2021 GMC SIERRA Owner's Manual

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
32 Keys, Doors, and Windows
Disarming the Alarm System
To disarm the alarm system or turn off the
alarm if it has been activated:
.PressKon the RKE transmitter.
.Start the vehicle.
To avoid setting off the alarm by mistake:
.Lock the vehicle after all occupants have
exited.
.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 three times, an alarm
occurred previously while the alarm system
was armed.
If the alarm has been activated, a message
will appear on the DIC.
Steering Column Lock
If equipped, the steering column lock is a
theft-deterrent device. This feature locks the
steering column when the vehicle is turned
off and the driver door is opened, or when the driver door is opened and then the
vehicle is turned off. The steering column
unlocks when the vehicle is turned on.
The Driver Information Center (DIC) may
display one of these messages:
.A message to service the steering column
lock indicates that an issue has been
detected with the column lock feature
and the vehicle should be serviced.
.A message that the steering column is
locked indicates that the engine is
running, but the steering column is still
locked. It is normal for the column to be
locked during a remote start, but the
column should unlock after the brake
pedal is pressed and the vehicle is started.
No message will display during a remote
start.
.A message that the steering wheel must
be turned and the vehicle must be started
again indicates that the column lock
mechanism is bound, the column locking
device was unable to unlock the steering
column, and the vehicle did not start.
If this happens, immediately turn the
steering wheel from side to side to
unbind the column lock. If this does not
unlock the steering column, turn the
vehicle off and open the driver door to
reset the system. Then turn the vehicle
on and immediately turn the steering
wheel side to side for about 15 seconds.
In some cases, it may take significant
force to unbind the column.
To keep the steering column from binding,
straighten the front wheels before turning
off the vehicle.
Immobilizer
See Radio Frequency Statement 0436.
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 system is automatically disarmed when
the ignition is turned from off to on.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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Keys, Doors, and Windows 33
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. SeeRemote
Keyless Entry (RKE) System Operation (Key
Access) 010 or
Remote Keyless Entry (RKE) System
Operation (Keyless Access) 013.
If the ignition mode will not change with
the other transmitter or with the
transmitter 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" under
Remote
Keyless Entry (RKE) System Operation (Key
Access) 010 or
Remote Keyless Entry (RKE) System
Operation (Keyless Access) 013
Do not leave the transmitter or device that
disarms or deactivates the vehicle theft
system in the vehicle.
When equipped with a key, if the engine
still does not start, and the key appears to
be undamaged, try another ignition key.
It may be necessary to check the fuse. See
Fuses and Circuit Breakers 0353. If the
engine still does not start with the other
key, the vehicle needs service. If the vehicle
does start, the first key may be faulty. See
your dealer. It is possible for the
immobilizer system to learn new or
replacement keys. Up to eight keys can be
programmed for the vehicle. To program additional keys, see
Keys (Key Access)07or
Keys (Keyless Access) 09. Do not leave the
key or device that disarms or deactivates
the vehicle theft system in the vehicle.
See your dealer to get a new key blank cut
exactly as the ignition key that operates the
system.
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.
Standard Mirrors
The passenger side mirror is convex shaped.
A convex mirror's surface is curved so more
can be seen from the driver seat.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
34 Keys, Doors, and Windows
Trailer-Tow Mirrors
The upper portion of both the driver and
passenger mirrors is flat.
The lower portion of both the driver and
passenger mirrors is convex. A convex
mirror’s surface is curved so more can be
seen from the driver seat. The lower portion
is adjusted manually.
Manual Mirrors
If equipped, adjust manual mirrors by
moving the mirror up and down or left to
right to see a little of the side of the vehicle
and to have a clear view behind the vehicle.
Using hood-mounted air deflectors and
add-on convex mirror attachments could
decrease mirror performance.
Trailer-Tow Mirrors
Extending Mirrors
Trailer tow mirrors can extend out for better
visibility when towing a trailer.
Manual Extend :If equipped, grasp the
mirror housing firmly and pull back in one
motion, arching slightly toward the rear of
the vehicle.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
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To return the mirror to its original position,
reverse the motion.
Power Extend :If equipped, press the power
extend button to fully extend the mirror.
Press again to retract.
Resetting the Power Extend Mirrors
Reset the power extend mirrors if:
.The mirrors are accidentally obstructed
while extending/retracting.
.The mirrors are accidentally manually
extended/retracted.
.The mirrors vibrate at normal driving
speeds. If a popping noise from the mirror is heard,
this sound is normal as the manual detents
are aligning after a manual extend/retract
operation has occurred.
Auxiliary Cargo Mirror Lamps
If equipped, cargo mirror lamps face
rearward to provide more light on the sides
of the vehicle, if needed. See
Exterior Cargo
Lamps 0144.
Advanced Trailering Vision System Side
Cameras
If equipped, the Advanced Trailering Vision
System side cameras are on the bottom of
the outside mirrors. See “Surround Vision
(360 Degrees)” underAssistance Systems for
Parking or Backing 0266.
Power Mirrors
To adjust each mirror:
1. Press
jor|to select the driver or
passenger side mirror. The indicator light
will illuminate.
2. Press the arrows on the control pad to move the mirror in the desired direction.
3. Adjust each outside mirror so that a little of the vehicle and the area behind it can
be seen.
