GMC SIERRA 2021 Owner's Manual

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
390 Vehicle Care
If equipped with a spare tire cable,
reattach the clip to the frame
attachment bracket. Note that there may
be slack in the cable.
Repeat this tightness check procedure
when checking the spare tire pressure
according to the scheduled maintenance
information or any time the spare tire is
handled due to service of other
components.
Correctly Stored
Incorrectly Stored
10. Reinstall the spare tire lock, if the vehicle has one.
Return the jack and tools to their original
location in the vehicle. See “Removing the
Spare Tire and Tools.”
Full-Size Spare Tire
If this vehicle came with a full-size spare
tire, it was fully inflated when new,
however, it can lose air over time. Check the
inflation pressure regularly. See Tire Pressure
0 367 and
Vehicle Load Limits 0222 for information
regarding proper tire inflation and loading
the vehicle. For instructions on how to
remove, install, or store a spare tire, see Tire
Changing 0381.
If equipped with a temporary use full-size
spare tire, it is indicated on the tire sidewall.
See Tire Sidewall Labeling 0362. This spare
tire should not be driven on over 112 km/h
(70 mph), or 88 km/h (55 mph) when
pulling a trailer, at the proper inflation
pressure. Repair and replace the road tire as
soon as it is convenient, and stow the spare
tire for future use.
Caution
If the vehicle has four-wheel drive and a
different size spare tire is installed, do
not drive in four-wheel drive until the flat
tire is repaired and/or replaced. The
vehicle could be damaged and the repairs
(Continued)

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 391
Caution (Continued)
would not be covered by the warranty.
Never use four-wheel drive when a
different size spare tire is installed on the
vehicle.
The vehicle may have a different size spare
tire than the road tires originally installed
on the vehicle. This spare tire was developed
for use on this vehicle, so it is all right to
drive on it. If the vehicle has four-wheel
drive and a different size spare tire is
installed, drive only in two-wheel drive.
After installing the spare tire on the vehicle,
stop as soon as possible and check that the
spare is correctly inflated. The spare tire is
made to perform well at speeds up to
112 km/h (70 MPH) at the recommended
inflation pressure, so you can finish
your trip.
Have the damaged or flat road tire repaired
or replaced and installed back onto the
vehicle as soon as possible so the spare tire
will be available in case it is needed again.
Do not mix tires and wheels of difference
sizes, because they will not fit. Keep the
spare tire and its wheel together. If the vehicle has a spare tire that does not
match the original road tires and wheels in
size and type, do not include the spare in
the tire rotation.
Jump Starting
Jump Starting - North America
For more information about the vehicle
battery, see
Battery - North America 0343.
If the vehicle's battery (or batteries) has run
down, you may want to use another vehicle
and some jumper cables to start your
vehicle. Be sure to use the following steps
to do it safely.
{Warning
WARNING: Battery posts, terminals, and
related accessories contain lead and lead
compounds, chemicals known to the
State of California to cause cancer and
birth defects or other reproductive harm.
Batteries also contain other chemicals
known to the State of California to cause
cancer. WASH HANDS AFTER HANDLING.
(Continued)
Warning (Continued)
For more information go to
www.P65Warnings.ca.gov/
passenger-vehicle.
See California Proposition 65 Warning 0322
and the back cover.
{Warning
Batteries can hurt you. They can be
dangerous because:
.They contain acid that can burn you.
.They contain gas that can explode or
ignite.
.They contain enough electricity to
burn you.
If you do not follow these steps exactly,
some or all of these things can hurt you.
Caution
Ignoring these steps could result in costly
damage to the vehicle that would not be
covered by the vehicle warranty. Trying
(Continued)

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
392 Vehicle Care
Caution (Continued)
to start the vehicle by pushing or pulling
it will not work, and it could damage the
vehicle.
