2021 GMC SIERRA transmission

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
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
414 Service and Maintenance
Maintenance Schedule Additional
Required Services - Severe12 000 km/7,500 mi
24 000 km/15,000 mi
36 000 km/22,500 mi
48 000 km/30,000 mi 60 000 km/37,500 mi
72 000 km/45,000 mi84 000 km/52,500 mi
96 000 km/60,000 mi
108 000 km/67,500 mi 120 000 km/75,000 mi 132 000 km/82,500 mi
144 000 km/90,000 mi 156 000 km/97,500 mi
168 000 km/105,000 mi 180 000 km/112,500 mi
192 000 km/120,000 mi 204 000 km/127,500 mi 216 000 km/135,000 mi
228 000 km/142,500 mi
240 000 km/150,000 mi
Rotate tires and perform Required Services. Check engine oil
level and oil life percentage. Change engine oil and filter,
if needed.
Check engine air filter life percentage and status. Change
engine air filter, if needed. (1)
@ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @
Replace passenger compartment air filter. (2)@ @@@@@
Inspect evaporative control system. (3)@ @@
Replace spark plugs. Inspect spark plug wires and/or boots.
(Except 2.7L L4 Turbo Engine)@
Replace spark plugs. Inspect spark plug wires and/or boots.
(2.7L L4 Turbo Engine Only)@ @
Change automatic transmission fluid and filter.@@@
Change transfer case fluid, if equipped with 4WD. (4)@@@
Drain and fill engine cooling system. (5)@
Visually inspect accessory drive belts. (6)@
Replace brake fluid. (7)
Replace windshield wiper blades. (8)
@ @ @ @ @ @ @ @ @ @
Replace hood gas struts and tailgate dampener. (9)@ @
Replace air conditioning desiccant. (10)

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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418 Service and Maintenance
Recommended Fluids, Lubricants, and Parts
Recommended Fluids and Lubricants
This maintenance section applies to vehicles with a gasoline engine. If the vehicle has a diesel engine, see“Recommended Fluids and Lubricants”
in the Duramax diesel supplement.
Fluids and lubricants identified below by name or specification, including fluids or lubricants not listed here, can be obtained from your dealer.
Usage Fluid/Lubricant
Automatic Transmission (6-Speed Transmission) DEXRON-VI Automatic Transmission Fluid.
Automatic Transmission (8-Speed Transmission) DEXRON-HP Automatic Transmission Fluid.
Automatic Transmission (10-Speed Transmission) DEXRON ULV Automatic Transmission Fluid.
Chassis Lubrication Chassis lubricant meeting requirements of NLGI #2, Category LB or GC-LB. Engine Coolant 50/50 mixture of clean, drinkable water and use only DEX-COOL coolant. See Cooling System
0 335.
Engine Oil Engine oil meeting the dexos1 specification of the proper SAE viscosity grade. ACDelco dexos1 full synthetic is recommended. See Engine Oil0330.
Front and Rear Axle Driveshaft Splines See your dealer.
Front Axle (Four-Wheel Drive) and Rear Axle See your dealer. Hydraulic Brake System DOT 4 Hydraulic Brake Fluid. See Brake Fluid0343.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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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./
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Customer Information 435
coverage is not available from your current
insurance carrier, consider switching to
another insurance carrier.
If the vehicle is leased, the leasing company
may require you to have insurance that
ensures repairs with Genuine GM Original
Equipment Manufacturer (OEM) parts or
Genuine Manufacturer replacement parts.
Read the lease carefully, as you may be
charged at the end of the lease for poor
quality repairs.
If a Crash Occurs
If there has been an injury, call emergency
services for help. Do not leave the scene of
a crash until all matters have been taken
care of. Move the vehicle only if its position
puts you in danger, or you are instructed to
move it by a police officer.
Give only the necessary information to
police and other parties involved in the
crash.
For emergency towing seeRoadside
Assistance Program 0431.
Gather the following information:
.Driver name, address, and telephone
number
.Driver license number
.Owner name, address, and telephone
number
.Vehicle license plate number
.Vehicle make, model, and model year
.Vehicle Identification Number (VIN)
.Insurance company and policy number
.General description of the damage to the
other vehicle
Choose a reputable repair facility that uses
quality replacement parts. See “Collision
Parts” earlier in this section.
If the airbag has inflated, see What Will You
See after an Airbag Inflates? 065.