4. Press
jor|again to deselect the
mirror.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
36 Keys, Doors, and Windows
Turn Signal Indicator
If equipped, the mirror has turn signal
indicator lights, which flash in the direction
of the turn or lane change.
Task Lighting
If equipped, task lighting projects light from
the outside mirrors to the sides of the
vehicle. SeeTask Lighting 0144.
Puddle Lamps
If equipped, puddle lamps project light from
the bottom of the mirror to the area of
ground below the driver and passenger
doors. See Entry Lighting 0146 and
Exit Lighting 0146.
Memory Mirrors
The vehicle may have memory mirrors. See
Memory Seats 049.
Lane Change Alert (LCA)
The vehicle may have LCA. See Lane Change
Alert (LCA) 0280.Folding Mirrors
Manual Folding Mirrors
If equipped, push the mirror toward the
vehicle to fold. Push the mirror outward to
return to its original position.
Manually fold the mirrors inward to prevent
damage when going through an automatic
car wash.
Power Folding Mirrors
If equipped, pressgto power fold the
mirrors. Press again to unfold. Resetting the Power Folding Mirrors
Reset the power folding mirrors if:
.The mirrors are accidentally obstructed
while folding.
.The mirrors are accidentally manually
folded/unfolded.
.The mirrors will not stay in the unfolded
position.
.The mirrors vibrate at normal driving
speeds.
Fold and unfold the mirrors one time using
the mirror controls to reset them to their
normal position. A noise may be heard
during the resetting of the power folding
mirrors. This sound is normal after a manual
folding operation.
Remote Mirror Folding
If equipped, press and holdQon the RKE
transmitter for approximately one second to
remotely fold the exterior mirrors. Press and
hold
Kon the RKE transmitter for
approximately one second to unfold. See
Remote Keyless Entry (RKE) System
Operation (Key Access) 010 or
Remote Keyless Entry (RKE) System
Operation (Keyless Access) 013.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Keys, Doors, and Windows 37
This feature can be turned on or off. See
Vehicle Personalization0131.
Heated Mirrors
If equipped with heated mirrors:
1REAR : Press to heat the outside
mirrors.
See “Rear Window Defogger” underDual
Automatic Climate Control System 0206.
Automatic Dimming Mirror
If equipped, the driver outside mirror
automatically adjusts for the glare of the
headlamps from behind. This feature comes
on when the vehicle is started.
Blind Spot Mirrors
If equipped, there is a small convex mirror
built into the upper and outer corner of the
driver outside mirror. It can show objects
that may be in the vehicle's blind zone.
Driving with the Blind Spot Mirror
Actual Mirror View 1. When the approaching vehicle is a long
distance away, the image in the main
mirror is small and near the inboard
edge of the mirror.
2. As the vehicle gets closer, the image in the main mirror gets larger and moves
outboard.
3. As the vehicle enters the blind zone, the image transitions from the main mirror
to the blind spot mirror.
4. When the vehicle is in the blind zone, the image only appears in the blind spot
mirror.
Using the Outside Mirror with the Blind
Spot Mirror
1. Set the main mirror so that the side ofthe vehicle can just be seen and the
blind spot mirror has an
unobstructed view.
2. When checking for traffic or before changing a lane, look at the main driver/
passenger side mirror to observe traffic
in the adjacent lane, behind your vehicle.
Check the blind spot mirror for a vehicle
in the blind zone. Then, glance over your
shoulder to double check before moving
slowly into the adjacent lane.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
38 Keys, Doors, and Windows
Reverse Tilt Mirrors
If equipped with reverse tilt mirrors and
memory seats, the passenger and/or driver
mirror tilts to a preselected position when
the vehicle is in R (Reverse). This allows the
curb to be seen when parallel parking.
The mirror(s) may move from their tilted
position when:
.The vehicle is shifted out of R (Reverse),
or remains in R (Reverse) for about
30 seconds.
.The vehicle is turned off.
.The vehicle is driven in R (Reverse) above
a set speed.
To turn this feature on or off, see Vehicle
Personalization 0131.
Interior Mirrors
Interior Rearview Mirrors
Adjust the rearview mirror for a clear view
of the area behind your vehicle.
Do not spray glass cleaner directly on the
mirror. Use a soft towel dampened with
water.
Manual Rearview Mirror
If equipped, push the tab forward for
daytime use and pull it rearward for
nighttime use to avoid glare from the
headlamps from behind.
Automatic Dimming Rearview
Mirror
If equipped, the mirror will automatically
reduce the glare of the headlamps from
behind. The dimming feature comes on each
time the vehicle is started.
Rear Camera Mirror
If equipped, this automatic dimming mirror
provides a wide angle camera view of the
area behind the vehicle.
Pull the tab to turn on the display. Push the
tab to turn it off. When off the mirror is
automatic dimming. Adjust the mirror for a
clear view of the area behind the vehicle
while the display is off.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Keys, Doors, and Windows 39
PressVto scroll through the adjustment
options.
Press
tanduto adjust the settings using
the indicators on the mirror. The indicators
will remain visible for five seconds after the
last button activation, and the settings will
remain saved. The adjustment options are:
.Brightness
.Zoom
.Tilt