2023 GMC SIERRA height

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
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.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
64 Seats and Restraints
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. Only a
GM dealer issued extender should be used.
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
reversing the latch plate on the webbing.
If the twist cannot be corrected, ask your
dealer to fix it.
Make sure the seat belt reminder light is
working. See
Seat Belt Reminders 0118.
Keep seat belts clean and dry. See Seat Belt
Care 064.
Seat Belt Care
Keep belts clean and dry.
Seat belts should be properly cared for and
maintained.
Seat belt hardware should be kept dry and
free of dust or debris. As necessary, exterior
hard surfaces and seat belt webbing may be
lightly cleaned with mild soap and water.
Ensure there is not excessive dust or debris
in the mechanism. If dust or debris exists in
the system please see the dealer. Parts may
need to be replaced to ensure proper
functionality of the system.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
74 Seats and Restraints
{Warning
For up to 10 seconds after the vehicle is
turned off and the battery is
disconnected, an airbag can still inflate
during improper service. You can be
injured if you are close to an airbag
when it inflates. Avoid yellow connectors.
They are probably part of the airbag
system. Be sure to follow proper service
procedures, and make sure the person
performing work for you is qualified to
do so.
Adding Equipment to the
Airbag-Equipped Vehicle
Adding accessories that change the vehicle's
frame, bumper system, height, front end,
or side sheet metal, may keep the airbag
system from working properly.
The operation of the airbag system can also
be affected by changing, including
improperly repairing or replacing, any parts
of the following:
.Airbag system, including airbag modules,
front or side impact sensors, sensing and
diagnostic module, or airbag wiring
.Front seats, including stitching, seams,
or zippers
.Seat belts
.Steering wheel, instrument panel,
overhead console, ceiling trim, or pillar
garnish trim
.Inner door seals, including speakers
Your dealer and the service manual have
information about the location of the airbag
modules and sensors, sensing and diagnostic
module, and airbag wiring along with the
proper replacement procedures.
In addition, the vehicle has a passenger
sensing system for the front outboard
passenger position, which includes sensors
that are part of the passenger seat. The
passenger sensing system may not operate
properly if the original seat trim is replaced
with non-GM covers, upholstery, or trim; or
with GM covers, upholstery, or trim
designed for a different vehicle. Any object,
such as an aftermarket seat heater or a
comfort-enhancing pad or device, installed
under or on top of the seat fabric, could
also interfere with the operation of the
passenger sensing system. This could either
prevent proper deployment of the passenger
airbag(s) or prevent the passenger sensing system from properly turning off the
passenger airbag(s). See
Passenger Sensing
System 070.
If the vehicle has rollover roof-rail airbags,
see Different Size Tires and Wheels 0353 for
additional important information.
If a snow plow is added to the vehicle, the
airbags should still work properly. The
airbag systems were designed to work
properly under a wide range of conditions,
including snow plowing with vehicles that
have the optional snow plow prep package
(RPO VYU). Do not change or defeat the
snow plow's “tripping mechanism.” If you
do, it can damage the snow plow and the
vehicle, and may cause an airbag
deployment.
If the vehicle must be modified because you
have a disability and have questions about
whether the modifications will affect the
vehicle's airbag system, or if you have
questions about whether the airbag system
will be affected if the vehicle is modified for
any other reason, call Customer Assistance.
See Customer Assistance Offices 0398.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Seats and Restraints 75
Airbag System Check
The airbag system does not need regularly
scheduled maintenance or replacement.
Make sure the airbag readiness light is
working. SeeAirbag Readiness Light 0119.
Caution
If an airbag covering is damaged, opened,
or broken, the airbag may not work
properly. Do not open or break the airbag
coverings. If there are any opened or
broken airbag coverings, have the airbag
covering and/or airbag module replaced.
For the location of the airbags, see Where
Are the Airbags? 067. See your dealer
for service.
Replacing Airbag System Parts
after a Crash
{Warning
A crash can damage the airbag systems
in the vehicle. A damaged airbag system
may not properly protect you and your
passenger(s) in a crash, resulting in
serious injury or even death. To help
make sure the airbag systems are
working properly after a crash, have
them inspected and any necessary
replacements made as soon as possible.
If an airbag inflates, you will need to
replace airbag system parts. See your dealer
for service.
If the airbag readiness light stays on after
the vehicle is started or comes on when you
are driving, the airbag system may not work
properly. Have the vehicle serviced right
away. See Airbag Readiness Light 0119.
