2021 GMC SIERRA Owner's Manual

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
320 Driving and Operating
For example, adding a 318 kg (700 lb) snow
plow actually adds more than 318 kg (700 lb)
to the front axle. Using the formula, if the
snow plow is 122 cm (4 ft) in front of the
front axle and the wheelbase is 305 cm
(10 ft), then:IW = 318 kg (700 lb)
IA = 122 cm (4 ft)
IW.B. = 305 cm (10 ft)
(W x (A + W.B.)/W.B. = (318 x (122 + 305))/305
= 445 kg (980 lb)
This means if the front axle reserve capacity
is more than 445 kg (980 lb), the snow plow
could be added without exceeding the
front GAWR.
Heavier equipment can be added on the
front of the vehicle if less cargo or fewer
passengers are carried, or by positioning
cargo toward the rear. This reduces the load
on the front. However, the front GAWR, rear
GAWR, and Gross Vehicle Weight
Rating (GVWR) must never be exceeded.{Warning
On some vehicles that have certain front
mounted equipment, such as a snow
plow, it may be possible to load the front
axle to the front Gross Axle Weight
Rating (GAWR) but not have enough
weight on the rear axle to have proper
braking performance. If the brakes cannot
work properly, the vehice could crash.
Always follow the snow plow
manufacturer or installer's
recommendation for rear ballast to
ensure a proper front and rear weight
distribution ratio. Maintaining a proper
front and rear weight distribution ratio is
necessary to provide proper braking
performance.
See your dealer for additional advice and
information about using a snow plow on the
vehicle. Also, see Vehicle Load Limits 0222.
Pickup Conversion to Chassis Cab
We are aware that some vehicle owners
might consider having the pickup box
removed and a commercial or recreational
body installed. Owners should be aware
that, as manufactured, there are differences
between a chassis cab and a pickup with the
box removed which could affect vehicle
safety. The components necessary to adapt
a pickup to permit its safe use with a
specialized body should be installed by the
body builder.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 321
Vehicle Care
General Information
General Information . . . . . . . . . . . . . . . . . . . 322
California Proposition 65 Warning . . . . . 322
California Perchlorate MaterialsRequirements . . . . . . . . . . . . . . . . . . . . . . . . 322
Accessories and Modifications . . . . . . . . . 323
Vehicle Checks
Doing Your Own Service Work . . . . . . . . . 323
Hood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Engine Compartment Overview . . . . . . . . 325
Engine Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Engine Oil Life System . . . . . . . . . . . . . . . . . 332
Automatic Transmission Fluid . . . . . . . . . . 333
Engine Air Filter Life System . . . . . . . . . . . 333
Engine Air Cleaner/Filter . . . . . . . . . . . . . . . 334
Cooling System . . . . . . . . . . . . . . . . . . . . . . . . 335
Engine Overheating . . . . . . . . . . . . . . . . . . . 338
Overheated Engine Protection Operating Mode . . . . . . . . . . . . . . . . . . . . . 340
Engine Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
Washer Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . 340
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
Brake Pad Life System . . . . . . . . . . . . . . . . . 342
Brake Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
Battery - North America . . . . . . . . . . . . . . . 343 Four-Wheel Drive . . . . . . . . . . . . . . . . . . . . . . 346
Front Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346
Rear Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346
Starter Switch Check . . . . . . . . . . . . . . . . . . 347
Automatic Transmission Shift Lock
Control Function Check . . . . . . . . . . . . . . 347
Ignition Transmission Lock Check . . . . . . 347
Park Brake and P (Park) Mechanism Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
Wiper Blade Replacement . . . . . . . . . . . . . 348
Glass Replacement . . . . . . . . . . . . . . . . . . . . 348
Windshield Replacement . . . . . . . . . . . . . . 348
Gas Strut(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
Headlamp Aiming
Front Headlamp Aiming . . . . . . . . . . . . . . . 350
