schedule GMC SIERRA 2021 Owner's Manual

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
112 Instruments and Controls
indicates oil pressure outside the normal
operating range, check the vehicle's oil as
soon as possible.
SeeEngine Oil 0330.
Caution
Lack of proper engine oil maintenance
can damage the engine. Driving with the
engine oil low can also damage the
engine. The repairs would not be covered
by the vehicle warranty. Check the oil
level as soon as possible. Add oil if
required, but if the oil level is within the
operating range and the oil pressure is
still low, have the vehicle serviced.
Always follow the maintenance schedule
for changing engine oil.
If the vehicle has a diesel engine, see the
Duramax diesel supplement.
Engine Coolant Temperature
Gauge
Metric Uplevel Shown, Midlevel and Base Level Similar
English Uplevel Shown, Midlevel and Base Level Similar
This gauge measures the temperature of the
vehicle's engine coolant.
While driving under normal operating
conditions, if the needle moves into the red
warning area, the engine is too hot. Pull off
the road, stop the vehicle, and turn off the
engine as soon as possible.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
122 Instruments and Controls
Tire Pressure Light
For vehicles with the Tire Pressure Monitor
System (TPMS), this light comes on briefly
when the engine is started. It provides
information about tire pressures and
the TPMS.
When the Light Is On Steady
This indicates that one or more of the tires
are significantly underinflated.
A Driver Information Center (DIC) tire
pressure message may also display. Stop as
soon as possible, and inflate the tires to the
pressure value shown on the Tire and
Loading Information label. SeeTire Pressure
0 367.
When the Light Flashes First and Then Is On
Steady
If the light flashes for about a minute and
then stays on, there may be a problem with
the TPMS. If the problem is not corrected, the light will come on at every ignition
cycle. See
Tire Pressure Monitor Operation
0 369.
Engine Oil Pressure Light (Uplevel
Cluster)
Caution
Lack of proper engine oil maintenance
can damage the engine. Driving with the
engine oil low can also damage the
engine. The repairs would not be covered
by the vehicle warranty. Check the oil
level as soon as possible. Add oil if
required, but if the oil level is within the
operating range and the oil pressure is
still low, have the vehicle serviced.
Always follow the maintenance schedule
for changing engine oil.
This light should come on briefly as the
engine is started. If it does not come on,
have the vehicle serviced by your dealer. If the light comes on and stays on, it means
that oil is not flowing through the engine
properly. The vehicle could be low on oil
and might have some other system
problem. See your dealer.
Low Fuel Warning Light
This light is near the fuel gauge and comes
on briefly when the ignition is turned on as
a check to show it is working.
It also comes on when the fuel tank is low
on fuel. The light turns off when fuel is
added. If it does not, have the vehicle
serviced.
Security Light

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Instruments and Controls 125
system monitoring the oil life, additional
maintenance is recommended. See
Maintenance Schedule0409.
The Oil Life display must be reset after each
oil change. It will not reset itself. Do not
reset the Oil Life display at any time other
than when the oil has just been changed.
It cannot be reset accurately until the next
oil change. To reset, see Engine Oil Life
System 0332.
Air Filter Life
Turn the trip odometer reset stem until AIR
FILTER LIFE displays. This displays an
estimate of the engine air filter’s remaining
useful life and the state of the system.
Engine Air Filter Life 95% means 95% of the
current air filter life remains. Messages will
display based on the engine air filter life
and the state of the system.
When the REPLACE AT NEXT OIL CHANGE
message displays, the engine air filter
should be replaced at the time of the next
oil change. When the REPLACE SOON
message displays, the engine air filter
should be replaced at the earliest
convenience. The Air Filter Life display must be reset after
the engine air filter replacement. To reset,
see
Engine Air Filter Life System 0333.
Brake Pad Life
This displays an estimate of the remaining
life of the front and rear brake pads.
Messages will display based on brake pad
wear and the state of the system. Reset the
Brake Pad Life display after replacing the
brake pads. See Brake Pad Life System
0 342.
Driver Information Center (DIC)
(Midlevel and Uplevel)
The DIC displays are shown in the center of
the instrument cluster in the Info app. See
Instrument Cluster 0106. The displays show
the status of many vehicle systems.
If the vehicle has a diesel engine, see the
Duramax diesel supplement.
SorT: Press to move left or right
between the interactive display zones in the
cluster. Press the thumbwheel to select.
yorz: Use the thumbwheel to scroll up
or down in a list. Press the thumbwheel to
select.
Info Page Options
The info pages on the DIC can be turned on
or off through the Options menu.
1. Press
Tto scroll to the Options
application.
2. Scroll
yorzto choose Info pages and
press the thumbwheel.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
126 Instruments and Controls
3. Scrollyorzto move through the list
of possible information displays.
4. Press the thumbwheel while an item is highlighted to select or deselect
that item.
The info pages can also be turned on or off
through the DIC page Info Page Options.
Info Pages
The following is the list of all possible DIC
info page displays. Some may not be
available for your particular vehicle. Some
items may not be turned on by default but
can be turned on through the Options app.