Managing the Vehicle Damage Repair
Process
In the event that the vehicle requires
damage repairs, GM recommends that you
take an active role in its repair. If you have
a pre-determined repair facility of choice,
take the vehicle there, or have it towed
there. Specify to the facility that any
required replacement collision parts be
original equipment parts, either new
Genuine GM parts or recycled original GM
parts. Remember, recycled parts will not be
covered by the GM vehicle warranty. Insurance pays the bill for the repair, but
you must live with the repair. Depending on
your policy limits, your insurance company
may initially value the repair using
aftermarket parts. Discuss this with the
repair professional, and insist on Genuine
GM parts. Remember, if the vehicle is
leased, you may be obligated to have the
vehicle repaired with Genuine GM parts,
even if your insurance coverage does not
pay the full cost.
If another party's insurance company is
paying for the repairs, you are not obligated
to accept a repair valuation based on that
insurance company's collision policy repair
limits, as you have no contractual limits
with that company. In such cases, you can
have control of the repair and parts choices
as long as the cost stays within reasonable
limits.
Publication Ordering Information
Service Manuals
Service manuals have the diagnosis and
repair information on the engine,
transmission, axle, suspension, brakes,
electrical system, steering system, body, etc.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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Customer Information 437
Administrator, NHTSA
1200 New Jersey Avenue, S.E.
Washington, D.C. 20590
You can also obtain other information
about motor vehicle safety from
http://www.safercar.gov
.
Reporting Safety Defects to the
Canadian Government
If you live in Canada, and you believe
that the vehicle has a safety defect,
notify Transport Canada immediately,
and notify General Motors of Canada
Company. Call Transport Canada at
1-800-333-0510; go to:
www.tc.gc.ca/recalls (English)
www.tc.gc.ca/rappels (French)
or write to:
Transport Canada
Motor Vehicle Safety Directorate
Defect Investigations and Recalls
Division
80 Noel Street
Gatineau
,QC J8Z 0A1
Reporting Safety Defects to
General Motors
In addition to notifying NHTSA (or Transport
Canada) in a situation like this, notify
General Motors.
In the U.S., call 1-800-462-8782, or write:
GMC Customer Assistance Center
P.O. Box 33172
Detroit, MI 48232-5172
In Canada, call 1-800-263-3777 (English) or
1-800-263-7854 (French), or write:
General Motors of Canada Company
Customer Care Centre, Mail Code:
CA1-163-005
1908 Colonel Sam Drive
Oshawa, Ontario L1H 8P7
In Mexico, call 800-466-0812 or
800-466-0801.
In other Central America and Caribbean
Countries, call 52-555-901-2369.
Vehicle Data Recording and
Privacy
The vehicle has a number of computers that
record information about the vehicle’s
performance and how it is driven or used.
For example, the vehicle uses computer
modules to monitor and control engine and
transmission performance, to monitor the
conditions for airbag deployment and
deploy them in a crash, and, if equipped, to
provide antilock braking to help the driver
control the vehicle. These modules may
store data to help the dealer technician
service the vehicle or to help GM improve
safety or features. Some modules may also
store data about how the vehicle is
operated, such as rate of fuel consumption
or average speed. These modules may retain
personal preferences, such as radio presets,
seat positions, and temperature settings.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
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444 OnStar
identify whether updates or changes are
available, or deliver updates or changes. An
active OnStar agreement constitutes consent
to these software updates or changes and
agreement that either OnStar or GM may
remotely deliver them to the vehicle.
Privacy
The complete OnStar Privacy Statement may
be found at www.onstar.com (U.S.),
or www.onstar.ca (Canada). We recommend
that you review it. If you have any
questions, call 1-888-4ONSTAR
(1-888-466-7827) or press
Qto speak with
an Advisor. Users of wireless
communications are cautioned that the
privacy of any information sent via wireless
cellular communications cannot be assured.
Third parties may unlawfully intercept or
access transmissions and private
communications without consent.
OnStar - Software Acknowledgements
To obtain the source code under GPL, LGPL,
MPL, and other open source licenses, that is
contained in this product, please visit
http://opensource.lge.com. In addition to
the source code, all referred license terms,
warranty disclaimers, and copyright notices
are available for download. This offer is valid
for a period of three years after our last
shipment of this product. This offer is valid
to anyone in receipt of this information.
*Provided through LG Electronics Inc., who is
solely responsible for provisions of related
OSS compliance.