ECU CHEVROLET SILVERADO 2500HD 2021 Owner's Manual

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Keys, Doors, and Windows 7
Keys, Doors, and
Windows
Keys and Locks
Keys (Key Access) . . . . . . . . . . . . . . . . . . . . . . . . 7
Keys (Keyless Access) . . . . . . . . . . . . . . . . . . . . 9
Remote Keyless Entry (RKE) System . . . . 10
Remote Keyless Entry (RKE) SystemOperation (Key Access) . . . . . . . . . . . . . . . 10
Remote Keyless Entry (RKE) System Operation (Keyless Access) . . . . . . . . . . . . 13
Remote Vehicle Start . . . . . . . . . . . . . . . . . . . 20
Door Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Power Door Locks . . . . . . . . . . . . . . . . . . . . . . . 22
Delayed Locking . . . . . . . . . . . . . . . . . . . . . . . . 22
Automatic Door Locks . . . . . . . . . . . . . . . . . . 22
Lockout Protection . . . . . . . . . . . . . . . . . . . . . . 22
Safety Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Doors
Tailgate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Power Assist Steps . . . . . . . . . . . . . . . . . . . . . 26
Vehicle Security
Vehicle Security . . . . . . . . . . . . . . . . . . . . . . . . 27
Vehicle Alarm System . . . . . . . . . . . . . . . . . . 27
Steering Column Lock . . . . . . . . . . . . . . . . . . 28
Immobilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Immobilizer Operation . . . . . . . . . . . . . . . . . . 29
Exterior Mirrors
Convex Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 30
Manual Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 30
Trailer-Tow Mirrors . . . . . . . . . . . . . . . . . . . . . 30
Power Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Folding Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 32
Heated Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 33
Automatic Dimming Mirror . . . . . . . . . . . . . 33
Blind Spot Mirrors . . . . . . . . . . . . . . . . . . . . . . 33
Reverse Tilt Mirrors . . . . . . . . . . . . . . . . . . . . . 34
Interior Mirrors
Interior Rearview Mirrors . . . . . . . . . . . . . . . 34
Manual Rearview Mirror . . . . . . . . . . . . . . . . 34
Automatic Dimming Rearview Mirror . . . 34
Rear Camera Mirror . . . . . . . . . . . . . . . . . . . . 34
Truck Bed Camera Rearview Mirror . . . . . 37
Windows
Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Manual Windows . . . . . . . . . . . . . . . . . . . . . . . 38
Power Windows . . . . . . . . . . . . . . . . . . . . . . . . 38
Rear Windows . . . . . . . . . . . . . . . . . . . . . . . . . 40
Sun Visors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Roof
Sunroof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Keys and Locks
Keys (Key Access)
{Warning
Leaving children in a vehicle with the
ignition key is dangerous and children or
others could be seriously injured or killed.
They could operate the power windows
or other controls or make the vehicle
move. The windows will function with
the keys in the ignition, and children or
others could be caught in the path of a
closing window. Do not leave children in
a vehicle with the ignition key.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Keys, Doors, and Windows 9
1. Insert the original, already programmedkey in the ignition and turn the
ignition on.
2. Turn the ignition off, and remove the key.
3. Quickly, within five seconds, insert the second original already programmed key
in the ignition and turn the ignition on.
4. Turn the ignition off, and remove the key.
5. Insert the key to be programmed and turn the ignition on within five seconds.
6. After a few seconds, the security light will turn off once the key has been
programmed.
7. Repeat Steps 1–5 if additional keys are to be programmed.
If a key is lost or damaged, see your dealer
to have a new key made.
Programming without Recognized Keys
Program a new key to the vehicle when a
recognized key is not available. Canadian
regulations require that owners see their
dealer.
If two currently recognized keys are not
available, follow this procedure to program
the first key. This procedure will take approximately
30 minutes to complete for the first key.
The vehicle must be off and all of the keys
you wish to program must be with you.
1. Insert the new vehicle key into the ignition.
2. Turn the ignition on. The security light will come on.
3. Wait 10 minutes until the security light turns off.
4. Turn the ignition off.
5. Repeat Steps 2–4 two more times. After the third time, turn the ignition on; the
key is learned and all previously known
keys will no longer work with the
vehicle.
6. To learn a second key, turn the ignition off, insert the second key to be learned,
and turn the ignition on.