See “Info Page Options” earlier in this
section.
While in the Info Page Options menu, the
info pages can be restored to the default
factory settings by pressing and holding
K
on the left steering wheel controls and the
thumbwheel on the right steering wheel
controls at the same time.
Speed : Shows the vehicle speed in either
kilometers per hour (km/h) or miles per
hour (mph). The vehicle odometer is also
shown on this page. If equipped, press the
thumbwheel to open the menu and select to
display speed limit signs. Speed limit signs in your vehicle display
may vary from actual road speed depending
on the version of your current
navigation map.
Trip 1 or Trip 2, and Average Fuel
Economy :
Shows the current distance
traveled, in either kilometers (km) or
miles (mi), since the trip odometer was last
reset.
The Average Fuel Economy display shows
the approximate average liters per
100 kilometers (L/100 km), kilometers per
liter (km/L), or miles per gallon (mpg). This
number is calculated based on the value
recorded since the last time this menu item
was reset. This number reflects only the
approximate average fuel economy that the
vehicle has right now, and will change as
driving conditions change.
Press the thumbwheel while this display is
active to reset the trip odometer and the
average fuel economy.
Fuel Range : Shows the approximate
distance the vehicle can be driven without
refueling. LOW will be displayed when the
vehicle is low on fuel. 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.
Timer :
This display can be used as a timer.
To start the timer, press the thumbwheel
while this display is active. The display will
show the amount of time that has passed
since the timer was last reset. To stop the
timer, press the thumbwheel briefly while
this display is active and the timer is
running.
Press the thumbwheel while this display is
active to reset the timer.
Oil Life : Shows an estimate of the oil's
remaining useful life. If REMAINING OIL
LIFE 99% is displayed, that means 99% of
the current oil life remains.
When the remaining oil life is low, the
CHANGE ENGINE OIL SOON message will
appear on the display. The oil should be
changed as soon as possible. See Engine Oil
0 330. In addition to the engine oil life
system monitoring the oil life, additional
maintenance is recommended. See
Maintenance Schedule 0409.
The Oil Life display must be reset after each
oil change. It will not reset itself. Do not
reset the Oil Life display at any time other

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Infotainment System 197
U.S. Patents at the following address
www.immersion.com/patent-marking.html
and other patents pending.
Bose
Bose AudioPilot and Bose Centerpoint
surround are registered trademarks of Bose
Corporation in the U.S. and other countries.
HD Radio Technology
HD Radio Technology manufactured under
license from iBiquity Digital Corporation. U.S.
and Foreign patents. HD Radio and the HD,
HD Radio, and“Arc”logos are proprietary
trademarks of iBiquity Digital Corp.
Bluetooth
The Bluetooth word mark and logos are
owned by the Bluetooth SIG, Inc. and any
use of such marks by General Motors is
under license. Other trademarks and trade
names are those of their respective owners. Java
Java is a registered trademark of Oracle
and/or its affiliates.
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GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Climate Controls 209
The solar sensor, on top of the instrument
panel near the windshield, monitors the
solar heat.
The climate control system uses the sensor
information to adjust the temperature, fan
speed, recirculation, and air delivery mode
for best comfort.
Do not cover the sensor; otherwise the
automatic climate control system may not
work properly.
Air Vents
Use the sliding knobs on the center and side
air vents to change the direction of the
airflow.
Air vents blow warm air on the side
windows in cold weather. If Floor, Defog,
or Defrost modes are selected, a small
amount of air will come from the vents
close to the window.
To close the front a/c vents, move the
sliding knobs to the full down position.
To close the rear a/c vents, move the sliding
knobs to the full inboard position.Operation Tips
.Clear away any ice, snow, or leaves from
air inlets at the base of the windshield
that could block the flow of air into the
vehicle.
.Clear snow off the hood to improve
visibility and help decrease moisture
drawn into the vehicle.
.Keep the path under the front seats clear
of objects to help circulate the air inside
of the vehicle more effectively.
.Use of non-GM approved hood deflectors
can adversely affect the performance of
the system. Check with your dealer
before adding equipment to the outside
of the vehicle.
.Do not attach any devices to the air vent
slats. This will restrict airflow and may
cause damage to the air vents.
Maintenance
Passenger Compartment Air Filter
The filter reduces the dust, pollen, and other
airborne irritants from outside air that is
pulled into the vehicle.
The filter should be replaced as part of
routine scheduled maintenance. See
Maintenance Schedule
0409. To find out
what type of filter to use, see Maintenance
Replacement Parts 0419.
1. Open the lower glove box door
completely.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
210 Climate Controls
2. Push the dampener arm to the left untilit releases the glovebox.
3. Press the sides of the glove box doorinward and rotate the door downward to
remove.
4. Pull lever on left side of the filter doorand slide left, then remove the door.
Remove the old filter.
5. Install the new air filter.
6. Reinstall the filter door.
7. Reverse the steps to reinstall the glove box.
See your dealer if additional assistance is
needed.
