GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Introduction 3
A circle with a slash through it is a safety
symbol which means“Do not,” “Do not do
this,” or“Do not let this happen.”
Symbols
The vehicle has components and labels that
use symbols instead of text. Symbols are
shown along with the text describing the
operation or information relating to a
specific component, control, message, gauge,
or indicator.
M:Shown when the owner’s manual has
additional instructions or information.
*: Shown when the service manual has
additional instructions or information.
0: Shown when there is more information
on another page — “see page.” Vehicle Symbol Chart
Here are some additional symbols that may
be found on the vehicle and what they
mean. See the features in this manual for
information.
u:
Air Conditioning System
G:Air Conditioning Refrigerant Oil
9:Airbag Readiness Light
!:Antilock Brake System (ABS)
$:Brake System Warning Light
9:Dispose of Used Components Properly
P:Do Not Apply High Pressure Water
B:Engine Coolant Temperature
_:Flame/Fire Prohibited
H: Flammable
[:Forward Collision Alert
R:Fuse Block Cover Lock Location
+:Fuses
j:ISOFIX/LATCH System Child Restraints
Q:Keep Fuse Block Covers Properly
Installed
|: Lane Change Alert
@:Lane Departure Warning
A:Lane Keep Assist
*: Malfunction Indicator Lamp
::Oil Pressure
X:Park Assist
~:Pedestrian Ahead Indicator
O:Power
7:Rear Cross Traffic Alert
I:Registered Technician
/:Remote Vehicle Start
h:Risk of Electrical Fire
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
50 Seats and Restraints
Adjust the head restraint so that the top of
the restraint is at the same height as the
top of the occupant's head. This position
reduces the chance of a neck injury in a
crash.
To raise or lower the head restraint, press
the button on the side of the head restraint
and pull up or push the head restraint down
and release the button.
Pull and push on the head restraint after the
button is released to make sure that it is
locked in place.
The front seat outboard head restraints are
not removable.
Rear Head Restraints
The vehicle’s rear seat has head restraints in
the outboard seating positions that cannot
be adjusted.
The head restraint can be folded forward to
allow for better visibility when the rear seat
is unoccupied. To fold the head restraint,
press the button on the side of the head
restraint.
When an occupant is in the seat, always
return the head restraint to the upright
position until it locks into place. Push and
pull on the head restraint to make sure that
it is locked.If you are installing a child restraint in the
rear seat, see
Lower Anchors and Tethers for
Children (LATCH System) 082.
Center Headrest
The vehicle’s rear seat may be equipped
with a headrest in the center seating
position that cannot be adjusted.
If you are installing a child restraint in the
rear seat, see Lower Anchors and Tethers for
Children (LATCH System) 082.
Front Seats
Seat Adjustment
{Warning
You can lose control of the vehicle if you
try to adjust a driver seat while the
vehicle is moving. Adjust the driver seat
only when the vehicle is not moving.
GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 57
To enable or disable remote start heated or
ventilated seats, select Settings > Vehicle >
Remote Lock, Unlock, and Start > Remote
Start Auto Heat Seats or Remote Start Auto
Cool Seats > ON or OFF. SeeRemote Vehicle
Start 022.
Rear Seats
Rear Seat Reminder
If equipped, the message REAR SEAT
REMINDER LOOK IN REAR SEAT displays
under certain conditions indicating there
may be an item or passenger in the rear
seat. Check before exiting the vehicle.
This feature will activate when a second row
door is opened while the vehicle is on or up
to 10 minutes before the vehicle is turned
on. There will be an alert when the vehicle
is turned off. The alert does not directly
detect objects in the rear seat; instead,
under certain conditions, it detects when a
rear door is opened and closed, indicating
that there may be something in the
rear seat. The feature is active only once each time
the vehicle is turned on and off, and will
require reactivation by opening and closing
the second row doors. There may be an
alert even when there is nothing in the rear
seat; for example, if a child entered the
vehicle through the rear door and left the
vehicle without the vehicle being shut off.
The feature can be turned on or off. Select
Settings > Vehicle > Rear Seat Reminder >
ON or OFF.
Folding the Rear Seat Cushion
Either side of the rear seat cushion can be
folded up for added cargo space.
Caution
Folding a rear seat with the seat belts
still fastened may cause damage to the
seat or the seat belts. Always unbuckle
the seat belts and return them to their
normal stowed position before folding a
rear seat.
Make sure that nothing is on the seat
cushion.
To fold the seat, slowly pull the seat
cushion up.
To return the seat to the normal seating
position, slowly pull the seat cushion down.
{Warning
A seat belt that is improperly routed, not
properly attached, or twisted will not
provide the protection needed in a crash.
The person wearing the belt could be
seriously injured. After raising the rear
seatback, always check to be sure that
the seat belts are properly routed and
attached, and are not twisted.
GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 59
When riding in a vehicle, you travel as fast
as the vehicle does. If the vehicle stops
suddenly, you keep going until something
stops you. It could be the windshield, the
instrument panel, or the seat belts!
