
GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Keys, Doors, and Windows 9
{Warning
If the key is unintentionally rotated while
the vehicle is running, the ignition could
be moved out of the RUN position. This
could be caused by heavy items hanging
from the key ring, or by large or long
items attached to the key ring that could
be contacted by the driver or steering
wheel. If the ignition moves out of the
RUN position, the engine will shut off,
braking and steering power assist may be
impacted, and airbags may not deploy.
To reduce the risk of unintentional
rotation of the ignition key, do not
change the way the ignition key and
Remote Keyless Entry (RKE) transmitter,
if equipped, are connected to the
provided key rings.
The ignition key and key rings, and RKE
transmitter, if equipped, are designed to
work together as a system to reduce the
risk of unintentionally moving the key out
of the RUN position. The ignition key has a
small hole to allow attachment of the
provided key ring. It is important that any replacement ignition keys have a small hole.
See your dealer if a replacement key is
required.
The combination and size of the rings that
came with your keys were specifically
selected for your vehicle. The rings are
connected to the key like two links of a
chain to reduce the risk of unintentionally
moving the key out of the RUN position. Do
not add any additional items to the ring
attached to the ignition key. Attach
additional items only to the second ring,
and limit added items to a few essential
keys or small, light items no larger than an
RKE transmitter.
Interference from radio-frequency
identification (RFID) tags may prevent the
key from starting the vehicle. Keep RFID
tags away from the key when starting the
vehicle.
The key is used for the ignition, all door
locks, and the glove box.
If equipped with memory seats, keys 1 and 2
are linked to seating positions of memory 1
or 2. See
Memory Seats 053.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
12 Keys, Doors, and Windows
With an active OnStar or connected service
plan, an OnStar Advisor may remotely
unlock the vehicle. SeeOnStar Overview
0 408.
If locked out of the vehicle, see Roadside
Assistance Program 0399.
If equipped with memory seats, RKE
transmitters 1 and 2 are linked to seating
positions of memory 1 or 2. See Memory
Seats 053.
Remote Keyless Entry (RKE)
System
See Radio Frequency Statement 0404.
If there is a decrease in the Remote Keyless
Entry (RKE) operating range:
.Check the distance. The transmitter may
be too far from the vehicle.
.Check the location. Other vehicles or
objects may be blocking the signal.
.Check the transmitter's battery. See
“Battery Replacement” later in this
section.
.If the transmitter is still not working
correctly, see your dealer or a qualified
technician for service.
Remote Keyless Entry (RKE)
System Operation (Key Access)
The RKE transmitter functions may work up
to 60 m (197 ft) away from the vehicle.
Other conditions can affect the performance
of the transmitter. See Remote Keyless Entry
(RKE) System 012.
/:Press and releaseQ, then immediately
press and hold
/until the turn signal
lamps flash or for at least four seconds. The
engine may be started from outside the
vehicle using the RKE transmitter. See
Remote Vehicle Start 022.
Q:Press to lock all doors. If enabled, the turn signal lamps may flash
and/or the horn may sound on the second
press to indicate locking has occurred.
If enabled, the horn chirps when
Qis
pressed again within three seconds. To view
available settings from the infotainment
screen, touch Settings > Vehicle > Remote
Lock, Unlock, Start.
Pressing
Qarms the alarm system. See
Vehicle Alarm System 034.
If equipped with remote mirror folding,
pressing and holding
Qfor one second will
fold the mirrors, if enabled. To view
available settings for this feature, touch the
Settings icon on the infotainment home
page. Select “Vehicle”to display the list of
available options and select “Comfort and
Convenience”.
K: Press once to unlock only the driver
door. If
Kis pressed again within
three seconds, all remaining doors unlock.
The interior lamps may come on and stay
on for 20 seconds or until the ignition is
turned on.
If enabled, the turn signal lamps flash twice
to indicate unlocking has occurred.
If enabled, the exterior lamps may turn on.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
16 Keys, Doors, and Windows
tailgate unlock. The interior lamps may
come on and stay on for 20 seconds or until
the ignition is turned on.
If enabled, the turn signal lamps flash twice
to indicate unlocking has occurred.
If enabled, the exterior lamps may turn on.
To view available settings for this feature,
touch the Settings icon on the infotainment
home page. Select“Vehicle”to display the
list of available options and select “Remote
Lock, Unlock, Start”.
Pressing
Kon the RKE transmitter disarms
the alarm system. See Vehicle Alarm System
0 34.
If equipped with remote mirror folding,
pressing and holding
Kfor one second will
unfold the mirrors, if enabled. To view
available settings for this feature, touch the
Settings icon on the infotainment home
page. Select “Vehicle”to display the list of
available options and select “Comfort and
Convenience”.
