2021 GMC ACADIA ECU

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
6 Keys, Doors, and Windows
Keys, Doors, and
Windows
Keys and Locks
Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Remote Keyless Entry (RKE) System . . . . . 7
Remote Keyless Entry (RKE) SystemOperation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Remote Vehicle Start . . . . . . . . . . . . . . . . . . . 13
Door Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Power Door Locks . . . . . . . . . . . . . . . . . . . . . . . 17
Delayed Locking . . . . . . . . . . . . . . . . . . . . . . . . 17
Automatic Door Locks . . . . . . . . . . . . . . . . . . . 17
Lockout Protection . . . . . . . . . . . . . . . . . . . . . . 17
Safety Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Doors
Liftgate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Vehicle Security
Vehicle Security . . . . . . . . . . . . . . . . . . . . . . . . 25
Vehicle Alarm System . . . . . . . . . . . . . . . . . . 25
Immobilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Immobilizer Operation . . . . . . . . . . . . . . . . . . 26
Exterior Mirrors
Convex Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 26
Power Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Folding Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 27
Heated Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 28
Automatic Dimming Mirror . . . . . . . . . . . . . 28
Reverse Tilt Mirrors . . . . . . . . . . . . . . . . . . . . . 28
Interior Mirrors
Interior Rearview Mirrors . . . . . . . . . . . . . . . 28
Manual Rearview Mirror . . . . . . . . . . . . . . . . 28
Automatic Dimming Rearview Mirror . . . 28
Rear Camera Mirror . . . . . . . . . . . . . . . . . . . . 28
Windows
Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Power Windows . . . . . . . . . . . . . . . . . . . . . . . . 31
Sun Visors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Roof
Sunroof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Keys and Locks
Keys
{Warning
Leaving children in a vehicle with a
Remote Keyless Entry (RKE) transmitter is
dangerous and children or others could
be seriously injured or killed. They could
operate the power windows or other
controls or make the vehicle move. The
windows will function with the RKE
transmitter in the vehicle, and children or
others could be caught in the path of a
closing window. Do not leave children in
a vehicle with an RKE transmitter.

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
16 Keys, Doors, and Windows
Driver Door Key Lock Cylinder Access (In
Case of Dead Battery)
To access the driver door key lock cylinder:1. Pull the door handle (1) to the open position and hold it open until cap
removal is complete.
2. Insert the key into the slot (3) on the bottom of the cap (2) and lift the key
upward.
3. Move the cap (2) rearward and remove.
4. Use the key in the cylinder.
To replace the cap: 1. Pull the door handle (1) to the open position and hold it open until cap
installation is complete.
2. Insert the two tabs (6) at the back of thecap between the seal (5) and the metal
base (4).3. Slide the cap forward and press theforward edge to install the cap in place.
4. Release the door handle.
5. Check that the cap is secure.
Free-Turning Locks
The door key lock cylinder turns freely when
either the wrong key is used, or the correct
key is not fully inserted. The free-turning
door lock feature prevents the lock from
being forced open. To reset the lock, turn it
to the vertical position with the correct key
fully inserted. Remove the key and insert it
again. If this does not reset the lock, turn
the key halfway around in the cylinder and
repeat the reset procedure.

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
Keys, Doors, and Windows 19
Warning (Continued)
.If the vehicle is equipped with a
power liftgate, disable the power
liftgate function.
See Engine Exhaust 0219.
Caution
To avoid damage to the liftgate or
liftgate glass, make sure the area above
and behind the liftgate is clear before
opening it.
Manual Liftgate
To unlock the liftgate, pressKon the
power door lock switch or press
Kon the
RKE transmitter twice within five seconds.
See Remote Keyless Entry (RKE) System
Operation 07.
To open the liftgate, press the touch pad on
the bottom of the liftgate handle and
lift up.
Use the pull cup to lower and close the
liftgate. Do not press the touch pad while
closing the liftgate. This will cause the
liftgate to be unlatched.
If equipped with Keyless Access, the liftgate
can be opened when locked if the RKE
transmitter is within 1 m (3 ft) of the touch
pad. See Remote Keyless Entry (RKE) System
Operation 07. The liftgate has an electric latch. If the
battery is disconnected or has low voltage,
the liftgate will not open. The liftgate will
resume operation when the battery is
reconnected and charged.
Always close the liftgate before driving.
Power Liftgate Operation
{Warning
You or others could be injured if caught
in the path of the power liftgate. Make
sure there is no one in the way of the
liftgate as it is opening and closing.
Caution
Driving with an open and unsecured
liftgate may result in damage to the
power liftgate components.