Child Restraints
Older Children
Older children who have outgrown booster
seats should wear the vehicle’s seat belts.
Refer to How to Wear Seat Belts Properly
0 59.
The manufacturer instructions that come
with the booster seat state the weight and
height limitations for that booster. Use a
booster seat with a lap-shoulder belt until
the child passes the fit test below:
.Sit all the way back on the seat. Do the
knees bend at the seat edge? If yes,
continue. If no, return to the booster seat.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
78 Seats and Restraints
{Warning
Children who are up against, or very
close to, any airbag when it inflates can
be seriously injured or killed. Never put a
rear-facing child restraint in the front
outboard seat. Secure a rear-facing child
restraint in a rear seat. It is also better to
secure a forward-facing child restraint in
a rear seat. If you must secure a
forward-facing child restraint in the front
outboard seat, always move the front
passenger seat as far back as it will go.
Child restraints are devices used to restrain,
seat, or position children in the vehicle and
are sometimes called child seats or car seats.There are three basic types of child
restraints:
.Forward-facing child restraints
.Rear-facing child restraints
.Belt-positioning booster seats
The proper child restraint for your child
depends on their size, weight, and age, and
also on whether the child restraint is
compatible with the vehicle in which it will
be used.
For each type of child restraint, there are
many different models available. When
purchasing a child restraint, be sure it is
designed to be used in a motor vehicle and
is designed by a genuine child restraint
manufacturer. If it is, the child restraint will
have a label saying that it meets federal
motor vehicle safety standards.
The instruction manual that is provided with
the child restraint states the weight and
height limitations for that particular child
restraint. In addition, there are many kinds
of child restraints available for children with
special needs.
{Warning
To reduce the risk of neck and head
injury in a crash, infants and toddlers
should be secured in a rear-facing child
restraint until age two, or until they
reach the maximum height and weight
limits of their child restraint.
{Warning
A young child's hip bones are still so
small that the vehicle seat belt may not
remain low on the hip bones, as it
should. Instead, it may settle up around
the child's abdomen. In a crash, the belt
would apply force on a body area that is
unprotected by any bony structure. This
alone could cause serious or fatal injuries.
To reduce the risk of serious or fatal
injuries during a crash, young children
should always be secured in an
appropriate child restraint.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16504257) - 2023 - CRC - 5/9/22
Instruments and Controls 135
.The HUD brightness setting is not too
dim or too bright.
.The HUD is adjusted to the proper height.
.Polarized sunglasses are not worn.
.The windshield and HUD lens are clean.
If the HUD image is not correct, contact
your dealer.
The windshield is part of the HUD system.
See Windshield Replacement 0324.
Vehicle Messages
Messages displayed on the Driver
Information Center (DIC) indicate the status
of the vehicle or some action that may be
needed to correct a condition. Multiple
messages may appear one after another.
The messages that do not require
immediate action can be acknowledged and
cleared by pressing the thumbwheel. The
messages that require immediate action
cannot be cleared until that action is
performed.
All messages should be taken seriously;
clearing the message does not correct the
problem.
If a SERVICE message appears, see your
dealer. Follow the instructions given in the
messages. The system displays messages
regarding the following topics:
.Service Messages
.Fluid Levels
.Vehicle Security
.Brakes
.Steering
.Ride Control Systems
.Driver Assistance Systems
.Cruise Control
.Lighting and Bulb Replacement
.Wiper/Washer Systems
.Doors and Windows
.Seat Belts
.Airbag Systems
.Engine and Transmission
.Tire Pressure
.Battery
Engine Power Messages
ENGINE POWER IS REDUCED
This message displays when the vehicle's
propulsion power is reduced. A reduction in
propulsion power can affect the vehicle's
ability to accelerate. If this message is on,
but there is no observed reduction in
performance, proceed to your destination.
Under certain conditions the performance
may be reduced the next time the vehicle is
driven. The vehicle may be driven while this
message is on, but maximum acceleration
and speed may be reduced. Anytime this
message stays on, or displays repeatedly,
the vehicle should be taken to your dealer
for service as soon as possible.
Under certain operating conditions,
propulsion will be disabled. Try restarting
after the ignition has been off for
30 seconds.
Vehicle Speed Messages
SPEED LIMITED TO XXX KM/H (MPH)
This message shows that the vehicle speed
has been limited to the speed displayed. The
limited speed is a protection for various
propulsion and vehicle systems, such as
lubrication, thermal, brakes, suspension,
Teen Driver if equipped, or tires.
Universal Remote System
See
Radio Frequency Statement 0404.