2021 GMC SIERRA trailer

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Introduction 5
1. Tow/Haul Mode (On Some Models). SeeDriver Mode Control 0251.
Automatic Transfer Case Control (If
Equipped). See Four-Wheel Drive 0242.
Driver Mode Control 0251 (If Equipped).
2. Air Vents 0209.
3. Head-Up Display (HUD) 0128 (If
Equipped).
4. Turn Signal Lever. See Turn and
Lane-Change Signals 0143.
Windshield Wiper/Washer 0101.
5. Instrument Cluster 0106.
6. Shift Lever. See Automatic Transmission
0 239.
Range Selection Mode. See Manual Mode
0 241.
7. Light Sensor. See Automatic Headlamp
System 0142.
8. Infotainment Controls. See Overview
0 149.
9. Climate Control Systems 0204 (If
Equipped).
Dual Automatic Climate Control System
0 206 (If Equipped).
10. Heated and Ventilated Front Seats 052
(If Equipped). 11.ALane Keep Assist (LKA)
0281 (If
Equipped).
XPark Assist Switch (If Equipped). See
Assistance Systems for Parking or Backing
0 266.
hAuto Stop Disable Switch (If
Equipped). See Stop/Start System 0233.
5Power Release Tailgate (If
Equipped). See Tailgate023.
|Hazard Warning Flashers 0142.
gTraction Control/Electronic Stability
Control 0248.
ADC/AC Switch. See Power Outlets
0 102.
5Hill Descent Control Switch (If
Equipped). See Hill Descent Control (HDC)
0 250.
jPower Assist Steps 030 (If
Equipped).
LExpress Window Down Button (If
Equipped). See Power Windows 041.
Tow/Haul Mode 0242 (On Some
Models).
Exhaust Brake (If Equipped). See Duramax
Diesel Supplement. Power Take-Off (PTO) (If Equipped). See
Duramax Diesel Supplement.
12. Power Outlet (Alternating Current) (If Equipped). See Power Outlets0102.
13. Power Outlet (Direct Current) Power
Outlets 0102.
14. USB Port 0158.
15. Wireless Charging 0103 (If Equipped).
16. Trailer Brake Control Panel (If Equipped). See“Integrated Trailer Brake Control
System” underTowing Equipment 0296.
17. ENGINE START/STOP. See Ignition
Positions (Keyless Access) 0230 or
Ignition Positions (Key Access) 0229.
18. Steering Wheel Controls 0100 (If
Equipped).
Driver Information Center (DIC) Controls.
See Driver Information Center (DIC) (Base
Level) 0124 or
Driver Information Center (DIC) (Midlevel
and Uplevel) 0125.
19. Horn 0101.
20. Hood Release. See Hood0323.
21. Steering Wheel Adjustment 0100 (Out
of View).

