2021 GMC YUKON heater

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
44 Seats and Restraints
Obstructions
If something has blocked the driver seat
while recalling a memory position, the recall
may stop. Remove the obstruction and try
the recall again. If the memory position still
does not recall, see your dealer.
Heated and Ventilated Front
Seats
{Warning
If temperature change or pain to the skin
cannot be felt, the seat heater may cause
burns. To reduce the risk of burns, use
care when using the seat heater,
especially for long periods of time. Do
not place anything on the seat that
insulates against heat, such as a blanket,
cushion, cover, or similar item. This may
cause the seat heater to overheat. An
overheated seat heater may cause a burn
or may damage the seat.Heated and Ventilated Seat Buttons Shown,Heated Seat Buttons Similar
If equipped, the buttons are near the
climate controls on the center stack. To
operate, the engine must be on.
Press
Ior+to heat the driver or
passenger seatback.
Press
Jorzto heat the driver or
passenger seatback and cushion.
Press
Cor{, if available, to ventilate the
driver or passenger seat. A ventilated seat
has a fan that pulls or pushes air through
the seat. The air is not cooled. When this feature is off, the heated and
ventilated seat symbols on the buttons are
white. When a heated seat is turned on, the
symbol turns red. When a ventilated seat is
turned on, the symbol turns blue.
Press the button once for the highest
setting. With each press of the button, the
seat will change to the next lower setting,
and then to the off setting. The indicator
lights next to the buttons indicate three for
the highest setting and one for the lowest.
If the heated seats are on high, the level
may automatically be lowered after
approximately 30 minutes.
The passenger seat may take longer to
heat up.
Auto Heated and Ventilated Seats
When the vehicle is on, this feature will
automatically activate the heated or
ventilated seats at the level required by the
vehicle’s interior temperature.
The active high, medium, low, or off heated
or ventilated seat level will be indicated by
the manual heated or ventilated seat
buttons on the center stack. Use the manual
heated or ventilated seat buttons on the
center stack to turn auto heated or
ventilated seats off. If the passenger seat is

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Seats and Restraints 45
unoccupied, the auto heated or ventilated
seats feature will not activate that seat. The
auto heated or ventilated seats feature can
be programmed to always be enabled when
the vehicle is on.
SeeVehicle Personalization 0126.
Remote Start Heated and Ventilated Seats
During a remote start, the heated or
ventilated seats, if equipped, can be turned
on automatically. When it is cold outside,
the heated seats turn on, and when it is hot
outside the ventilated seats turn on. If the
auto heated or ventilated seats feature,
if equipped, is not turned on, the heated or
ventilated seats may be canceled when the
ignition is turned on. If necessary, press the
heated or ventilated seat button to use the
heated or ventilated seats after the vehicle
is started.
The heated or ventilated seat indicator lights
may turn on during a remote start.
The temperature performance of an
unoccupied seat may be reduced. This is
normal. The remote start heated or ventilated seats
may be enabled or disabled in the vehicle
personalization menu. See
Remote Vehicle
Start 014 and
Vehicle Personalization 0126.
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. See
Vehicle Personalization
0126.
Heated Rear Seats
{Warning
If temperature change or pain to the skin
cannot be felt, the seat heater may cause
burns. See the Warning under Heated
and Ventilated Front Seats 044.
The buttons are on the rear of the center
console.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Seats and Restraints 67
The passenger sensing system is designed to
turn off the front outboard passenger
frontal airbag if:
.The front outboard passenger seat is
unoccupied.
.The system determines an infant is
present in a child restraint.
.A front outboard passenger takes his/her
weight off of the seat for a period
of time.
When the passenger sensing system has
turned off the front outboard passenger
frontal airbag, the OFF indicator will light
and stay lit as a reminder that the airbag is
off. See Passenger Airbag Status Indicator
0 110.
The passenger sensing system is designed to
turn on the front outboard passenger frontal
airbag anytime the system senses that a
person of adult size is sitting properly in the
front outboard passenger seat.
When the passenger sensing system has
allowed the airbag to be enabled, the ON
indicator will light and stay lit as a reminder
that the airbag is active.
For some children, including children in child
restraints, and for very small adults, the
passenger sensing system may or may not turn off the front outboard passenger
frontal airbag, depending upon the person's
seating posture and body build. Everyone in
the vehicle who has outgrown child
restraints should wear a seat belt
properly
—whether or not there is an
airbag for that person.{Warning
If the airbag readiness light ever comes
on and stays on, it means that
something may be wrong with the airbag
system. To help avoid injury to yourself
or others, have the vehicle serviced right
away. See Airbag Readiness Light 0109
for more information, including important
safety information.
