ignition position GMC SIERRA 2021 User Guide

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/6/20
Lighting 139
Lighting
Exterior Lighting
Exterior Lamp Controls . . . . . . . . . . . . . . . . 139
Exterior Lamps Off Reminder . . . . . . . . . . . 141
Headlamp High/Low-Beam Changer . . . . 141
Flash-to-Pass . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Daytime Running Lamps (DRL) . . . . . . . . . 141
Automatic Headlamp System . . . . . . . . . . 142
Hazard Warning Flashers . . . . . . . . . . . . . . 142
Turn and Lane-Change Signals . . . . . . . . . 143
Fog Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Task Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Auxiliary Roof-Mounted Lamp . . . . . . . . . 144
Exterior Cargo Lamps . . . . . . . . . . . . . . . . . . 144
Interior Lighting
Instrument Panel IlluminationControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Dome Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Reading Lamps . . . . . . . . . . . . . . . . . . . . . . . . 146
Lighting Features
Entry Lighting . . . . . . . . . . . . . . . . . . . . . . . . . 146
Exit Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Battery Load Management . . . . . . . . . . . . 146
Battery Power Protection . . . . . . . . . . . . . . 147
Exterior Lighting Battery Saver . . . . . . . . 147
Exterior Lighting
Exterior Lamp Controls
The exterior lamp control is on the
instrument panel to the left of the steering
wheel.
O: Turns off the automatic headlamps and
Daytime Running Lamps (DRL). Turn the
headlamp control to
Oagain to turn the
automatic headlamps or DRL back on.
For vehicles first sold in Canada, off will only
work when the vehicle is in P (Park). AUTO :
Automatically turns on the
headlamps, parking lamps, taillamps,
instrument panel lights, roof marker lamps
(if equipped), front/rear sidemarker lamps,
and license plate lamps.
;: Turns on the parking lamps including
all lamps, except the headlamps and fog
lamps, if equipped.
For some trim levels and series of trucks
first sold in Canada, the headlamps may
turn on with the parking lamps.
2: Turns on the headlamps together with
the parking lamps, taillamps, instrument
panel lights, roof marker lamps (if
equipped), front/rear sidemarker lamps, and
license plate lamps.
When the headlamps are turned on while
the vehicle is on, the headlamps turn off
automatically 10 minutes after the ignition
is turned off. When the headlamps are
turned on while the vehicle is off, the
headlamps will stay on for 10 minutes
before turning off to prevent the battery
from being drained. Turn the headlamp
control off and then back to the headlamp
on position to make the headlamps stay on

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/6/20
140 Lighting
for an additional 10 minutes. To keep the
lamps on for more than 10 minutes, the
ignition must be on or in ACC/ACCESSORY.
K:If equipped, turns on the task
lighting. See Task Lighting 0144.
IntelliBeam System
If equipped, this system turns the vehicle's
high-beam headlamps on and off according
to surrounding traffic conditions.
The system turns the high-beam headlamps
on when it is dark enough and there is no
other traffic present.
This light
bcomes on in the instrument
cluster when the IntelliBeam system is
enabled.
Turning On and Enabling IntelliBeam
To enable the IntelliBeam system, press
bon the turn signal lever when it is
dark outside and the exterior lamp control is
in AUTO or
2.
Driving with IntelliBeam
The system only activates the high beams
when driving over 40 km/h (25 mph).
The blue high-beam on light appears on the
instrument cluster when the high beams
are on.
There is a sensor near the top center of the
windshield that automatically controls the
system. Keep this area of the windshield
clear of debris to allow for best system
performance.
The high-beam headlamps remain on, under
the automatic control, until one of the
following situations occurs:
.The system detects an approaching
vehicle's headlamps.
.The system detects a preceding vehicle's
taillamps.
.The outside light is bright enough that
high-beam headlamps are not required.
.The vehicle's speed drops below 20 km/h
(12 mph).
.The IntelliBeam system is disabled by the
button on the turn signal lever. If this
happens, press
bon the turn signal
lever when the exterior lamp control is in
the AUTO or
2position to reactivate the
IntelliBeam system. The instrument
cluster light will come on to indicate the
IntelliBeam system is reactivated.
The high beams may not turn off
automatically if the system cannot detect
another vehicle's lamps because of any of
the following:
.The other vehicle's lamps are missing,
damaged, obstructed from view,
or otherwise undetected.
.The other vehicle's lamps are covered
with dirt, snow, and/or road spray.
