2021 CHEVROLET SILVERADO 2500HD Emission

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Driving and Operating 297
If Tow/Haul Mode is off and this setting is
on for a Trailer Profile, each time the
ignition is turned on a reminder will appear
to turn on Tow/Haul Mode when the Trailer
Profile is active.
If Tow/Haul Mode is on and this setting is
on for a Trailer Profile, the reminder will not
appear when the Trailer Profile is active.
Trailer Length Indicator
Touch Trailer Length Indicator to view the
Trailer Length Indicator settings page. If this
setting is ON a guideline is displayed in the
side mirror camera view to indicate the rear
of the attached trailer. If this setting is OFF
the guideline will not be displayed.
This setting will default to OFF if the trailer
length indicator feature is not set up. See
"Towing Assistance" for details on the setup.
Conversions and Add-Ons
Add-On Electrical Equipment
{Warning
The Data Link Connector (DLC) is used for
vehicle service and Emission Inspection/
Maintenance testing. SeeMalfunction
Indicator Lamp (Check Engine Light) 0111.
A device connected to the DLC —such as
an aftermarket fleet or driver-behavior
tracking device —may interfere with
vehicle systems. This could affect vehicle
operation and cause a crash. Such devices
may also access information stored in the
vehicle’s systems.
Caution
Some electrical equipment can damage
the vehicle or cause components to not
work and would not be covered by the
vehicle warranty. Always check with your
dealer before adding electrical equipment.
Add-on equipment can drain the vehicle's
12-volt battery, even if the vehicle is not
operating. The vehicle has an airbag system. Before
attempting to add anything electrical to the
vehicle, see
Servicing the Airbag-Equipped
Vehicle 066 and
Adding Equipment to the Airbag-Equipped
Vehicle 066.
For information on wiring auxiliary switches,
see www.gmupfitter.com or contact your
dealer.
Adding a Snow Plow or Similar
Equipment
Caution
Do not exceed 72 km/h (45 mph) with a
snow plow mounted to the vehicle. The
vehicle could overheat and be damaged.
Before installing a snow plow on the vehicle,
follow these guidelines:
Caution
If the vehicle does not have the snow
plow prep package, RPO VYU, adding a
plow can damage the vehicle, and the
repairs would not be covered by the
vehicle warranty. Unless the vehicle was
built to carry a snow plow, do not add
(Continued)

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
302 Vehicle Care
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 066.
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 0408.
This vehicle has an airbag system. Before
attempting to do your own service work,
see Servicing the Airbag-Equipped Vehicle
0 66. 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
0 396.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
Turn the vehicle off before opening the
hood. If the engine is running with the
hood open, you or others could be
injured.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
320 Vehicle Care
Four-Wheel Drive
Transfer Case
When to Check Lubricant
Refer toMaintenance Schedule 0384 to
determine when to check the lubricant.
1. Fill Plug
2. Drain Plug
To get an accurate reading, the vehicle
should be on a level surface.
If the level is below the bottom of the fill
plug (1) hole, located on the transfer case,
some lubricant will need to be added. Add enough lubricant to raise the level to the
bottom of the fill plug (1) hole. Use care not
to overtighten the plug.
When to Change Lubricant
Refer to
Maintenance Schedule 0384 to
determine how often to change the
lubricant.
What to Use
Refer to Recommended Fluids and Lubricants
0 393 to determine what kind of lubricant
to use.
Front Axle
When to Check Lubricant
It is not necessary to regularly check the
front axle fluid unless a leak is suspected or
an unusual noise is heard. A fluid loss could
indicate a problem. Have it inspected and
repaired. This service can be complex. See
your dealer.
Do not directly power wash the transfer
case and/or front/rear axle output seals.
High pressure water can overcome the seals
and contaminate the fluid. Contaminated
fluid will decrease the life of the transfer
case and/or drive axles and should be
replaced.
Rear Axle
When to Check Lubricant
It is not necessary to regularly check the
rear axle fluid unless a leak is suspected or
an unusual noise is heard. A fluid loss could
indicate a problem. Have it inspected and
repaired. This service can be complex. See
your dealer.
Do not directly power wash the transfer
case and/or front/rear axle output seals.
High pressure water can overcome the seals
and contaminate the fluid. Contaminated
fluid will decrease the life of the transfer
case and/or drive axles and should be
replaced.
Noise Control System
NOISE EMISSIONS WARRANTY
General Motors LLC, warrants to the first
person who purchases this vehicle for
purposes other than resale and to each
subsequent purchaser that this vehicle as
manufactured by General Motors LLC, was
designed, built and equipped to conform at
the time it left General Motors LLC’s control
with all applicable U.S. EPA Noise Control
Regulations. This warranty covers this
vehicle as designed, built and equipped by