Bulb Replacement
Bulb Replacement . . . . . . . . . . . . . . . . . . . . . 350
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . 350
LED Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Headlamps, Front Turn Signal, Sidemarker, and Parking Lamps . . . . . . 350
Taillamps, Turn Signal, Stoplamps, and Back-Up Lamps . . . . . . . . . . . . . . . . . . . . . . . 351
Center High-Mounted Stoplamp (CHMSL) and Cargo Lamp . . . . . . . . . . . . 352
License Plate Lamp . . . . . . . . . . . . . . . . . . . . 352
Electrical System
Electrical System Overload . . . . . . . . . . . . . 352
Fuses and Circuit Breakers . . . . . . . . . . . . . 353
Engine Compartment Fuse Block . . . . . . . 353
Instrument Panel Fuse Block (Left) . . . . . 357
Instrument Panel Fuse Block (Right) . . . 358
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360
All-Season Tires . . . . . . . . . . . . . . . . . . . . . . . . 361
Winter Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
All-Terrain Tires . . . . . . . . . . . . . . . . . . . . . . . 362
Tire Sidewall Labeling . . . . . . . . . . . . . . . . . 362
Tire Designations . . . . . . . . . . . . . . . . . . . . . . 364
Tire Terminology and Definitions . . . . . . 365
Tire Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . 367
Tire Pressure Monitor System . . . . . . . . . 368
Tire Pressure Monitor Operation . . . . . . 369
Tire Inspection . . . . . . . . . . . . . . . . . . . . . . . . . 373
Tire Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . 374
When It Is Time for New Tires . . . . . . . . 375
Buying New Tires . . . . . . . . . . . . . . . . . . . . . 376
Different Size Tires and Wheels . . . . . . . . 377
Uniform Tire Quality Grading . . . . . . . . . . 377
Wheel Alignment and Tire Balance . . . . 378
Wheel Replacement . . . . . . . . . . . . . . . . . . . 378
Tire Chains . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
If a Tire Goes Flat . . . . . . . . . . . . . . . . . . . . . 380
Tire Changing . . . . . . . . . . . . . . . . . . . . . . . . . . 381
Full-Size Spare Tire . . . . . . . . . . . . . . . . . . . . 390

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
322 Vehicle Care
Jump Starting
Jump Starting - North America . . . . . . . . 391
Towing the Vehicle
Towing the Vehicle . . . . . . . . . . . . . . . . . . . . 394
Recreational Vehicle Towing . . . . . . . . . . . 395
Appearance Care
Exterior Care . . . . . . . . . . . . . . . . . . . . . . . . . . 398
Interior Care . . . . . . . . . . . . . . . . . . . . . . . . . . 403
Floor Mats . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
General Information
For service and parts needs, visit your
dealer. You will receive genuine GM parts
and GM-trained and supported service
people.
Genuine GM parts have one of these marks:
California Proposition 65 Warning
{Warning
Most motor vehicles, including this one,
as well as many of its service parts and
fluids, contain and/or emit chemicals
known to the State of California to cause(Continued)
Warning (Continued)
cancer and birth defects or other
reproductive harm. Engine exhaust, many
parts and systems, many fluids, and
some component wear by-products
contain and/or emit these chemicals. For
more information go to
www.P65Warnings.ca.gov/
passenger-vehicle.
See Battery - North America 0343 and
Jump Starting - North America 0391 and the
back cover.
California Perchlorate Materials
Requirements
Certain types of automotive applications,
such as airbag initiators, seat belt
pretensioners, and lithium batteries
contained in electronic keys, may contain
perchlorate materials. Perchlorate Material –
special handling may apply. See
www.dtsc.ca.gov/hazardouswaste/
perchlorate.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 323
Accessories and Modifications
Adding non-dealer accessories or making
modifications to the vehicle can affect
vehicle performance and safety, including
such things as airbags, braking, stability,
ride and handling, emissions systems,
aerodynamics, durability, and electronic
systems like antilock brakes, traction control,
and stability control. These accessories or
modifications could even cause malfunction
or damage not covered by the vehicle
warranty.
