2021 GMC YUKON ECU

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Seats and Restraints 37
Seats and Restraints
Head Restraints
Head Restraints . . . . . . . . . . . . . . . . . . . . . . . . . 37
Front Seats
Power Seat Adjustment . . . . . . . . . . . . . . . . 40
Lumbar Adjustment . . . . . . . . . . . . . . . . . . . . 40
Reclining Seatbacks . . . . . . . . . . . . . . . . . . . . . 41
Memory Seats . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Heated and Ventilated Front Seats . . . . . 44
Rear Seats
Rear Seats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Heated Rear Seats . . . . . . . . . . . . . . . . . . . . . . 45
Second Row Seats . . . . . . . . . . . . . . . . . . . . . . 46
Third Row Seats . . . . . . . . . . . . . . . . . . . . . . . . 50
Seat Belts
Seat Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
How to Wear Seat Belts Properly . . . . . . 54
Lap-Shoulder Belt . . . . . . . . . . . . . . . . . . . . . . . 56
Seat Belt Use During Pregnancy . . . . . . . . 59
Seat Belt Extender . . . . . . . . . . . . . . . . . . . . . . 59
Safety System Check . . . . . . . . . . . . . . . . . . . 59
Seat Belt Care . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Replacing Seat Belt System Parts after aCrash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Airbag System
Airbag System . . . . . . . . . . . . . . . . . . . . . . . . . 60 Where Are the Airbags? . . . . . . . . . . . . . . . . 62
When Should an Airbag Inflate? . . . . . . . . 63
What Makes an Airbag Inflate? . . . . . . . . 64
How Does an Airbag Restrain? . . . . . . . . . 64
What Will You See after an Airbag
Inflates? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Passenger Sensing System . . . . . . . . . . . . . 66
Servicing the Airbag-Equipped Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Adding Equipment to the Airbag-Equipped Vehicle . . . . . . . . . . . . . . 69
Airbag System Check . . . . . . . . . . . . . . . . . . . 70
Replacing Airbag System Parts after a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Child Restraints
Older Children . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Infants and Young Children . . . . . . . . . . . . . 72
Child Restraint Systems . . . . . . . . . . . . . . . . 74
Where to Put the Restraint . . . . . . . . . . . . . 76
Lower Anchors and Tethers for Children(LATCH System) . . . . . . . . . . . . . . . . . . . . . . . 77
Replacing LATCH System Parts After a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Securing Child Restraints (With the Seat Belt in the Rear Seat) . . . . . . . . . . . . . . . . 84
Securing Child Restraints (With the Seat Belt in the Front Passenger Seat) . . . . . 86
Securing Child Restraints (With the Seat Belt in the Center Front Seat) . . . . . . . . 88
Head Restraints
The vehicle’s front seats have adjustable
head restraints in the outboard seating
positions.
{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.
If your vehicle has rear head restraints
that fold down, always return them to
the full upright position whenever an
occupant is seated in the seat.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
52 Seats and Restraints
1. Ensure the seat belt is in the beltstowage clip.
2. Open the liftgate to access the controls for the seat.
3. Press and hold the switch (2) on the side trim of the cargo area to raise the third
row seatback.
The left switch raises the left seatback,
and the right switch raises the right
seatback.
{Warning
A seat belt that is improperly routed, not
properly attached, or twisted will not
provide the protection needed in a crash.
(Continued)
Warning (Continued)
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.
4. Reconnect the center seat belt mini-latch to the mini-buckle. Do not let it twist.
5. Pull on the seat belt to be sure the mini-latch is secure.
6. Repeat the steps for the other seatback, if desired.
Manual Seatback Folding (If Equipped)
1. Pull up on the lever to release theseatback.
2. Push the seatback forward to lay flat.
3. Repeat for the other seatback, if necessary.
Returning the Third Row Seatback to the
Upright Position
1. Ensure the seat belt is in the belt stowage clip.
2. From the rear of the vehicle, raise the seatback to the upright position using
the pull strap on the back of the third
row seat, or lift the seatback and push it
into place from inside the vehicle.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Seats and Restraints 53
{Warning
If either seatback is not locked, it could
move forward in a sudden stop or crash.
That could cause injury to the person
sitting there. Always push and pull on
the seatbacks to be sure they are locked.
3. Push and pull on the seatback to make sure it is locked in place.
{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.
4. Reconnect the center seat belt mini-latch to the mini-buckle. Do not let it twist.
5. Pull on the seat belt to be sure the mini-latch is secure. Folding the Third Row Seats from the
Overhead Console
To fold the seats from the overhead console,
if equipped:
The vehicle must be in P (Park) for this
feature to work.
1. Press and hold the switch to fold the third row seatback.
The left switch folds the left seatback,
and the right switch folds the right
seatback.
2. Repeat the steps for the other seatback, if desired.
3. Press and hold the switch to return the seatback to the seating position. If the red light on the switch is
illuminated, the third row seatback is not
in the seating position.
There are additional switches which can be
used to fold the third row seatbacks from
the cargo area. See Third Row Seats050.
Seat Belts
This section describes how to use seat belts
properly, and some things not to do.
{Warning
Do not let anyone ride where a seat belt
cannot be worn properly. In a crash,
if you or your passenger(s) are not
wearing seat belts, injuries can be much
worse than if you are wearing seat belts.
You can be seriously injured or killed by
hitting things inside the vehicle harder or
by being ejected from the vehicle. In
addition, anyone who is not buckled up
can strike other passengers in the vehicle.
It is extremely dangerous to ride in a
cargo area, inside or outside of a vehicle.
In a collision, passengers riding in these
areas are more likely to be seriously
(Continued)

