engine overheat GMC SIERRA DENALI 2015 User Guide

Black plate (28,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-28 Driving and Operating
Engine Heater The engine heater can provide
easier starting and better fuel
economy during engine warm-up in
cold weather conditions at or below
− 18°C (0°F). Vehicles with an
engine heater should be plugged in
at least four hours before starting.
An internal thermostat in the
plug-end of the cord may exist,
which will prevent engine coolant
heater operation at temperatures
above − 18°C (0°F).
If the vehicle has a diesel engine,
see the Duramax diesel
supplement.
To Use the Engine Coolant
Heater
1. Turn off the engine. 2. Open the hood and unwrap the
electrical cord. The cord is
secured to the driver side fender
with a clip, next to the engine
compartment fuse block.
Carefully remove the wire tie
that bundles the electrical plug.
Do not cut the electrical cord.
Check the heater cord for
damage. If it is damaged, do not
use it. See your dealer for a
replacement. Inspect the cord for
damage yearly.
3. Plug the cord into a normal,
grounded 110-volt AC outlet.
{ Warning
Improper use of the heater cord
or an extension cord can damage
the cord and may result in
overheating and fire. .
Plug the cord into a
three-prong electrical utility
receptacle that is protected
(Continued) Warning (Continued) by a ground fault detection
function. An ungrounded
outlet could cause an electric
shock. .
Use a weatherproof,
heavy-duty, 15 amp-rated
extension cord if needed.
Failure to use the
recommended extension cord
in good operating condition,
or using a damaged heater or
extension cord, could make it
overheat and cause a fire,
property damage, electric
shock, and injury. .
Do not operate the vehicle
with the heater cord
permanently attached to the
(Continued)

Black plate (30,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-30 Driving and Operating
Shifting Into Park
{ WarningIt can be dangerous to get out of
the vehicle if the shift lever is not
fully in P (Park) with the parking
brake firmly set. The vehicle can
roll. If you have left the engine
running, the vehicle can move
suddenly. You or others could be
injured. To be sure the vehicle will
not move, even when you are on
fairly level ground, use the steps
that follow. If the vehicle has a
four-wheel drive transfer case
with a N (Neutral) position, and
the transfer case is in N (Neutral),
the vehicle will be free to roll,
even if the shift lever is in
P (Park). Be sure the transfer
case is in a drive gear. If towing a
trailer, see Driving Characteristics
and Towing Tips on page 9-68 . 1. Hold the brake pedal down, then
set the parking brake.
See Parking Brake on
page 9-47 .
2. Move the shift lever into the
P (Park) position by pulling the
shift lever toward you and
moving it up as far as it will go.
3. Be sure the transfer case is in a
drive gear — not in N (Neutral).
4. Turn the ignition key to
LOCK/OFF.
5. Remove the key and take it with
you. If you can leave the vehicle
with the ignition key in your
hand, the vehicle is in P (Park).
Leaving the Vehicle with the
Engine Running
{ Warning
It can be dangerous to leave the
vehicle with the engine running.
The vehicle could move suddenly
(Continued) Warning (Continued) if the shift lever is not fully in
P (Park) with the parking brake
firmly set.
If you have four-wheel drive and
the transfer case is in N (Neutral),
the vehicle will be free to roll,
even if the shift lever is in
P (Park). So be sure the transfer
case is in a drive gear — not in
N (Neutral).
And, if you leave the vehicle with
the engine running, it could
overheat and even catch fire. You
or others could be injured. Do not
leave the vehicle with the engine
running unless you have to.
If you have to leave the vehicle with
the engine running, be sure the
vehicle is in P (Park) and the
parking brake is firmly set before
you leave it. After you move the shift
lever into P (Park), hold the regular
brake pedal down. Then, see if you