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Keys, Doors, and Windows 7
Keys, Doors, and
Windows
Keys and Locks
Keys (Key Access) . . . . . . . . . . . . . . . . . . . . . . . . 7
Keys (Keyless Access) . . . . . . . . . . . . . . . . . . . . 9
Remote Keyless Entry (RKE) System . . . . 10
Remote Keyless Entry (RKE) SystemOperation (Key Access) . . . . . . . . . . . . . . . 10
Remote Keyless Entry (RKE) System Operation (Keyless Access) . . . . . . . . . . . . 13
Remote Vehicle Start . . . . . . . . . . . . . . . . . . . 20
Door Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Power Door Locks . . . . . . . . . . . . . . . . . . . . . . . 22
Delayed Locking . . . . . . . . . . . . . . . . . . . . . . . . 22
Automatic Door Locks . . . . . . . . . . . . . . . . . . 22
Lockout Protection . . . . . . . . . . . . . . . . . . . . . . 22
Safety Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Doors
Tailgate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Power Assist Steps . . . . . . . . . . . . . . . . . . . . . 30
Vehicle Security
Vehicle Security . . . . . . . . . . . . . . . . . . . . . . . . . 31
Vehicle Alarm System . . . . . . . . . . . . . . . . . . . 31
Steering Column Lock . . . . . . . . . . . . . . . . . . . 32
Immobilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Immobilizer Operation . . . . . . . . . . . . . . . . . . 32
Exterior Mirrors
Convex Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 33
Manual Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 34
Trailer-Tow Mirrors . . . . . . . . . . . . . . . . . . . . . 34
Power Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Folding Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 36
Heated Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . 37
Automatic Dimming Mirror . . . . . . . . . . . . . 37
Blind Spot Mirrors . . . . . . . . . . . . . . . . . . . . . . 37
Reverse Tilt Mirrors . . . . . . . . . . . . . . . . . . . . . 38
Interior Mirrors
Interior Rearview Mirrors . . . . . . . . . . . . . . . 38
Manual Rearview Mirror . . . . . . . . . . . . . . . . 38
Automatic Dimming Rearview Mirror . . . 38
Rear Camera Mirror . . . . . . . . . . . . . . . . . . . . 38
Windows
Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Manual Windows . . . . . . . . . . . . . . . . . . . . . . . 41
Power Windows . . . . . . . . . . . . . . . . . . . . . . . . 41
Rear Windows . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Sun Visors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Roof
Sunroof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Keys and Locks
Keys (Key Access)
{Warning
Leaving children in a vehicle with the
ignition key is dangerous and children or
others could be seriously injured or killed.
They could operate the power windows
or other controls or make the vehicle
move. The windows will function with
the keys in the ignition, and children or
others could be caught in the path of a
closing window. Do not leave children in
a vehicle with the ignition key.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
28 Keys, Doors, and Windows
To open the inner tailgate, press the upper
touch pad on the tailgate handle after
unlocking all doors. Pull the top of the
tailgate to open.
Caution
Do not open the inner tailgate with the
primary tailgate open if there is a hitch
ball or trailer attached. This may damage
the tailgate.
To close the inner tailgate with the primary
tailgate closed, firmly push or pull it upward
until it latches. Pull it back to be sure it is
latched securely.
To close the inner tailgate with the primary
tailgate open:
.Hold the primary tailgate and firmly close
the inner tailgate.
.Raise the inner tailgate so it meets the
primary tailgate and close together at the
same time.
When using the tailgate step as a load stop,
the load must be secured as the load could
shift. See Cargo Tie-Downs 097.
Tailgate Step
{Warning
To avoid personal injury, keep hands
away from the hinges when operating
the tailgate step. With the primary and inner tailgates open,
the tailgate step can be lowered to access
the pickup bed.
Using the Step
Caution
When using the tailgate as a step, the
load rating is 170 kg (375 lb), which
includes a person and cargo. Overloading
the tailgate step can cause damage to
the tailgate system.
.To lower the tailgate step, press the
button at the center of the step. Make
sure it lowers to the fully open position.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
34 Keys, Doors, and Windows
Trailer-Tow Mirrors
The upper portion of both the driver and
passenger mirrors is flat.
The lower portion of both the driver and
passenger mirrors is convex. A convex
mirror’s surface is curved so more can be
seen from the driver seat. The lower portion
is adjusted manually.
Manual Mirrors
If equipped, adjust manual mirrors by
moving the mirror up and down or left to
right to see a little of the side of the vehicle
and to have a clear view behind the vehicle.
Using hood-mounted air deflectors and
add-on convex mirror attachments could
decrease mirror performance.
Trailer-Tow Mirrors
Extending Mirrors
Trailer tow mirrors can extend out for better
visibility when towing a trailer.
Manual Extend :If equipped, grasp the
mirror housing firmly and pull back in one
motion, arching slightly toward the rear of
the vehicle.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Keys, Doors, and Windows 35
To return the mirror to its original position,
reverse the motion.
Power Extend :If equipped, press the power
extend button to fully extend the mirror.
Press again to retract.
