2021 GMC SIERRA SERVICE MODE

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Instruments and Controls 121
serviced by your dealer. If the system is
working normally, the indicator light then
turns off. This light comes on when the
Electronic Stability Control (ESC) system is
turned off. If ESC is off, the Traction Control
System (TCS) is also off. To turn ESC off and
on, seeTraction Control/Electronic Stability
Control 0248.
If ESC and TCS are off, the systems do not
assist in controlling the vehicle. Adjust
driving accordingly.
Engine Coolant Temperature
Warning Light
This light comes on briefly while starting
the vehicle.
If it does not, have the vehicle serviced by
your dealer. If the system is working
normally the indicator light goes off.
Caution
The engine coolant temperature warning
light indicates that the vehicle has
overheated. Driving with this light on can
damage the engine and it may not be
covered by the vehicle warranty. See
Engine Overheating 0338.
The engine coolant temperature warning
light comes on when the engine has
overheated.
If this happens, pull over and turn off the
engine as soon as possible. See Engine
Overheating 0338.
Driver Mode Control Light
This light comes on when Sport Mode is
selected.
This light comes on when Snow/Ice Mode is
selected.
This light comes on when Terrain Mode is
selected.
This light comes on when Off-Road Mode is
selected.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Instruments and Controls 135
Ride Height
Touch and the following may display:
.Automatic Entry/Egress
Automatic Entry/Egress
This feature specifies if the vehicle will
automatically lower to make it easier to
enter or exit the vehicle.
Touch Off or On.
Running Boards
Touch and the following may display:
.Automatic Running Boards
.Deploy Running Boards
Automatic Running Boards
This feature specifies the position and use of
the running boards.
Touch Off or On.
Deploy Running Boards
This feature moves the running boards to a
deployed position so they can be used with
the doors closed.
Touch Off or Deploy.
Seating Position
Touch and the following may display:
.Seat Entry Memory
.Seat Exit Memory
Seat Entry Memory
This feature automatically recalls the
previously stored 1 or 2 button positions
when the ignition is changed from off to on
or ACC/ACCESSORY. See Memory Seats049.
Touch Off or On.
Seat Exit Memory
This feature automatically recalls the
previously stored exit button position when
the ignition is changed from on or ACC/
ACCESSORY to off and the driver door is
open. See Memory Seats 049.
Touch Off or On.
Suspension
Touch and the following may display:
.Service Mode
.Alignment Mode Service Mode
This feature disables the air suspension
system and is used to prevent unintended
raising or lowering of the suspension.
Touch Off or On.
Alignment Mode
This feature will optimize the vehicle height
to provide the most accurate wheel
alignment.
Touch Off or On.
Trailering
Touch and the following may display:
.Side Trailer Camera
.Bed View Camera Lighting
Side Trailer Camera
This feature specifies if using the turn signal
during a lane change will also display an
applicable side view of the trailer and
vehicle. See Assistance Systems for Parking
or Backing 0266.
Touch Off or On.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
158 Infotainment System
by model and require a complete working
electrical system, cell reception, and GPS
signal. An active connected plan is required.
Reference the SiriusXM user guide for use
and subscription information.
Radio Reception
Unplug electronic devices from the accessory
power outlets if there is interference or
static in the radio.
FM
FM signals only reach about 16 to 65 km (10
to 40 mi). Although the radio has a built-in
electronic circuit that automatically works to
reduce interference, some static can occur,
especially around tall buildings or hills,
causing the sound to fade in and out.
AM
The range for most AM stations is greater
than for FM, especially at night. The longer
range can cause station frequencies to
interfere with each other. Static can also
occur when things like storms and power
lines interfere with radio reception. When
this happens, try reducing the treble on the
radio.
SiriusXM Satellite Radio Service
If equipped, SiriusXM Satellite Radio Service
provides digital radio reception. Tall
buildings or hills can interfere with satellite
radio signals, causing the sound to fade in
and out. In addition, traveling or standing
under heavy foliage, bridges, garages,
or tunnels may cause loss of the SiriusXM
signal for a period of time. Some cellular
services may interfere with SXM reception
causing loss of signal.