Black plate (70,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-70 Driving and Operating If the trailer turn signal bulbs burn
out, the arrows on the instrument
cluster will still flash for turns. It is
important to check occasionally to
be sure the trailer bulbs are still
working.
Driving on Grades Reduce speed and shift to a lower
gear before starting down a long or
steep downgrade. If the
transmission is not shifted down, the
brakes might get hot and no longer
work well.
Vehicles can tow in D (Drive). Shift
the transmission to a lower gear if
the transmission shifts too often
under heavy loads and/or hilly
conditions.
The Tow/Haul Mode may be used if
the transmission shifts too often.
See Tow/Haul Mode on page 9-39 .
When towing at high altitude on
steep uphill grades, consider the
following: Engine coolant will boil at
a lower temperature than at normal
altitudes. If the engine is turned off immediately after towing at high
altitude on steep uphill grades, the
vehicle may show signs similar to
engine overheating. To avoid this,
let the engine run while parked,
preferably on level ground, with the
transmission in P (Park) for a few
minutes before turning the engine
off. If the overheat warning comes
on, see Engine Overheating on
page 10-21 .
Parking on Hills
{ WarningParking the vehicle on a hill with
the trailer attached can be
dangerous. If something goes
wrong, the rig could start to move.
People can be injured, and both
the vehicle and the trailer can be
damaged. When possible, always
park the rig on a flat surface. If parking the rig on a hill:
1. Press the brake pedal, but do
not shift into P (Park) yet. Turn
the wheels into the curb if facing
downhill or into traffic if facing
uphill.
2. Have someone place chocks
under the trailer wheels.
3. When the wheel chocks are in
place, release the regular brakes
until the chocks absorb the load.
4. Reapply the brake pedal. Then
apply the parking brake and shift
into P (Park).
5. Release the brake pedal.
Leaving After Parking on a Hill 1. Apply and hold the brake pedal.
2. Start the engine.
3. Shift into a gear.
4. Release the parking brake.
5. Let up on the brake pedal.
6. Drive slowly until the trailer is
clear of the chocks.

Black plate (1,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-1
Vehicle Care General Information General Information . . . . . . . . . . 10-2
California Proposition
65 Warning . . . . . . . . . . . . . . . . . 10-2
California Perchlorate
Materials Requirements . . . . 10-3
Accessories and
Modifications . . . . . . . . . . . . . . . 10-3
Vehicle Checks Doing Your Own
Service Work . . . . . . . . . . . . . . . 10-3
Hood . . . . . . . . . . . . . . . . . . . . . . . . 10-4
Engine Compartment
Overview . . . . . . . . . . . . . . . . . . . 10-5
Engine Oil . . . . . . . . . . . . . . . . . . . 10-8
Engine Oil Life System . . . . . 10-11
Automatic Transmission
Fluid (6 Speed
Transmission) . . . . . . . . . . . . . 10-12
Automatic Transmission
Fluid (8 Speed
Transmission) . . . . . . . . . . . . . 10-15
Engine Air Cleaner/Filter . . . . 10-15
Cooling System . . . . . . . . . . . . 10-17
Engine Coolant . . . . . . . . . . . . . 10-18 Engine Overheating . . . . . . . . 10-21
Overheated Engine
Protection
Operating Mode . . . . . . . . . . . 10-23
Engine Fan . . . . . . . . . . . . . . . . . 10-24
Power Steering Fluid (1500
Series) . . . . . . . . . . . . . . . . . . . . 10-24
Power Steering Fluid (2500/
3500 Series) . . . . . . . . . . . . . . 10-24
Washer Fluid . . . . . . . . . . . . . . . 10-25
Brakes . . . . . . . . . . . . . . . . . . . . . 10-26
Brake Fluid . . . . . . . . . . . . . . . . . 10-27
Battery . . . . . . . . . . . . . . . . . . . . . 10-29
Four-Wheel Drive . . . . . . . . . . . 10-29
Front Axle . . . . . . . . . . . . . . . . . . 10-30
Rear Axle . . . . . . . . . . . . . . . . . . 10-31
Noise Control System . . . . . . 10-32
Starter Switch Check . . . . . . . 10-33
Automatic Transmission Shift
Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . 10-34
Ignition Transmission Lock
Check . . . . . . . . . . . . . . . . . . . . . 10-34
Park Brake and P (Park)
Mechanism Check . . . . . . . . 10-34
Wiper Blade
Replacement . . . . . . . . . . . . . . 10-35
Glass Replacement . . . . . . . . 10-35 Headlamp Aiming Headlamp Aiming . . . . . . . . . . 10-36
Bulb Replacement Bulb Replacement . . . . . . . . . . 10-36
Halogen Bulbs . . . . . . . . . . . . . . 10-36
LED Lighting . . . . . . . . . . . . . . . 10-36
Headlamps, Front Turn
Signal, Sidemarker, and
Parking Lamps . . . . . . . . . . . . 10-36
Fog Lamps . . . . . . . . . . . . . . . . . 10-37
Taillamps, Turn Signal,
Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . 10-37
Center High-Mounted
Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . 10-39
Replacement Bulbs . . . . . . . . . 10-40
Electrical System Electrical System
Overload . . . . . . . . . . . . . . . . . . 10-40
Fuses . . . . . . . . . . . . . . . . . . . . . . 10-41
Engine Compartment Fuse
Block . . . . . . . . . . . . . . . . . . . . . 10-41
Instrument Panel Fuse
Block (Left) . . . . . . . . . . . . . . . 10-45
Instrument Panel Fuse Block
(Right) . . . . . . . . . . . . . . . . . . . . 10-48

