2021 GMC SIERRA Owner's Manual

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
400 Vehicle Care
The bright metal moldings on the vehicle
are aluminum, chrome or stainless steel. To
prevent damage always follow these
cleaning instructions:
.Be sure the molding is cool to the touch
before applying any cleaning solution.
.Use only approved cleaning solutions for
aluminum, chrome or stainless steel.
Some cleaners are highly acidic or contain
alkaline substances and can damage the
moldings.
.Always dilute a concentrated cleaner
according to the manufacturer’s
instructions.
.Do not use cleaners that are not intended
for automotive use.
.Use a nonabrasive wax on the vehicle
after washing to protect and extend the
molding finish.
Spray-In Bedliner Care
Caution
Using silicone-based products may
damage the bedliner, reduce the
slip-resistant texture, and attract dirt. A spray-in bedliner is a permanent coating
that bonds to the truck bed and cannot be
removed. Promptly rinse the bedliner surface
following a chemical spill to avoid
permanent damage.
Spray-in bedliners can fade from oxidation,
road dirt, heavy-duty hauling, and hard
water stains. Clean it periodically by
washing off the loose dirt and using a mild
detergent. To restore the original
appearance, apply the bedliner conditioner
available through your dealer.
CarbonPro Box Care
Caution
To prevent surface damage to the pickup
box, rinse chemical spills quickly, never
use alcohol wipes to clean, and avoid
scraping the surface.
If equipped with a CarbonPro Pickup Box,
use the following instructions for cleaning:
.Clean the box periodically by washing off
the loose dirt with water and a mild
detergent.
.Promptly rinse the bed surface following
a chemical spill to avoid permanent
damage.
.Use a dry rag to remove oil.
Cleaning Exterior Lamps/Lenses,
Emblems, Decals and Stripes
Use only lukewarm or cold water, a soft
cloth, and a car washing soap to clean
exterior lamps, lenses, emblems, decals and
stripes. Follow instructions under "Washing
the Vehicle" previously in this section.
Lamp covers are made of plastic, and some
have a UV protective coating. Do not clean
or wipe them while they are dry.
Do not use any of the following on lamp
covers:
.Abrasive or caustic agents.
.Washer fluids and other cleaning agents
in higher concentrations than suggested
by the manufacturer.
.Solvents, alcohols, fuels, or other harsh
cleaners.
.Ice scrapers or other hard items.
.Aftermarket appearance caps or covers
while the lamps are illuminated, due to
excessive heat generated.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 401
Caution
Failure to clean lamps properly can cause
damage to the lamp cover that would
not be covered by the vehicle warranty.
Caution
Using wax on low gloss black finish
stripes can increase the gloss level and
create a non-uniform finish. Clean low
gloss stripes with soap and water only.
Air Intakes
Clear debris from the air intakes, between
the hood and windshield, when washing the
vehicle.
Shutter System
The vehicle may have a shutter system
designed to help improve fuel economy.
Keep the shutter system clear of debris,
snow and ice. If the check engine light is
activated, please check to see if the shutter
system is clear of debris, snow or ice.
Windshield and Wiper Blades
Clean the outside of the windshield with
glass cleaner.
Clean rubber blades using a lint-free cloth or
paper towel soaked with windshield washer
fluid or a mild detergent. Wash the
windshield thoroughly when cleaning theblades. Bugs, road grime, sap, and a buildup
of vehicle wash/wax treatments may cause
wiper streaking.
Replace the wiper blades if they are worn or
damaged. Damage can be caused by
extreme dusty conditions, sand, salt, heat,
sun, snow, and ice.
Weatherstrips
Apply weatherstrip lubricant on
weatherstrips to make them last longer, seal
better, and not stick or squeak. Lubricate
weatherstrips once a year. Hot, dry climates
may require more frequent application. Black
marks from rubber material on painted
surfaces can be removed by rubbing with a
clean cloth. See
Recommended Fluids and
Lubricants 0418.
Tires
Use a stiff brush with tire cleaner to clean
the tires.
Caution
Using petroleum-based tire dressing
products on the vehicle may damage the
paint finish and/or tires. When applying a
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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,
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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
Vehicle Care 403
and contaminate the fluid. Contaminated
fluid will decrease the life of the transfer
case and/or axles and should be replaced.
