2021 GMC SIERRA Get To Know Guide

17F Optional equipment
POWER MIRRORSF/TRAILERING MIRRORSF
POWER MIRROR ADJUSTMENT
Press the Mirror Selector button to select the driver or passenger side mirror; use the four-way control pad to adjust the mirror.
POWER FOLDING MIRROR
Press the Folding Mirror button to
fold or unfold the mirrors.
TRAILERING MIRRORS
The mirrors can be extended for better visibility when towing a trailer. The lower
wide-field view mirror adjusts manually.
To extend the manual mirror, grasp the
mirror housing and pull back and rear -
ward in one motion. The housing extends
on a curved arc. Push in the housing to
return the mirror to its original position.
Note: Reset the power mirrors if they are adjusted manually by using the power controls to fold/
unfold the mirrors to their normal position.
See Keys, Doors and Windows in your Owner’s Manual.
UNIVERSAL REMOTE SYSTEMF
The Universal Remote System on the overhead console enables your vehicle to control
3 different devices, ranging from garage doors and gates to home lighting. Go to
homelink.com for detailed videos and instructions on how to program the Universal
Remote System. For additional assistance, call 1-800-355-3515.
See Instruments and Controls in your Owner’s Manual.
HILL DESCENT CONTROLF
Hill Descent Control sets and maintains vehicle speed from 1–14 mph while descending
a steep incline in a forward or reverse gear.
1. Press the Hill Descent Control button on the center of the instrument panel.
Vehicle speed must be below 31 mph to enable the system. The
symbol will illuminate on the instrument cluster.
2. Increase or decrease speed by applying the accelerator or brake pedal or use the Cruise Control +/– buttons on the steering wheel. The adjusted speed becomes the
new set speed. The symbol flashes when the system is actively applying the
brakes to maintain vehicle speed.
See Driving and Operating in your Owner’s Manual.

18F Optional equipment
TRAILERINGF
PROGRADE TRAILERING SYSTEMF
The in-vehicle trailering app on the info-
tainment screen allows customized trailer
profiles with a variety of helpful towing
assistance features, including a hitching
and setup checklist, trailer tire pressure and
temperature monitoring
F, trailer light test-
ing, Jack-Knife Alert, trailer length indicator,
trailer theft detection and more. Trailering
App information also is available with the
myGMC mobile app.
Note: The Trailering App will monitor trailer presence, even while the vehicle is off, by periodically
checking the trailer lighting circuits. On trailers equipped with LED lights, these periodic checks may
cause the trailer lights to flash. This flashing will become more frequent if Theft Alert is enabled.
HITCH AREA LIGHTING
Press the Cargo Lamp button on the left side of the instrument panel to turn
the cargo bed lamp or conventional hitch lamp on/off.
TRAILERING INFORMATION LABEL
The Trailering information label, located by the driver’s door latch, provides vehicle-
specific weight information to help when loading the vehicle.
INTEGRATED TRAILER BRAKE CONTROL (ITBC)F
The ITBC system can be used to adjust the
power output, or Trailer Gain, to the trailer
brakes. The control panel is on the center
of the instrument panel. ITBC information
is displayed on the ITBC page on the Driver
Information Center.
Squeeze the control together (right s ide does not move) to manually apply the
trailer brakes.
Adjust the Trailer Gain by pressing the +/– adjustment buttons. See Driving and Operating in your Owner’s Manual.
TRUCK TIRE PRESSURE MONITORING SYSTEM
The Low Tire Pressure warning light on the instrument cluster illuminates when one
or more of the vehicle’s tires is significantly underinflated. Fill the tires to the proper tire
pressures listed on the Tire and Loading Information label, located below the driver’s
door latch. Current tire pressures can be viewed on the Driver Information Center.
With the ignition On or in Accessory mode, the Tire Fill Alert will provide visual and
audible alerts to help with inflating a tire to the recommended tire pressure (does not apply to spare tire). When the recommended pressure is reached, the horn sounds and
the turn signals change from flashing to solid.
Note: Refer to your Owner’s Manual for accessory trailer tire pressure monitoring system
information.
See Vehicle Care in your Owner’s Manual.

