GMC SIERRA 2020 Service Manual

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
40 Keys, Doors, and Windows
Transmitters to the Vehicle" under
Remote Keyless Entry (RKE)
System Operation (Key Access)
013 or
Remote Keyless Entry (RKE)
System Operation (Keyless Access)
0 15
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 0370.
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) 09or
Keys (Keyless Access) 012. 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.
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

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Keys, Doors, and Windows 41
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.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
42 Keys, Doors, and Windows
Manual Extend :If equipped, grasp
the mirror housing firmly and pull
back in one motion, arching slightly
toward the rear of the vehicle.
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 0171.
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
0 257.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Keys, Doors, and Windows 43
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. 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. See
Task
Lighting 0171.
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 0173 and
Exit Lighting 0173.
Memory Mirrors
The vehicle may have memory
mirrors. See Memory Seats 059.
Lane Change Alert (LCA)
The vehicle may have LCA. See
Lane Change Alert (LCA) 0274.
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 with power folding
mirrors:

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
44 Keys, Doors, and Windows
1. Pressgto fold the mirrors in
to the folded position.
2. Press
gagain to fold the
mirrors out to the driving
position.
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.
Manually fold both mirrors if they
are out of sync. Fold and unfold the
mirrors three times using the mirror
controls to reset them to their
normal position. A popping noise
may be heard. 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) 013 or
Remote Keyless Entry (RKE)
System Operation (Keyless Access)
0 15.
This feature can be turned on or off.
See Vehicle Personalization 0157.
Heated Mirrors
If equipped with heated mirrors:
1REAR : Press to heat the
outside mirrors.
See “Rear Window Defogger” under
Dual Automatic Climate Control
System 0179.
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.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Keys, Doors, and Windows 45
Driving with the Blind Spot
Mirror
Actual Mirror View1. 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 theside of the 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.
Reverse Tilt Mirrors
If equipped with 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) return to the original
position when:
.
The vehicle is shifted out of
R (Reverse), or remains in
R (Reverse) for about
30 seconds.
. The ignition is turned off.
. The vehicle is driven in
R (Reverse) above a set speed.
To turn this feature on or off, see
Vehicle Personalization 0157.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
46 Keys, Doors, and Windows
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.
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:

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Keys, Doors, and Windows 47
.Brightness
.Zoom
.Tilt
{Warning
The Rear Camera Mirror (RCM)
has a limited view. Portions of the
road, vehicles, and other objects
may not be seen. Do not drive or
park the vehicle using only this
camera. Objects may appear
closer than they are. Check the
outside mirrors or glance over
your shoulder when making lane
changes or merging. Failure to
use proper care may result in
injury, death, or vehicle damage.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
48 Keys, Doors, and Windows
Troubleshooting
See your dealer for service if a blue
screen and
3are displayed in
the mirror, and the display shuts off.
Also, push the tab as indicated to
return to the automatic
dimming mode.
The Rear Camera Mirror may not
work properly or display a clear
image if:
. There is glare from the sun or
headlamps. This may obstruct
objects from view. If needed,
push the tab to turn off the
display. .
Dirt, snow, or other debris blocks
the camera lens. Clean the lens
with a soft damp cloth.
. The camera’s mounting on the
vehicle has been damaged, and/
or the position or the mounting
angle of the camera has
changed.
Windows
{Warning
Never leave a child, a helpless
adult, or a pet alone in a vehicle,
especially with the windows
closed in warm or hot weather.
They can be overcome by the
extreme heat and suffer
permanent injuries or even death
from heat stroke.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Keys, Doors, and Windows 49
The vehicle aerodynamics are
designed to improve fuel economy
performance. This may result in a
pulsing sound when either rear
window is down and the front
windows are up. To reduce the
sound, open either a front window
or the sunroof, if equipped.
Manual Windows
If equipped, turn the hand crank on
each door to manually raise or lower
the manual windows.
Power Windows
{Warning
Children could be seriously
injured or killed if caught in the
path of a closing window. Never
leave the Remote Keyless Entry
(RKE) transmitter or keys in a
vehicle with children. When there
are children in the rear seat, use
the window lockout button to(Continued)
Warning (Continued)
prevent operation of the windows.
SeeKeys (Key Access) 09or
Keys (Keyless Access) 012.
The power windows work when the
ignition is on, in ACC/ACCESSORY,
or when Retained Accessory Power
(RAP) is active. See Retained
Accessory Power (RAP) 0217.
Using the window switch, press to
open or pull to close the window. The windows may be temporarily
disabled if they are used repeatedly
within a short time.
Window Lockout
With Power Folding Mirrors,
Without Similar
This feature stops the rear door
passenger window switches from
working except from the driver
position.
Press
2to engage the rear
window lockout feature. The
indicator light is on when engaged.
Press
2again to disengage.