1. Good Battery Positive Terminal
2. Good Battery Negative Terminal
3. Discharged Battery Remote NegativeTerminal
4. Discharged Battery Remote Positive Terminal
The jump start positive post (1) and negative
post (2) are on the battery of the vehicle
providing the jump start. The jump start positive post (4) and the
negative grounding point (3) for the
discharged battery are on the passenger side
of the vehicle.
The positive jump start connection for the
discharged battery is under a cover. Slide
the cover to expose the terminal.
1. Check the other vehicle. It must have a 12-volt battery with a negative ground
system.
Caution
If the other vehicle does not have a
12-volt system with a negative ground,
both vehicles can be damaged. Only use
a vehicle that has a 12-volt system with a
negative ground for jump starting.
2. If you have a vehicle with a diesel engine with two batteries, you should
know before you begin that, especially in
cold weather, you may not be able to
get enough power from a single battery
in another vehicle to start your diesel
engine. If your vehicle has more than
one battery, using the battery that is
closer to the starter will reduce electrical resistance. This is located on the
passenger side, in the rear of the engine
compartment.
3. Get the vehicles close enough so the jumper cables can reach, but be sure the
vehicles are not touching each other.
If they are, it could cause an unwanted
ground connection. You would not be
able to start your vehicle, and the bad
grounding could damage the electrical
systems.
To avoid the possibility of the vehicles
rolling, set the parking brake firmly on
both vehicles involved in the jump start
procedure. Put the automatic
transmission in P (Park) before setting
the parking brake. If you have a
four-wheel-drive vehicle, be sure the
transfer case is in a drive gear, not in
N (Neutral).
Caution
If any accessories are left on or plugged
in during the jump starting procedure,
they could be damaged. The repairs
would not be covered by the vehicle
warranty. Whenever possible, turn off or
unplug all accessories on either vehicle
when jump starting.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 393
4. Turn the ignition off on both vehicles.Unplug unnecessary accessories plugged
into the accessory power outlets. Turn
off the radio and all the lamps that are
not needed. This will avoid sparks and
help save both batteries. And it could
save the radio!
5. Open the hood on the other vehicle and locate the positive (+) and negative (−)
terminal locations on that vehicle.
The positive (+) terminal is under a red
plastic cover at the positive battery post.
To uncover the positive (+) terminal,
open the red plastic cover.
For more information on the location of
the remote positive (+) and remote
negative (−) terminals, see Engine
Compartment Overview 0325.
{Warning
An electric fan can start up even when
the engine is not running and can injure
you. Keep hands, clothing, and tools
away from any underhood electric fan.
{Warning
Using a match near a battery can cause
battery gas to explode. People have been
hurt doing this, and some have been
blinded. Use a flashlight if you need
more light.
Battery fluid contains acid that can burn
you. Do not get it on you. If you
accidentally get it in your eyes or on
your skin, flush the place with water and
get medical help immediately.
{Warning
Fans or other moving engine parts can
injure you badly. Keep your hands away
from moving parts once the engine is
running.
6. Check that the jumper cables do not have loose or missing insulation. If they
do, you could get a shock. The vehicles
could be damaged too.
Before you connect the cables, here are
some basic things you should know.
Positive (+) will go to positive (+) or to a
remote positive (+) terminal if the vehicle has one. Negative (−) will go to a
heavy, unpainted metal engine part or to
a remote negative (−) terminal if the
vehicle has one.
Do not connect positive (+) to negative
(−) or you will get a short that would
damage the battery and maybe other
parts too. And do not connect the
negative (−) cable to the negative (−)
terminal on the dead battery because
this can cause sparks.
7. Connect one end of the red positive (+) cable to the remote positive (+) terminal
of the vehicle with the discharged
battery.
8. Do not let the other end touch metal. Connect it to the positive (+) terminal of
the good battery. Use a remote
positive (+) terminal if the vehicle
has one.
9. Connect one end of the black negative (−) cable to the negative (−) terminal of
the good battery. Use a remote negative
(−) terminal if the vehicle has one.
Do not let the other end touch anything
until the next step.