Resetting the Power Extend Mirrors
Reset the power extend mirrors if:
.The mirrors are accidentally obstructed
while extending/retracting.
.The mirrors are accidentally manually
extended/retracted.
.The mirrors vibrate at normal driving
speeds. If a popping noise from the mirror is heard,
this sound is normal as the manual detents
are aligning after a manual extend/retract
operation has occurred.
Auxiliary Cargo Mirror Lamps
If equipped, cargo mirror lamps face
rearward to provide more light on the sides
of the vehicle, if needed. See
Exterior Cargo
Lamps 0144.
Advanced Trailering Vision System Side
Cameras
If equipped, the Advanced Trailering Vision
System side cameras are on the bottom of
the outside mirrors. See “Surround Vision
(360 Degrees)” underAssistance Systems for
Parking or Backing 0266.
Power Mirrors
To adjust each mirror:
1. Press
jor|to select the driver or
passenger side mirror. The indicator light
will illuminate.
2. Press the arrows on the control pad to move the mirror in the desired direction.
3. Adjust each outside mirror so that a little of the vehicle and the area behind it can
be seen.
4. Press
jor|again to deselect the
mirror.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
116 Instruments and Controls
Caution
If the vehicle is driven continually with
this light on, the emission control system
may not work as well, the fuel economy
may be lower, and the vehicle may not
run smoothly. This could lead to costly
repairs that might not be covered by the
vehicle warranty.
Caution
Modifications to the engine, transmission,
exhaust, intake, or fuel system, or the
use of replacement tires that do not
meet the original tire specifications, can
cause this light to come on. This could
lead to costly repairs not covered by the
vehicle warranty. This could also affect
the vehicle’s ability to pass an Emissions
Inspection/Maintenance test. See
Accessories and Modifications0323.
If the light is flashing : A malfunction has
been detected that could damage the
emission control system and increase vehicle
emissions. Diagnosis and service may be
required. To help prevent damage, reduce vehicle
speed and avoid hard accelerations and
uphill grades. If towing a trailer, reduce the
amount of cargo being hauled as soon as
possible.
If the light continues to flash, find a safe
place to park. Turn the vehicle off and wait
at least 10 seconds before restarting the
engine. If the light is still flashing, follow
the previous guidelines and see your dealer
for service as soon as possible.
If the light is on steady :
A malfunction has
been detected. Diagnosis and service may be
required.
Check the following:
.If fuel has been added to the vehicle
using the capless funnel adapter, make
sure that it has been removed. See
“Filling the Tank with a Portable
Gas Can” underFilling the Tank (Pickup
Model) 0285 or
Filling the Tank (Chassis Cab Model) 0287. The diagnostic system can
detect if the adapter has been left
installed in the vehicle, allowing fuel to
evaporate into the atmosphere. A few
driving trips with the adapter removed
may turn off the light.
.Poor fuel quality can cause inefficient
engine operation and poor driveability,
which may go away once the engine is
warmed up. If this occurs, change the fuel
brand. It may require at least one full
tank of the proper fuel to turn the light
off. See Recommended Fuel (Except 6.2L
V8 Engine) 0283 or
Recommended Fuel (6.2L V8 Engine)
0 284.
If the light remains on, see your dealer.
Emissions Inspection and Maintenance
Programs
If the vehicle requires an Emissions
Inspection/Maintenance test, the test
equipment will likely connect to the
vehicle's Data Link Connector (DLC).
The DLC is under the instrument panel to
the left of the steering wheel. Connecting
devices that are not used to perform an
Emissions Inspection/Maintenance test or to

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
120 Instruments and Controls
Traction Off Light
This light comes on briefly when the vehicle
is turned on. If it does not, have the vehicle
serviced by your dealer. If the system is
working normally, the indicator light then
turns off.
The traction off light comes on when the
Traction Control System (TCS) has been
turned off. If Electronic Stability Control
(ESC) is turned off, TCS is also turned off. To
turn TCS and ESC off and on, seeTraction
Control/Electronic Stability Control 0248.
