2021 GMC SIERRA warning light

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 371
{Warning
Overinflating a tire could cause the tire
to rupture and you or others could be
injured. Do not exceed the maximum
pressure listed on the tire sidewall. See
Tire Sidewall Labeling0362 and
Vehicle Load Limits 0222.
If the tire is overinflated by more than
35 kPa (5 psi), the horn will sound multiple
times and the turn signal lamp will continue
to flash for several seconds after filling
stops. To release and correct the pressure,
while the turn signal lamp is still flashing,
briefly press the center of the valve stem.
When the recommended pressure is reached,
the horn sounds once.
If the turn signal lamp does not flash within
15 seconds after starting to inflate the tire,
the tire fill alert has not been activated or is
not working.
If the hazard warning flashers are on, the
tire fill alert visual feedback will not work
properly. The TPMS will not activate the tire fill alert
properly under the following conditions:.There is interference from an external
device or transmitter.
.The air pressure from the inflation device
is not sufficient to inflate the tire.
.There is a malfunction in the TPMS.
.There is a malfunction in the horn or turn
signal lamps.
.The identification code of the TPMS
sensor is not registered to the system.
.The battery of the TPMS sensor is low.
If the tire fill alert does not operate due to
TPMS interference, move the vehicle about
1 m (3 ft) back or forward and try again.
If the tire fill alert feature is not working,
use a tire pressure gauge.
TPMS Sensor Matching Process
Each TPMS sensor has a unique
identification code. The identification code
needs to be matched to a new tire/wheel
position after rotating the vehicle’s tires or
replacing one or more of the TPMS sensors.
Also, the TPMS sensor matching process
should be performed after replacing a spare
tire with a road tire containing the TPMS
sensor. The malfunction light and the DIC
message should go off at the next ignition cycle. The sensors are matched to the tire/
wheel positions, using a TPMS relearn tool,
in the following order: driver side front tire,
passenger side front tire, passenger side rear
tire, and driver side rear. See your dealer for
service or to purchase a relearn tool.
A TPMS relearn tool can also be purchased.
See Tire Pressure Monitor Sensor Activation
Tool at www.gmtoolsandequipment.com or
call 1-800-GM TOOLS (1-800-468-6657).
There are two minutes to match the first
tire/wheel position, and five minutes overall
to match all four tire/wheel positions. If it
takes longer, the matching process stops
and must be restarted.
The TPMS sensor matching process is:
1. Set the parking brake.
2. Turn the ignition on without starting the vehicle.
3. Uplevel DIC Only: Make sure the Tire Pressure info page option is turned on.
The info pages on the DIC can be turned
on and off through the Options menu.
See Driver Information Center (DIC) (Base
Level) 0124 or
Driver Information Center (DIC) (Midlevel
and Uplevel) 0125.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 375
Lightly coat the inner diameter of the
wheel hub opening with wheel bearing
grease after a wheel change or tire
rotation to prevent corrosion or rust
build-up.
{Warning
Do not apply grease to the wheel
mounting surface, wheel conical
seats, or the wheel nuts or bolts.
Grease applied to these areas could
cause a wheel to become loose or
come off, resulting in a crash.
When It Is Time for New Tires
Factors, such as maintenance, temperatures,
driving speeds, vehicle loading, and road
conditions affect the wear rate of the tires.
Treadwear indicators are one way to tell
when it is time for new tires. Treadwear
indicators appear when the tires have only
1.6 mm (1/16 in) or less of tread remaining.
See Tire Inspection 0373 and
Tire Rotation 0374 for additional
information.
