2021 GMC SIERRA key

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
396 Vehicle Care
Dinghy Towing (Vehicles with a
Two-Speed Transfer Case)
Only dinghy tow four-wheel-drive vehicles
with a two-speed transfer case that have an
N (Neutral) and a 4
n(Four-Wheel Drive
Low) setting.
{Warning
Shifting a four-wheel-drive vehicle's
transfer case into N (Neutral) can allow
the vehicle to move even if the
transmission is in P (Park). You or others
could be injured. Set the parking brake
and use wheel blocks before shifting the
transfer case to N (Neutral). To dinghy tow:
1. Position the vehicle being towed behind the tow vehicle, facing forward and on a
level surface.
2. Securely attach the vehicle being towed to the tow vehicle.
3. Apply the parking brake and start the engine.
4. Shift the transfer case to N (Neutral). See “Shifting into N (Neutral)” under
Four-Wheel Drive 0242.
5. With the engine running, release the parking brake and verify that the
transfer case is in N (Neutral) by shifting
the transmission to D (Drive) and then to
R (Reverse). There should be no
movement while shifting the
transmission.
6. Shift the transmission to D (Drive).
7. If equipped with an ignition key, turn the ignition to ACC/ACCESSORY.
If equipped with Keyless Access, turn the
engine off. Disregard the Shift to P (Park)
DIC message. See Ignition Positions
(Keyless Access) 0230 or
Ignition Positions (Key Access) 0229.
{Warning
To avoid death, serious injury,
or property damage, before dinghy
towing the vehicle, always disconnect and
secure the negative battery cable and
cover the negative battery post and cable
with a non-conductive material. If the
battery is left connected or the battery
cable contacts the post, the Electric
Parking Brake may activate during
towing, which could cause a crash.
8. Disconnect the negative (–) battery cable. See “Negative Battery Cable
Disconnection” inBattery - North
America 0343.
9. Shift the transmission to P (Park).
Caution
If the steering column is locked, vehicle
damage may occur.
10. Move the steering wheel to make sure the steering column is unlocked.
11. If the vehicle has an ignition key, keep it in the towed vehicle in ACC/ACCESSORY
to prevent the steering column from
locking. If the vehicle is equipped with

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 397
Keyless Access, keep the RKE transmitter
outside of the vehicle and manually lock
the doors. Access the vehicle by using
the key in the door lock. SeeDoor Locks
0 21.
Disconnecting the Towed Vehicle
Before disconnecting from the tow vehicle: 1. Park on a level surface. Secure the vehicle with wheel blocks.
2. Re-connect the negative (–) battery. See Battery - North America 0343.
3. Turn on the ignition with the engine off. For vehicles with a key, turn the ignition
to ON/RUN with the engine off. If the
vehicle is equipped with Keyless Access,
with your foot off the brake pedal, press
and hold ENGINE START/STOP for
five seconds until the green light comes
on in the button. See Ignition Positions
(Keyless Access) 0230 or
Ignition Positions (Key Access) 0229.
4. Set the parking brake. See Electric
Parking Brake 0247.
5. Disconnect from the tow vehicle.
6. Shift the transmission to N (Neutral). 7. Shift the transfer case to 2m(Two-Wheel
Drive High). When the shift to 2
m
(Two-Wheel Drive High) is complete, the
light in the instrument cluster will stop
flashing and stay lit. See
Four-Wheel-Drive Light 0118.
8. Start the engine. Check that the vehicle is in 2
m(Two-Wheel Drive High) by
starting the engine and shifting the
transmission to D (Drive) and then to
R (Reverse). There should be movement
of the vehicle while shifting.
9. Shift the transmission to P (Park) and turn off the ignition.
10. Release the parking brake and remove the wheel blocks.
11. Reset any lost presets. The outside temperature display will
default to 0 °C (32 °F) but will reset with
normal usage.
