2021 GMC SIERRA engine

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
340 Vehicle Care
If there is still no sign of steam and the
vehicle is equipped with an engine driven
cooling fan, push down the accelerator until
the engine speed is about twice as fast as
normal idle speed for at least five minutes
while the vehicle is parked. If the warning is
still there, turn off the engine and get
everyone out of the vehicle until it
cools down.
If there is no sign of steam, idle the engine
for five minutes while parked. If the warning
is still displayed, turn off the engine until it
cools down.
Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and
the ENGINE POWER IS REDUCED message
displays, an overheat protection mode which
alternates firing groups of cylinders helps to
prevent engine damage. In this mode, a loss
in power and engine performance will be
noticed. This operating mode allows the
vehicle to be driven to a safe place in an
emergency. Driving extended distances and/
or towing a trailer in the overheat
protection mode should be avoided.If the engine or transmission detects an
impending hot fluid condition, then the
transmission may force upshifts to limit
temperatures. Downshifts may also be
prevented in this instance. Normal operation
may continue unless the display indicates
there is a hot condition and engine should
be idled.
Caution
After driving in the overheated engine
protection operating mode, the engine oil
will be severely degraded. Any repairs
performed before the engine is cool may
cause engine damage. Allow the engine
to cool before attempting any repair.
Repair the cause of coolant loss, change
the oil, and reset the oil life system. See
Engine Oil
0330.
Engine Fan
If the vehicle has the Duramax diesel
engine, see the Duramax diesel supplement.
The vehicle has electric cooling fan(s). The
fans may be heard spinning at low speed
during most everyday driving. The fans may
turn off if no cooling is required. Under
heavy vehicle loading, trailer towing, high outside temperatures, or operation of the air
conditioning system, the fans may change
to high speed and an increase in fan noise
may be heard. This is normal and indicates
that the cooling system is functioning
properly. The fans will change to low speed
when additional cooling is no longer
required.
The electric engine cooling fans may run
after the engine has been turned off. This is
normal and no service is required.
Washer Fluid
What to Use
When windshield washer fluid needs to be
added, be sure to read the manufacturer's
instructions before use. Use a fluid that has
sufficient protection against freezing in an
area where the temperature may fall below
freezing.
Adding Washer Fluid
The vehicle has a low washer fluid message
on the DIC that comes on when the washer
fluid is low. The message is displayed for
15 seconds at the start of each ignition cycle.
When the WASHER FLUID LOW ADD FLUID

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 341
message displays, washer fluid will need to
be added to the windshield washer fluid
reservoir.
Open the cap with the washer symbol on it.
Add washer fluid until the tank is full. See
Engine Compartment Overview0325 for
reservoir location.
Caution
.Do not use washer fluid that contains
any type of water repellent coating.
This can cause the wiper blades to
chatter or skip.
.Do not use engine coolant (antifreeze)
in the windshield washer. It can
damage the windshield washer system
and paint.
(Continued)
Caution (Continued)
.Do not mix water with ready-to-use
washer fluid. Water can cause the
solution to freeze and damage the
washer fluid tank and other parts of
the washer system.
.When using concentrated washer fluid,
follow the manufacturer instructions
for adding water.
.Fill the washer fluid tank only
three-quarters full when it is very cold.
This allows for fluid expansion if
freezing occurs, which could damage
the tank if it is completely full.
Brakes
Disc brake linings have built-in wear
indicators that make a high-pitched warning
sound when the brake linings are worn and
new linings are needed. The sound can come
and go or can be heard all the time when
the vehicle is moving, except when applying
the brake pedal firmly.
{Warning
The brake wear warning sound means
that soon the brakes will not work well.
That could lead to a crash. When the
brake wear warning sound is heard, have
the vehicle serviced.
Caution
Continuing to drive with worn-out brake
linings could result in costly brake
repairs.
Some driving conditions or climates can
cause a brake squeal when the brakes are
first applied, clearing up following several
applications. This does not mean something
is wrong with the brakes.
Properly torqued wheel nuts are necessary
to help prevent brake pulsation. When tires
are rotated, inspect brake linings for wear
and evenly tighten wheel nuts in the proper
sequence to torque specifications. See
Capacities and Specifications 0424.
Brake pads should be replaced as complete
axle sets.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 343
Brake Fluid
The brake master cylinder reservoir is filled
with GM approved DOT 4 brake fluid as
indicated on the reservoir cap. SeeEngine
Compartment Overview 0325 for the
location of the reservoir.
Checking Brake Fluid
With the vehicle in P (Park) on a level
surface, the brake fluid level should be
between the minimum and maximum marks
on the brake fluid reservoir.
There are only two reasons why the brake
fluid level in the reservoir may go down:
.Normal brake lining wear. When new
linings are installed, the fluid level goes
back up.
.A fluid leak in the brake hydraulic system.
Have the brake hydraulic system fixed.