The rubber in tires ages over time. This also
applies to the spare tire, if the vehicle has
one, even if it is never used. Multiple factors
including temperatures, loading conditions,
and inflation pressure maintenance affect
how fast aging takes place. GM recommends
that tires, including the spare if equipped,
be replaced after six years, regardless of
tread wear. To identify the age of a tire, use
the tire manufacture date, which is the last four digits of the DOT Tire Identification
Number (TIN) molded into one side of the
tire sidewall. The last four digits of the TIN
indicate the tire manufactured date. The
first two digits represent the week and the
last two digits, the year. For example, the
third week of the year 2020 would have a
4-digit DOT date of 0320. Week 01 is the
first full week (Sunday through Saturday) of
each year.
Vehicle Storage
Tires age when stored normally mounted on
a parked vehicle. Park a vehicle that will be
stored for at least a month in a cool, dry,
clean area away from direct sunlight to slow
aging. This area should be free of grease,
gasoline, or other substances that can
deteriorate rubber.
Parking for an extended period can cause
flat spots on the tires that may result in
vibrations while driving. When storing a
vehicle for at least a month, remove the
tires or raise the vehicle to reduce the
weight from the tires.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 377
If the vehicle tires must be replaced
with a tire that does not have a TPC
Spec number, make sure they are the
same size, load range, speed rating, and
construction (radial) as the original
tires.
The Tire and Loading Information label
indicates the original equipment tires
on the vehicle. SeeVehicle Load Limits
0 222.
Different Size Tires and Wheels
If wheels or tires are installed that are a
different size than the original equipment
wheels and tires, vehicle performance,
including its braking, ride and handling
characteristics, stability, and resistance to
rollover may be affected. If the vehicle has
electronic systems such as antilock brakes,
rollover airbags, traction control, electronic
stability control, or All-Wheel Drive, the
performance of these systems can also be
affected.
{Warning
If different sized wheels are used, there
may not be an acceptable level of
performance and safety if tires not
recommended for those wheels are
selected. This increases the chance of a
crash and serious injury. Only use GM
specific wheel and tire systems developed
for the vehicle, and have them properly
installed by a GM certified technician.
See Buying New Tires 0376 and
Accessories and Modifications 0323.
Uniform Tire Quality Grading
The following information relates to the
system developed by the United States
National Highway Traffic Safety
Administration (NHTSA), which grades
tires by treadwear, traction, and
temperature performance. This applies
only to vehicles sold in the United
States. The grades are molded on the
sidewalls of most passenger car tires.
The Uniform Tire Quality Grading
(UTQG) system does not apply to deep
tread, winter tires, compact spare tires, tires with nominal rim diameters of
10 to 12 inches (25 to 30 cm), or to some
limited-production tires.
While the tires available on General
Motors passenger cars and light trucks
may vary with respect to these grades,
they must also conform to federal
safety requirements and additional
General Motors Tire Performance
Criteria (TPC) standards.
Quality grades can be found where
applicable on the tire sidewall between
tread shoulder and maximum section
width. For example:Treadwear 200 Traction AA Temperature A
All Passenger Car Tires Must Conform to
Federal Safety Requirements In Addition
To These Grades.
Treadwear
The treadwear grade is a comparative
rating based on the wear rate of the
tire when tested under controlled
conditions on a specified government
test course. For example, a tire graded
150 would wear one and one-half (1½)

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
378 Vehicle Care
times as well on the government course
as a tire graded 100. The relative
performance of tires depends upon the
actual conditions of their use, however,
and may depart significantly from the
norm due to variations in driving habits,
service practices and differences in road
characteristics and climate.