Black plate (12,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-12 Vehicle Care The oil life system can also be reset
as follows:
1. Turn the ignition to ON/RUN with
the engine off.
2. Fully press the accelerator pedal
slowly three times within
five seconds.
3. Display the OIL LIFE
REMAINING on the DIC. If the
display shows 100%, the system
is reset.
If the vehicle has a CHANGE
ENGINE OIL SOON message and it
comes back on when the vehicle is
started and/or the OIL LIFE
REMAINING is near 0%, the engine
oil life system has not been reset.
Repeat the procedure. Automatic Transmission
Fluid (6 Speed
Transmission) When to Check and Change
Automatic Transmission Fluid It is usually not necessary to check
the transmission fluid level. The only
reason for fluid loss is a
transmission leak or overheated
transmission. If a small leak is
suspected, then use the following
checking procedures to check the
fluid level. However, if there is a
large leak, then it may be necessary
to have the vehicle towed to a
dealer service department and have
it repaired before driving the vehicle
further.
{ Caution
Use of the incorrect automatic
transmission fluid may damage
the vehicle, and the damage may
(Continued) Caution (Continued) not be covered by the vehicle
warranty. Always use the
automatic transmission fluid listed
in Recommended Fluids and
Lubricants on page 11-12 .
Change the fluid and filter at the
scheduled maintenance intervals
listed in Maintenance Schedule on
page 11-3 . Be sure to use the
transmission fluid listed in
Recommended Fluids and
Lubricants on page 11-12 .
How to Check Automatic
Transmission Fluid
{ Caution
Too much or too little fluid can
damage the transmission. Too
much can mean that some of the
fluid could come out and fall on
hot engine parts or exhaust
(Continued)

Black plate (13,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-13Caution (Continued)system parts, starting a fire. Too
little fluid could cause the
transmission to overheat. Be sure
to get an accurate reading if
checking the transmission fluid.
Before checking the fluid level,
prepare the vehicle:
1. Start the engine and park the
vehicle on a level surface. Keep
the engine running.
2. Apply the parking brake and
place the shift lever in P (Park).
3. With your foot on the brake
pedal, move the shift lever
through each gear range,
pausing for about three seconds
in each range. Then, move the
shift lever back to P (Park).
4. Allow the engine to idle (500 –
800 rpm) for at least one minute.
Slowly release the brake pedal. 5. Keep the engine running and
check the transmission fluid
temperature on the Driver
Information Center (DIC). See
Driver Information Center (DIC)
on page 5-27 .
6. Using the transmission fluid
temperature reading, determine
and perform the appropriate
check procedure. If the
transmission fluid temperature
reading is not within the required
temperature ranges, allow the
vehicle to cool, or operate the
vehicle until the appropriate
transmission fluid temperature is
reached.
Cold Check Procedure
Use this procedure only as a
reference to determine if the
transmission has enough fluid to be
operated safely until a hot check
procedure can be made. The hot
check procedure is the most
accurate method to check the fluid
level. Perform the hot check
procedure at the first opportunity. Use this cold check procedure to
check fluid level when the
transmission temperature is
between 27°C and 32°C (80°F and
90°F).
1. Locate the transmission dipstick
at the rear of the engine
compartment, on the passenger
side of the vehicle.
See Engine Compartment
Overview on page 10-5 .
2. Flip the handle up, then pull out
the dipstick and wipe it with a
clean rag or paper towel.
3. Install the dipstick by pushing it
back in all the way; wait
three seconds, and then pull it
back out again.

