Page 47 of 502

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:
Page 111 of 502

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
110 Seats and Restraints
the instructions that come with the
child restraint say that the top tether
must be anchored.
In Canada, the law requires that
forward-facing child restraints have
a top tether, and that the tether be
attached.
When using the lap-shoulder belt to
secure the child restraint in this
position, follow the instructions that
came with the child restraint and the
following instructions:1. Move the seat as far back as it will go before securing the
forward-facing child restraint.
Move the seat upward or the
seatback to an upright position,
if needed, to get a tight
installation of the child
restraint.
When the passenger sensing
system has turned off the front
outboard passenger frontal
airbag, the OFF indicator on
the passenger airbag status
indicator should light and stay lit when you start the vehicle.
See
Passenger Airbag Status
Indicator 0137.
2. Put the child restraint on the seat.
3. Pick up the latch plate, and run the lap and shoulder portions
of the vehicle seat belt through
or around the child restraint.
The child restraint instructions
will show you how.
Tilt the latch plate to adjust the
belt if needed.
4. Push the latch plate into thebuckle until it clicks.
Position the release button on
the buckle, away from the child
restraint, so that the seat belt
could be quickly unbuckled if
necessary.
Page 209 of 502

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
208 Driving and Operating
Starting and
Operating
New Vehicle Break-In
Caution
The vehicle does not need an
elaborate break-in. But it will
perform better in the long run if
you follow these guidelines:. Keep the vehicle speed at
88 km/h (55 mph) or less for
the first 805 km (500 mi).
. Do not drive at any one
constant speed, fast or slow,
for the first 805 km (500 mi).
Do not make full-throttle
starts. Avoid downshifting to
brake or slow the vehicle.
. Avoid making hard stops for
the first 322 km (200 mi) or
so. During this time the new
brake linings are not yet
broken in. Hard stops with
new linings can mean
(Continued)
Caution (Continued)
premature wear and earlier
replacement. Follow this
breaking-in guideline every
time you get new brake
linings.
. Do not tow a trailer during
break-in. See Trailer Towing
0 292 for the trailer towing
capabilities of the vehicle
and more information.
Following break-in, engine speed
and load can be gradually
increased.
Ignition Positions
(Keyless Access)
Vehicles equipped with Keyless
Access have pushbutton starting.
The Remote Keyless Entry (RKE)
transmitter must be in the vehicle for
the system to operate. If the
pushbutton start is not working, the
vehicle may be near a strong radio
antenna signal causing interference
to the Keyless Access system. See
Remote Keyless Entry (RKE)
System Operation (Key Access)
0 13 or
Page 214 of 502

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 213
Move the shift lever to P (Park) or
N (Neutral). To restart the engine
when the vehicle is already moving,
use N (Neutral) only.
Caution
Do not try to shift to P (Park) if the
vehicle is moving. If you do, you
could damage the transmission.
Shift to P (Park) only when the
vehicle is stopped.
Starting Procedure
1. For Key Access vehicles, turnthe ignition key to START.
When the engine starts, let go
of the key.
For Keyless Access vehicles,
the RKE transmitter must be in
the vehicle. Press ENGINE
START/STOP with the brake
pedal applied. When the
engine begins cranking, let go
of the button.
The idle speed will go down as
the engine gets warm. Do not
race the engine immediately after starting it. Operate the
engine and transmission gently
to allow the oil to warm up and
lubricate all moving parts.
When the low fuel warning light
is on and the FUEL LEVEL
LOW message is displayed in
the Driver Information Center
(DIC), hold the ignition switch
in the START position to
continue engine cranking.
Caution
Cranking the engine for long
periods of time, by returning the
ignition to the START position
immediately after cranking has
ended, can overheat and damage
the cranking motor, and drain the
battery. Wait at least 15 seconds
between each try, to let the
cranking motor cool down.
2. If the engine does not start after five to 10 seconds,
especially in very cold weather
(below −18 °C or 0 °F), it could
be flooded with too much gasoline. Try pushing the
accelerator pedal all the way to
the floor and holding it there
while holding the key in START
or ENGINE START/STOP for
up to a maximum of
15 seconds. Wait at least
15 seconds between each try,
to allow the cranking motor to
cool down. When the engine
starts, let go of the key or
button and accelerator. If the
vehicle starts briefly but then
stops again, do the same thing.
This clears the extra gasoline
from the engine. Do not race
the engine immediately after
starting it. Operate the engine
and transmission gently until
the oil warms up and lubricates
all moving parts.
Stop/Start System
If equipped, the Stop/Start system
will shut off the engine to help
conserve fuel. It has components
designed for the increased number
of starts.