19
The tailgate has 6 functional positions to improve loading, unloading and access to the cargo box.
1. Primary Gate
Open the primary gate for ac cess to the cargo box.
2. Primary Gate Load Stop
With the primary gate open, the load stop helps keep longer items secure in the cargo box.
3. Easy Access
The inner ga te folds down for easier reach into the cargo box to access items near the cab.
4. Full-width Step
With the primary gate open, the inner gate folds into a sturdy step (up to 375 lbs.) with a conve-
nient handle for easy cargo box entry and exit.
5. Inner Gate Load Stop
With the primary gate closed, fold the inner gate for two-tier storage and open the load stop to
help keep longer items secure.
6. Inner Gate Work Surface
With the primary gate closed, fold the inner gate for two-tier storage or for use as a standing-
height work surface.
Note: Do not lower the inner gate with the primary gate
open if a hitch ball or trailer is attached.
OPEN THE INNER GATE
Press the upper button (A) on the tailgate.
OPEN THE PRIMARY GATE
Press the lower button (B) on the tailgate.
Press the Power Tailgate button twice on the
Remote Keyless Entry transmitter.
Press the Power Tailgate button on the center of the instrument panel.
OPEN THE PRIMARY
GATE AND INNER GATE
Press the lower button and then upper button
(B then A) on the tail -
gate consecutively.
OPEN THE LOAD STOP
OR STEP
Press the release bar (C).
GMC MULTIPRO TAILGATE OPERATIONF
F Optional equipmentSee Keys, Doors and Windows in your Owner’s Manual.
A
B
C
1
2
3
4
5
6

20
Download the myGMC app to your compatible smartphone (or device) and, if your vehicle is properly equipped, you can start or turn off your engine, lock or unlock your doors, view key diagnostic information, set parking information and more.
The app is available on select Apple and Android devices. Service availability, features and functionality vary by vehicle, device and data plan. Device data connection
required. Visit onstar.com for more details. Download the mobile app from your
compatible mobile device’s app store.
ROADSIDE ASSISTANCE
1-888-881-3302 TTY Users: 1-888-889-2438
As the owner of a new GMC, you are automatically enrolled in the GMC Roadside
Assistance program for up to 5 years/60,000 miles, whichever occurs first, at no
expense to you. GMC’s Roadside Assistance toll-free number is staffed by a team of
trained advisors who are available 24 hours a day, 365 days a year, to contact a service
provider for light services (fuel delivery, jump-starts, flat tire and lock-outs) or make
arrangements to tow your vehicle to the nearest GMC dealer for any repairs.
ONSTAR® ROADSIDE ASSISTANCE
If you have a current OnStar Safety & Security plan, push the blue OnStar button or red
Emergency button to get the help you need. An OnStar advisor will use GPS technology
to pinpoint your vehicle location and contact the nearest service provider.
To learn more about OnStar services, push the blue OnStar button, visit onstar.com, call
1-888-4-ONSTAR (1-888-466-7827), or refer to your Owner’s Manual.
GMC OWNER CENTER
Get to know your vehicle inside and out with the GMC Owner Center. Check out person -
alized information, including an online Owner’s Manual and helpful how-to videos, track
your service history and warranty status, manage your OnStar and Connected Services
vehicle plans, review your current Vehicle Diagnostics report (active service required)
and more. Create an account today at my.gmc.com.
MYGMC MOBILE APP
!84550395=A!84550395 A
We recommend always using ACDelco or GM Genuine Parts
Certain restrictions, precautions and safety procedures apply to your vehicle. Please read your Owner’s Manual
for complete instructions. All information contained in this guide is based on the latest information available at
the time of printing and is subject to change without notice. Copyright 2020 General Motors. All rights reserved.