After two keys are learned, the remaining
keys can be learned by following the
procedure in “Programming with Two
Recognized Keys.”
The key has a bar-coded key tag that the
dealer or qualified locksmith can use to
make new keys. Store this information in a
safe place, not in the vehicle. See your dealer if a replacement key or
additional key is needed.
If it becomes difficult to turn a key, inspect
the key blade for debris. Periodically clean
with a brush or pick.
If locked out of the vehicle, see
Roadside
Assistance Program 0404.
With an active OnStar or connected service
plan, an OnStar Advisor may remotely
unlock the vehicle. See OnStar Overview
0 412.
Keys (Keyless Access)
{Warning
Leaving children in a vehicle with an
ignition key or Remote Keyless Entry
(RKE) transmitter is dangerous and
children or others could be seriously
injured or killed. They could operate the
power window or other controls or make
the vehicle move. The windows will
function with the key in the ignition or
with the RKE transmitter in the vehicle,
and children or others could be caught in
(Continued)

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
24 Keys, Doors, and Windows
Use the key to unlock the tailgate.
Open the tailgate by lifting up on its handle
while pulling the tailgate down.
To shut the tailgate, firmly push it upward
until it latches.
After closing the tailgate, pull it back to be
sure it is latched securely.
Some tailgates have an electric latch. If the
battery is disconnected or has low voltage,
the tailgate will not open. The tailgate will
resume operation when the battery is
reconnected or recharged.
Power Release Tailgate
{Warning
Make sure there is no one in the way of
the power tailgate as it is opening and
closing, and keep hands away from the
tailgate hinges when in use. You or
others could be injured if caught in the
path of the power tailgate or tailgate
hinges.
Caution
To avoid damage to the tailgate, make
sure the area behind the tailgate is clear
before opening it.
In the case of a dead battery, the tailgate
can be opened manually. Contact your
dealer or Roadside Assistance.
If equipped, to lock or unlock the tailgate,
use the RKE transmitter or the key. See
Remote Keyless Entry (RKE) System
Operation (Key Access) 010 or
Remote Keyless Entry (RKE) System
Operation (Keyless Access) 013.
The vehicle must be in P (Park).
To open the tailgate:
.Pressxtwice quickly on the RKE
transmitter until the tailgate moves.
.Press5on the center stack.
.Press the touch pad on the tailgate
handle after unlocking all doors. Use the
top of the tailgate to pull against if

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Keys, Doors, and Windows 25
assistance is required. If equipped with
Keyless Access, a locked tailgate can be
opened if the RKE transmitter is within
1 m (3 ft).
To close the tailgate, firmly push it upward
until it latches. Pull it back to be sure it is
latched securely.
Power Tailgate
{Warning
Make sure there is no one in the way of
the power tailgate as it is opening and
closing, and keep hands away from the
tailgate hinges when in use. You or
others could be injured if caught in the
path of the power tailgate or tailgate
hinges.
Caution
To avoid damage to the tailgate, make
sure the area behind the tailgate is clear
before opening it.
If equipped with a power open/close
tailgate, the tailgate can be opened or
closed in several ways. To open the tailgate,
do one of the following:
.Pressxtwice quickly on the RKE
transmitter until the tailgate moves. See
Remote Keyless Entry (RKE) System
Operation (Key Access) 010 or
Remote Keyless Entry (RKE) System
Operation (Keyless Access) 013.
If equipped with Keyless Access, a locked
tailgate can be opened if the RKE
transmitter is within 1 m (3 ft).
.Press5on the center stack.
.Press the touch pad on the tailgate
handle after unlocking all doors.
To close the tailgate, do one of the
following:
.Pressxon the RKE transmitter once,
then quickly press and hold
xuntil the
tailgate completely closes. If
xis
released prior to it being fully closed, the
tailgate will reopen.
.Press and hold5on the center stack
until the tailgate is fully closed. If
5
is released prior to the tailgate being
fully closed, it will reopen. A chime will
sound when the tailgate is fully closed.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Keys, Doors, and Windows 27
Warning (Continued)
hands or other body parts between the
extended power assist step and the
vehicle.
If equipped, the power assist steps will
deploy when the door is opened and
automatically retract three seconds after the
door is closed. The power assist steps will
retract immediately if the vehicle starts
moving.
