tires is incorrect.
.This is the first navigation use after the
map data is updated.
.The 12-volt battery has been disconnected
for several days.
.The vehicle is driving in heavy traffic
where driving is at low speeds, and the
vehicle is stopped and started repeatedly.
Problems with Route Guidance
Inappropriate route guidance can occur
under one or more of the following
conditions:
.The turn was not made on the road
indicated.
.Route guidance might not be available
when using automatic rerouting for the
next right or left turn.
.The route might not be changed when
using automatic rerouting.
.There is no route guidance when turning
at an intersection.
.Plural names of places might be
announced occasionally.
.It could take a long time to operate
automatic rerouting during high-speed
driving.
.Automatic rerouting might display a route
returning to the set waypoint if heading
for a destination without passing through
a set waypoint.
.The route prohibits the entry of a vehicle
due to a regulation by time or season or
any other regulation which may be given.
.Some routes might not be searched.
.The route to the destination might not be
shown if there are new roads, if roads
have recently changed, or if certain roads
are not listed in the map data. See Maps
0 166.
To recalibrate the vehicle's position on the
map, park with the vehicle running for two
to five minutes, until the vehicle position
updates. Make sure the vehicle is parked in

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
216 Driving and Operating
Caution
Operating the vehicle for extended
periods without the front fascia lower air
dam installed can cause improper airflow
to the engine. Reattach the front fascia
air dam after off-road driving.
Loading the Vehicle for Off-Road Driving
{Warning
.Unsecured cargo on the load floor can
be tossed about when driving over
rough terrain. You or your passengers
can be struck by flying objects. Secure
the cargo properly.
.Keep cargo in the cargo area as far
forward and as low as possible. The
heaviest things should be on the floor,
forward of the rear axle.
.Heavy loads on the roof raise the
vehicle's center of gravity, making it
more likely to roll over. You can be
seriously or fatally injured if the
vehicle rolls over. Put heavy loads
inside the cargo area, not on the roof.For more information about loading the
vehicle, see
Vehicle Load Limits 0222 and
Tires 0360.
Environmental Concerns
.Always use established trails, roads, and
areas that have been set aside for public
off-road recreational driving and obey all
posted regulations.
.Do not damage shrubs, flowers, trees,
or grasses or disturb wildlife.
.Do not park over things that burn. See
Parking over Things That Burn 0237.
Driving on Hills
Driving safely on hills requires good
judgment and an understanding of what the
vehicle can and cannot do.
{Warning
Many hills are simply too steep for any
vehicle. Driving up hills can cause the
vehicle to stall. Driving down hills can
cause loss of control. Driving across hills
can cause a rollover. You could be injured
or killed. Do not drive on steep hills. Before driving on a hill, assess the
steepness, traction, and obstructions. If the
terrain ahead cannot be seen, get out of the
vehicle and walk the hill before driving
further.
When driving on hills:
.Use a low gear and keep a firm grip on
the steering wheel.
.Maintain a slow speed.
.When possible, drive straight up or down
the hill.
.Slow down when approaching the top of
the hill.
.Use headlamps even during the day to
make the vehicle more visible.
{Warning
Driving to the top of a hill at high speed
can cause a crash. There could be a
drop-off, embankment, cliff, or even
another vehicle. You could be seriously
injured or killed. As you near the top of a
hill, slow down and stay alert.
.Never go downhill forward or backward
with either the transmission or transfer
case in N (Neutral). The brakes could
overheat and you could lose control.