When you wear a seat belt, you and the
vehicle slow down together. There is more
time to stop because you stop over a longer
distance and, when worn properly, your
strongest bones take the forces from the
seat belts. That is why wearing seat belts
makes such good sense.
Questions and Answers About Seat Belts
Q: Will I be trapped in the vehicle after acrash if I am wearing a seat belt?
A: You could be— whether you are
wearing a seat belt or not. Your chance
of being conscious during and after a
crash, so you canunbuckle and get out,
is much greater if you are belted.
Q: If my vehicle has airbags, why should I have to wear seat belts?
A: Airbags are supplemental systems only.
They work withseat belts —not instead
of them. Whether or not an airbag is
provided, all occupants still have to
buckle up to get the most protection. Also, in nearly all states and in all
Canadian provinces, the law requires
wearing seat belts.
How to Wear Seat Belts Properly
Follow these rules for everyone's protection.
There are additional things to know about
seat belts and children, including smaller
children and infants. If a child will be riding
in the vehicle, see
Older Children075 or
Infants and Young Children 077. Review and
follow the rules for children in addition to
the following rules.
It is very important for all occupants to
buckle up. Statistics show that unbelted
people are hurt more often in crashes than
those who are wearing seat belts.
There are important things to know about
wearing a seat belt properly.
.Sit up straight and always keep your feet
on the floor in front of you (if possible).
.Wear the lap part of the belt low and
snug on the hips, just touching the
thighs. In a crash, this applies force to the
strong pelvic bones and you would be
less likely to slide under the lap belt.
If you slid under it, the belt would apply
force on your abdomen. This could cause
serious or even fatal injuries.
.Wear the shoulder belt over the shoulder
and across the chest. These parts of the
body are best able to take belt
restraining forces. The shoulder belt locks
if there is a sudden stop or crash.
GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 61
Never route the lap or shoulder belt over an
armrest.
{Warning
The seat belt can be pinched if it is
routed under plastic trim on the seat,
such as trim around the rear seatback
folding handle or side airbag. In a crash,
pinched seat belts might not provide
adequate protection. Never allow seat
belts to be routed under plastic trim
pieces.
{Warning
You can be seriously injured or killed if
the shoulder belt is worn behind your
back, under your legs, or wrapped around
your neck. The shoulder belt can tighten
but cannot be loosened if it is locked. The
shoulder belt locks when it is pulled all
the way out of the retractor. It unlocks
when the shoulder belt is allowed to go
all the way back into the retractor, but it
cannot do this if it is wrapped around
you. You may have to cut the seat belt if
it is locked and tightened around you.
Lap-Shoulder Belt
All seating positions in the vehicle have a
lap-shoulder belt.
The following instructions explain how to
wear a lap-shoulder belt properly.1. Adjust the seat, if the seat is adjustable, so you can sit up straight. To see how,
see “Seats” in the Index.
2. Pick up the latch plate and pull the belt
across you. Do not let it get twisted.
The lap-shoulder belt may lock if you
pull the belt across you very quickly.
If this happens, let the belt go back
slightly to unlock it. Then pull the belt
across you more slowly.
If the shoulder portion of a passenger
belt is pulled out all the way, the child
restraint locking feature may be
engaged. See Child Restraint Systems
0 79. If this occurs, let the belt go back
all the way and start again. If the
locking feature stays engaged after
letting the belt go back to stowed
GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
62 Seats and Restraints
position on the seat, move the seat
rearward or recline the seat until the
shoulder belt retractor lock releases.
Engaging the child restraint locking
feature in the front outboard seating
position may affect the passenger
sensing system, if equipped. See
Passenger Sensing System070.
If the webbing locks in the latch plate
before it reaches the buckle, tilt the latch
plate flat to unlock.
3. Push the latch plate into the buckle until
it clicks.
Pull up on the latch plate to make sure
it is secure. If the belt is not long
enough, see Seat Belt Extender 064.
Position the release button on the buckle
so that the seat belt could be quickly
unbuckled if necessary.
If equipped with a shoulder belt height
adjuster, move it to the height that is
right for you. See "Shoulder Belt Height
Adjuster" later in this section for
instructions on use and important safety
information.4. To make the lap part tight, pull up on the shoulder belt.
GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 63
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.
Shoulder Belt Height Adjuster
The vehicle may have a shoulder belt height
adjuster for the driver and front outboard
passenger positions.
Adjust the height so the shoulder portion of
the belt is on the shoulder and not falling
off of it. The belt should be close to, but not
contacting, the neck. Improper shoulder belt
height adjustment could reduce the
effectiveness of the seat belt in a crash. See
How to Wear Seat Belts Properly059.
Push the release button to move the height
adjuster to the desired position.
After the adjuster is set to the desired
position, try to move it down without
pushing the release button to make sure it
has locked into position.
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.
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. See
Replacing Seat Belt System
Parts after a Crash 065.
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.