Disable the power assist steps before jacking
or placing any object under the vehicle. Too
much ice buildup may prevent deployment
of the power assist steps. Check the step
position before exiting the vehicle. If this
happens, disable the power assist steps,
clear the ice, then enable the assist steps
and confirm normal function prior to use.
Keep hands, children, pets, objects, and
clothing clear of the power assist steps
when in motion. The steps will reverse
direction if they encounter an obstruction
when opening or closing. Remove the
obstruction, then open and close the door
on the same side to complete the motion of the assist steps. If the obstruction is not
cleared. the assist steps remain extended
while driving.
To extend both power assist steps
for cleaning, press
jwhile the vehicle is
in P (Park) or N (Neutral). Press
jagain
to retract them. The Driver Information
Center (DIC) will display a message.
Enable/Disable
Press and hold
jfor four seconds to lock
and disable the power assist steps. Press
and hold
jfor four seconds again to
enable them. The DIC will display a
message.
Vehicle Security
This vehicle has theft-deterrent features;
however, they do not make the vehicle
impossible to steal.
Vehicle Alarm System
The indicator light, on the instrument panel
near the windshield, indicates the status of
the system.
Off : Alarm system is disarmed.
On Solid : Vehicle is secured during the
delay to arm the system.
Fast Flash : Vehicle is unsecured. A door or
the hood is open.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Keys, Doors, and Windows 29
column, and the vehicle did not start.
If this happens, immediately turn the
steering wheel from side to side to
unbind the column lock. If this does not
unlock the steering column, turn the
vehicle off and open the driver door to
reset the system. Then turn the vehicle
on and immediately turn the steering
wheel side to side for about 15 seconds.
In some cases, it may take significant
force to unbind the column.
To keep the steering column from binding,
straighten the front wheels before turning
off the vehicle.
Immobilizer
See Radio Frequency Statement 0409.
Immobilizer Operation
This vehicle has a passive theft-deterrent
system. The system does not have to be manually
armed or disarmed.
The vehicle is automatically immobilized
when the vehicle is turned off.
The system is automatically disarmed when
the ignition is turned from off to on.
The security light, in the instrument cluster,
comes on if there is a problem with arming
or disarming the theft-deterrent system.
The system has one or more RKE
transmitters matched to an immobilizer
control unit in your vehicle. Only a correctly
matched RKE transmitter will start the
vehicle. If the transmitter is ever damaged,
you may not be able to start your vehicle.
When trying to start the vehicle, the
security light may come on briefly when the
ignition is turned on. If the engine does not
start and the security light stays on, there is
a problem with the system. Turn the
ignition off and try again.
If the vehicle will not change ignition modes
(ACC/ACCESSORY, on, off), and the RKE
transmitter appears to be undamaged, try
another transmitter. Or, you may try placing
the transmitter in the transmitter pocket
located in the center console. See
Remote
Keyless Entry (RKE) System Operation (Key
Access) 010 or
Remote Keyless Entry (RKE) System
Operation (Keyless Access) 013.
If the ignition mode will not change with
the other transmitter or with the
transmitter in the transmitter pocket, your
vehicle needs service. If the ignition does
change modes, the first transmitter may be
faulty. See your dealer who can service the
theft-deterrent system and have a new RKE
transmitter programmed to the vehicle.
It is possible for the immobilizer system to
learn new or replacement RKE transmitters.
Up to eight transmitters can be
programmed for the vehicle. To program
additional transmitters, see "Programming
Transmitters to the Vehicle" under Remote
Keyless Entry (RKE) System Operation (Key
Access) 010 or
Remote Keyless Entry (RKE) System
Operation (Keyless Access) 013
Do not leave the transmitter or device that
disarms or deactivates the vehicle theft
system in the vehicle.