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
20 Keys, Doors, and Windows
If equipped, the power liftgate switch is on
the driver door. The vehicle must be in
P (Park). The taillamps flash when the power
liftgate moves.
The modes are:
.MAX: Opens to maximum height.
.3/4: Opens to a reduced height that can
be set from 3/4 to fully open. Use to
prevent the liftgate from opening into
overhead obstructions such as a garage
door or roof-mounted cargo. The liftgate
can be manually opened all the way.
.OFF: Opens manually only.
To power open or close the liftgate, select
MAX or 3/4 mode.
.Pressbtwice quickly on the RKE
transmitter until the liftgate moves.
.Press8on the driver door. The driver
door must either be unlocked or locked
without the security armed.
.Press the touch pad on the bottom of the
liftgate after unlocking all doors.
If equipped with Keyless Access, a locked
vehicle can be opened if the RKE
transmitter is within 1 m (3 ft) of the
touch pad.
Presslon the bottom of the liftgate
next to the pull cup to close. Press any liftgate button, the touch pad,
or
bon the RKE transmitter while the
liftgate is moving to stop it. Pressing any
liftgate button or pressing
btwice quickly
on the RKE transmitter again restarts the
operation in the reverse direction. Pressing
the touch pad on the liftgate handle will
restart the motion, but only in the opening
direction.
Caution
Manually forcing the liftgate to open or
close during a power cycle can damage
the vehicle. Allow the power cycle to
complete.
The power liftgate may be temporarily
disabled under extreme low temperatures,
or after repeated power cycling over a short
period of time. If this occurs, the liftgate can
still be operated manually.
If the vehicle is shifted out of P (Park) while
the power function is in progress, the
liftgate will continue to completion. If the
vehicle is accelerated before the liftgate has
completed moving, the liftgate may stop or
reverse direction. Check for Driver

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
Keys, Doors, and Windows 25
Vehicle Security
This vehicle has theft-deterrent features;
however, they do not make the vehicle
impossible to steal.
Vehicle Alarm System
This vehicle has an anti-theft alarm system.
The indicator light, on the instrument panel
near the windshield, indicates the status of
the system.
Off :Alarm system is disarmed.
On Solid : Vehicle is secured during the
delay to arm the system. Fast Flash :
Vehicle is unsecured. A door, the
hood, or the liftgate is open.
Slow Flash : Alarm system is armed.
Arming the Alarm System
1. Close the liftgate and the hood. Turn off
the vehicle.
2. Lock the vehicle in one of three ways:
.Use the RKE transmitter.
.Use the Keyless Access system.
.With a door open, press the
inside
Q.
3. After 30 seconds the alarm system will arm, and the indicator light will begin to
slowly flash indicating the alarm system
is operating. Pressing
Qon the RKE
transmitter a second time will bypass
the 30-second delay and immediately
arm the alarm system.
The vehicle alarm system will not arm if the
doors are locked with the key.
If the driver door is opened without first
unlocking with the RKE transmitter, the horn
will chirp and the lights will flash to indicate
pre-alarm. If the vehicle is not started, or the door is not unlocked by pressing
K
on the RKE transmitter during the 10-second
pre-alarm, the alarm will be activated.
The alarm will also be activated if a
passenger door, the liftgate, or the hood is
opened without first disarming the system.
When the alarm is activated, the turn
signals flash and the horn sounds for about
30 seconds. The alarm system will then
re-arm to monitor for the next unauthorized
event.
Disarming the Alarm System
To disarm the alarm system or turn off the
alarm if it has been activated:
.PressKon the RKE transmitter.
.Unlock the vehicle using the Keyless
Access system.
.Start the vehicle.
To avoid setting off the alarm by accident:
.Lock the vehicle after all occupants have
left the vehicle and all doors are closed.
.Always unlock a door with the RKE
transmitter or use the Keyless Access
system.
Unlocking the driver door with the key will
not disarm the system or turn off the alarm.