Press and hold
Kuntil the windows fully
open, if remote window operation is
enabled. To view available settings for this
feature, touch the Settings icon on the infotainment home page. Select
“Vehicle”to
display the list of available options and
select “Remote Lock, Unlock, Start”.
x:Press twice quickly to release the
tailgate, if equipped.
7: Press and release to initiate vehicle
locator. The turn signal lamps flash and the
horn sounds three times.
Press and hold
7for more than
three seconds to activate the panic alarm.
The turn signal lamps flash and the horn
sounds repeatedly for 30 seconds. The alarm
turns off when the ignition is turned on or
7is pressed again. The ignition must be off
for the panic alarm to work.
Keyless Access Operation
The Keyless Access system allows for doors
and the tailgate to be accessed without
pressing the RKE transmitter button. The RKE
transmitter must be within 1 m (3 ft) of the
tailgate or door being opened. If the vehicle
has this feature, there will be a button on
the outside door handles. Keyless Access can be programmed to
unlock all doors on the first lock/unlock
press from the driver door. Keyless
Unlocking can also be turned off. To view
available settings for this feature, touch the
Settings icon on the infotainment home
page. Select
“Vehicle”to display the list of
available options and select “Remote Lock,
Unlock, Start”.
If equipped with memory seats, RKE
transmitters 1 and 2 are linked to seating
positions of memory 1 or 2. See Memory
Seats 053.
Keyless Unlocking/Locking from the
Driver Door
When the doors are locked and the RKE
transmitter is within 1 m (3 ft) of the door
handle, pressing the lock/unlock button on
the driver door handle will unlock the driver
door. If the lock/unlock button is pressed
again within five seconds, all passenger
doors and the tailgate will unlock.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
38 Keys, Doors, and Windows
If a popping noise from the mirror is heard,
this sound is normal as the manual detents
are aligning after a manual extend/retract
operation has occurred.
Auxiliary Cargo Mirror Lamps
If equipped, cargo mirror lamps face
rearward to provide more light on the sides
of the vehicle, if needed. SeeExterior Cargo
Lamps 0144.
Advanced Trailering Vision System Side
Cameras
If equipped, the Advanced Trailering Vision
System side cameras are on the bottom of
the outside mirrors. See “Surround Vision
(360 Degrees)” underAssistance Systems for
Parking or Backing 0248.Power Mirrors
To adjust each mirror:
1. Press
jor|to select the driver or
passenger side mirror. The indicator light
will illuminate.
2. Press the arrows on the control pad to move the mirror in the desired direction.
3. Adjust each outside mirror so that a little of the vehicle and the area behind it can
be seen.
4. Press
jor|again to deselect the
mirror. Turn Signal Indicator
If equipped, the mirror has turn signal
indicator lights, which flash in the direction
of the turn or lane change.
Task Lighting
If equipped, task lighting projects light from
the outside mirrors to the sides of the
vehicle. See
Task Lighting 0144.
Puddle Lamps
If equipped, puddle lamps project light from
the bottom of the mirror to the area of
ground below the driver and passenger
doors. See Entry Lighting 0146 and
Exit Lighting 0146.
Memory Mirrors
The vehicle may have memory mirrors. See
Memory Seats 053.
Lane Change Alert (LCA)
The vehicle may have LCA. See Lane Change
Alert (LCA) 0261.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
40 Keys, Doors, and Windows
Driving with the Blind Spot Mirror
Actual Mirror View1. When the approaching vehicle is a long
distance away, the image in the main
mirror is small and near the inboard
edge of the mirror.
2. As the vehicle gets closer, the image in the main mirror gets larger and moves
outboard.
3. As the vehicle enters the blind zone, the image transitions from the main mirror
to the blind spot mirror.
4. When the vehicle is in the blind zone, the image only appears in the blind spot
mirror.
Using the Outside Mirror with the Blind
Spot Mirror
1. Set the main mirror so that the side ofthe vehicle can just be seen and the
blind spot mirror has an
unobstructed view.
2. When checking for traffic or before changing a lane, look at the main driver/
passenger side mirror to observe traffic
in the adjacent lane, behind your vehicle.
Check the blind spot mirror for a vehicle
in the blind zone. Then, glance over your
shoulder to double check before moving
slowly into the adjacent lane.
Reverse Tilt Mirrors
If equipped with reverse tilt mirrors and
memory seats, the passenger and/or driver
mirror tilts to a preselected position when
the vehicle is in R (Reverse). This allows the
curb to be seen when parallel parking.
The mirror(s) may move from their tilted
position when:
.The vehicle is shifted out of R (Reverse),
or remains in R (Reverse) for about
30 seconds.
.The vehicle is turned off.
.The vehicle is driven in R (Reverse) above
a set speed.
To view available settings from the
infotainment screen, touch Settings >
Vehicle > Comfort and Convenience.
Interior Mirrors
Interior Rearview Mirrors
Adjust the rearview mirror for a clear view
of the area behind the vehicle.