Traction
The traction grades, from highest to
lowest, are AA, A, B, and C. Those
grades represent the tire's ability to
stop on wet pavement as measured
under controlled conditions on specified
government test surfaces of asphalt and
concrete. A tire marked C may have
poor traction performance. Warning:
The traction grade assigned to this tire
is based on straight-ahead braking
traction tests, and does not include
acceleration, cornering, hydroplaning,
or peak traction characteristics.Temperature
The temperature grades are A (the
highest), B, and C, representing the
tire's resistance to the generation of
heat and its ability to dissipate heat
when tested under controlled conditions
on a specified indoor laboratory test
wheel. Sustained high temperature can
cause the material of the tire to
degenerate and reduce tire life, and
excessive temperature can lead to
sudden tire failure. The grade C
corresponds to a level of performance
which all passenger car tires must meet
under the Federal Motor Safety
Standard No. 109. Grades B and A
represent higher levels of performance
on the laboratory test wheel than the
minimum required by law. Warning:
The temperature grade for this tire is
established for a tire that is properly
inflated and not overloaded. Excessive
speed, underinflation, or excessive
loading, either separately or in
combination, can cause heat buildup
and possible tire failure.Wheel Alignment and Tire
Balance
The tires and wheels were aligned and
balanced at the factory to provide the
longest tire life and best overall
performance. Adjustments to wheel
alignment and tire balancing are not
necessary on a regular basis. Consider an
alignment check if there is unusual tire wear
or the vehicle is significantly pulling to one
side or the other. Some slight pull to the
left or right, depending on the crown of the
road and/or other road surface variations
such as troughs or ruts, is normal. If the
vehicle is vibrating when driving on a
smooth road, the tires and wheels may
need to be rebalanced. See your dealer for
proper diagnosis.
Wheel Replacement
Replace any wheel that is bent, cracked,
or badly rusted or corroded. If wheel nuts
keep coming loose, the wheel, wheel bolts,
and wheel nuts should be replaced. If the
wheel leaks air, replace it. Some aluminum
wheels can be repaired. See your dealer if
any of these conditions exist.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 393
4. Turn the ignition off on both vehicles.Unplug unnecessary accessories plugged
into the accessory power outlets. Turn
off the radio and all the lamps that are
not needed. This will avoid sparks and
help save both batteries. And it could
save the radio!
5. Open the hood on the other vehicle and locate the positive (+) and negative (−)
terminal locations on that vehicle.
The positive (+) terminal is under a red
plastic cover at the positive battery post.
To uncover the positive (+) terminal,
open the red plastic cover.
For more information on the location of
the remote positive (+) and remote
negative (−) terminals, see Engine
Compartment Overview 0325.
{Warning
An electric fan can start up even when
the engine is not running and can injure
you. Keep hands, clothing, and tools
away from any underhood electric fan.
{Warning
Using a match near a battery can cause
battery gas to explode. People have been
hurt doing this, and some have been
blinded. Use a flashlight if you need
more light.
Battery fluid contains acid that can burn
you. Do not get it on you. If you
accidentally get it in your eyes or on
your skin, flush the place with water and
get medical help immediately.
{Warning
Fans or other moving engine parts can
injure you badly. Keep your hands away
from moving parts once the engine is
running.
6. Check that the jumper cables do not have loose or missing insulation. If they
do, you could get a shock. The vehicles
could be damaged too.
Before you connect the cables, here are
some basic things you should know.
Positive (+) will go to positive (+) or to a
remote positive (+) terminal if the vehicle has one. Negative (−) will go to a
heavy, unpainted metal engine part or to
a remote negative (−) terminal if the
vehicle has one.
Do not connect positive (+) to negative
(−) or you will get a short that would
damage the battery and maybe other
parts too. And do not connect the
negative (−) cable to the negative (−)
terminal on the dead battery because
this can cause sparks.
7. Connect one end of the red positive (+) cable to the remote positive (+) terminal
of the vehicle with the discharged
battery.
8. Do not let the other end touch metal. Connect it to the positive (+) terminal of
the good battery. Use a remote
positive (+) terminal if the vehicle
has one.
9. Connect one end of the black negative (−) cable to the negative (−) terminal of
the good battery. Use a remote negative
(−) terminal if the vehicle has one.
Do not let the other end touch anything
until the next step.
10. Connect the other end of the negative (−) cable to the remote negative (−)
terminal to the discharged battery.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
398 Vehicle Care
Caution
Do not tow this vehicle with two wheels
on the ground, or vehicle damage could
occur. This damage would not be covered
by the vehicle warranty.