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Seats and Restraints 57
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. SeeChild Restraint Systems
0 74. 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
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. See Passenger Sensing
System 066.
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 059.
Position the release button on the buckle
so that the seat belt could be quickly
unbuckled if necessary.
4. If equipped with a shoulder belt height adjuster, move it to the height that is
right for you. See “Shoulder Belt Height
Adjuster” in this section for instructions
on use and important safety information.5. To make the lap part tight, pull up on the shoulder belt.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Seats and Restraints 59
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
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 0109.
Keep seat belts clean and dry. See Seat Belt
Care 059.
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 Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Seats and Restraints 61
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
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? 063.
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
(Continued)
Warning (Continued)
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
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 front center armrest or
console in vehicles with a front center
airbag.
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 071 or
Infants and Young Children 072.
There is an airbag readiness light on the
instrument cluster, which shows the airbag
symbol.
The system checks the airbag electrical
system for malfunctions. The light tells you
if there is an electrical problem. See Airbag
Readiness Light 0109.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Seats and Restraints 63
Driver Side Shown, Passenger Side Similar
The roof-rail airbags for the driver, front
outboard passenger, and second and third
row outboard seating positions are in the
ceiling above the side windows.
{Warning
If something is between an occupant and
an airbag, the airbag might not inflate
properly or it might force the object into
that person causing severe injury or even
death. The path of an inflating airbag
must be kept clear. Do not put anything
between an occupant and an airbag, and (Continued)
Warning (Continued)
do not attach or put anything on the
steering wheel hub or on or near any
other airbag covering.
Do not use seat or console accessories
that block the inflation path of a
seat-mounted side impact airbag or the
front center airbag, if equipped.
Never secure anything to the roof of a
vehicle with roof-rail airbags by routing a
rope or tie-down through any door or
window opening. If you do, the path of
an inflating roof-rail airbag will be
blocked.
When Should an Airbag Inflate?
This vehicle is equipped with airbags. See
Airbag System060. Airbags are designed to
inflate if the impact exceeds the specific
airbag system's deployment threshold.
Deployment thresholds are used to predict
how severe a crash is likely to be in time
for the airbags to inflate and help restrain
the occupants. The vehicle has electronic
sensors that help the airbag system determine the severity of the impact.
Deployment thresholds can vary with
specific vehicle design.
Frontal airbags are designed to inflate in
moderate to severe frontal or near frontal
crashes to help reduce the potential for
severe injuries, mainly to the driver's or
front outboard passenger's head and chest.
Whether the frontal airbags will or should
inflate is not based primarily on how fast
the vehicle is traveling. It depends on what
is hit, the direction of the impact, and how
quickly the vehicle slows down.
Frontal airbags may inflate at different crash
speeds depending on whether the vehicle
hits an object straight on or at an angle,
and whether the object is fixed or moving,
rigid or deformable, narrow or wide.
Frontal airbags are not intended to inflate
during vehicle rollovers, rear impacts,
or many side impacts.
In addition, the vehicle has advanced
technology frontal airbags. Advanced
technology frontal airbags adjust the
restraint according to crash severity.
The front center airbag, if equipped, is
designed to inflate in moderate to severe
side crashes depending upon the location of

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
66 Seats and Restraints
.Let only qualified technicians work on the
airbag systems. Improper service can
mean that an airbag system will not work
properly. See your dealer for service.
Passenger Sensing System
The vehicle has a passenger sensing system
for the front outboard passenger position.
The passenger airbag status indicator will
light on the overhead console when the
vehicle is started.
United States and Canada
The words ON and OFF, and the symbols for
on and off, will be visible during the system
check. When the system check is complete,
either the word ON or OFF, and the symbol
for on or off, will be visible. See Passenger
Airbag Status Indicator 0110.
The passenger sensing system turns off the
front outboard passenger frontal airbag
under certain conditions. No other airbag is
affected by the passenger sensing system. The passenger sensing system works with
sensors that are part of the front outboard
passenger seat and seat belt. The sensors
are designed to detect the presence of a
properly seated occupant and determine if
the front outboard passenger frontal airbag
should be allowed to inflate or not.
According to accident statistics, children are
safer when properly secured in a rear seat
in the correct child restraint for their weight
and size.
Whenever possible, children aged 12 and
under should be secured in a rear seating
position.
Never put a rear-facing child seat in the
front. This is because the risk to the
rear-facing child is so great, if the airbag
inflates.
{Warning
A child in a rear-facing child restraint can
be seriously injured or killed if the
passenger frontal airbag inflates. This is
because the back of the rear-facing child
restraint would be very close to the
inflating airbag. A child in a
forward-facing child restraint can be
(Continued)
Warning (Continued)
seriously injured or killed if the passenger
frontal airbag inflates and the passenger
seat is in a forward position.
Even if the passenger sensing system has
turned off the passenger frontal airbag,
no system is fail-safe. No one can
guarantee that an airbag will not deploy
under some unusual circumstance, even
though the airbag is turned off.
Never put a rear-facing child restraint in
the front seat, even if the airbag is off.
If securing a forward-facing child restraint
in the front outboard passenger seat,
always move the seat as far back as it
will go. It is better to secure child
restraints in the rear seat. Consider using
another vehicle to transport the child
when a rear seat is not available.
If the vehicle does not have a rear seat that
will accommodate a rear-facing child
restraint, a rear-facing child restraint should
not be installed in the vehicle, even if the
airbag is off.