Mobile Device Usage
Mobile device usage, such as making or
receiving calls, charging, or just having the
mobile device on may cause static
interference in the radio. Unplug the mobile
device or turn it off if this happens.
Fixed Mast Antenna
The fixed mast antenna will go through
most car washes as long as it is securely
attached. If the antenna becomes slightly
bent, straighten it out by hand. If it is badly
bent, replace it.
Occasionally check that the antenna is tight
at the base. If tightening is required, protect
the paint from damage.
Multi-Band Antenna
The roof antenna is for SiriusXM Satellite
Radio, OnStar, and GPS (Global Positioning
System), depending on the equipped
options. Keep clear of obstructions for clear
reception. If the vehicle has a sunroof, and it
is open, reception can also be affected.
Audio Players
Avoiding Untrusted Media Devices
When using media devices such as SD cards,
USB devices, and mobile devices, consider
the source. Untrusted media devices could
contain files that affect system operation or
performance. Avoid use if the content or
origin cannot be trusted.
USB Port
This vehicle is equipped with two USB ports
in the center console under the armrest and
another two in the center stack. These ports
are for data and charging.
There may also be two USB ports for
charging only at the rear of the center
console.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Infotainment System 163
details, and system limitations. Service and
connectivity may vary by make, model,
year, carrier, availability, and conditions.
4G LTE service is available in select markets.
4G LTE performance is based on industry
averages and vehicle systems design. Some
services require a data plan.
The OnStar App
If equipped, the infotainment system has
OnStar controls in the embedded OnStar app
on the Home Page. Most OnStar functions
that can be performed with the buttons can
be done using the app. To open the app,
touch the OnStar icon on the Home Page.
App updates require a corresponding service
plan. Features vary by region and model.
Features are subject to change. For more
information, see my.gmc.com/learn or
press
Q.
Services
The Services tab displays the default view
for the app. Use this page to launch the
available OnStar services. Touch a service to
open its display. Touch Wi-Fi to launch the
connections manager. Turn-by-Turn and
Advisor Call are the other tiled options. Account
The Account tab displays a snapshot of the
account linked with the vehicle. If there is
no such account, this tab will show all
values as
——. The advisor call icon will be
active even if there is no active account.
Advisor Call
Selecting Advisor Call is the same as
pressing
Qor calling 1-888-4ONSTAR
(1-888-466-7827). The X option in the upper
right corner of the screen does not end the
call, but returns to the previous screen.
Turn-by-Turn Directions
With a connected plan, an OnStar Advisor
can download a destination to the vehicle or
its embedded navigation system,
if equipped. Select Turn-by-Turn Directions
from the Services tab of the OnStar app to
call an Advisor or select a recent or favorite
destination. Touch the navigation icons to
select home, address or place. A destination
transfer from OnStar will show the detail
view of the destination when it is
transferred from OnStar to the Navigation
application. See www.onstar.com for a
coverage map. Services vary by model. Map
coverage is available in the United States,
Puerto Rico, and Canada. Wi-Fi Hotspot
Touch to display the Settings page, which
shows the configurations for the vehicle
hotspot and allows them to be changed.
For more information, see www.onstar.com.
Navigation
Using the Navigation System
If equipped, launch the Nav application by
touching the Nav icon on the Home Page or
on the shortcut tray near the bottom of the
infotainment display.
When the Nav application is launched for
the first time, a product walkthrough is
available. Use of the feature requires the
Terms and Conditions and the Privacy
statement to be confirmed. If available and
signed into a profile, it is also suggested to
enable and confirm Predictive Navigation.
Predictive Navigation (If Equipped)
If Predictive Navigation is available and
confirmed, this feature learns preferences by
remembering where the vehicle has been.
It uses the locations and navigation history
to personalize routes and results.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Infotainment System 165
.About
To exit a list, touch
zin the top right
corner to return to the main map view.
Make sure to set up preferences before
setting a destination and starting active
guidance.
Map Preferences
Touch to choose between basic map feature
configurations:
Map Colors
.Auto –Touch to automatically change
modes based on lighting conditions.