.The other vehicle's lamps cannot be
detected due to dense exhaust, smoke,
fog, snow, road spray, mist, or other
airborne obstructions.
.The vehicle's windshield is dirty, cracked,
or obstructed by something that blocks
the view of the light sensor.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/6/20
Lighting 141
.The vehicle is loaded such that the front
end points upward, causing the light
sensor to aim high and not detect
headlamps and taillamps.
.Driving on winding or hilly roads.
The automatic high-beam headlamps may
need to be disabled if any of the above
conditions exist.
Exterior Lamps Off Reminder
A reminder chime sounds when the
headlamps or parking lamps are manually
turned on, the ignition is off, and a door is
open. To disable the chime, turn the
lamps off.
Headlamp High/Low-Beam
Changer
Push the turn signal lever toward the
instrument panel to change the headlamps
from low to high beam.
Pull or push the turn signal lever to return
to low-beam headlamps.
When the high-beam headlamps are on, this
indicator light on the instrument cluster will
also be on.
Flash-to-Pass
This feature lets you use the high-beam
headlamps to signal a driver in front of you
that you want to pass. It works even if the
headlamps are in the automatic position.
To use it, pull the turn signal lever toward
you, then release it.
If the headlamps are in the automatic
position or on low beam, the high-beam
headlamps will turn on. Depending on the
type of headlamp, they will either turn off
after a short duration or stay on as long as
you hold the lever toward you. The
high-beam indicator on the instrument
cluster will come on. Release the lever to
return to normal operation.
Daytime Running Lamps (DRL)
DRL can make it easier for others to see the
front of the vehicle during the day. Fully
functional DRL are required on all vehicles
first sold in Canada.
The DRL system comes on when the
following conditions are met:
.The ignition is on.
.The exterior lamp control is in AUTO.
.The transmission is not in P (Park).
.The light sensor determines it is daytime.
When the DRL system is on, only the DRL
are on. The taillamps, sidemarker lamps,
instrument panel lights, and other lamps
will not be on.
When it begins to get dark, the automatic
headlamp system switches from DRL to the
headlamps.
To turn off the DRL, turn the exterior lamp
control to
Oand then release. For vehicles
first sold in Canada, off will only work when
the vehicle is parked.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/6/20
142 Lighting
Automatic Headlamp System
When the exterior lamp control is set to
AUTO and it is dark enough outside, the
headlamps come on automatically.
There is a light sensor on top of the
instrument panel. Do not cover the sensor,
otherwise the headlamps will come on when
they are not needed.
The system may also turn on the headlamps
when driving through a parking garage or
tunnel.
If the vehicle is started in a dark garage, the
automatic headlamp system comes on
immediately. If it is light outside when the
vehicle leaves the garage, there is a slightdelay before the automatic headlamp
system changes to the Daytime Running
Lamps (DRL). During that delay, the
instrument cluster may not be as bright as
usual. Make sure the instrument panel
illumination control is in the full bright
position. See
Instrument Panel Illumination
Control 0145.
When it is bright enough outside, the
headlamps will turn off or may change
to DRL.
The automatic headlamp system turns off
when the exterior lamp control is turned to
Oor the ignition is off.
Lights On with Wipers
If the windshield wipers are activated in
daylight with the engine on, and the
exterior lamp control is in AUTO, the
headlamps, parking lamps, and other
exterior lamps come on. The transition time
for the lamps coming on varies based on
wiper speed. When the wipers are not
operating, these lamps turn off. Move the
exterior lamp control to
Oor;to disable
this feature.
Hazard Warning Flashers
|: Press this button to make the front
and rear turn signal lamps flash on and off.
Press again to turn the flashers off.
When the hazard warning flashers are on,
the vehicle's turn signals will not work.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/6/20
Lighting 143
Turn and Lane-Change Signals
An arrow on the instrument cluster flashes
in the direction of the turn or lane change.
Move the turn signal lever all the way up or
down to signal a turn.
Partially raise or lower the lever for less
than one second until the arrow starts to
flash to signal a lane change. This causes
the turn signals to automatically flash three
times. It will flash six times if Tow/Haul
Mode is active. Holding the turn signal lever
for more than one second will cause the
turn signals to flash until the lever is
released.The lever returns to its starting position
whenever it is released.
If after signaling a turn or a lane change the
arrows flash rapidly or do not come on, a
signal bulb could be burned out. If equipped
with LED turn signals, see your dealer.
Replace any burned out bulbs. If a bulb is
not burned out, check the fuse. See
Fuses
and Circuit Breakers 0353.
