2020 GMC YUKON ECU

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Keys, Doors, and Windows 37
The security light in the instrument
cluster comes on when there is a
problem with arming or disarming
the theft-deterrent system.
The system has one or more
transmitters matched to an
immobilizer control unit in your
vehicle. Only a correctly matched
transmitter will start the vehicle.
If the transmitter is ever damaged,
you may not be able to start your
vehicle.
When trying to start the vehicle, the
security light comes on briefly when
the ignition is turned on.
If the engine does not start and the
security light stays on, there is a
problem with the system. Turn the
vehicle off and try again.
If the vehicle will not change ignition
modes (ACC/ACCESSORY, on, off),
and the RKE transmitter appears to
be undamaged, try another
transmitter. Or, you may try placing
the transmitter in the front
cupholder. See“Starting the Vehicle
with a Low Transmitter Battery” under
Remote Keyless Entry (RKE)
System Operation (Key Access)
0 13 or
Remote Keyless Entry (RKE)
System Operation (Keyless Access)
0 16.
If the engine does not start with the
other transmitter or when the
transmitter is in the pocket in the
front cupholder, the vehicle needs
service. See your dealer who can
service the theft-deterrent system
and have a new transmitter
programmed to the vehicle.
Do not leave the transmitter or
device that disarms or deactivates
the theft-deterrent system in the
vehicle.Exterior Mirrors
Convex Mirrors
{Warning
A convex mirror can make things,
like other vehicles, look farther
away than they really are. If you
cut too sharply into the right lane,
you could hit a vehicle on the
right. Check the inside mirror or
glance over your shoulder before
changing lanes.
The passenger side mirror is convex
shaped. A convex mirror's surface is
curved so more can be seen from
the driver seat.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
46 Seats and Restraints
Seats and
Restraints
Head Restraints
Head Restraints . . . . . . . . . . . . . . . 47
Front Seats
Center Seat . . . . . . . . . . . . . . . . . . . . 48
Power Seat Adjustment . . . . . . . . 48
Lumbar Adjustment . . . . . . . . . . . . 49
Reclining Seatbacks . . . . . . . . . . . 50
Memory Seats . . . . . . . . . . . . . . . . . 51
Heated and Ventilated FrontSeats . . . . . . . . . . . . . . . . . . . . . . . . . 54
Rear Seats
Rear Seats . . . . . . . . . . . . . . . . . . . . 55
Heated Rear Seats . . . . . . . . . . . . 55
Second Row Seats . . . . . . . . . . . . 56
Third Row Seats . . . . . . . . . . . . . . . 60
Seat Belts
Seat Belts . . . . . . . . . . . . . . . . . . . . . 62
How to Wear Seat BeltsProperly . . . . . . . . . . . . . . . . . . . . . . 63
Lap-Shoulder Belt . . . . . . . . . . . . . 65
Seat Belt Use During Pregnancy . . . . . . . . . . . . . . . . . . . . 70
Lap Belt . . . . . . . . . . . . . . . . . . . . . . . 71 Seat Belt Extender . . . . . . . . . . . . . 71
Safety System Check . . . . . . . . . . 71
Seat Belt Care . . . . . . . . . . . . . . . . . 72
Replacing Seat Belt System
Parts after a Crash . . . . . . . . . . . 72
Airbag System
Airbag System . . . . . . . . . . . . . . . . . 73
Where Are the Airbags? . . . . . . . 75
When Should an Airbag
Inflate? . . . . . . . . . . . . . . . . . . . . . . . 77
What Makes an Airbag Inflate? . . . . . . . . . . . . . . . . . . . . . . . 78
How Does an Airbag Restrain? . . . . . . . . . . . . . . . . . . . . . 78
What Will You See after an Airbag Inflates? . . . . . . . . . . . . . . 78
Passenger Sensing System . . . 80
Servicing the Airbag-Equipped Vehicle . . . . . . . . . . . . . . . . . . . . . . . 84
Adding Equipment to the Airbag-Equipped Vehicle . . . . . 84
Airbag System Check . . . . . . . . . . 85
Replacing Airbag System Parts after a Crash . . . . . . . . . . . . . . . . . 86
Child Restraints
Older Children . . . . . . . . . . . . . . . . . 86
Infants and Young Children . . . . 88
Child Restraint Systems . . . . . . . 90
Where to Put the Restraint . . . . . 92
Lower Anchors and Tethers forChildren (LATCH System) . . . . 93
Replacing LATCH System Parts After a Crash . . . . . . . . . 103
Securing Child Restraints (With the Seat Belt in the
Rear Seat) . . . . . . . . . . . . . . . . . . 103
Securing Child Restraints (With the Seat Belt in the Center
Front Seat) . . . . . . . . . . . . . . . . . . 105
Securing Child Restraints (With the Seat Belt in the Front
Passenger Seat) . . . . . . . . . . . . 106