Sheet Metal Damage
If the vehicle is damaged and requires sheet
metal repair or replacement, make sure the
body repair shop applies anti-corrosion
material to parts repaired or replaced to
restore corrosion protection.
Original manufacturer replacement parts will
provide the corrosion protection while
maintaining the vehicle warranty.
Finish Damage
Quickly repair minor chips and scratches
with touch-up materials available from your
dealer to avoid corrosion. Larger areas of
finish damage can be corrected in your
dealer's body and paint shop.
Chemical Paint Spotting
Airborne pollutants can fall upon and attack
painted vehicle surfaces causing blotchy,
ring-shaped discolorations, and small,
irregular dark spots etched into the paint
surface. Refer to“Finish Care”previously in
this section.
Interior Care
To prevent dirt particle abrasions, regularly
clean the vehicle's interior. Immediately
remove any soils. Newspapers or dark
garments can transfer color to the vehicle’s
interior.
Use a soft bristle brush to remove dust from
knobs and crevices on the instrument
cluster. Using a mild soap solution,
immediately remove hand lotions,
sunscreen, and insect repellent from all
interior surfaces or permanent damage may
result.
Use cleaners specifically designed for the
surfaces being cleaned to prevent
permanent damage. Apply cleaners directly
to the cleaning cloth. Do not spray cleaners
on any switches or controls. Remove
cleaners quickly.
Before using cleaners, read and follow all
safety instructions on the label. While
cleaning the interior, open the doors and
windows to get proper ventilation. To prevent damage, do not clean the
interior using the following cleaners or
techniques:
.Never use a razor or any other sharp
object to remove soil from any interior
surface.
.Never use a brush with stiff bristles.
.Never rub any surface aggressively or
with too much pressure.
.Do not use laundry detergents or
dishwashing soaps with degreasers. For
liquid cleaners, use approximately
20 drops per 3.8 L (1 gal) of water.
A concentrated soap solution will create
streaks and attract dirt. Do not use
solutions that contain strong or
caustic soap.
.Do not heavily saturate the upholstery
when cleaning.
.Do not use solvents or cleaners containing
solvents.
Interior Glass
To clean, use a terry cloth fabric dampened
with water. Wipe droplets left behind with a
clean dry cloth. If necessary, use a
commercial glass cleaner after cleaning with
plain water.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
404 Vehicle Care
Caution
To prevent scratching, never use abrasive
cleaners on automotive glass. Abrasive
cleaners or aggressive cleaning may
damage the rear window defogger.
Cleaning the windshield with water during
the first three to six months of ownership
will reduce tendency to fog.
Speaker Covers
Vacuum around a speaker cover gently, so
that the speaker will not be damaged. Clean
spots with water and mild soap.
Coated Moldings
Coated moldings should be cleaned.
.When lightly soiled, wipe with a sponge
or soft, lint-free cloth dampened with
water.
.When heavily soiled, use warm soapy
water.
Fabric/Carpet/Suede
Start by vacuuming the surface using a soft
brush attachment. If a rotating vacuum
brush attachment is being used, only use it
on the floor carpet. Before cleaning, gently
remove as much of the soil as possible:
.Gently blot liquids with a paper towel.
Continue blotting until no more soil can
be removed.
.For solid soils, remove as much as
possible prior to vacuuming.
To clean: 1. Saturate a clean, lint-free colorfast cloth with water. Microfiber cloth is
recommended to prevent lint transfer to
the fabric or carpet.
2. Remove excess moisture by gently wringing until water does not drip from
the cleaning cloth.
3. Start on the outside edge of the soil and gently rub toward the center. Fold the
cleaning cloth to a clean area frequently
to prevent forcing the soil in to the
fabric.
4. Continue gently rubbing the soiled area until there is no longer any color
transfer from the soil to the cleaning
cloth. 5. If the soil is not completely removed,
use a mild soap solution followed only
by plain water.
If the soil is not completely removed, it may
be necessary to use a commercial upholstery
cleaner or spot lifter. Test a small hidden
area for colorfastness before using a
commercial upholstery cleaner or spot lifter.
If ring formation occurs, clean the entire
fabric or carpet.
After cleaning use a paper towel to blot
excess moisture.