If TCS is off, wheel spin is not limited unless
necessary to help protect the driveline from
damage. Adjust driving accordingly.
Traction Control System (TCS)/
Electronic Stability Control Light
This light comes on briefly when the vehicle
is turned on.
If the light does not come on, have the
vehicle serviced by your dealer. If the
system is working normally, the indicator
light turns off.
If the light is on and not flashing, the TCS
and potentially the ESC system are not fully
operational and may not assist in
maintaining control. Adjust driving
accordingly. If the condition persists, see
your dealer as soon as possible. A Driver
Information Center (DIC) message may
display.
The light flashes when the TCS and/or the
ESC system is actively working.
See Traction Control/Electronic Stability
Control 0248.
Trailer Sway Control Light (Uplevel
Cluster)
This light will flash when Trailer Sway
Control is active. See Trailer Sway Control
(TSC) 0306.
Electronic Stability Control (ESC)
Off Light
This light comes on briefly when the vehicle
is turned on. If the light does not come on,
have the vehicle serviced by your dealer.
If the system is working normally, the
indicator light then turns off.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Instruments and Controls 127
than when the oil has just been changed.
It cannot be reset accurately until the next
oil change. To reset, seeEngine Oil Life
System 0332.
Tire Pressure : Shows the approximate
pressures of all four tires. Tire pressure is
displayed in either kilopascal (kPa) or in
pounds per square inch (psi). If the pressure
is low, the value for that tire is shown in
amber. See Tire Pressure Monitor System
0 368 and
Tire Pressure Monitor Operation 0369.
Air Filter Life : Shows an estimate of the
engine air filter’s remaining useful life and
the state of the system. Engine Air Filter Life
95% means 95% of the current air filter life
remains. Messages will display based on the
engine air filter life and the state of the
system. When the REPLACE AT NEXT OIL
CHANGE message displays, the engine air
filter should be replaced at the time of the
next oil change. When the REPLACE SOON
message displays, the engine air filter
should be replaced at the earliest
convenience.
The Air Filter Life display must be reset after
the engine air filter replacement. To reset,
see Engine Air Filter Life System 0333. Brake Pad Life :
This displays an estimate of
the remaining life of the front and rear
brake pads. Messages will display based on
brake pad wear and the state of the system.
Reset the Brake Pad Life display after
replacing the brake pads. See Brake Pad Life
System 0342.
Fuel Economy : Displays average fuel
economy, the best fuel economy over the
selected distance, and a bar graph showing
instantaneous fuel economy.
Press the thumbwheel to change the
selected distance. Press and hold the
thumbwheel while this display is active to
reset the best fuel economy and average
fuel economy. This display can also be reset
by selecting reset in the menu.
Engine Hours (Hourmeter) : Shows the total
number of hours the engine has run. This
display also shows the engine idle hours.
Transmission Fluid Temperature : Shows the
temperature of the automatic transmission
fluid in either degrees Celsius (°C) or degrees
Fahrenheit (°F).
Trailer Brake : On vehicles with the
Integrated Trailer Brake Control (ITBC)
system, the trailer brake display appears in
the DIC. TRAILER GAIN shows the trailer gain setting.
This setting can be adjusted from 0.0 to 10.0
with either a trailer connected or
disconnected.
TRAILER OUTPUT shows the power output to
the trailer any time a trailer with electric
brakes is connected. Output is displayed as a
bar graph. Dotted lines may appear in the
OUTPUT display if a trailer is not connected.
Off Road :
Displays vehicle pitch and roll
information, road wheel angle, and
four-wheel drive (4WD) status.
Follow Distance : If equipped, the current
follow time to the vehicle ahead is displayed
as a time value on this page.
Driver Assistance : If equipped, shows
information for Lane Keep Assist (LKA) and
Forward Collision Alert (FCA).
Info Page Options : Scroll to choose which
info pages appear on the DIC. Press the
thumbwheel to select or deselect.
Blank Page : Shows no information.