2024 GMC SIERRA DENALI Duramax

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/13/22
218 Driving and Operating
The vehicle will switch from accessory mode
to off after five minutes to prevent battery
rundown.
ON/RUN/START (Green Indicator Light) :This
mode is for driving and starting. With the
vehicle off, and the brake pedal applied,
pressing ENGINE START/STOP button once
will turn the ignition on. Once engine
cranking begins, release the button. Engine
cranking will continue until the engine
starts. See Starting the Engine 0218.
Service Mode
This power mode is available for service and
diagnostics, and to verify the proper
operation of the malfunction indicator lamp
as may be required for emission inspection
purposes. With the vehicle off, and the
brake pedal not applied, pressing and
holding the ENGINE START/STOP button for
more than five seconds will place the vehicle
in Service Mode. The instruments and audio
systems will operate as they do when the
vehicle is on, but the vehicle will not be able
to be driven. The engine will not start in
Service Mode. Press the ENGINE START/STOP
button again to turn the vehicle off.Starting the Engine
If the vehicle has a diesel engine, see the
Duramax diesel supplement.
Caution
If you add electrical parts or accessories,
you could change the way the engine
operates. Any resulting damage would
not be covered by the vehicle warranty.
See Add-On Electrical Equipment 0306.
Move the shift lever to P (Park) or
N (Neutral). To restart the engine when the
vehicle is already moving, use
N (Neutral) only.
Caution
Do not try to shift to P (Park) if the
vehicle is moving. If you do, you could
damage the transmission. Shift to P (Park)
only when the vehicle is stopped.
Starting Procedure
1. The remote key must be in the vehicle. Press ENGINE START/STOP with the brake
pedal applied. When the engine begins
cranking, let go of the button. The driver may observe a minor, and
temporary, brake pedal kickback when
starting the vehicle. This is normal.
The idle speed will go down as the
engine gets warm. Do not race the
engine immediately after starting it.
Operate the engine and transmission
gently to allow the oil to warm up and
lubricate all moving parts.
When the low fuel warning light is on
and the FUEL LEVEL LOW message is
displayed in the Driver Information
Center (DIC), press ENGINE START/STOP
to continue engine cranking.
Caution
Cranking the engine for long periods of
time, by returning the ignition to the
START position immediately after
cranking has ended, can overheat and
damage the cranking motor, and drain
the battery. Wait at least 15 seconds
between each try, to let the cranking
motor cool down.
2. If the engine does not start after five to 10 seconds, especially in very cold
weather (below −18 °C or 0 °F), it could
be flooded with too much gasoline. Try

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/13/22
272 Driving and Operating
Recommended Fuel
For diesel engine vehicles, see“Fuel for
Diesel Engines” in the Duramax diesel
supplement.
If the vehicle has a yellow sticker on the
fuel door, E85 or FlexFuel can be used. If the
vehicle does not have a yellow sticker, do
not use gasoline with ethanol levels greater
than 15% by volume. See E85 or FlexFuel
0 272.
Regular unleaded gasoline meeting ASTM
specification D4814 with a posted octane
rating (R+M)/2 of 87 or greater is
recommended. Do not use gasoline with a
posted octane rating of less than 87, as this
will result in reduced performance and
driveability. If heavy knocking is heard when
using gasoline rated at 87 or greater, the
engine needs service.
Prohibited Fuels
Caution
Do not use fuels with any of the
following conditions; doing so may
damage the vehicle and void its
warranty:
.For vehicles that are not FlexFuel, fuel
labeled greater than 15% ethanol by
volume, such as mid-level ethanol
blends (16–50% ethanol), E85,
or FlexFuel.
.Fuel with any amount of methanol,
methylal, ferrocene, and aniline. These
fuels can corrode metal fuel system
parts or damage plastic and rubber
parts.
.Fuel containing metals such as
methylcyclopentadienyl manganese
tricarbonyl (MMT), which can damage
the emissions control system and
spark plugs.
.Fuel with a posted octane rating of
less than the recommended fuel. Using
this fuel will lower fuel economy and
performance, and may decrease the
life of the emissions catalyst.
Fuels in Foreign Countries
The U.S., Canada, and Mexico post fuel
octane ratings in anti-knock index (AKI). For
fuel not to use in a foreign country, see
Prohibited Fuels 0272.
Fuel Additives
TOP TIER Detergent Gasoline is highly
recommended for use with your vehicle.