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Vehicle Care 321
General Motors LLC, and is not limited to
any particular part, component or system of
the vehicle manufactured by General Motors
LLC. Defects in design, assembly or in any
part, component or system of the vehicle as
manufactured by General Motors LLC, which,
at the time it left General Motors LLC’s
control, caused noise emissions to exceed
Federal standards, are covered by this
warranty for the life of the vehicle.
TAMPERING WITH NOISE CONTROL
SYSTEM PROHIBITED
Federal law prohibits the following acts or
the causing thereof:1. The removal or rendering inoperative by any person, other than for purposes of
maintenance, repair, or replacement, of
any device or element of design
incorporated into any new vehicle for
the purpose of noise control prior to its
sale or delivery to the ultimate purchaser
or while it is in use; or
2. the use of the vehicle after such device or element of design has been removed
or rendered inoperative by any person.
Among those acts presumed to constitute
tampering are the acts listed below. Insulation:
Removal of the noise shields or any
undercab insulation.
Engine:
Removal or rendering engine speed
governor, if so equipped, inoperative so as
to allow engine speed to exceed
manufacturer specifications.
Modification of the engine control system or
calibration.
Fan and Drive:.Removal of fan clutch or rendering clutch
inoperative.
.Removal of the fan shroud.
Air Intake:
.Removal of air cleaner silencer.
.Reversing air cleaner cover.
Exhaust:
.Removal of muffler, catalytic converter,
and/or resonator.
.Removal of exhaust pipes and exhaust
pipe clamps.
Starter Switch Check
{Warning
When you are doing this inspection, the
vehicle could move suddenly. If the
vehicle moves, you or others could be
injured.
1. Before starting this check, be sure there is enough room around the vehicle.
2. Apply both the parking brake and the regular brake.
Do not use the accelerator pedal, and be
ready to turn off the engine immediately
if it starts.
3. Try to start the engine in each gear. The vehicle should start only in P (Park) or
N (Neutral). If the vehicle starts in any
other position, contact your dealer for
service.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Service and Maintenance 383
Service and Maintenance
General Information
General Information . . . . . . . . . . . . . . . . . . . 383
Maintenance Schedule
Maintenance Schedule . . . . . . . . . . . . . . . . 384
Special Application Services
Special Application Services . . . . . . . . . . . 390
Additional Maintenance and Care
Additional Maintenance and Care . . . . . 390
Recommended Fluids, Lubricants, and
Parts
Recommended Fluids andLubricants . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
Maintenance Replacement Parts . . . . . . 394
Maintenance Records
Maintenance Records . . . . . . . . . . . . . . . . . 396
General Information
This maintenance section applies to vehicles
with a gasoline engine. For diesel engine
vehicles, see "Maintenance Schedule" in the
Duramax diesel supplement.
Your vehicle is an important investment.
This section describes the required
maintenance for the vehicle. Follow this
schedule to help protect against major
repair expenses resulting from neglect or
inadequate maintenance. It may also help to
maintain the value of the vehicle if it is
sold. It is the responsibility of the owner to
have all required maintenance performed.
Your dealer has trained technicians who can
perform required maintenance using genuine
replacement parts. They have up-to-date
tools and equipment for fast and accurate
diagnostics. Many dealers have extended
evening and Saturday hours, courtesy
transportation, and online scheduling to
assist with service needs.
Your dealer recognizes the importance of
providing competitively priced maintenance
and repair services. With trained technicians,
the dealer is the place for routine maintenance such as oil changes and tire
rotations and additional maintenance items
like tires, brakes, batteries, and wiper blades.
Caution
Damage caused by improper maintenance
can lead to costly repairs and may not be
covered by the vehicle warranty.
Maintenance intervals, checks,
inspections, recommended fluids, and
lubricants are important to keep the
vehicle in good working condition.
Do not have chemical flushes that are not
approved by GM performed on the
vehicle. The use of flushes, solvents,
cleaners, or lubricants that are not
approved by GM could damage the
vehicle, requiring expensive repairs that
are not covered by the vehicle warranty.
The Tire Rotation and Required Services are
the responsibility of the vehicle owner. It is
recommended to have your dealer perform
these services every 12 000 km/7,500 mi.
Proper vehicle maintenance helps to keep
the vehicle in good working condition,
improves fuel economy, and reduces vehicle
emissions.