Turn Signal On Chime
If the turn signal is left on for more than
1.2 km (0.75 mi), a chime sounds at each
flash of the turn signal. A message may
appear in the Driver Information Center
(DIC). See Vehicle Messages 0130. To turn
the chime and message off, move the turn
signal lever to the off position.
Fog Lamps
If equipped, the fog lamp control is near the
exterior lamp control to the left of the
steering column.
The ignition must be on for the fog lamps
to come on.
#: Press to turn the fog lamps on or off.
A light will come on in the instrument
cluster.
When the fog lamps are turned on, the
parking lamps automatically turn on.
When the headlamps are changed to high
beam, the fog lamps also go off. When the
high-beam headlamps are turned off, the fog
lamps will come on again.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/6/20
Lighting 147
When the battery's state of charge is low,
the voltage is raised slightly to quickly bring
the charge back up. When the state of
charge is high, the voltage is lowered
slightly to prevent overcharging. The
voltmeter gauge or the voltage display on
the Driver Information Center (DIC),
if equipped, may show the voltage moving
up or down. This is normal. If there is a
problem, an alert will be displayed.
The battery can be discharged at idle if the
electrical loads are very high. This is true for
all vehicles. This is because the generator
(alternator) may not be spinning fast
enough at idle to produce all the power that
is needed for very high electrical loads.
A high electrical load occurs when several of
the following are on, such as: headlamps,
high beams, fog lamps, rear window
defogger, climate control fan at high speed,
heated seats, engine cooling fans, trailer
loads, and loads plugged into accessory
power outlets.EPM works to prevent excessive discharge of
the battery. It does this by balancing the
generator's output and the vehicle's
electrical needs. It can increase engine idle
speed to generate more power, whenever
needed. It can temporarily reduce the power
demands of some accessories.
Normally, these actions occur in steps or
levels, without being noticeable. In rare
cases at the highest levels of corrective
action, this action may be noticeable to the
driver. If so, a DIC message might be
displayed and it is recommended that the
driver reduce the electrical loads as much as
possible.
Battery Power Protection
This feature shuts off the dome and reading
lamps, if they are left on for more than
10 minutes after the ignition is turned off.
The cargo lamp shuts off after 20 minutes.
This prevents the battery from
running down.
Exterior Lighting Battery Saver
The exterior lamps turn off about 10 minutes
after the ignition is turned off, if the parking
lamps or headlamps have been manually
left on. This protects against draining the
battery. To restart the 10-minute timer, turn
the exterior lamp control to the
Oposition
and then back to the
;or2position.
To keep the lamps on for more than
10 minutes, the ignition must be on or in
ACC/ACCESSORY.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Infotainment System 189
.Tutorial Mode: Touch Off or On to
provide tutorial feedback on the display.
.Allow Prompt Interruptions: This setting
controls whether voice commands can be
spoken before voice prompts finish. Turn
this on to speak commands without
hearing the full prompt. Speaking while
the prompt is still playing will
immediately stop playing the current
prompt and recognize your command.
Background noise may cause accidental
interruptions. Touch Off or On.
Favorites
Touch and the following may display:
.Manage Favorites: Touch to display a list
of Audio, Phone, and Navigation favorites.
Favorites can be moved, renamed,
or deleted.
To move, touch and hold the favorite, and
then drag up or down to rearrange the
position.
.Set Number of Audio Favorites: Touch to
select how many favorites pages can be
viewed from the audio application. The
Auto setting will automatically adjust this
number based on the number of favorites
you have saved. Touch Auto, 5, 10, 15, 20,
25, 30, 35, or 40. Updates
If equipped, the vehicle can download and
install select software updates over a
wireless connection. The system will prompt
for certain updates to be downloaded and
installed. There is also an option to check
for updates manually.
To manually check for updates, touch
Settings on the Home Page and select the
System tab. Go to the Vehicle Software
section and touch Updates. Follow the
on-screen prompts. The steps to check for,
download, and install updates may vary by
vehicle.
The vehicle can be used normally during the
software download. Once the download is
complete, there may be a prompt to accept
the installation of the update upon the next
ignition cycle or the next time the vehicle is
shifted into P (Park). For most updates, the
vehicle will be disabled and cannot be driven
during the installation. The system will
deliver messages indicating success or error
during and after the download and
installation processes.
Downloading Over-the-Air vehicle software
updates requires Internet connectivity, which
can be accessed through the vehicle’s
built-in 4G LTE connection, if equipped and active. If required, data plans are provided
by a third party. Optionally, a secure Wi-Fi
hotspot such as a compatible mobile device
hotspot, home hotspot, or public hotspot
can be used. Applicable data rates may
apply.