If your country does not have TOP TIER
Detergent Gasoline, add ACDelco Fuel
System Treatment Plus−Gasoline to the
vehicle’s gasoline fuel tank at every oil
change or 15 000 km (9,000 mi), whichever
occurs first. TOP TIER Detergent Gasoline and
ACDelco Fuel System Treatment Plus
−Gasoline will help keep your vehicle’s
engine fuel deposit free and performing
optimally.
E85 or FlexFuel
Vehicles with a yellow fuel sticker on the
fuel door can use either unleaded gasoline
or fuel containing up to 85% ethanol (E85).
All other vehicles should use only the
unleaded gasoline as described in
Recommended Fuel 0272.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/13/22
Driving and Operating 273
The use of E85 or FlexFuel is encouraged
when the vehicle is designed to use it. E85
or FlexFuel is made from renewable sources.
To help locate fuel stations that carry E85 or
FlexFuel, the U.S. Department of Energy has
an alternative fuel website. See
www.afdc.energy.gov/afdc/locator/stations.
E85 or FlexFuel should meet ASTM
Specification D 5798 or CAN/CGSB–3.512 in
Canada. Do not use the fuel if the ethanol
content is greater than 85%. Fuel mixtures
that do not meet ASTM or CGSB
specifications can affect driveability and
could cause the malfunction indicator lamp
to come on.
The starting characteristics of E85 or FlexFuel
make it unsuitable for use when
temperatures fall below−18 °C (0 °F). Use
gasoline or add gasoline to the E85 or
FlexFuel.
Because E85 or FlexFuel has less energy per
liter (gallon) than gasoline, the vehicle will
need to be refilled more often. See Filling
the Tank (Chassis Cab and Box Delete
Models) 0275 or
Filling the Tank (Pickup Models) 0273. The only GM approved aftermarket additive
is ACDelco Fuel System Treatment
Plus-FlexFuel. Follow the instructions on the
bottle for proper use. This product is
available at your GM dealer.
Caution
Some additives are not compatible with
E85 or FlexFuel and can harm the
vehicle's fuel system. Use only additives
approved by GM for E85 or FlexFuel
vehicles. Damage caused by unapproved
additives would not be covered by the
vehicle warranty.
Caution
Do not use fuel containing methanol.
It can corrode metal parts in the fuel
system and also damage plastic and
rubber parts. That damage would not be
covered under the vehicle warranty.
To help keep the engine running efficiently,
fill the tank with gasoline, up to E15, after
filling the tank with E85 one or two times.
Filling the Tank (Pickup Models)
If the vehicle has a diesel engine, see the
Duramax diesel supplement.
An arrow on the fuel gauge indicates which
side of the vehicle the fuel door is on. See
Fuel Gauge 0116.
{Warning
Fuel vapors and fuel fires burn violently
and can cause injury or death.
Follow these guidelines to help avoid
injuries to you and others:
.Read and follow all the instructions on
the fuel pump island.
.Turn off the engine when refueling.
.Keep sparks, flames, and smoking
materials away from fuel.
.Do not leave the fuel pump
unattended.
.Avoid using electronic devices while
refueling.
.Do not re-enter the vehicle while
pumping fuel.
(Continued)

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/13/22
Driving and Operating 275
Filling the Tank (Chassis Cab and
Box Delete Models)
If the vehicle has a diesel engine, see the
Duramax diesel supplement.
An arrow on the fuel gauge indicates which
side of the vehicle the fuel fill is on. See
Fuel Gauge0116.
{Warning
Fuel vapors and fuel fires burn violently
and can cause injury or death.
Follow these guidelines to help avoid
injuries to you and others:
.Read and follow all the instructions on
the fuel pump island.
.Turn off the engine when refueling.
.Keep sparks, flames, and smoking
materials away from fuel.
.Do not leave the fuel pump
unattended.
.Avoid using electronic devices while
refueling.
.Do not re-enter the vehicle while
pumping fuel.
(Continued)
Warning (Continued)
.Keep children away from the fuel
pump and never let children
pump fuel.
.Before touching the fill nozzle, touch a
metallic object to discharge static
electricity from your body.
.Fuel can spray out if the fuel cap is
opened too quickly. This spray can
happen if the tank is nearly full, and is
more likely in hot weather. Open the
fuel cap slowly and wait for any hiss
noise to stop, then unscrew the cap all
the way.
Turn the fuel cap counterclockwise to
remove. Fully insert and latch the fill nozzle,
begin fueling. For models with dual fuel
tanks, the fuel gauge shows an average of
both tanks. When refueling, refuel the
primary front tank first, then add fuel to the
auxiliary rear tank.
