2021 GMC SIERRA ECO mode

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
188 Infotainment System
recognition system. Touch Off to prevent
the sharing and possible recording of your
voice commands with this system. This
may limit the system’s ability to
understand your voice commands and
may disable some features.
.Types: This setting lists all
Android-defined as dangerous permissions
currently used by the infotainment
system, the number of applications that
have requested this permission, and the
number of applications that are allowed
to use this permission.
.Used By Applications: This setting lists all
applications that are requested or are
using Android-defined as dangerous
permissions. Only requested and active
permissions are shown.
Display
Touch and the following may display:
.Mode: This adjusts the appearance of the
navigation map view and any
downloaded apps optimized for day or
night time conditions. Set to Auto for the
display to automatically adjust based on
bright/dark conditions.
Touch Auto, Day, or Night to adjust the
display.
.Calibrate Touchscreen: Touch to calibrate
the infotainment display and follow the
prompts.
.Turn Display Off: Touch to turn the
display off. Touch anywhere on the
infotainment display or press any
infotainment control on the center stack
again to turn the display on.
Sounds
Touch and the following may display:
.Maximum Startup Volume: This feature
adjusts the maximum volume of the
infotainment system when you start your
vehicle. To set the maximum startup
volume, touch the controls on the
infotainment display to increase or
decrease.
.Audio Cues: This feature determines if
sounds play when the infotainment
system starts up and shuts down. This
feature can be turned off or on.
.Set Audio Cue Volume: This setting
controls the volume of Audio Cues played
on startup and shut down. Touch the
controls on the infotainment display to
increase or decrease.
.Audible Touch Feedback: This setting
determines if a sound plays when
touching the infotainment display or
radio controls. This feature can be turned
off or on.
Voice
Touch and the following may display:
.Confirm More/Less: This setting specifies
how often the voice recognition system
confirms commands. Touch Confirm More
to have the system check with you more
often before acting on your commands.
.Prompt Length: This setting specifies the
amount of detail the voice recognition
system provides when giving you
feedback. Touch Auto to have the system
automatically adjust to your speech
habits. Touch Informative, Short, or Auto.
.Audio Feedback Speed: Touch Slow,
Medium, or Fast to adjust how quickly
the voice recognition system speaks.
.Friendly Prompts: This setting adjusts the
formality of voice prompts. Touch Off for
shorter prompts. Touch On to hear
prompts with more personality. Touch
Auto to have the prompt match your
command style.

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
192 Infotainment System
.Active Call View: Shows active call display
when answering a call.
Touch the controls on the infotainment
display to disable or enable.
.Privacy: Only show call alerts in the
instrument cluster.
Touch Off or On.
.Sort Contacts: Touch to sort by first or
last name.
.Re-sync Device Contacts:
This allows the device contacts to re-sync
if you are having difficulty accessing all of
the contacts on your cell phone.
.Delete All Vehicle Contacts: Touch to
delete all vehicle stored contacts.
.OnStar Phone TTY Mode: This enables
OnStar cell phone TTY mode.
Touch Disable or Enable.
Vehicle
This menu allows adjustment of different
vehicle features. SeeVehicle Personalization
0 131.
Personal
If equipped, this menu allows adjustment of
different user profile settings. See “Users”in
Using the System 0152 for information on
setting up user profiles.
The menu may contain the following:
Name
Touch to edit your user name that will be
displayed in the vehicle.
Vehicle Account Information
Touch to view the vehicle account
information and to change the account
password.
An “unverified user account” pop-up will
display until the account information
verification process has been completed on
the Internet. Check your registered e-mail
account for an activation e-mail to complete
the verification process.
Profile Picture
Touch to choose or change your profile
picture.
Profile Identifiers
Touch to have the vehicle recognize the
identifier you choose. Touch Vehicle Key 1 and/or Vehicle Key 2.
If the Remote Keyless Entry (RKE)
transmitter is lost or stolen, see your dealer.
Security
Touch to have your profile secured with
a PIN.
Touch No or Yes.
Vehicle Name
Touch to edit your vehicle name.
Vehicle Account
Touch to view the vehicle account
information and to change the account
password.
Delete Profile
Touch to remove the profile from the
vehicle.
Touch Remove or Cancel.
Teen Driver
If equipped, this allows multiple keys to be
registered for beginner drivers to encourage
safe driving habits. When the vehicle is
started with a Teen Driver key, it will
automatically activate certain safety
systems, allow setting of some features, and

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
206 Climate Controls
Dual Automatic Climate Control System
The heating, cooling, and ventilation in the vehicle can be controlled with this system.
1. Driver and Passenger TemperatureControls
2. MAX Defrost
3. Air Delivery Mode Controls
4. A/C (Air Conditioning)
5. SYNC (Synchronized Temperature) 6. Recirculation
7. Power Button
8. Fan Control
9. Rear Window Defogger (If Equipped) or
Heated Mirrors (If Equipped)
10. AUTO (Automatic Operation)
Climate Control Display
1. Driver and Passenger Temperature Settings
2. Fan Control
3. Driver and Passenger Temperature Controls
4. Sync (Synchronized Temperature)
5. Recirculation
6. Air Delivery Mode Controls
7. Auto (Automatic Operation)
8. A/C (Air Conditioning)
9. On/Off (Power)