Black plate (15,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-155. Safe operating level is within the
HOT cross hatch band on the
dipstick. If the fluid level is not
within the HOT band, and the
transmission temperature is
between 71°C and 93°C (160°F
and 200°F), add or drain fluid as
necessary to bring the level into
the HOT band. If the fluid level is
low, add only enough fluid to
bring the level into the HOT
band. It does not take much
fluid, generally less than 0.5 L
(1 pt). Do not overfill.
6. If the fluid level is in the
acceptable range, push the
dipstick back in all the way, then
flip the handle down to lock the
dipstick in place.
Consistency of Readings
Always check the fluid level at least
twice using the procedure described
previously. Consistency (repeatable
readings) is important to maintaining
proper fluid level. If readings are still
inconsistent, contact the dealer. Automatic Transmission
Fluid (8 Speed
Transmission) When to Check and Change
Automatic Transmission Fluid It is usually not necessary to check
the transmission fluid level. The only
reason for fluid loss is a
transmission leak or overheated
transmission. This vehicle is not
equipped with a transmission fluid
level dipstick. There is a special
procedure for checking and
changing the transmission fluid in
these vehicles. Because this
procedure is difficult, this should be
done at the dealer. Contact the
dealer for additional information or
the procedure can be found in the
service manual. See Service
Publications Ordering Information
on page 13-11 .{ CautionUse of the incorrect automatic
transmission fluid may damage
the vehicle, and the damage may
not be covered by the vehicle
warranty. Always use the
automatic transmission fluid listed
in Recommended Fluids and
Lubricants on page 11-12 .
Change the fluid and filter at the
scheduled maintenance intervals
listed in Maintenance Schedule on
page 11-3 . Be sure to use the
transmission fluid listed in
Recommended Fluids and
Lubricants on page 11-12 .
Engine Air Cleaner/Filter If the vehicle has a diesel engine,
see “ Pickup Models ” under “ Engine
Air Cleaner/Filter ” in the Duramax
diesel supplement for the correct
inspection and replacement
procedures.

Black plate (18,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-18 Vehicle Care
{ WarningHeater and radiator hoses, and
other engine parts, can be very
hot. Do not touch them. If you do,
you can be burned.
Do not run the engine if there is a
leak. If you run the engine, it
could lose all coolant. That could
cause an engine fire, and you
could be burned. Get any leak
fixed before you drive the vehicle.
{ Caution
Using coolant other than
DEX-COOL ®
can cause
premature engine, heater core,
or radiator corrosion. In addition,
the engine coolant could require
changing sooner. Any repairs
would not be covered by the
(Continued) Caution (Continued) vehicle warranty. Always use
DEX-COOL (silicate-free) coolant
in 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,
see Engine Overheating on
page 10-21 . What to Use
{ WarningAdding only plain water or some
other liquid to the cooling system
can be dangerous. Plain water
and other liquids, can boil before
the proper coolant mixture will.
The coolant warning system is set
for the proper coolant mixture.
With plain water or the wrong
mixture, the engine could get too
hot but you would not get the
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.

Black plate (19,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-19Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
coolant. If using this mixture,
nothing else needs to be added.
This mixture: .
Gives freezing protection down
to − 37°C ( − 34°F), outside
temperature. .
Gives boiling protection up to
129°C (265°F), engine
temperature. .
Protects against rust and
corrosion. .
Will not damage aluminum parts. .
Helps keep the proper engine
temperature.
{ Caution
If improper coolant mixture,
inhibitors, or additives are used in
the vehicle cooling system, the
engine could overheat and be
damaged. Too much water in the
(Continued) Caution (Continued) mixture can freeze and crack
engine cooling parts. The repairs
would not be covered by the
vehicle warranty. Use only the
proper mixture of engine coolant
for the cooling system. See
Recommended Fluids and
Lubricants on page 11-12 .
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
passenger side of the vehicle. See
Engine Compartment Overview on
page 10-5 .
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, do not do anything else until
it cools down. If coolant is visible
but the coolant level is not at or
above the FULL COLD mark, add a
50/50 mixture of clean, drinkable
water and DEX-COOL coolant at the
coolant surge tank, but be sure the
cooling system is cool before this
is done.

Black plate (20,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-20 Vehicle Care
5.3L V8 Engine Shown, 6.2L
V8 Engine Similar
6.0L V8 Engine The coolant level should be at or
above the FULL COLD mark. If it is
not, there may be a leak in the
cooling system.
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.
{ WarningYou can be burned if you spill
coolant on hot engine parts.
Coolant contains ethylene glycol
and it will burn if the engine parts
are hot enough. Do not spill
coolant on a hot engine. { CautionThis vehicle has a specific
coolant fill procedure. Failure to
follow this procedure could cause
the engine to overheat and be
severely damaged.
{ WarningSteam and scalding liquids from a
hot cooling system can blow out
and burn you badly. Never turn
the cap when the cooling system,
including the surge tank pressure
cap, is hot. Wait for the cooling
system and surge tank pressure
cap to cool.
If no coolant is visible in the surge
tank, add coolant.