Do not spray glass cleaner directly on the
mirror. Use a soft towel dampened with
water.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
44 Keys, Doors, and Windows
Once the horizontal guideline is in the
desired location, press and hold the button
for another three seconds and repeat the
above step for the vertical guideline
programing. To readjust the horizontal
location of the guidelines after adjusting the
vertical location, press and hold the button
for three seconds.
After eight seconds since the last button
press, the position of the guidelines is
locked into memory.
Windows{
Warning
Never leave a child, a helpless adult, or a
pet alone in a vehicle, especially with the
windows closed in warm or hot weather.
They can be overcome by the extreme
heat and suffer permanent injuries or
even death from heat stroke.
The vehicle aerodynamics are designed to
improve fuel economy performance. This
may result in a pulsing sound when either
rear window is down and the front windows
are up. To reduce the sound, open either a
front window or the sunroof, if equipped.
Manual Windows
If equipped, turn the hand crank on each
door to manually raise or lower the manual
windows.
Power Windows
{Warning
Children could be seriously injured or
killed if caught in the path of a closing
window. Never leave the Remote Keyless
Entry (RKE) transmitter or keys in a
vehicle with children. When there are
children in the rear seat, use the window
lockout button to prevent operation of
the windows. See Keys (Key Access)08
or
Keys (Keyless Access) 011.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 49
Seats and Restraints
Head Restraints
Head Restraints . . . . . . . . . . . . . . . . . . . . . . . . 49
Front Seats
Seat Adjustment . . . . . . . . . . . . . . . . . . . . . . . 50
Center Seat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Power Seat Adjustment . . . . . . . . . . . . . . . . . 51
Reclining Seatbacks . . . . . . . . . . . . . . . . . . . . . 52
Lumbar Adjustment . . . . . . . . . . . . . . . . . . . . . 53
Memory Seats . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Heated and Ventilated Front Seats . . . . . 56
Rear Seats
Rear Seats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Heated Rear Seats . . . . . . . . . . . . . . . . . . . . . . 58
Seat Belts
Seat Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
How to Wear Seat Belts Properly . . . . . . 59
Lap-Shoulder Belt . . . . . . . . . . . . . . . . . . . . . . . 61
Seat Belt Use During Pregnancy . . . . . . . . 64
Seat Belt Extender . . . . . . . . . . . . . . . . . . . . . 64
Safety System Check . . . . . . . . . . . . . . . . . . . 64
Seat Belt Care . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Replacing Seat Belt System Parts after aCrash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Airbag System
Airbag System . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Where Are the Airbags? . . . . . . . . . . . . . . . . 67
When Should an Airbag Inflate? . . . . . . . . 68
What Makes an Airbag Inflate? . . . . . . . . 68
How Does an Airbag Restrain? . . . . . . . . . 69
What Will You See after an Airbag
Inflates? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Passenger Sensing System . . . . . . . . . . . . . 70
Servicing the Airbag-Equipped Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Adding Equipment to the Airbag-Equipped Vehicle . . . . . . . . . . . . . . 74
Airbag System Check . . . . . . . . . . . . . . . . . . . 75
Replacing Airbag System Parts after a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Child Restraints
Older Children . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Infants and Young Children . . . . . . . . . . . . . 77
Child Restraint Systems . . . . . . . . . . . . . . . . 79
Where to Put the Restraint . . . . . . . . . . . . 80
Lower Anchors and Tethers for Children(LATCH System) . . . . . . . . . . . . . . . . . . . . . . . 82
Replacing LATCH System Parts After a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Securing Child Restraints (With the Seat Belt in the Rear Seat) . . . . . . . . . . . . . . . . . 92
Securing Child Restraints (With the Seat Belt in the Front Passenger Seat) . . . . . 96
Securing Child Restraints (With the Seat Belt in the Center Front Seat) . . . . . . . . 99
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.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 53
2. Push and pull on the seatback to makesure it is locked.
Power Reclining Seatbacks
To recline a power seatback, if equipped:
.Tilt the top of the control rearward to
recline.
.Tilt the top of the control forward to
raise.
Lumbar Adjustment
Power Lumbar
To adjust the lumbar support, if equipped:
.Press and hold the control forward to
increase or rearward to decrease upper
and lower lumbar support at the
same time.
Memory Seats
Overview
If equipped, the memory seat feature allows
drivers to save their unique driving positions
and a shared exit position. See “Saving
Seating Positions” later in this section. The
saved positions can be recalled manually by
all drivers, see “Manually Recalling Seating
Positions” later in this section, and drivers
with remote key 1 and 2 can also recall
them automatically. See “Auto Seat Entry
Memory Recall” or“Auto Seat Exit Memory
Recall” later in this section. To enable
automatic recalls, turn on Seat Entry
Memory and/or Seat Exit Memory. See
“Enabling Automatic Recalls” later in this