When equipped with a key, if the engine
still does not start, and the key appears to
be undamaged, try another ignition key.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
42 Seats and Restraints
Seats and Restraints
Head Restraints
Head Restraints . . . . . . . . . . . . . . . . . . . . . . . . 42
Front Seats
Seat Adjustment . . . . . . . . . . . . . . . . . . . . . . . . 43
Center Seat . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Power Seat Adjustment . . . . . . . . . . . . . . . . 44
Lumbar Adjustment . . . . . . . . . . . . . . . . . . . . 45
Reclining Seatbacks . . . . . . . . . . . . . . . . . . . . . 45
Memory Seats . . . . . . . . . . . . . . . . . . . . . . . . . 46
Heated and Ventilated Front Seats . . . . . 49
Rear Seats
Rear Seats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Heated Rear Seats . . . . . . . . . . . . . . . . . . . . . . 51
Seat Belts
Seat Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
How to Wear Seat Belts Properly . . . . . . . 52
Lap-Shoulder Belt . . . . . . . . . . . . . . . . . . . . . . . 54
Seat Belt Use During Pregnancy . . . . . . . . 56
Seat Belt Extender . . . . . . . . . . . . . . . . . . . . . . 56
Safety System Check . . . . . . . . . . . . . . . . . . . 56
Seat Belt Care . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Replacing Seat Belt System Parts after aCrash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Airbag System
Airbag System . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Where Are the Airbags? . . . . . . . . . . . . . . . . 59
When Should an Airbag Inflate? . . . . . . . 60
What Makes an Airbag Inflate? . . . . . . . . . 61
How Does an Airbag Restrain? . . . . . . . . . . 61
What Will You See after an Airbag
Inflates? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Passenger Sensing System . . . . . . . . . . . . . 62
Servicing the Airbag-Equipped Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Adding Equipment to the Airbag-Equipped Vehicle . . . . . . . . . . . . . . 66
Airbag System Check . . . . . . . . . . . . . . . . . . . 67
Replacing Airbag System Parts after a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Child Restraints
Older Children . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Infants and Young Children . . . . . . . . . . . . 69
Child Restraint Systems . . . . . . . . . . . . . . . . . 71
Where to Put the Restraint . . . . . . . . . . . . . 73
Lower Anchors and Tethers for Children(LATCH System) . . . . . . . . . . . . . . . . . . . . . . . 74
Replacing LATCH System Parts After a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Securing Child Restraints (With the Seat Belt in the Rear Seat) . . . . . . . . . . . . . . . . 84
Securing Child Restraints (With the Seat Belt in the Center Front Seat) . . . . . . . . 87
Securing Child Restraints (With the Seat Belt in the Front Passenger Seat) . . . . . 87
Head Restraints
{
Warning
With head restraints that are not
installed and adjusted properly, there is a
greater chance that occupants will suffer
a neck/spinal injury in a crash. Do not
drive until the head restraints for all
occupants are installed and adjusted
properly.
Front Seats
The vehicle's front seats have adjustable
head restraints in the outboard seating
positions.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
Seats and Restraints 55
3. Push the latch plate into the buckle untilit clicks.
Pull up on the latch plate to make sure
it is secure. If the belt is not long
enough, see Seat Belt Extender 056.
Position the release button on the buckle
so that the seat belt could be quickly
unbuckled if necessary.4. To make the lap part tight, pull up on the shoulder belt.
To unlatch the belt, push the button on the
buckle. The belt should return to its stowed
position.
Always stow the seat belt slowly. If the seat
belt webbing returns quickly to the stowed
position, the retractor may lock and cannot
be pulled out. If this happens, pull the seat
belt straight out firmly to unlock the
webbing, and then release it. If the webbing
is still locked in the retractor, see your
dealer.
Before a door is closed, be sure the seat belt
is out of the way. If a door is slammed
against a seat belt, damage can occur to
both the seat belt and the vehicle.
Seat Belt Pretensioners
This vehicle has seat belt pretensioners for
the front outboard occupants. Although the
seat belt pretensioners cannot be seen, they
are part of the seat belt assembly. They can
help tighten the seat belts during the early
stages of a moderate to severe frontal, near
frontal, or rear crash if the threshold
conditions for pretensioner activation are
met. Seat belt pretensioners can also help
tighten the seat belts in a side crash or
rollover event.

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
S./Canada/Mexico-14632154) - 2021 - CRC - 11/20/20
56 Seats and Restraints
Pretensioners work only once. If the
pretensioners activate in a crash, the
pretensioners and probably other parts of
the vehicle's seat belt system will need to
be replaced. SeeReplacing Seat Belt System
Parts after a Crash 057.
Do not sit on the outboard seat belt while
entering or exiting the vehicle or at any
time while sitting in the seat. Sitting on the
seat belt can damage the webbing and
hardware.