10. Connect the other end of the negative (−) cable to the remote negative (−)
terminal to the discharged battery.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
394 Vehicle Care
11. Start the vehicle with the good batteryand run the engine for a while.
12. Try to start the vehicle that had the dead battery. If it will not start after a
few tries, it probably needs service.
Caution
If the jumper cables are connected or
removed in the wrong order, electrical
shorting may occur and damage the
vehicle. The repairs would not be covered
by the vehicle warranty. Always connect
and remove the jumper cables in the
correct order, making sure that the cables
do not touch each other or other metal.
Jumper Cable Removal
Reverse the sequence exactly when
removing the jumper cables.
After starting the disabled vehicle and
removing the jumper cables, allow it to idle
for several minutes.
Towing the Vehicle
Caution
Incorrectly towing a disabled vehicle may
cause damage. The damage would not be
covered by the vehicle warranty. Do not
lash or hook to suspension components.
Use the proper straps around the tires to
secure the vehicle. Do not drag a locked
wheel/tire. Use tire skates or dollies
under any locked wheel/tire while
loading the vehicle. Do not use a sling
type lift to tow the vehicle. This could
damage the vehicle.
Caution
Improper use of the tow eye can damage
the vehicle. If equipped, use the tow eye
to load a disabled vehicle onto a flatbed
tow truck from a flat road surface, or to
move the vehicle a short distance. Use
caution and low speeds. The transmission
must be in (N) Neutral when moving the
vehicle. GM recommends a flatbed tow truck to
transport a disabled vehicle. Use ramps to
help reduce approach angles, if necessary.
A towed vehicle should have its drive wheels
off the ground. Contact Roadside Assistance
or a professional towing service if the
disabled vehicle must be towed.
Front Attachment Points
The vehicle is equipped with specific
attachment points to be used to pull the
vehicle onto a flatbed car carrier from a flat
road surface. Do not use these attachment
points to pull the vehicle from snow, mud
or sand.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 395
Recreational Vehicle Towing
Recreational vehicle towing means towing
the vehicle behind another vehicle, such as a
motor home. The two most common types
of recreational vehicle towing are dinghy
and dolly towing. Dinghy towing is towing
the vehicle with all four wheels on the
ground. Dolly towing is towing the vehicle
with two wheels on the ground and two
wheels on a dolly.
Here are some important things to consider
before recreational vehicle towing:
.Before towing the vehicle, become
familiar with the local laws that apply to
recreational vehicle towing. These laws
may vary by region.
.The towing capacity of the towing
vehicle. Read the tow vehicle
manufacturer's recommendations.
.How far the vehicle can be towed. Some
vehicles have restrictions on how far and
how long the vehicle can be towed.
.Whether the vehicle has the proper
towing equipment. See your dealer or
trailering professional for additional
advice and equipment recommendations.
.Whether the vehicle is ready to be towed.
Just as preparing the vehicle for a long
trip, make sure the vehicle is prepared to
be towed.
Follow the tow vehicle manufacturer’s
instructions. See your dealer or trailering
professional for additional advice and
equipment recommendations.
Caution
Use of a shield mounted in front of the
vehicle grille could restrict airflow and
cause damage to the transmission. The
repairs would not be covered by the
vehicle warranty. If using a shield, only
use one that attaches to the towing
vehicle.
Dinghy Towing (Two-Wheel-Drive
Vehicles and Vehicles with a
Single-Speed Transfer Case)
Caution
If a vehicle with two-wheel drive or a
single-speed transfer case is towed with
all four wheels on the ground, the
drivetrain components could be damaged.
The repairs would not be covered by the
vehicle warranty.
Two-wheel-drive vehicles and vehicles with a
single-speed transfer case should not be
towed with all four wheels on the ground.

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
398 Vehicle Care
Caution
Do not tow this vehicle with two wheels
on the ground, or vehicle damage could
occur. This damage would not be covered
by the vehicle warranty.
Dolly towing this vehicle is not allowed with
either the front or the rear tires on the
ground for two-wheel drive or four-wheel
drive, regardless of transfer case.