Dolly Towing

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
402 Vehicle Care
Caution (Continued)
tire dressing, always wipe off any
overspray from all painted surfaces on
the vehicle.
Wheels and Wheel Trim
Use a soft, clean cloth with mild soap and
water to clean the wheels. After rinsing
thoroughly with clean water, dry with a
soft, clean towel. A wax may then be
applied.
Caution
Chrome wheels and chrome wheel trim
may be damaged if the vehicle is not
washed after driving on roads that have
been sprayed with magnesium chloride or
calcium chloride. These are used on roads
for conditions such as dust and ice.
Always wash the chrome with soap and
water after exposure.
Caution
To avoid surface damage on wheels and
wheel trim, do not use strong soaps,
chemicals, abrasive polishes, cleaners,
(Continued)
Caution (Continued)
or brushes. Use only GM approved
cleaners. Do not drive the vehicle through
an automatic car wash that uses silicon
carbide tire/wheel cleaning brushes.
Damage could occur and the repairs
would not be covered by the vehicle
warranty.
Brake System
Visually inspect brake lines and hoses for
proper hook-up, binding, leaks, cracks,
chafing, etc. Inspect disc brake pads for wear
and rotors for surface condition. Inspect
drum brake linings/shoes for wear or cracks.
Inspect all other brake parts.
Steering, Suspension, and Chassis
Components
Visually inspect steering, suspension, and
chassis components for damaged, loose,
or missing parts or signs of wear at least
once a year.
Inspect power steering for proper
attachment, connections, binding, cracks,
chafing, etc.Visually check constant velocity joint boots
and axle seals for leaks.
Caution
Lubrication of applicable suspension
points should not be done unless the
temperature is
−12 °C (10 °F) or higher,
or damage could result.
Body Component Lubrication
Lubricate all key lock cylinders, hood hinges,
liftgate hinges, and the steel fuel door hinge
unless the components are plastic. Applying
silicone grease on weatherstrips with a clean
cloth will make them last longer, seal better,
and not stick or squeak.
Underbody Maintenance
At least twice a year, spring and fall, use
plain water to flush any corrosive materials
from the underbody. Take care to
thoroughly clean any areas where mud and
other debris can collect. If equipped with
power assist steps, extend them and then
use a high pressure wash to clean all joints
and gaps.
Do not directly power wash the transfer
case and/or front/rear axle output seals.
High pressure water can overcome the seals

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Service and Maintenance 411
missing boots, loose or missing boot
clamps, center bearing excessive
looseness, missing or loose fasteners.
.Check restraint system components. See
Safety System Check060.
.Visually inspect fuel system for damage
or leaks.
.Visually inspect exhaust system and
nearby heat shields for loose or damaged
parts.
.Lubricate body components. See Exterior
Care 0398.
.Check starter switch. See Starter Switch
Check 0347.
.Check automatic transmission shift lock
control function. See Automatic
Transmission Shift Lock Control Function
Check 0347.
.Check ignition transmission lock. See
Ignition Transmission Lock Check 0347.
.Check parking brake and automatic
transmission park mechanism. See Park
Brake and P (Park) Mechanism Check
0 347.
.Check accelerator pedal for damage, high
effort, or binding. Replace if needed.
.Visually inspect gas strut for signs of
wear, cracks, or other damage. Check the
hold open ability of the strut. If the hold
open is low, service the gas strut. See Gas
Strut(s) 0349.
.Inspect sunroof track and seal,
if equipped. See Sunroof043.
.Verify spare tire key lock operation and
lubricate as needed. See Tire Changing
0 381.
.Visually inspect the spare tire to ensure
that it is tightly stowed under the vehicle.
Push, pull, and try to turn the tire. If the
spare tire moves, tighten as necessary.