.Day (Light)
.Night (Dark)
3D Landmark (Default is On) : Touch On or
Off. When turned on, the system will
display all 3D Landmarks on the map
depending on the zoom level.
3D Building (Default is Off) : Touch On or
Off. When turned on, the system will
display all of the possible 3D building shapes
on the map depending on the zoom level.
Show Terrain in 3D (Default is Off) :
If equipped, touch On or Off. When turned
on, the system will display terrain
information on the map in 3D view. Auto-Zoom (Default is On) :
Touch On or
Off. When turned on, the system will
automatically adjust the zoom level when
the vehicle is approaching a turn. After the
turn is completed, the system automatically
brings the zoom back to the originally set
level. If the vehicle is approaching a turn
with the next turn occurring shortly after,
the Auto-Zoom will remain on until both
turns are completed.
Route Preferences
Touch to access the Route Preferences. The
choices are:
.Preferred Route –Choose from two
different route options: Fastest or
Eco-Friendly.
‐ Fastest would be the route with the
shortest drive time.
‐ Eco-Friendly would be the most
fuel-efficient route.
.Avoid on Current Route –Choose any of
the road features to avoid while on route:
‐ Highways
‐ Unpaved Roads
‐ Ferries
‐ Carpool Lanes
‐ Toll Roads ‐
Tunnels
‐ Country Borders
Navigation Voice Control
Touch to access the voice control setting
display.
.Navigation Volume –To adjust the
volume level, touch the up and down
arrows. If the voice guidance prompt is
being heard, volume can also be adjusted
using the knob on the center stack or the
volume switch on the steering wheel.
.Navigation Voice Prompt Level during a
Call. Options available are:
‐ Full Prompt (Selected by default)
‐ Tone Only
‐ None
Traffic Events (If Equipped)
This feature provides a list of events that
are on the route or nearby. Touch
Aand
then select Traffic Events. An OnStar
connected Navigation service plan is
required.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Infotainment System 167
This indicates the vehicle’s current location
and direction on the map.
This is the vehicle’s current location icon
during inactive guidance mode. Once a user
profile is created, the current location icon
can be customized.
This icon indicates the vehicle’s current
location and direction on the map.
The destination pin marks the location of
the final destination. Touch the pin to view
the destination address or to add it or
remove it from the Favorites list. Hide the
information by touching the pin one more
time. It will automatically time out if no
action is taken.
If equipped, smart Points of Interest (POIs)
are places of interest for parking and gas
stations.
The progress bar provides an overview of
the route progress and may show traffic and
incidents along the way. As the route
proceeds, the vehicle icon moves up the bar.Touch the icon to zoom out on the map and
view the entire route. Touch it again to
return to the previous view.
View the drive time by touching the
estimated time of arrival (ETA).
Current Location
When the vehicle is parked and not in a
Navigation session, the user icon is centered
on the map view, highlighting the current
location.
Destination
Receiving Destination Directions from
Different Sources
Destinations can be received or transferred
from different sources to the Nav application
for route guidance. If equipped, some of
these sources may include:
.Navigation from search results.
.OnStar Advisor destination download.
.An address from the Contacts list.
.An application on the smartphone that
can send destinations to the vehicle.
.An application downloaded to the vehicle
such as OnStar Services that can send
destinations to the navigation system.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
204 Climate Controls
Climate Controls
Climate Control Systems
Climate Control Systems . . . . . . . . . . . . . . 204
Dual Automatic Climate ControlSystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Air Vents
Air Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
Maintenance
Passenger Compartment Air Filter . . . . . 209
Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
Climate Control Systems
The heating, cooling, and ventilation in the vehicle can be controlled with this system.
1. Fan Control
2. MAX Defrost
3. Air Delivery Mode Controls
4. A/C (Air Conditioning)
5. TEMP (Temperature Control)
6. Recirculation
7. Rear Window Defogger (If Equipped) or Heated Mirrors (If Equipped)9:Turn clockwise or counterclockwise to
increase or decrease the fan speed. Turn the
knob all the way counterclockwise to turn
the fan off.
TEMP : Turn clockwise or counterclockwise
to increase or decrease the temperature
inside the vehicle.

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.