To connect the infotainment system to a
secured mobile device hotspot, home
hotspot, or public hotspot, touch Settings on
the Home Page, select the System tab,
followed by Wi-Fi Networks. Select the
appropriate Wi-Fi network, and follow the
on-screen prompts. Download speeds
may vary.
On most compatible mobile devices,
activation of the Wi-Fi hotspot is in the
Settings menu under Mobile Network
Sharing, Personal Hotspot, Mobile Hotspot,
or similar.
Availability of Over-the-Air software updates
varies by vehicle and country. Features are
subject to change. For more information on
this feature, see my.gmc.com/learn.
Preferences
Touch the controls on the infotainment
display to disable or enable the download of
new updates in the background.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Driving and Operating 211
Driving and Operating
Driving Information
Driving for Better Fuel Economy . . . . . . . 212
Distracted Driving . . . . . . . . . . . . . . . . . . . . . . 212
Defensive Driving . . . . . . . . . . . . . . . . . . . . . . 213
Impaired Driving . . . . . . . . . . . . . . . . . . . . . . . 213
Control of a Vehicle . . . . . . . . . . . . . . . . . . . . 213
Braking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Steering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Off-Road Recovery . . . . . . . . . . . . . . . . . . . . . 214
Loss of Control . . . . . . . . . . . . . . . . . . . . . . . . . 215
Off-Road Driving . . . . . . . . . . . . . . . . . . . . . . . 215
Driving on Wet Roads . . . . . . . . . . . . . . . . . 219
Hill and Mountain Roads . . . . . . . . . . . . . . 219
Winter Driving . . . . . . . . . . . . . . . . . . . . . . . . 220
If the Vehicle Is Stuck . . . . . . . . . . . . . . . . . . 221
Vehicle Load Limits . . . . . . . . . . . . . . . . . . . . 222
Truck-Camper Loading Information . . . . 226
Starting and Operating
New Vehicle Break-In . . . . . . . . . . . . . . . . . . 228
Ignition Positions (Key Access) . . . . . . . . 229
Ignition Positions (Keyless Access) . . . . . 230
Starting the Engine . . . . . . . . . . . . . . . . . . . . 232
Stop/Start System . . . . . . . . . . . . . . . . . . . . . 233
Engine Heater . . . . . . . . . . . . . . . . . . . . . . . . . 234
Retained Accessory Power (RAP) . . . . . . . 236
Shifting Into Park . . . . . . . . . . . . . . . . . . . . . 236
Shifting out of Park . . . . . . . . . . . . . . . . . . . 237Parking over Things That Burn . . . . . . . . . 237
Active Fuel Management . . . . . . . . . . . . . . 237
Extended Parking . . . . . . . . . . . . . . . . . . . . . . 238
Engine Exhaust
Engine Exhaust . . . . . . . . . . . . . . . . . . . . . . . . 238
Running the Vehicle While Parked . . . . . 238
Automatic Transmission
Automatic Transmission . . . . . . . . . . . . . . . 239
Manual Mode . . . . . . . . . . . . . . . . . . . . . . . . . 241
Tow/Haul Mode . . . . . . . . . . . . . . . . . . . . . . . 242
Drive Systems
Four-Wheel Drive . . . . . . . . . . . . . . . . . . . . . . 242
Brakes
Electric Brake Boost . . . . . . . . . . . . . . . . . . . 246
Antilock Brake System (ABS) . . . . . . . . . . 246
Electric Parking Brake . . . . . . . . . . . . . . . . . . 247
Brake Assist . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Hill Start Assist (HSA) . . . . . . . . . . . . . . . . . 248
Ride Control Systems
Traction Control/Electronic Stability
Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Hill Descent Control (HDC) . . . . . . . . . . . . 250
Driver Mode Control . . . . . . . . . . . . . . . . . . . 251
Limited-Slip Differential . . . . . . . . . . . . . . . . 254
Locking Rear Axle . . . . . . . . . . . . . . . . . . . . . 254
Cruise Control
Cruise Control . . . . . . . . . . . . . . . . . . . . . . . . . 254
Adaptive Cruise Control (Camera) . . . . . . 256
Driver Assistance Systems
Driver Assistance Systems . . . . . . . . . . . . . 265
Assistance Systems for Parking or Backing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Assistance Systems for Driving . . . . . . . . 274
Forward Collision Alert (FCA) System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
Automatic Emergency Braking (AEB) . . . 277
Front Pedestrian Braking (FPB) System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
Side Blind Zone Alert (SBZA) . . . . . . . . . . 280
Lane Change Alert (LCA) . . . . . . . . . . . . . . . 280
Lane Keep Assist (LKA) . . . . . . . . . . . . . . . . . 281
Fuel
Top Tier Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . 283
Recommended Fuel (Except 6.2L V8 Engine) . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
Recommended Fuel (6.2L V8 Engine) . . . . . . . . . . . . . . . . . . . . . . . . . . 284
Prohibited Fuels . . . . . . . . . . . . . . . . . . . . . . . 284
Fuels in Foreign Countries . . . . . . . . . . . . . 284
Fuel Additives . . . . . . . . . . . . . . . . . . . . . . . . . 284
E85 or FlexFuel . . . . . . . . . . . . . . . . . . . . . . . . 284
Filling the Tank (Pickup Model) . . . . . . . . 285
Filling the Tank (Chassis Cab Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Driving and Operating 229
Ignition Positions (Key Access)
0. Stopping the Engine/LOCK/OFF
1. ACC/ACCESSORY
2. ON/RUN
3. START
The ignition switch has four positions.