Service
All vehicles have a label underhood that
identifies the refrigerant used in the vehicle.
The refrigerant system should only be
serviced by trained and certified technicians.
The air conditioning evaporator should never
be repaired or replaced by one from a
salvage vehicle. It should only be replaced
by a new evaporator to ensure proper and
safe operation.
During service, all refrigerants should be
reclaimed with proper equipment. Venting
refrigerants directly to the atmosphere is
harmful to the environment and may also
create unsafe conditions based on
inhalation, combustion, frostbite, or other
health-based concerns.
The air conditioning system requires periodic
maintenance. See Maintenance Schedule
0 409.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
212 Driving and Operating
Filling a Portable Fuel Container . . . . . . . 288
Trailer Towing
General Towing Information . . . . . . . . . . 288
Driving Characteristics andTowing Tips . . . . . . . . . . . . . . . . . . . . . . . . . 288
Trailer Towing . . . . . . . . . . . . . . . . . . . . . . . . . 293
Towing Equipment . . . . . . . . . . . . . . . . . . . . 296
Trailer Sway Control (TSC) . . . . . . . . . . . . 306
Trailering App . . . . . . . . . . . . . . . . . . . . . . . . . 307
Conversions and Add-Ons
Add-On Electrical Equipment . . . . . . . . . . . 318
Adding a Snow Plow or Similar Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . 318
Pickup Conversion to Chassis Cab . . . . . 320
Driving Information
Driving for Better Fuel Economy
Driving habits can affect fuel mileage. Here
are some driving tips to get the best fuel
economy possible:
.Set the climate controls to the desired
temperature after the engine is started,
or turn them off when not required.
.Avoid fast starts and accelerate smoothly.
.Brake gradually and avoid abrupt stops.
.Avoid idling the engine for long periods
of time.
.When road and weather conditions are
appropriate, use cruise control.
.Always follow posted speed limits or
drive more slowly when conditions
require.
.Keep vehicle tires properly inflated.
.Combine several trips into a single trip.
.Replace the vehicle's tires with the same
TPC Spec number molded into the tire's
sidewall near the size.
.Follow recommended scheduled
maintenance.
Distracted Driving
Distraction comes in many forms and can
take your focus from the task of driving.
Exercise good judgment and do not let other
activities divert your attention away from
the road. Many local governments have
enacted laws regarding driver distraction.
Become familiar with the local laws in
your area.
To avoid distracted driving, keep your eyes
on the road, keep your hands on the
steering wheel, and focus your attention on
driving.
.Do not use a phone in demanding driving
situations. Use a hands-free method to
place or receive necessary phone calls.
.Watch the road. Do not read, take notes,
or look up information on phones or
other electronic devices.
.Designate a front seat passenger to
handle potential distractions.
.Become familiar with vehicle features
before driving, such as programming
favorite radio stations and adjusting
climate control and seat settings. Program
all trip information into any navigation
device prior to driving.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Driving and Operating 219
After operation in mud or sand, have the
brake linings cleaned and checked. These
substances can cause glazing and uneven
braking. Check the body structure, driveline,
steering, suspension, wheels, tires, and
exhaust system for damage and check the
fuel lines and cooling system for any
leakage.
More frequent maintenance service is
required. See theMaintenance Schedule
0 409.
Driving on Wet Roads
Rain and wet roads can reduce vehicle
traction and affect your ability to stop and
accelerate. Always drive slower in these
types of driving conditions and avoid driving
through large puddles and deep-standing or
flowing water.
{Warning
Wet brakes can cause crashes. They
might not work as well in a quick stop
and could cause pulling to one side. You
could lose control of the vehicle.
(Continued)
Warning (Continued)
After driving through a large puddle of
water or a car/vehicle wash, lightly apply
the brake pedal until the brakes work
normally.
Flowing or rushing water creates strong
forces. Driving through flowing water
could cause the vehicle to be carried
away. If this happens, you and other
vehicle occupants could drown. Do not
ignore police warnings and be very
cautious about trying to drive through
flowing water.
Hydroplaning
Hydroplaning is dangerous. Water can build
up under the vehicle's tires so they actually
ride on the water. This can happen if the
road is wet enough and you are going fast
enough. When the vehicle is hydroplaning, it
has little or no contact with the road.
There is no hard and fast rule about
hydroplaning. The best advice is to slow
down when the road is wet.
Other Rainy Weather Tips
Besides slowing down, other wet weather
driving tips include:
.Allow extra following distance.
.Pass with caution.
.Keep windshield wiping equipment in
good shape.
.Keep the windshield washer fluid reservoir
filled.
.Have good tires with proper tread depth.
SeeTires 0360.
.Turn off cruise control.
Hill and Mountain Roads
Driving on steep hills or through mountains
is different than driving on flat or rolling
terrain. Tips include:
.Keep the vehicle serviced and in good
shape.
.Check all fluid levels and brakes, tires,
cooling system, and transmission.
.Shift to a lower gear when going down
steep or long hills.