{Warning
Overfilling the fuel tank by more than
three clicks of a standard fill nozzle may
cause:
.Vehicle performance issues, including
engine stalling and damage to the fuel
system.
.Fuel spills.
.Under certain conditions, fuel fires.
Be careful not to spill fuel. Wait five seconds
after you have finished pumping before
removing the fill nozzle. Clean fuel from
painted surfaces as soon as possible. See
Exterior Care 0383. Reinstall the cap by
turning it clockwise until it clicks.
{Warning
If a fire starts while you are refueling, do
not remove the fill nozzle. Shut off the
flow of fuel by shutting off the pump or
by notifying the station attendant. Leave
the area immediately.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/13/22
280 Driving and Operating
5. Gradually release the brake pedal toallow the chocks to absorb the load of
the trailer.
6. Reapply the brake pedal. Then, apply the parking brake and shift into P (Park).
7. Release the brake pedal.
Pulling the Trailer from the Water
To pull the trailer out of the water: 1. Press and hold the brake pedal.
2. Start the engine and shift into gear.
3. Release the parking brake.
4. Let up on the brake pedal.
5. Drive slowly until the tires are clear of the chocks.
6. Stop and have someone pick up and store the chocks.
7. Slowly pull the trailer from the water.
8. Once the vehicle and trailer have been driven from the sloped part of the boat
ramp, the vehicle can be shifted from
four-wheel-drive high. Shift into the drive
mode that is appropriate for the road
conditions.Caution
If the vehicle tires begin to spin and the
vehicle begins to slide toward the water,
remove your foot from the accelerator
pedal and apply the brake pedal. Seek
help to have the vehicle towed up
the ramp.
Maintenance when Trailer Towing
The vehicle needs service more often when
used to tow trailers. See Maintenance
Schedule 0394. It is especially important to
check the engine oil, axle lubricant, belts,
cooling system, and brake system before
and during each trip.
Check periodically to see that all nuts and
bolts on the trailer hitch are tight.
Engine Cooling When Trailer Towing
The cooling system may temporarily
overheat during severe operating conditions.
See Engine Overheating 0321.
Trailer Towing
If equipped with a diesel engine, see the
Duramax diesel supplement.
Caution
Towing a trailer improperly can damage
the vehicle and result in costly repairs
not covered by the vehicle warranty. To
tow a trailer correctly, follow the
directions in this section and see your
dealer for important information about
towing a trailer with the vehicle.
Trailering is different than just driving the
vehicle by itself. Trailering means changes in
handling, acceleration, braking, and
durability. Successful, safe trailering takes
correct equipment, and it has to be used
properly.
The following information has many
time-tested, important trailering tips and
safety rules. Many of these are important
for your safety and that of your passengers.
Read this section carefully before pulling a
trailer.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
314 Vehicle Care
1. Remote Negative (–) Location. SeeJump
Starting - North America 0376.
2. Positive (+) Terminal (Under Cover). See Jump Starting - North America 0376.
3. Battery - North America 0327.
4. Engine Air Cleaner/Filter 0318.
5. Engine Oil Dipstick. See “Checking Engine
Oil” under Engine Oil 0314.
6. Engine Cooling Fan (Out of View). See Cooling System 0319.
7. Power Steering Fluid Reservoir. See Power Steering Fluid 0323.
8. Engine Oil Fill Cap. See “When to Add
Engine Oil” underEngine Oil 0314.
9. Auxiliary Battery. Battery - North
America 0327.
10. Brake Fluid Reservoir. See Brake Fluid
0 326.
11. Engine Compartment Fuse Block 0337.
12. Coolant Surge Tank and Pressure Cap. SeeCooling System 0319.
13. Windshield Washer Fluid Reservoir. See “Adding Washer Fluid” underWasher
Fluid 0324.
If the vehicle has a diesel engine, see the
Duramax diesel supplement.Engine Oil
For diesel engine vehicles, see “Engine Oil”
in the Duramax diesel supplement.
To ensure proper engine performance and
long life, careful attention must be paid to
engine oil. Following these simple, but
important steps will help protect your
investment:
.Use engine oil approved to the proper
specification and of the proper viscosity
grade. See “Selecting the Right Engine
Oil” in this section.
.Check the engine oil level regularly and
maintain the proper oil level. See
“Checking Engine Oil” and“When to Add
Engine Oil” in this section.
.Change the engine oil at the appropriate
time. SeeEngine Oil Life System 0316.
.Always dispose of engine oil properly. See
“What to Do with Used Oil” in this
section.
Checking Engine Oil
Check the engine oil level regularly, every
650 km (400 mi), especially prior to a long
trip. The engine oil dipstick handle is a loop.