Rear Seat Belt Comfort Guides
Rear seat belt comfort guides may provide
added seat belt comfort for older children
who have outgrown booster seats and for
some adults. When installed on a shoulder
belt, the comfort guide positions the
shoulder belt away from the neck and head.
Comfort guides are available through your
dealer for the rear outboard seating
positions. Instructions are included with the
comfort guides.
Seat Belt Use During Pregnancy
Seat belts work for everyone, including
pregnant women. Like all occupants, they
are more likely to be seriously injured if
they do not wear seat belts.
A pregnant woman should wear a
lap-shoulder belt, and the lap portion should
be worn as low as possible, below the
rounding, throughout the pregnancy.
The best way to protect the fetus is to
protect the mother. When a seat belt is
worn properly, it is more likely that the
fetus will not be hurt in a crash. For
pregnant women, as for anyone, the key to
making seat belts effective is wearing them
properly.
Seat Belt Extender
If the vehicle's seat belt will fasten around
you, you should use it. But if a seat belt is not long enough, your
dealer will order you an extender. When
you go in to order it, take the heaviest coat
you will wear, so the extender will be long
enough for you. To help avoid personal
injury, do not let someone else use it, and
use it only for the seat it is made to fit. The
extender has been designed for adults.
Never use it for securing child restraints. For
more information on the proper use and fit
of seat belt extenders see the instruction
sheet that comes with the extender.
Safety System Check
Periodically check the seat belt reminder,
seat belts, buckles, latch plates, retractors,
shoulder belt height adjusters (if equipped),
and seat belt anchorages to make sure they
are all in working order. Look for any other
loose or damaged seat belt system parts
that might keep a seat belt system from
performing properly. See your dealer to
have it repaired. Torn, frayed, or twisted
seat belts may not protect you in a crash.
Torn or frayed seat belts can rip apart under
impact forces. If a belt is torn or frayed,
have it replaced immediately. If a belt is
twisted, it may be possible to untwist by

Chevrolet Silverado 2500 HD/3500 HD Owner Manual (GMNA-Localizing-U.
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58 Seats and Restraints
All vehicle airbags have the word AIRBAG on
the trim or on a label near the deployment
opening.
For frontal airbags, the word AIRBAG is on
the center of the steering wheel for the
driver and on the instrument panel for the
front outboard passenger.
For seat-mounted side impact airbags, the
word AIRBAG is on the side of the seatback
or side of the seat closest to the door.
For roof-rail airbags, the word AIRBAG is on
the ceiling or trim.
Airbags are designed to supplement the
protection provided by seat belts. Even
though today's airbags are also designed to
help reduce the risk of injury from the force
of an inflating bag, all airbags must inflate
very quickly to do their job.
Here are the most important things to know
about the airbag system:
{Warning
You can be severely injured or killed in a
crash if you are not wearing your seat
belt, even with airbags. Airbags are
designed to work with seat belts, not(Continued)
Warning (Continued)
replace them. Also, airbags are not
designed to inflate in every crash. In
some crashes seat belts are the only
restraint. SeeWhen Should an Airbag
Inflate? 060.
Wearing your seat belt during a crash
helps reduce your chance of hitting
things inside the vehicle or being ejected
from it. Airbags are “supplemental
restraints” to the seat belts. Everyone in
the vehicle should wear a seat belt
properly, whether or not there is an
airbag for that person.
{Warning
Because airbags inflate with great force
and faster than the blink of an eye,
anyone who is up against, or very close
to, any airbag when it inflates can be
seriously injured or killed. Do not sit
unnecessarily close to any airbag, as you
would be if sitting on the edge of the
seat or leaning forward. Seat belts help
keep you in position before and during a
(Continued)
Warning (Continued)
crash. Always wear a seat belt, even with
airbags. The driver should sit as far back
as possible while still maintaining control
of the vehicle. The seat belts and the
front outboard passenger airbags are
most effective when you are sitting well
back and upright in the seat with both
feet on the floor.
Occupants should not lean on or sleep
against the door or side windows in
seating positions with seat-mounted side
impact airbags and/or roof-rail airbags.
{Warning
Children who are up against, or very
close to, any airbag when it inflates can
be seriously injured or killed. Always
secure children properly in the vehicle. To
read how, seeOlder Children 068 or
Infants and Young Children 069.