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
26 Keys, Doors, and Windows
How to Detect a Tamper Condition
IfKis pressed and the horn chirps and the
lights flash three times, the alarm was
activated while the alarm system was
armed.
If the alarm system has been activated, a
message will appear on the Driver
Information Center (DIC).
Immobilizer
See Radio Frequency Statement 0371.
Immobilizer Operation
This vehicle has a passive theft-deterrent
system.
The system does not have to be manually
armed or disarmed.
The vehicle is automatically immobilized
when the vehicle is turned off.
The immobilization system is disarmed
when the ignition is on or in ACC/
ACCESSORY and a valid transmitter is
present in the vehicle.
The security light, in the instrument cluster,
comes on if there is a problem with arming
or disarming the theft-deterrent system.
The system has one or more RKE
transmitters matched to an immobilizer
control unit in your vehicle. Only a correctly
matched RKE 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 may come 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 ignition 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 transmitter pocket
located in the center console. See Remote
Keyless Entry (RKE) System Operation 07. If the ignition mode will not change with
the other transmitter or in the transmitter
pocket, your vehicle needs service. If the
ignition does change modes, the first
transmitter may be faulty. See your dealer
who can service the theft-deterrent system
and have a new RKE transmitter
programmed to the vehicle.
It is possible for the immobilizer system to
learn new or replacement RKE transmitters.
Up to eight transmitters can be
programmed for the vehicle. To program
additional transmitters, see
“Programming
Transmitters to the Vehicle” underRemote
Keyless Entry (RKE) System Operation 07.
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 (Continued)

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
Seats and Restraints 35
Seats and Restraints
Head Restraints
Head Restraints . . . . . . . . . . . . . . . . . . . . . . . . . 35
Front Seats
Seat Adjustment . . . . . . . . . . . . . . . . . . . . . . . . 37
Power Seat Adjustment . . . . . . . . . . . . . . . . . 37
Lumbar Adjustment . . . . . . . . . . . . . . . . . . . . 38
Reclining Seatbacks . . . . . . . . . . . . . . . . . . . . . 38
Memory Seats . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Heated and Ventilated Front Seats . . . . . 41
Rear Seats
Rear Seats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Heated Rear Seats . . . . . . . . . . . . . . . . . . . . . . 45
Third Row Seats . . . . . . . . . . . . . . . . . . . . . . . . 46
Seat Belts
Seat Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
How to Wear Seat Belts Properly . . . . . . 48
Lap-Shoulder Belt . . . . . . . . . . . . . . . . . . . . . . . 50
Seat Belt Use During Pregnancy . . . . . . . . 52
Seat Belt Extender . . . . . . . . . . . . . . . . . . . . . . 53
Safety System Check . . . . . . . . . . . . . . . . . . . 53
Seat Belt Care . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Replacing Seat Belt System Parts after aCrash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Airbag System
Airbag System . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Where Are the Airbags? . . . . . . . . . . . . . . . . 55
When Should an Airbag Inflate? . . . . . . . . 57
What Makes an Airbag Inflate? . . . . . . . . . 58
How Does an Airbag Restrain? . . . . . . . . . 58
What Will You See after an AirbagInflates? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Passenger Sensing System . . . . . . . . . . . . . 59
Servicing the Airbag-Equipped Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Adding Equipment to the Airbag-Equipped Vehicle . . . . . . . . . . . . . . 63
Airbag System Check . . . . . . . . . . . . . . . . . . . 64
Replacing Airbag System Parts after a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Child Restraints
Older Children . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Infants and Young Children . . . . . . . . . . . . 66
Child Restraint Systems . . . . . . . . . . . . . . . . 68
Where to Put the Restraint . . . . . . . . . . . . 69
Lower Anchors and Tethers for Children(LATCH System) . . . . . . . . . . . . . . . . . . . . . . . 71
Replacing LATCH System Parts After a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Securing Child Restraints (With the Seat Belt in the Rear Seat) . . . . . . . . . . . . . . . . . 78
Securing Child Restraints (With the Seat Belt in the Front Seat) . . . . . . . . . . . . . . . 80
Head Restraints
Front Seats
{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.
The vehicle's front seats have adjustable
head restraints in the outboard seating
positions.

GMC Acadia/Acadia Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-14608671) - 2021 - CRC - 10/26/20
Seats and Restraints 51
3. Push the latch plate into the buckle untilit clicks.
Pull up on the latch plate to make sure
it is secure. If the belt is not long
enough, see Seat Belt Extender 053.
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” later in this section for
instructions on use and important safety
information.5. To make the lap part tight, pull up on the shoulder belt.
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 has a shoulder belt height
adjuster for the driver and front outboard
passenger seating positions.
Adjust the height so that 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 Properly
0 48.