If the On Indicator Is Lit for a Child
Restraint
The passenger sensing system is designed to
turn off the front outboard passenger
frontal airbag if the system determines that
an infant is present in a child restraint. If a
child restraint has been installed and the ON
indicator is lit:
1. Turn the vehicle off. 2. Remove the child restraint from the
vehicle.
3. Remove any additional items from the seat such as blankets, cushions, seat
covers, seat heaters, or seat massagers.
4. Reinstall the child restraint following the directions provided by the child restraint
manufacturer and refer to Securing Child
Restraints (With the Seat Belt in the Rear
Seat) 084 or
Securing Child Restraints (With the Seat
Belt in the Center Front Seat) 088 or
Securing Child Restraints (With the Seat
Belt in the Front Passenger Seat) 086.
Make sure the seat belt retractor is
locked by pulling the shoulder belt all
the way out of the retractor when
installing the child restraint, even if the
child restraint is equipped with a seat
belt lock off. When the retractor lock is
set, the belt can be tightened but not
pulled out of the retractor.
5. If, after reinstalling the child restraint and restarting the vehicle, the ON
indicator is still lit, turn the vehicle off.
Then slightly recline the vehicle seatback
and adjust the seat cushion,

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
68 Seats and Restraints
if adjustable, to make sure that the
vehicle seatback is not pushing the child
restraint into the seat cushion.
Also make sure the child restraint is not
trapped under the vehicle head restraint.
If this happens, adjust the head restraint.
SeeHead Restraints 037.
6. Restart the vehicle.
The passenger sensing system may or may
not turn off the airbag for a child in a child
restraint depending upon the child’s size.
It is better to secure child restraints in a
rear seat. Consider using another vehicle to
transport the child when a rear seat is not
available. Never put a rear-facing child
restraint in the front seat, even if the ON
indicator is not lit.If the Off Indicator Is Lit for an
Adult-Sized Occupant
If a person of adult size is sitting in the
front outboard passenger seat, but the OFF
indicator is lit, it could be because that
person is not sitting properly in the seat or
that the child restraint locking feature is
engaged. Use the following steps to allow
the system to detect that person and enable
the front outboard passenger frontal airbag: 1. Turn the vehicle off.
2. Remove any additional material from the seat, such as blankets, cushions, seat
covers, seat heaters, or seat massagers.
3. Place the seatback in the fully upright position. 4. Have the person sit upright in the seat,
centered on the seat cushion, with legs
comfortably extended.
5. If the shoulder portion of the belt is pulled out all the way, the child restraint
locking feature will be engaged. This
may unintentionally cause the passenger
sensing system to turn the airbag off for
some adult-sized occupants. If this
happens, unbuckle the belt, let the belt
go back all the way, and then buckle the
belt again without pulling the belt out
all the way.
6. Restart the vehicle and have the person remain in this position for two to
three minutes after the ON indicator
is lit.
{Warning
If the front outboard passenger airbag is
turned off for an adult-sized occupant,
the airbag will not be able to inflate and
help protect that person in a crash,
resulting in an increased risk of serious
injury or even death. An adult-sized
occupant should not ride in the front
outboard passenger seat, if the passenger
airbag OFF indicator is lit.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Seats and Restraints 69
Additional Factors Affecting System
Operation
Seat belts help keep the passenger in
position on the seat during vehicle
maneuvers and braking, which helps the
passenger sensing system maintain the
passenger airbag status. See“Seat Belts”
and “Child Restraints” in the Index for
additional information about the importance
of proper restraint use.
A thick layer of additional material, such as
a blanket or cushion, or aftermarket
equipment such as seat covers, seat heaters,
and seat massagers can affect how well the
passenger sensing system operates. We
recommend that you not use seat covers or
other aftermarket equipment except when
approved by GM for your specific vehicle.
See Adding Equipment to the
Airbag-Equipped Vehicle 069 for more
information about modifications that can
affect how the system operates.
The ON indicator may be lit if an object,
such as a briefcase, handbag, grocery bag,
laptop, or other electronic device, is put on
an unoccupied seat. If this is not desired,
remove the object from the seat.
{Warning
Stowing articles under the passenger seat
or between the passenger seat cushion
and seatback may interfere with the
proper operation of the passenger
sensing system.
Servicing the Airbag-Equipped
Vehicle
Airbags affect how the vehicle should be
serviced. There are parts of the airbag
system in several places around the vehicle.
Your dealer and the service manual have
information about servicing the vehicle and
the airbag system. To purchase a service
manual, see Publication Ordering
Information 0406.
{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
(Continued)
Warning (Continued)
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, airbag wiring, or front
center console
.Front seats, including stitching, seams or
zippers
.Seat belts
.Steering wheel, instrument panel,
overhead console, ceiling trim, or pillar
garnish trim

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
70 Seats and Restraints
.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's 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 066.