Dolly towing this vehicle is not allowed with
either the front or the rear tires on the
ground for two-wheel drive or four-wheel
drive, regardless of transfer case.
Appearance Care
Exterior Care
Locks
Locks are lubricated at the factory. Use a
de-icing agent only when absolutely
necessary, and have the locks greased after
using. See Recommended Fluids and
Lubricants 0418.
Washing the Vehicle
To preserve the vehicle's finish, wash it
often and out of direct sunlight.
{Warning
Do not power wash any part of the
vehicle’s interior, including the vinyl floor
covering. This could damage safety and
other systems in the vehicle, which
would not be covered by the vehicle
warranty.
Caution
Do not use petroleum-based, acidic,
or abrasive cleaning agents as they can
damage the vehicle's paint, metal,
or plastic parts. If damage occurs, it
would not be covered by the vehicle
warranty. Approved cleaning products can
be obtained from your dealer. Follow all
manufacturer directions regarding correct
product usage, necessary safety
precautions, and appropriate disposal of
any vehicle care product.
Caution
Avoid using high-pressure washes closer
than 30 cm (12 in) to the surface of the
vehicle. Use of power washers exceeding
8 274 kPa (1,200 psi) can result in
damage or removal of paint and decals.
Cleaning Underhood Components
Caution
Do not power wash any component
under the hood that has this
e
symbol.
This could cause damage that would not
be covered by the vehicle warranty.
Solvents or aggressive cleaners may harm
underhood components. The usages of these
chemicals should be avoided.
Recommend water only.
A pressure washer may be used, but care
must be utilized. The following criteria must
be followed:
.Water pressure must be kept below
14 000 KPa (2,000 PSI).
.Water temperature must be below 80 °C
(180 °F).

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./Cana-
da/Mexico-14632426) - 2021 - CRC - 11/5/20
448 Index
IndexA
Accessories and Modifications . . . . . . . . . . . 323
Accessory Power . . . . . . . . . . . . . . . . . . . . . . . . . 236
Active Fuel Management . . . . . . . . . . . . . . . . 237
Adaptive Cruise Control . . . . . . . . . . . . . . . . . . 256
Add-On Electrical Equipment . . . . . . . . . . . . . .318
Adding a Snow Plow or SimilarEquipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .318
Additional Information OnStar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441
Additional Maintenance and Care . . . . . . . . .415
Adjustments Lumbar, Front Seats . . . . . . . . . . . . . . . . . . . . 48
Agreements
Trademarks and License . . . . . . . . . . . . . . . 195
Air Cleaner/Filter, Engine . . . . . . . . . . . . . . . . 334
Air Conditioning . . . . . . . . . . . . . . . . . . . . 204, 206
Air Filter Life System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
Air Filter, Passenger Compartment . . . . . . . 209
Air Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
Airbag System Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
How Does an Airbag Restrain? . . . . . . . . . . 64
Passenger Sensing System . . . . . . . . . . . . . . 66
What Makes an Airbag Inflate? . . . . . . . . . 64
What Will You See after an AirbagInflates? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Airbag System (cont'd)
When Should an Airbag Inflate? . . . . . . . . 63
Where Are the Airbags? . . . . . . . . . . . . . . . . 62
Airbags Adding Equipment to the Vehicle . . . . . . . 69
Passenger Status Indicator . . . . . . . . . . . . . . 114
Readiness Light . . . . . . . . . . . . . . . . . . . . . . . . . 114
Servicing Airbag-Equipped Vehicles . . . . . . 69
System Check . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Alarm Vehicle Security . . . . . . . . . . . . . . . . . . . . . . . . . 31
Alert
Lane Change . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Side Blind Zone (SBZA) . . . . . . . . . . . . . . . . . 280
All-Season Tires . . . . . . . . . . . . . . . . . . . . . . . . . . 361
All-Terrain Tires . . . . . . . . . . . . . . . . . . . . . . . . . . 362