See Engine Compartment Overview 0313 for
the location.
{Warning
The engine oil dipstick handle may be
hot; it could burn you. Use a towel or
glove to touch the dipstick handle.
If a low oil Driver Information Center (DIC)
message displays, check the oil level.
Follow these guidelines:
.To get an accurate reading, park the
vehicle on level ground. Check the engine
oil level after the engine has been off for
at least two hours. Checking the engine
oil level on steep grades or too soon after
engine shutoff can result in incorrect
readings. Accuracy improves when
checking a cold engine prior to starting.
Remove the dipstick and check the level.
.If unable to wait two hours, the engine
must be off for at least 15 minutes if the
engine is warm, or at least 30 minutes if
the engine is not warm. Pull out the
dipstick, wipe it with a clean paper towel
or cloth, then push it back in all the way.
Remove it again, keeping the tip down,
and check the level.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
Vehicle Care 319
Caution
If the air cleaner/filter is off, dirt can
easily get into the engine, which could
damage it. Always have the air
cleaner/filter in place when driving.
Cooling System
If the vehicle has the Duramax diesel
engine, see the Duramax diesel supplement.
The cooling system allows the engine to
maintain the correct working temperature.
{Warning
An underhood electric fan can start up
even when the engine is not running and
can cause injury. Keep hands, clothing,
and tools away from any underhood
electric fan.
1. Engine Cooling Fan (Out of View)
2. Coolant Surge Tank and Pressure Cap
{Warning
Do not touch heater, radiator, a/c pipes
or hoses, or other engine parts. They can
be very hot and can burn you. Do not
run the engine if there is a leak; all
coolant could leak out. That could cause
an engine fire and can burn you. Fix any
leak before driving the vehicle.
Engine Coolant
The cooling system in the vehicle is filled
with DEX-COOL engine coolant. This coolant
is designed to remain in the vehicle for
5 years or 240 000 km (150,000 mi),
whichever occurs first.
The following explains the cooling system
and how to check and add coolant when it
is low. If there is a problem with engine
overheating, seeEngine Overheating 0321.
What to Use
{Warning
Plain water, or other liquids such as
alcohol, can boil before the proper
coolant mixture will. With plain water or
the wrong mixture, the engine could get
too hot but there would not be an
overheat warning. The engine could catch
fire and you or others could be burned.
Use a 50/50 mixture of clean, drinkable
water and DEX-COOL coolant. This mixture:
.Gives freezing protection down to −37 °C
(−34 °F), outside temperature.
.Gives boiling protection up to 129 °C
(265 °F), engine temperature.

GMC Sierra/Sierra Denali 2500 HD/3500 HD Owner Manual (GMNA-
Localizing-U.S./Canada-16908340) - 2024 - CRC - 12/7/22
320 Vehicle Care
.Protects against rust and corrosion.
.Will not damage aluminum parts.
.Helps keep the proper engine
temperature.
Caution
Do not use anything other than a mix of
DEX-COOL coolant that meets GM
Standard GMW3420 and clean, drinkable
water. Anything else can cause damage
to the engine cooling system and the
vehicle, which would not be covered by
the vehicle warranty.
Never dispose of engine coolant by putting
it in the trash, or by pouring it on the
ground, or into sewers, streams, or bodies of
water. Have the coolant changed by an
authorized service center, familiar with legal
requirements regarding used coolant
disposal. This will help protect the
environment and your health.
Checking Coolant
The coolant surge tank is in the engine
compartment on the driver side of the
vehicle. See Engine Compartment Overview
0 313. The vehicle must be on a level surface when
checking the coolant level.
Check to see if coolant is visible in the
coolant surge tank. If the coolant inside the
coolant surge tank is boiling, wait until it
cools down. The coolant level should be at
or above the indicated mark. If it is not,
there may be a leak in the cooling system.
If coolant is visible but the coolant level is
not at or above the indicated mark, see the
following sections on how to add coolant to
the coolant surge tank following.
How to Add Coolant to the Coolant
Surge Tank
If the vehicle has a diesel engine, see
“Cooling System”
in the Duramax diesel
supplement for the proper coolant fill
procedure.
{Warning
Spilling coolant on hot engine parts can
burn you. Coolant contains ethylene
glycol and it will burn if the engine parts
are hot enough.
{Warning
Plain water, or other liquids such as
alcohol, can boil before the proper
coolant mixture will. With plain water or
the wrong mixture, the engine could get
too hot but there would not be an
overheat warning. The engine could catch
fire and you or others could be burned.