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
48 Seats and Restraints
Second Row Seats
The vehicle's second row seats
have head restraints in the outboard
seating positions that cannot be
adjusted.
The second row seat outboard head
restraints are not removable.
Third Row Seats
The third row seat head restraint
can be lowered to allow for better
visibility when the rear seat is
unoccupied.To lower the head restraint, press
the button located on the top of the
seatback and push the head
restraint down.
Return the lowered head restraint to
the upright position until it locks into
place. Push and pull on the head
restraint to make sure it is locked.
If you are installing a child restraint
in the third row seat, see
“Securing
a Child Restraint Designed for the
LATCH System” underLower
Anchors and Tethers for Children
(LATCH System) 093.
Front Seats
Center Seat
If equipped, the center front
seatback doubles as an armrest and
cupholder/storage area for the driver
and passenger when the center
front seat is not used. Do not use it
as a seating position when the
seatback is folded down.
Power 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 Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
60 Seats and Restraints
Folding and Tumbling the Seat
from the Cargo Area
1. Second Row Power SeatSwitches
2. Third Row Power Seat Switches
To fold and tumble the seat from the
cargo area:
1. Make sure that there is nothing under, in front of, or on
the seat.
2. Press the switch (1) on the side trim of the cargo area to fold
the seatback. The left switch folds the left
seatback, and the right switch
folds the right seatback.
3. Press the switch again to release the rear of the seat
from the floor. The seat will
tumble forward.
The switches (2) can be used to fold
and unfold the third row seatbacks
from the cargo area. See Third Row
Seats 060.
Returning the Seat to the
Sitting Position
{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.
To return the seat to the sitting
position from the tumbled position: 1. Pull the seat down until both
sides of the seat are latched to
the floor. Make sure the seat is
securely latched to the floor
before raising the seatback.
If both sides are not latched to
the floor, the seatback will not
raise.
2. Lift the seatback and push it rearward. Push and pull on the
seatback to make sure it is
locked.
Third Row Seats
Folding the Seatback
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.
The transmission must be in
P (Park) for this feature to work.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
62 Seats and Restraints
Returning the Third Row
Seatback to the Upright
Position
1. Second Row Power SeatFold and Tumble Switches
2. Third Row Power Seat Fold and Raise Switches
To return the third row seatback to
the upright position:
1. Open the liftgate to access the controls for the seat.
2. 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. 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.
3. Reconnect the center seat belt mini-latch to the mini-buckle.
Do not let it twist.
4. Pull on the seat belt to be sure the mini-latch is secure.
5. Repeat the steps for the other seatback, if desired.
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
injured or killed. Do not allow
(Continued)

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Seats and Restraints 67
3. Push the latch plate into thebuckle until it clicks. If the latch
plate will not go fully into the
buckle, check if the correct
buckle is being used.
Pull up on the latch plate to
make sure it is secure. If the
belt is not long enough, see
Seat Belt Extender 071.
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.
For third row seats, it may be
necessary to pull stitching on
the seat belt through the latch
plate to fully tighten the lap belt
on smaller occupants.
To unlatch the belt, push the button
on the buckle. The belt should
return to its stowed position.
For third row seats, slide the latch
plate up the safety webbing when
the seat belt is not in use. The latch
plate should rest on the stitching on
the seat belt.
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.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Seats and Restraints 71
Lap Belt
This section is only for the lap belt.
To learn how to wear a lap-shoulder
belt, seeLap-Shoulder Belt 065.
The vehicle may have a center
seating position with a lap seat belt.
The lap seat belt does not have a
retractor.
To make the belt longer, tilt the latch
plate and pull it along the belt.
Buckle, position, and release it the
same way as the lap part of a
lap-shoulder belt.
To make the belt shorter, pull its free
end as shown until the belt is snug.
If the belt is not long enough, see
Seat Belt Extender 071.
Make sure the release button on the
buckle is positioned so you would
be able to unbuckle the seat belt
quickly if necessary.
If you find that the latch plate will
not go fully into the buckle, see if
you are using the correct buckle. Be
sure that the latch plate clicks when
inserted into the buckle.
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

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
74 Seats and Restraints
{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? 077.
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 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.
(Continued)
Warning (Continued)
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 086 or
Infants and Young Children 088.