Cleaning High Gloss Surfaces and Vehicle
Information and Radio Displays
Use a microfiber cloth on high gloss surfaces
or vehicle displays. First, use a soft bristle
brush to remove dirt that can scratch the
surface. Then gently clean by rubbing with a
microfiber cloth. Never use window cleaners
or solvents. Periodically hand wash the
microfiber cloth separately, using mild soap.
Do not use bleach or fabric softener. Rinse
thoroughly and air dry before next use.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 405
Caution
Do not attach a device with a suction cup
to the display. This may cause damage
and would not be covered by the vehicle
warranty.
Instrument Panel, Leather, Vinyl, Other
Plastic Surfaces, Low Gloss Paint Surfaces
and Natural Open Pore Wood Surfaces
Use a soft microfiber cloth dampened with
water to remove dust and loose dirt. For a
more thorough cleaning, use a soft
microfiber cloth dampened with a mild soap
solution.
Caution
Soaking or saturating leather, especially
perforated leather, as well as other
interior surfaces, may cause permanent
damage. Wipe excess moisture from
these surfaces after cleaning and allow
them to dry naturally. Never use heat,
steam, or spot removers. Do not use
cleaners that contain silicone or
wax-based products. Cleaners containing
(Continued)
Caution (Continued)
these solvents can permanently change
the appearance and feel of leather or soft
trim, and are not recommended.
Do not use cleaners that increase gloss,
especially on the instrument panel. Reflected
glare can decrease visibility through the
windshield under certain conditions.
Caution
Use of air fresheners may cause
permanent damage to plastics and
painted surfaces. If an air freshener
comes in contact with any plastic or
painted surface in the vehicle, blot
immediately and clean with a soft cloth
dampened with a mild soap solution.
Damage caused by air fresheners would
not be covered by the vehicle warranty.
Care of Seat Belts
Keep belts clean and dry.
{Warning
Do not bleach or dye seat belt webbing.
It may severely weaken the webbing. In
a crash, they might not be able to
provide adequate protection. Clean and
rinse seat belt webbing only with mild
soap and lukewarm water. Allow the
webbing to dry.
Floor Mats
{Warning
If a floor mat, a liner, or a liner insert is
the wrong size or is not properly
installed, it can interfere with the pedals.
Interference with the pedals can cause
unintended acceleration and/or increased
stopping distance, which can cause a
crash and injury. Make sure the floor
mat, liner, or liner insert does not
interfere with the pedals.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
406 Vehicle Care
Use the following guidelines for proper floor
mat/liner usage:
.The original equipment floor mats/liners
were designed for your vehicle. If the
floor mats/liners need replacing, it is
recommended that GM certified floor
mats/liners be purchased. Non-GM floor
mats/liners may not fit properly and may
interfere with the pedals. Always check
that the floor mat, liner, or liner insert
does not interfere with the pedals.
.Do not use a floor mat/liner if the vehicle
is not equipped with a floor mat retainer
on the driver side floor.
.Use the floor mat/liner insert with the
correct side up. Do not turn it over.
.Do not place anything on top of the
driver side floor mat/liner.
.Use only a single floor mat/liner on the
driver side.
.Do not place one floor mat/liner on top
of another.
Removing and Replacing the Floor Mats/
Liners
Pull up on the rear of the driver side floor
mat/liner to unlock each retainer and
remove.
Reinstall by lining up the floor mat/liner
retainer openings over the carpet retainers
and snapping into position.
Make sure the floor mat/liner is properly
secured in place.
Verify the floor mat/liner does not interfere
with the pedals.
Removing and Replacing the Floor Liner
Inserts
Pull up on the edge of the driver side floor
liner insert to unlock each button clip and
remove.
Reinstall by lining up the floor liner insert
button clips over the liner retainers and
snapping into position.
Make sure the floor liner insert is properly
secure in place using all button clips.
Verify the floor liner insert does not
interfere with the pedals.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 407
Cleaning Rubber Floor Mats (All-Weather
Mats and Floor Liners)
{Warning
Do not use cleaners that contain silicone,
wax-based products, or cleaners that
increase gloss on rubber floor mats/liners.
These cleaners can permanently change
the appearance and feel of the rubber
and can make the floor mats/liners
slippery. Your foot could slip while
operating the vehicle, and you could lose
control, resulting in a crash. You or
others could be injured.
Use a soft cloth and/or a brush dampened
with water to remove dust and loose dirt.
For more thorough cleaning, use a mild soap
solution.