If the vehicle has rollover roof-rail airbags,
see Different Size Tires and Wheels 0352 for
additional important information. If the vehicle must be modified because you
have a disability and you 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 0401.
Airbag System Check
The airbag system does not need regularly
scheduled maintenance or replacement.
Make sure the airbag readiness light is
working. See Airbag Readiness Light 0109.
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? 062. 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 0109.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
320 Vehicle Care
6.2L V8 Engine
1. Engine Electric Cooling Fans (Outof View)
2. Coolant Surge Tank and Pressure Cap
{Warning
An underhood electric fan can start up
even when the engine is not running and
can cause injury. Keep hands, clothing,
and tools away from any underhood
electric fan.
{Warning
Do not touch heater, radiator, a/c pipes
or hoses, or other engine parts. They can
be very hot and can burn you. Do not
run the engine if there is a leak; all
coolant could leak out. That could cause
an engine fire and can burn you. Fix any
leak before driving the vehicle.
Engine Coolant
The cooling system in the vehicle is filled
with DEX-COOL engine coolant. This coolant
is designed to remain in the vehicle for
5 years or 240 000 km (150,000 mi),
whichever occurs first.
The following explains the cooling system
and how to check and add coolant when it
is low. If there is a problem with engine
overheating, see Engine Overheating 0322.
What to Use
{Warning
Plain water, or other liquids such as
alcohol, can boil before the proper
coolant mixture will. With plain water or
(Continued)
Warning (Continued)
the wrong mixture, the engine could get
too hot but there would not be an
overheat warning. The engine could catch
fire and you or others could be burned.
Use a 50/50 mixture of clean, drinkable
water and DEX-COOL coolant. This mixture:
.Gives freezing protection down to −37 °C
(−34 °F), outside temperature.
.Gives boiling protection up to 129 °C
(265 °F), engine temperature.
.Protects against rust and corrosion.
.Will not damage aluminum parts.
.Helps keep the proper engine
temperature.
Caution
Do not use anything other than a mix of
DEX-COOL coolant that meets GM
Standard GMW3420 and clean, drinkable
water. Anything else can cause damage
to the engine cooling system and the
vehicle, which would not be covered by
the vehicle warranty.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Vehicle Care 323
If the decision is made to lift the hood,
make sure the vehicle is parked on a level
surface.
Check to see if the engine cooling fan(s) are
running. If the engine is overheating, the
fans should be running. If they are not, do
not continue to run the engine. Have the
vehicle serviced.
If Steam is Coming from the Engine
Compartment
{Warning
Steam and scalding liquids from a hot
cooling system are under pressure.
Turning the pressure cap, even a little,
can cause them to come out at high
speed and you could be burned. Never
turn the cap when the cooling system,
including the pressure cap, is hot. Wait
for the cooling system and pressure cap
to cool.
If No Steam is Coming from the Engine
Compartment
The ENGINE OVERHEATED STOP ENGINE or
the ENGINE OVERHEATED IDLE ENGINE
message, along with a low coolant
condition, can indicate a serious problem.
If there is an engine overheat warning, but
no steam is seen or heard, the problem may
not be too serious. Sometimes the engine
can get a little too hot when the vehicle:
.Climbs a long hill on a hot day.
.Stops after high-speed driving.
.Idles for long periods in traffic.
.Tows a trailer; seeTrailer Towing0284.
If the ENGINE OVERHEATED STOP ENGINE or
the ENGINE OVERHEATED IDLE ENGINE
message appears with no sign of steam, try
this for a minute or so: 1. Turn the air conditioning off.
2. Turn the heater on to the highest temperature and to the highest fan
speed. Open the windows as necessary.
3. When it is safe to do so, pull off the road, shift to P (Park) or N (Neutral), and
let the engine idle. If the engine coolant temperature gauge is
no longer in the overheat zone or an
overheat warning no longer displays, the
vehicle can be driven. Continue to drive the
vehicle slowly for about 10 minutes. Keep a
safe vehicle distance from the vehicle in
front. If the warning does not come back on,
continue to drive normally and have the
cooling system checked for proper fill and
function.
If the warning continues, pull over, stop, and
park the vehicle right away.
If there is still no sign of steam and the
vehicle is equipped with an engine driven
cooling fan, push down the accelerator until
the engine speed is about twice as fast as
normal idle speed for at least five minutes
while the vehicle is parked. If the warning is
still there, turn off the engine and get
everyone out of the vehicle until it
cools down.
If there is no sign of steam, idle the engine
for five minutes while parked. If the warning
is still displayed, turn off the engine until it
cools down.