Damage to suspension components caused
by modifying vehicle height outside of
factory settings will not be covered by the
vehicle warranty.
Damage to vehicle components resulting
from modifications or the installation or use
of non-GM certified parts, including control
module or software modifications, is not
covered under the terms of the vehicle
warranty and may affect remaining
warranty coverage for affected parts.
GM Accessories are designed to complement
and function with other systems on the
vehicle. See your dealer to accessorize the
vehicle using genuine GM Accessories
installed by a dealer technician.Also, see
Adding Equipment to the
Airbag-Equipped Vehicle 069.
Vehicle Checks
Doing Your Own Service Work
{Warning
It can be dangerous to work on your
vehicle if you do not have the proper
knowledge, service manual, tools,
or parts. Always follow owner’s manual
procedures and consult the service
manual for your vehicle before doing any
service work.
If doing some of your own service work, use
the proper service manual. It tells you much
more about how to service the vehicle than
this manual can. To order the proper service
manual, see Publication Ordering
Information 0435.
This vehicle has an airbag system. Before
attempting to do your own service work,
see Servicing the Airbag-Equipped Vehicle
0 69. If equipped with remote vehicle start, open
the hood before performing any service
work to prevent remote starting the vehicle
accidentally. See
Remote Vehicle Start 020.
Keep a record with all parts receipts and list
the mileage and the date of any service
work performed. See Maintenance Records
0 422.Caution
Even small amounts of contamination can
cause damage to vehicle systems. Do not
allow contaminants to contact the fluids,
reservoir caps, or dipsticks.
Hood
{Warning
For vehicles with auto engine stop/start,
turn the vehicle off before opening the
hood. If the vehicle is on, the engine will
start when the hood is opened. You or
others could be injured.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
324 Vehicle Care
{Warning
Components under the hood can get hot
from running the engine. To help avoid
the risk of burning unprotected skin,
never touch these components until they
have cooled, and always use a glove or
towel to avoid direct skin contact.
Clear any snow from the hood before
opening.
To open the hood: 1. Pull the hood release lever with the
isymbol. It is on the lower left side
of the instrument panel.
2. Go to the front of the vehicle and locate the secondary release lever under the
front center of the hood. Push the
secondary hood release lever to the right
to release.
3. After you have partially lifted the hood, the gas strut system will automatically
lift the hood and hold it in the fully
open position.
To close the hood: 1. Before closing the hood, be sure all filler caps are on properly, and all tools are
removed.
2. Pull the hood down until the strut system is no longer holding up the hood.
3. Allow the hood to fall. Check to make sure the hood is latched completely.
Repeat this process with additional force
if necessary.
{Warning
Do not drive the vehicle if the hood is
not latched completely. The hood could
open fully, block your vision, and cause a
crash. You or others could be injured.
Always close the hood completely before
driving. The Driver Information Center (DIC) will
display a message if the hood is not fully
closed, and the vehicle is moving. Stop and
turn off the vehicle, check the hood for
obstructions, and close the hood again.
Check to see if the message still appears on
the DIC.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 325
Engine Compartment Overview
2.7L L4 Engine (L3B)

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
326 Vehicle Care
1. Remote Negative (–) Location. SeeJump
Starting - North America 0391.
2. Positive (+) Terminal (Under Cover). See Jump Starting - North America 0391.
3. Battery - North America 0343.
4. Engine Compartment Fuse Block 0353.
5. Engine Cooling Fans (Out of View). See Cooling System 0335.
6. Engine Oil Fill Cap. See “When to Add
Engine Oil” underEngine Oil 0330.
7. Engine Oil Dipstick. See “Checking Engine
Oil” under Engine Oil 0330.
8. Coolant Surge Tank and Pressure Cap. See Cooling System 0335.
9. Engine Air Cleaner/Filter 0334.
10. Brake Fluid Reservoir. See Brake Fluid
0 343.
11. Windshield Washer Fluid Reservoir. See “Adding Washer Fluid” underWasher
Fluid 0340.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 327
4.3L V6 Engine (LV3)