See Tire Changing 0381.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Service and Maintenance 419
UsageFluid/Lubricant
Key Lock Cylinders, Hood Hinges, Body Door Hinge Pins, Tailgate Hinge and Linkage, Fuel Door Hinge, Tailgate Handle Pivot Points, Hinges, Latch Bolt, and Linkage Multi-Purpose Lubricant, Superlube. See your dealer.
Transfer Case (Four-Wheel Drive) DEXRON-VI Automatic Transmission Fluid. Windshield Washer Automotive windshield washer fluid that meets regional freeze protection requirements.
Maintenance Replacement Parts
Replacement parts identified below by name, part number, or specification can be obtained from your dealer.
If the vehicle has a diesel engine, see the Duramax diesel supplement.
Part GM Part Number ACDelco Part Number
Engine Air Cleaner/Filter
IWith high capacity air cleaner 84121219 A3244C
IWithout high capacity air cleaner 84121217 A3246C

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
OnStar 441
.Receive a Diagnostic check of the vehicle's
key operating systems.
.Receive Roadside Assistance.
.Manage Wi-Fi Settings, if equipped.
Press
>to get a priority connection to an
OnStar Advisor available 24/7 to:
.Get help for an emergency.
.Be a Good Samaritan or respond to an
AMBER Alert.
.Get assistance in severe weather or other
crisis situations and find evacuation
routes.
OnStar Services
Emergency
Emergency Services require an active safety
and security plan. With Automatic Crash
Response, built-in sensors can automatically
alert a specially trained OnStar Advisor who
is immediately connected in to the vehicle
to help.
Press
>for a priority connection to an
OnStar Advisor who can contact emergency
service providers, direct them to your exact
location, and relay important information. With OnStar Crisis Assist, specially trained
Advisors are available 24 hours a day, 7 days
a week, to provide a central point of
contact, assistance, and information during a
crisis.
With Roadside Assistance, Advisors can
locate a nearby service provider to help with
a flat tire, a battery jump, or an empty
gas tank.
Security
If equipped, OnStar provides these services:
.With Stolen Vehicle Assistance, OnStar
Advisors can use GPS to pinpoint the
vehicle and help authorities quickly
recover it.
.With Remote Ignition Block, if equipped,
OnStar can block the engine from being
restarted.
.With Stolen Vehicle Slowdown,
if equipped, OnStar can work with law
enforcement to gradually slow the
vehicle down.
Theft Alarm Notification
If equipped, if the doors are locked and the
vehicle alarm sounds, a notification by text,
e-mail, or phone call will be sent. If the
vehicle is stolen, an OnStar Advisor can work
with authorities to recover the vehicle.
OnStar Additional
Information
In-Vehicle Audio Messages
Audio messages may play important
information at the following times:
.Prior to vehicle purchase. PressQto set
up an account.
.After change in ownership and at
90 days.
Transferring Service
PressQto request account transfer
eligibility information. The Advisor can
cancel or change account information.
Selling/Transferring the Vehicle
Call 1-888-4ONSTAR (1-888-466-7827)
immediately to terminate your OnStar or
connected services if the vehicle is disposed
of, sold, transferred, or if the lease ends.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Connected Services 447
.Request Roadside Assistance.
.Set a parking reminder with pin drop,
take a photo, make a note, and set a
timer.
.Connect with GMC on social media.
Features are subject to change. For myGMC
mobile app information and compatibility,
see my.gmc.com.
An active OnStar or connected service plan
may be required. A compatible device,
factory-installed remote start, and power
locks are required. Data rates apply. See
www.onstar.com for details and system
limitations.
Remote Services
Contact an OnStar Advisor to unlock the
doors or sound the horn and flash the
lamps.
Marketplace
OnStar Advisors can provide offers from
restaurants and retailers on your route, help
locate hotels, or book a room. These services
vary by market.
Diagnostics
By monitoring and reporting on the vehicle's
key systems, OnStar Advanced Diagnostics,
if equipped, provides a way to keep up on
maintenance. Capabilities vary by model.