Appearance Care
Exterior Care
Locks
Locks are lubricated at the factory. Use a
de-icing agent only when absolutely
necessary, and have the locks greased after
using. See Recommended Fluids and
Lubricants 0418.
Washing the Vehicle
To preserve the vehicle's finish, wash it
often and out of direct sunlight.
{Warning
Do not power wash any part of the
vehicle’s interior, including the vinyl floor
covering. This could damage safety and
other systems in the vehicle, which
would not be covered by the vehicle
warranty.
Caution
Do not use petroleum-based, acidic,
or abrasive cleaning agents as they can
damage the vehicle's paint, metal,
or plastic parts. If damage occurs, it
would not be covered by the vehicle
warranty. Approved cleaning products can
be obtained from your dealer. Follow all
manufacturer directions regarding correct
product usage, necessary safety
precautions, and appropriate disposal of
any vehicle care product.
Caution
Avoid using high-pressure washes closer
than 30 cm (12 in) to the surface of the
vehicle. Use of power washers exceeding
8 274 kPa (1,200 psi) can result in
damage or removal of paint and decals.
Cleaning Underhood Components
Caution
Do not power wash any component
under the hood that has this
e
symbol.
This could cause damage that would not
be covered by the vehicle warranty.
Solvents or aggressive cleaners may harm
underhood components. The usages of these
chemicals should be avoided.
Recommend water only.
A pressure washer may be used, but care
must be utilized. The following criteria must
be followed:
.Water pressure must be kept below
14 000 KPa (2,000 PSI).
.Water temperature must be below 80 °C
(180 °F).

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 399
.Spray nozzle with a 40 degree wide angle
spray pattern or wider must be used.
.Nozzle must be kept at least 30 cm (1 ft)
away from all surfaces.
Automatic Car Wash
Caution
Some automatic car washes can cause
damage to the vehicle, wheels and
ground effects. Automatic car washes are
not recommended, due to lack of
clearance for the undercarriage and/or
wide rear tires and wheels.
Caution
Automatic car washes can cause damage
to the vehicle, wheels, ground effects,
and convertible top (if equipped).
Do not use automatic car washes due to
lack of clearance for the undercarriage,
wide rear tires, and wheels.
If using an automatic car wash, follow with
the car wash instructions. The windshield
wiper and rear window wiper, if equipped, must be turned off. Remove any accessories
that may be damaged or interfere with the
car wash equipment.
See
Power Assist Steps 030 for cleaning
information.
Rinse the vehicle well, before washing and
after, to remove all cleaning agents
completely. If they are allowed to dry on
the surface, they could stain.
Dry the finish with a soft, clean chamois or
an all-cotton towel to avoid surface
scratches and water spotting.
Finish Care
Application of aftermarket clearcoat sealant/
wax materials is not recommended.
If painted surfaces are damaged, see your
dealer to have the damage assessed and
repaired. Foreign materials such as calcium
chloride and other salts, ice melting agents,
road oil and tar, tree sap, bird droppings,
chemicals from industrial chimneys, etc., can
damage the vehicle's finish if they remain
on painted surfaces. Wash the vehicle as
soon as possible. If necessary, use
non-abrasive cleaners that are marked safe
for painted surfaces to remove foreign
matter. Occasional hand waxing or mild polishing
should be done to remove residue from the
paint finish. See your dealer for approved
cleaning products.
Do not apply waxes or polishes to uncoated
plastic, vinyl, rubber, decals, simulated
wood, or flat paint as damage can occur.
Caution
Machine compounding or aggressive
polishing on a basecoat/clearcoat paint
finish may damage it. Use only
non-abrasive waxes and polishes that are
made for a basecoat/clearcoat paint finish
on the vehicle.
To keep the paint finish looking new, keep
the vehicle garaged or covered whenever
possible.
Protecting Exterior Bright Metal Moldings
Caution
Failure to clean and protect the bright
metal moldings can result in a hazy
white finish or pitting. This damage
would not be covered by the vehicle
warranty.