To shift out of P (Park), the ignition must be
ON/RUN and the brake pedal must be
applied.0 (Stopping the Engine/LOCK/OFF) :
This
position turns off the vehicle. It also locks
the ignition, the transmission, and the
steering column, if equipped with a locking
steering column.
To turn off the vehicle:
1. Make sure that the vehicle is stopped.
2. Shift to P (Park).
3. Continue to hold the brake pedal, then set the parking brake. See Electric
Parking Brake 0247.
4. Push the key all the way in toward the steering column, then turn the key to
LOCK/OFF. 5. Remove the key.
6. Release the brake pedal.
See your dealer if the key can be removed
in any other position.
Retained Accessory Power (RAP) will remain
active. See Retained Accessory Power (RAP)
0 236.
A warning chime will sound when the driver
door is opened and the key is in the
ignition.
If equipped with a locking steering column,
the steering can bind with the front wheels
turned off center, which may prevent key
rotation out of LOCK/OFF. If this happens,
move the steering wheel from right to left
while turning the key to ACC/ACCESSORY.
If this does not work, then the vehicle needs
service.
{Warning
Turning off the vehicle while moving may
cause loss of power assist in the brake
and steering systems and disable the
airbags. While driving, turn off the
vehicle only in an emergency.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
230 Driving and Operating
In an emergency, if the vehicle cannot be
pulled over and must be turned off while
driving:1. Push the key all the way in toward the steering column, then turn the key to
ACC/ACCESSORY.
2. Brake using firm and steady pressure. Do not pump the brakes repeatedly. This
may deplete power assist, requiring
increased brake pedal force.
3. Shift the vehicle to N (Neutral). This can be done while the vehicle is moving.
Continue braking and steer the vehicle to
a safe location.
4. Come to a complete stop.
5. Shift to P (Park).
6. Push the key all the way in toward the steering column (1), then turn the
ignition to LOCK/OFF (2).
7. Set the parking brake. See Electric
Parking Brake 0247.
8. Remove the key.
9. Release the brake pedal.Caution
Use the correct key, make sure it is all
the way in —or pushed all the way in
toward the steering column when turning
off the vehicle —and turn it only with
your hand.
1 (ACC/ACCESSORY) : This position allows
features such as the infotainment system to
operate while the vehicle is off. It also
unlocks the steering column, if equipped
with a locking steering column. Use this
position if the vehicle must be pushed or
towed. See Retained Accessory Power (RAP)
0 236.
From ON/RUN, push the key all the way in
toward the steering column, then turn the
key to ACC/ACCESSORY.
If the key is left in ACC/ACCESSORY with the
engine off, the battery could drain and the
vehicle may not start.
A warning chime will sound when the driver
door is opened and the key is in the
ignition.
2 (ON/RUN) : This position can be used to
operate the electrical accessories and to
display some instrument cluster warning
and indicator lights. This position can also be used for service and diagnostics, and to
verify the proper operation of the
malfunction indicator lamp as may be
required for emission inspection purposes.
The switch stays in this position when the
engine is running. The transmission is also
unlocked in this position.
If the key is left in ON/RUN with the engine
off, the battery could drain and the vehicle
may not start.
3 (START) :
This is the position that starts
the engine. When the engine starts, release
the key. The ignition returns to ON/RUN for
driving.
Ignition Positions (Keyless Access)