AM-FM Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Antenna Fixed Mast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Multi-band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Antilock Brake System (ABS) . . . . . . . . . . . . . 246
Warning Light . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Appearance Care Exterior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398
Interior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403
Apple CarPlay and Android Auto . . . . . . . . . .185

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./Cana-
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Index 449
Assistance Program, Roadside . . . . . . . . . . . . .431
Assistance Systems for Driving . . . . . . . . . . 274
Assistance Systems for Parking andBacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Audio Bluetooth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Auto Stop
Stop/Start System . . . . . . . . . . . . . . . . . . . . . 233
Automatic Dimming Mirrors . . . . . . . . . . . . . . . . . . . . . . . 37
Door Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Emergency Braking (AEB) . . . . . . . . . . . . . . 277
Headlamp System . . . . . . . . . . . . . . . . . . . . . 142
Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Transmission Fluid . . . . . . . . . . . . . . . . . . . . . 333
Automatic Transmission
Manual Mode . . . . . . . . . . . . . . . . . . . . . . . . . 241
Shift Lock Control Function Check . . . . . . 347
Auxiliary Roof Mounted Lamp . . . . . . . . . . . . . . . . . . . 144
Auxiliary Jack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Avoiding Untrusted Media Devices . . . . . . . .158
Axle, Front . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346
Axle, Rear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346B
Battery
Exterior Lighting Battery Saver . . . . . . . . 147
Load Management . . . . . . . . . . . . . . . . . . . . . 146
Power Protection . . . . . . . . . . . . . . . . . . . . . . 147
Battery - North America . . . . . . . . . . . . .343, 391
Blade Replacement, Wiper . . . . . . . . . . . . . . . 348
Blind Spot Mirrors . . . . . . . . . . . . . . . . . . . . . . . . .37
Bluetooth Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 180, 181
Bluetooth Audio . . . . . . . . . . . . . . . . . . . . . . . . . 162
Brake Electric Boost . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Parking, Electric . . . . . . . . . . . . . . . . . . . . . . . . 247
System Warning Light . . . . . . . . . . . . . . . . . . 117
Brake Pad Life System . . . . . . . . . . . . . . . . . . . 342
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .341 Antilock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Assist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
Pad Life System . . . . . . . . . . . . . . . . . . . . . . . 342
Braking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 Automatic Emergency (AEB) . . . . . . . . . . . 277
Braking System
Front Pedestrian (FPB) . . . . . . . . . . . . . . . . . 278
Break-In, New Vehicle . . . . . . . . . . . . . . . . . . . . 228 Bulb Replacement
Center High-Mounted Stoplamp
(CHMSL) and Cargo Lamp . . . . . . . . . . . . 352
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . 350
Headlamp Aiming . . . . . . . . . . . . . . . . . . . . . . 350
Headlamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Headlamps, Front Turn Signal, Sidemarker, and Parking Lamps . . . . . . 350
License Plate Lamps . . . . . . . . . . . . . . . . . . . 352
Taillamps, Turn Signal, Stoplamps, and Back-up Lamps . . . . . . . . . . . . . . . . . . 351
Buying New Tires . . . . . . . . . . . . . . . . . . . . . . . . 376
C
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
California Perchlorate Materials Requirements . . . 322
California Proposition 65 Warning . . . . . . . . . . . . . . . . . . .322, 343, 391, Back Cover
Canadian Vehicle Owners . . . . . . . . . . . . . . . . . . .2
Capacities and Specifications . . . . . . . . . . . . . 424
Carbon Monoxide
Engine Exhaust . . . . . . . . . . . . . . . . . . . . . . . . 238
Tailgate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Winter Driving . . . . . . . . . . . . . . . . . . . . . . . . . 220
Cargo Tie-Downs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97