2021 GMC TERRAIN ECU

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Power Door Locks . . . . . . . . . . . . . . . . . . . . . . . 16
Delayed Locking . . . . . . . . . . . . . . . . . . . . . . . . 16
Automatic Door Locks . . . . . . . . . . . . . . . . . . 16
Lockout Protection . . . . . . . . . . . . . . . . . . . . . . 16
Safety Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Doors
Liftgate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Vehicle Security
Vehicle Security . . . . . . . . . . . . . . . . . . . . . . . . 22
Vehicle Alarm System . . . . . . . . . . . . . . . . . . 22
Immobilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Immobilizer Operation . . . . . . . . . . . . . . . . . . 23
Exterior Mirrors
Convex Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 24
Power Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Folding Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 24
Heated Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 25 Automatic Dimming Mirror . . . . . . . . . . . . . 25
Reverse Tilt Mirrors . . . . . . . . . . . . . . . . . . . . . 25
Interior Mirrors
Interior Rearview Mirrors . . . . . . . . . . . . . . . 25
Manual Rearview Mirror . . . . . . . . . . . . . . . . 25
Automatic Dimming Rearview Mirror . . . 25
Windows
Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Power Windows . . . . . . . . . . . . . . . . . . . . . . . . 26
Sun Visors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Roof
Sunroof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
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 Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
Keys, Doors, and Windows 11
1. Remove the key from the RKEtransmitter.
2. Remove the key lock cylinder cap on the driver door handle. See Door Locks014.
Insert the vehicle key of the transmitter
into the key lock cylinder on the driver
door handle and turn the key,
counterclockwise, to the unlock position
five times within 10 seconds.
The DIC displays REMOTE LEARN
PENDING, PLEASE WAIT.
3. Wait for 10 minutes until the DIC displays PRESS ENGINE START BUTTON TO
LEARN and then press ENGINE
START/STOP.
The DIC display will again show REMOTE
LEARN PENDING, PLEASE WAIT.
4. Repeat Step 2 two additional times. After the third time all previously known
transmitters will no longer work with the
vehicle. Remaining transmitters can be
relearned during the next steps.
The DIC display should now show READY
FOR REMOTE # 1.
5. Place the new transmitter into thecupholder.
6. Press ENGINE START/STOP. When the transmitter is learned the DIC display
will show that it is ready to program the
next transmitter.
7. Remove the transmitter from the cupholder and press
KorQon the RKE
transmitter.
To program additional transmitters,
repeat Steps 4–6.
When all additional transmitters are
programmed, press and hold ENGINE
START/STOP for 12 seconds to exit
programming mode.
8. Put the key back into the transmitter. 9. Replace the key lock cylinder cap. See
Door Locks 014.
Starting the Vehicle with a Low
Transmitter Battery
When the vehicle is started, if the
transmitter battery is weak, the DIC may
display NO REMOTE DETECTED or NO
REMOTE KEY WAS DETECTED PLACE KEY IN
TRANSMITTER POCKET THEN START YOUR
VEHICLE. The DIC may also display REPLACE
BATTERY IN REMOTE KEY.
To start the vehicle:
1. Place the transmitter in the cupholder.

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
Keys, Doors, and Windows 15
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 Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
18 Keys, Doors, and Windows
Warning (Continued)
.If the vehicle is equipped with a
power liftgate, disable the power
liftgate function.
See Engine Exhaust 0207.
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
Remote Keyless Entry (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 and lift up.
Use the pull cup to lower and close the
liftgate. Do not press the touch pad while
closing the liftgate. This may 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
liftgate. 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 Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
22 Keys, Doors, and Windows
.Do not keep your foot under the bumper;
the liftgate will not activate.
.Do not touch the liftgate until it has
stopped moving.
.This feature may be temporarily disabled
under some conditions. If the liftgate
does not respond to the kick, open or
close the liftgate by another method or
start the vehicle. The feature will be
re-enabled.
When closing the liftgate using this feature,
there will be a short delay. The taillamps
will flash and a chime will sound. Step away
from the liftgate before it starts moving.
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. Turn off the vehicle.
2. Lock the vehicle in one of two ways:
.Use the RKE transmitter.
.With a door open, press the
interior
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.
If a door, the hood, or the liftgate is opened
without first disarming the system, the turn
signals will flash and the horn will sound 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:

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
Keys, Doors, and Windows 23
.PressKon the RKE transmitter.
.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.
Unlocking the driver door with the key will
not disarm the system or turn off the alarm.
How to Detect a Tamper Condition
IfKis pressed on the RKE transmitter and
the horn chirps and the lights flash three
times, an alarm occurred previously while
the alarm system was armed.
If the alarm has been activated, a message
will appear on the Driver Information
Center (DIC).
Immobilizer
See Radio Frequency Statement 0354.
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 transmitter leaves the vehicle.
The immobilization system is disarmed
when the ignition is turned on or in ACC/
ACCESSORY and a valid Remote Keyless
Entry (RKE) transmitter is 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 ignition will not change from off to
on or ACC/ACCESSORY, and the RKE
transmitter appears to be undamaged, try
another transmitter. Or, you may try placing
the transmitter in the cupholder in the
center console. See
Remote Keyless Entry
(RKE) System Operation 07.
If the ignition mode will not change with
the other transmitter, or with the
transmitter in the cupholder, 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 to the vehicle. To program
additional transmitters, see “Programming
Transmitters to the Vehicle” underRemote
Keyless Entry (RKE) System Operation 07.
Do not leave the key or device that disarms
or deactivates the theft-deterrent system in
the vehicle.

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
Seats and Restraints 29
Seats and Restraints
Head Restraints
Head Restraints . . . . . . . . . . . . . . . . . . . . . . . . 29
Front Seats
Seat Adjustment . . . . . . . . . . . . . . . . . . . . . . . 30
Power Seat Adjustment . . . . . . . . . . . . . . . . . 31
Lumbar Adjustment . . . . . . . . . . . . . . . . . . . . . 32
Reclining Seatbacks . . . . . . . . . . . . . . . . . . . . . 32
Memory Seats . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Heated and Ventilated Front Seats . . . . . 35
Folding Seatback . . . . . . . . . . . . . . . . . . . . . . . 36
Rear Seats
Rear Seats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Heated Rear Seats . . . . . . . . . . . . . . . . . . . . . . 39
Seat Belts
Seat Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
How to Wear Seat Belts Properly . . . . . . . 41
Lap-Shoulder Belt . . . . . . . . . . . . . . . . . . . . . . . 42
Seat Belt Use During Pregnancy . . . . . . . . 46
Seat Belt Extender . . . . . . . . . . . . . . . . . . . . . 46
Safety System Check . . . . . . . . . . . . . . . . . . . 46
Seat Belt Care . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Replacing Seat Belt System Parts after aCrash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Airbag System
Airbag System . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Where Are the Airbags? . . . . . . . . . . . . . . . . 48
When Should an Airbag Inflate? . . . . . . . . 50
What Makes an Airbag Inflate? . . . . . . . . . 50
How Does an Airbag Restrain? . . . . . . . . . . 51
What Will You See after an Airbag
Inflates? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Passenger Sensing System . . . . . . . . . . . . . . 52
Servicing the Airbag-Equipped Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Adding Equipment to the Airbag-Equipped Vehicle . . . . . . . . . . . . . . 56
Airbag System Check . . . . . . . . . . . . . . . . . . . 56
Replacing Airbag System Parts after a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Child Restraints
Older Children . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Infants and Young Children . . . . . . . . . . . . . 58
Child Restraint Systems . . . . . . . . . . . . . . . . 60
Where to Put the Restraint . . . . . . . . . . . . . 62
Lower Anchors and Tethers for Children(LATCH System) . . . . . . . . . . . . . . . . . . . . . . 63
Replacing LATCH System Parts After a Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Securing Child Restraints (With the Seat Belt in the Rear Seat) . . . . . . . . . . . . . . . . 69
Securing Child Restraints (With the Seat Belt in the Front Seat) . . . . . . . . . . . . . . . . 70
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.

GMC Terrain/Terrain Denali Owner Manual(GMNA-Localizing-U.S./Canada/
Mexico-14420055) - 2021 - CRC - 11/13/20
36 Seats and Restraints
If equipped, the buttons are on the center
console. To operate, the engine must be
running.
Press
Ior+, if equipped, to heat the
driver or passenger seatback only.
Press
Jorzto heat the driver or
passenger cushion and seatback.
Press
Cor{, if equipped, to ventilate the
driver or passenger seat. A ventilated seat
has a fan that pulls air through the cushion
and seatback. The air is not cooled.
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.
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. The
heated or ventilated seats are canceled
when the ignition is turned on. 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
do not 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 013 and
Vehicle Personalization 0108.
Folding Seatback
The front passenger seatback folds flat.
{Warning
If you fold the seatback forward to carry
longer objects, such as skis, be sure any
such cargo is not near an airbag. In a
crash, an inflating airbag might force that
object toward a person. This could cause
severe injury or even death. Secure
objects away from the area in which an
airbag would inflate. For more
(Continued)
Warning (Continued)
information, seeWhere Are the Airbags?
0 48 and
Vehicle Load Limits 0196.
{Warning
Things you put on this seatback can
strike and injure people in a sudden stop
or turn, or in a crash. Remove or secure
all items before driving.
To fold the seatback: 1. Lower the head restraint all the way. See Head Restraints 029.
2. Move the seat as far back as possible. See Seat Adjustment 030.