See www.onstar.com for details and system
limitations. Features are subject to change.
For updates on feature capabilities, see
my.gmc.com. Message and data rates
may apply.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./Cana-
da/Mexico-14632426) - 2021 - CRC - 11/5/20
Index 453
H
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Hazard Warning Flashers . . . . . . . . . . . . . . . . .142
HD Radio Technology . . . . . . . . . . . . . . . . . . . . 156
Head Restraints . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Head-up Display . . . . . . . . . . . . . . . . . . . . . . . . . .128
HeadlampsAiming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Automatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Bulb Replacement . . . . . . . . . . . . . . . . . . . . . . 350
Daytime Running Lamps (DRL) . . . . . . . . . . 141
Flash-to-Pass . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Headlamps, Front Turn Signal,Sidemarker, and Parking Lamps . . . . . . 350
High-Beam On Light . . . . . . . . . . . . . . . . . . . 123
High/Low Beam Changer . . . . . . . . . . . . . . . 141
Lamps On Reminder . . . . . . . . . . . . . . . . . . . 123
Heated Rear Seats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Steering Wheel . . . . . . . . . . . . . . . . . . . . . . . . 100
Heated and Ventilated Front Seats . . . . . . . .52
Heated Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Heater Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204, 206
High-Beam On Light . . . . . . . . . . . . . . . . . . . . . . 123
Hill and Mountain Roads . . . . . . . . . . . . . . . . 219
Hill Descent Control (HDC) . . . . . . . . . . . . . . . 250 Hill Descent Control Light . . . . . . . . . . . . . . . . . 119
Hill Start Assist (HSA) . . . . . . . . . . . . . . . . . . . . 248
Hood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101
How to Wear Seat Belts Properly . . . . . . . . . .55
HVAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204, 206
I
If the System Needs Service . . . . . . . . . . . . . . 175
Ignition Positions . . . . . . . . . . . . . . . . . . . 229, 230
Ignition Transmission Lock Check . . . . . . . . 347
Immobilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Indicator
Pedestrian Ahead . . . . . . . . . . . . . . . . . . . . . . . 119
Vehicle Ahead . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Infants and Young Children, Restraints . . . . .72
Information Publication Ordering . . . . . . . . . . . . . . . . . . . 435
Infotainment System . . . . . . . . . . . . . . . . . . . . 439
Instrument Cluster . . . . . . . . . . . . . . . . . . . . . . . 106
Instrument Panel Overview . . . . . . . . . . . . . . . . 4
Interior Rearview Mirrors . . . . . . . . . . . . . . . . . 38
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 148
J
Jack Auxiliary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Jump Starting - North America . . . . . . . . . . . 391
K
Keyless Entry Remote (RKE) System . . . . . . . . . . . . . . . . 10, 13
Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7, 9
L
Labeling, Tire Sidewall . . . . . . . . . . . . . . . . . . . 362
Lamps Auxiliary Roof Mounted Lamp . . . . . . . . . 144
Daytime Running (DRL) . . . . . . . . . . . . . . . . . 141
Dome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Exterior Cargo . . . . . . . . . . . . . . . . . . . . . . . . . 144
Exterior Controls . . . . . . . . . . . . . . . . . . . . . . . 139
Exterior Lamps Off Reminder . . . . . . . . . . . 141
Exterior Lighting Battery Saver . . . . . . . . 147
License Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
Malfunction Indicator (CheckEngine) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
On Reminder . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Lane Change Alert (LCA) . . . . . . . . . . . . . . . . . 280
Lane Keep Assist (LKA) . . . . . . . . . . . . . . . . . . . .281
Lane Keep Assist Light . . . . . . . . . . . . . . . . . . . . 119
Lap-Shoulder Belt . . . . . . . . . . . . . . . . . . . . . . . . . .57
LATCH System Replacing Parts after a Crash . . . . . . . . . . . 88
LATCH, Lower Anchors and Tethers for Children . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77