With a leak, the brakes will not
work well. Always clean the brake fluid reservoir cap
and the area around the cap before
removing it.
Do not top off the brake fluid. Adding fluid
does not correct a leak. If fluid is added
when the linings are worn, there will be too
much fluid when new brake linings are
installed. Add or remove fluid, as necessary,
only when work is done on the brake
hydraulic system.
{Warning
If too much brake fluid is added, it can
spill on the engine and burn, if the
engine is hot enough. You or others could
be burned, and the vehicle could be
damaged. Add brake fluid only when
work is done on the brake hydraulic
system.
When the brake fluid falls to a low level,
the brake warning light comes on. See Brake
System Warning Light 0117.
Brake fluid absorbs water over time which
degrades the effectiveness of the brake fluid.
Replace brake fluid at the specified intervals
to prevent increased stopping distance. See
Maintenance Schedule 0409. What to Add
Use only GM approved DOT 4 brake fluid
from a clean, sealed container. See
Recommended Fluids and Lubricants
0418.
{Warning
The wrong or contaminated brake fluid
could result in damage to the brake
system. This could result in the loss of
braking leading to a possible injury.
Always use the proper GM approved
brake fluid.
Caution
If brake fluid is spilled on the vehicle's
painted surfaces, the paint finish can be
damaged. Immediately wash off any
painted surface.
Battery - North America
The original equipment battery is
maintenance free. Do not remove the cap
and do not add fluid.
Refer to the replacement number shown on
the original battery label when a new
battery is needed. See Engine Compartment
Overview 0325 for battery location.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
344 Vehicle Care
Stop/Start System
Vehicles equipped with a 2.7L L3B, 3.0L LM2,
5.3L L84 or 6.2L L87 are equipped with a
Stop/Start system to shut off the engine to
help conserve fuel. SeeStop/Start System
0 233.
Vehicles with the Stop/Start system have an
Absorbed Glass Mat (AGM) 12-volt battery.
Installation of a standard 12-volt battery will
result in reduced 12-volt battery life. When
using a 12-volt battery charger on the 12-volt
AGM battery, some chargers have an AGM
battery setting on the charger. If available,
use the AGM setting on the charger to limit
charge voltage to 14.8 volts. Follow the
charger manufacturer’s instructions.
{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.
Vehicle Storage
{Warning
Batteries have acid that can burn you and
gas that can explode. You can be badly
hurt if you are not careful. See Jump
Starting - North America 0391 for tips on
working around a battery without
getting hurt.
Infrequent Usage: Remove the black,
negative (−) cable from the battery to keep
the battery from running down.
Extended Storage: Remove the black,
negative (−) cable from the battery or use a
battery trickle charger.
Negative Battery Cable Disconnection
{Warning
Before disconnecting the negative battery
cable, turn off all features, turn the
ignition off, and remove the key,
if equipped, from the vehicle. If this is
not done, you or others could be injured,
and the vehicle could be damaged.
Caution
If the battery is disconnected with the
ignition on or the vehicle in Retained
Accessory Power (RAP), the OnStar
back-up battery will be permanently
discharged and will need to be replaced.
1. Make sure the lamps, features, and accessories are turned off.
2. Turn the ignition off and remove the key, if equipped.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 347
Starter Switch Check
{Warning
When you are doing this inspection, the
vehicle could move suddenly. If the
vehicle moves, you or others could be
injured.
1. Before starting this check, be sure there is enough room around the vehicle.
2. Apply both the parking brake and the regular brake.
Do not use the accelerator pedal, and be
ready to turn off the engine immediately
if it starts.
3. Try to start the engine in each gear. The vehicle should start only in P (Park) or
N (Neutral). If the vehicle starts in any
other position, contact your dealer for
service.
Automatic Transmission Shift Lock
Control Function Check
{Warning
When you are doing this inspection, the
vehicle could move suddenly. If the
vehicle moves, you or others could be
injured.
1. Before starting this check, be sure there is enough room around the vehicle.
It should be parked on a level surface.
2. Apply the parking brake. Be ready to apply the regular brake immediately if
the vehicle begins to move.
3. With the engine off, turn the ignition on, but do not start the engine. Without
applying the regular brake, try to move
the shift lever out of P (Park) with
normal effort. If the shift lever moves
out of P (Park), contact your dealer for
service.
Ignition Transmission Lock Check
If equipped with Key Access ignition, while
parked, and with the parking brake set, try
to turn the ignition off in each shift lever
position. The ignition should turn to off only
when the shift lever is in P (Park).
The ignition key should come out only when
the ignition is off. Contact your dealer if
service is required.
Park Brake and P (Park)
Mechanism Check
{Warning
When you are doing this check, the
vehicle could begin to move. You or
others could be injured and property
could be damaged. Make sure there is
room in front of the vehicle in case it
begins to roll. Be ready to apply the
regular brake at once should the vehicle
begin to move.