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 231
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. SeeRemote
Keyless Entry (RKE) System Operation (Key
Access) 010 or
Remote Keyless Entry (RKE) System
Operation (Keyless Access) 013.
To shift out of P (Park), the ignition must be
on or in Service Mode, and the brake pedal
must be applied.
{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, only shut the
vehicle off in an emergency.
Stopping the Engine/LOCK/OFF (No Indicator
Lights) : When the vehicle is stopped, press
ENGINE START/STOP once to turn the
engine off. If the vehicle is in P (Park), the ignition will
turn off, and Retained Accessory Power (RAP)
will remain active. See
Retained Accessory
Power (RAP) 0236.
If the vehicle is not in P (Park), the ignition
will return to ACC/ACCESSORY and display
the message SHIFT TO PARK in the Driver
Information Center (DIC). When the vehicle is
shifted into P (Park), the ignition system will
turn off.
The vehicle may have an electric steering
column lock. The lock is activated when the
ignition is turned off and driver door is
opened. A sound may be heard as the lock
actuates or releases. The steering column
lock may not release with the wheels turned
off center. If this happens, the vehicle may
not start. Move the steering wheel from left
to right while attempting to start the
vehicle. If this does not work, the vehicle
needs service.
Unless an emergency exists, do not turn the
engine off when the vehicle is moving. This
will cause a loss of power assist in the brake
and steering systems and disable the
airbags. If the vehicle must be shut off in an
emergency:
1. If the vehicle cannot be pulled over, and must be shut off while driving, press and
hold ENGINE START/STOP button for
longer than two seconds, or press twice
in five seconds.
2. Brake using a 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.
After shifting to N (Neutral), firmly apply
the brakes and steer the vehicle to a
safe location.
4. Come to a complete stop, shift to P (Park), and make sure engine is off.
The shift lever must be in P (Park) to
turn the ignition off.
5. Set the parking brake. See Electric
Parking Brake 0247.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
232 Driving and Operating
{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, only shut the
vehicle off in an emergency.
ACC/ACCESSORY (Amber Indicator Light) :
This mode allows some electrical accessories
to be used when the engine is off.
With the ignition off, pressing the ENGINE
START/STOP button one time without the
brake pedal applied will place the ignition
system in ACC/ACCESSORY.
The ignition will switch from ACC/
ACCESSORY to off after five minutes to
prevent battery rundown.
ON/RUN/START (Green Indicator Light) : This
mode is for driving and starting. With the
ignition off, and the brake pedal applied,
pressing ENGINE START/STOP button once
will turn the ignition on. Once engine
cranking begins, release the button. Engine
cranking will continue until the engine
starts. See Starting the Engine 0232. Service Mode
This power mode is available for service and
diagnostics, and to verify the proper
operation of the malfunction indicator lamp
as may be required for emission inspection
purposes. With the vehicle off, and the
brake pedal not applied, pressing and
holding the ENGINE START/STOP button for
more than five seconds will place the vehicle
in Service Mode. The instruments and audio
systems will operate as they do when the
ignition is on, but the vehicle will not be
able to be driven. The engine will not start
in Service Mode. Press the ENGINE START/
STOP button again to turn the ignition off.
Starting the Engine
If the vehicle has a diesel engine, see the
Duramax diesel supplement.
Caution
If you add electrical parts or accessories,
you could change the way the engine
operates. Any resulting damage would
not be covered by the vehicle warranty.
See
Add-On Electrical Equipment 0318. 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, turn the 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 driver may observe a minor, and
temporary, brake pedal kickback when
starting the vehicle. This is normal.
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.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Driving and Operating 233
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
This vehicle has a Stop/Start system to shut
off the engine to help conserve fuel. It has
components designed for the increased
number of starts.
{Warning
The automatic engine Stop/Start feature
causes the engine to shut off while the
vehicle is still on. Do not exit the vehicle
before shifting to P (Park). The vehicle
may restart and move unexpectedly.
Always shift to P (Park), and then turn
the ignition off before exiting the vehicle.
Auto Engine Stop/Start
When the brakes are applied and the vehicle
is at a complete stop, the engine may turn
off. When stopped, the tachometer displays
AUTO STOP. See Tachometer0110. When the brake pedal is released or the
accelerator pedal is pressed, the engine will
restart.
To maintain vehicle performance, other
conditions may cause the engine to
automatically restart before the brake pedal
is released.
Auto Stops may not occur and/or Auto
Starts may occur because:
.The climate control settings require the
engine to be running to cool or heat the
vehicle interior.
.The vehicle battery charge is low.
.The vehicle battery has recently been
disconnected.
.Minimum vehicle speed has not been
reached since the last Auto Stop.
.The accelerator pedal is pressed.
.The engine or transmission is not at the
required operating temperature.
.The outside temperature is not in the
required operating range.
.The vehicle is in any gear other than
D (Drive).
.Tow/Haul Mode or other driver modes
have been selected.
.The vehicle is on a steep hill or grade.