Park on a fairly steep hill, with the vehicle
facing downhill. Keeping your foot on the
regular brake, set the parking brake.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
348 Vehicle Care
.To check the parking brake's holding
ability: With the engine running and the
transmission in N (Neutral), slowly remove
foot pressure from the regular brake
pedal. Do this until the vehicle is held by
the parking brake only.
.To check the P (Park) mechanism's holding
ability: With the engine running, shift to
P (Park). Then release the parking brake
followed by the regular brake.
Contact your dealer if service is required.
Wiper Blade Replacement
Windshield wiper blades should be replaced
periodically. See Maintenance Schedule
0 409.
Replacement blades come in different types
and are removed in different ways. For
proper type and length, see Maintenance
Replacement Parts 0419.
Caution
Allowing the wiper arm to touch the
windshield when no wiper blade is
installed could damage the windshield.
Any damage that occurs would not be
(Continued)
Caution (Continued)
covered by the vehicle warranty. Do not
allow the wiper arm to touch the
windshield.
Front Wiper Blade Replacement
To replace the wiper blade:
1. Pull the wiper assembly away from the windshield.
2. Lift up on the latch in the middle of the
wiper blade where the wiper arm
attaches. 3. With the latch open, pull the wiper blade
down toward the windshield far enough
to release it from the J-hooked end of
the wiper arm.
4. Remove the wiper blade.
5. Reverse Steps 1–3 for wiper blade replacement.
Glass Replacement
If the windshield or front side glass must be
replaced, see your dealer to determine the
correct replacement glass.
Windshield Replacement
HUD System
The windshield is part of the HUD system.
If the windshield must be replaced, get one
that is designed for HUD or the HUD image
may look out of focus.
Driver Assistance Systems
If the windshield needs to be replaced and
the vehicle is equipped with a front camera
sensor for the Driver Assistance Systems, a
GM replacement windshield is
recommended. The replacement windshield
must be installed according to GM
specifications for proper alignment. If it is

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 353
Choose some feature of the vehicle that is
not needed to use and replace it as soon as
possible.
Headlamp Wiring
An electrical overload may cause the lamps
to go on and off, or in some cases to
remain off. Have the headlamp wiring
checked right away if the lamps go on and
off or remain off.
Windshield Wipers
If the wiper motor overheats due to heavy
snow or ice, the windshield wipers will stop
until the motor cools and will then restart.
Although the circuit is protected from
electrical overload, overload due to heavy
snow or ice may cause wiper linkage
damage. Always clear ice and heavy snow
from the windshield before using the
windshield wipers.
If the overload is caused by an electrical
problem and not snow or ice, be sure to get
it fixed.
Fuses and Circuit Breakers
The wiring circuits in the vehicle are
protected from short circuits by a
combination of fuses and circuit breakers.
This greatly reduces the chance of damage
caused by electrical problems.
{Danger
Fuses and circuit breakers are marked
with their ampere rating. Do not exceed
the specified amperage rating when
replacing fuses and circuit breakers. Use
of an oversized fuse or circuit breaker can
result in a vehicle fire. You and others
could be seriously injured or killed.
{Warning
Installation or use of fuses that do not
meet GM’s original fuse specifications is
dangerous. The fuses could fail, and result(Continued)
Warning (Continued)
in a fire. You or others could be injured
or killed, and the vehicle could be
damaged.
See Accessories and Modifications 0323 and
General Information 0322.
To check a fuse, look at the silver-colored
band inside the fuse. If the band is broken
or melted, replace the fuse. Be sure to
replace a bad fuse with a new one of the
identical size and rating.
Fuses of the same amperage can be
temporarily borrowed from another fuse
location, if a fuse goes out. Replace the fuse
as soon as possible.
Engine Compartment Fuse Block
If the vehicle has a diesel engine, see the
Duramax diesel supplement.
The engine compartment fuse block is in the
engine compartment, on the passenger side
of the vehicle.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 355
FusesUsage
6 –
7 –
8 Fog lamp
9 –
10 –
11 Police upfitter
12 –
13 Washer front
14 Washer rear 15 –
16 –
17 IECL 1
19 DC/AC inverter
20 IECR 2 (LD) / EBCM2 (HD)
21 –
22 IECL 2
24 EBCM 1 25 –
26 – Fuses
Usage
27 Horn
28 –
29 –
30 –
31 –
32 Rear window defogger
33 Heated mirror
34 Parking lamp left 37 –
38 –
39 –
40 Misc ignition 41 Trailer parking lamp
42 Park lamp right
44 –
45 –
46 Engine control module ignition
47 Transmission control module ignition Fuses
Usage
48 –
49 Transmission control module
50 A/C clutch 51 Transfer case control module
52 Front wiper
53 Center high-mounted stop lamp
54 Trailer reverse lamp 55 Trailer back-up lamp
56 SADS 57 TTPM/SBZA
58 Starter motor (LD & HD DSL)
60 Active fuel management 1
61 VES
62 Integrated chassis control module/CVS
63 Trailer battery