2015 GMC SIERRA DENALI coolant temperature

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 (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 (17,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-17Warning (Continued)cleaner not only cleans the air; it
helps to stop flames if the engine
backfires. Use caution when
working on the engine and do not
drive with the air cleaner/filter off.
{ CautionIf 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 you are driving.
Cooling System If the vehicle has the Duramax ®
diesel engine, see the Duramax
diesel supplement for more
information.
The cooling system allows the
engine to maintain the correct
working temperature. 5.3L V8 Engine Shown, 6.2L
V8 Engine Similar
1. Coolant Surge Tank
2. Coolant Surge Tank
Pressure Cap
3. Engine Cooling Fan 6.0L V8 Engine
1. Coolant Surge Tank
2. Coolant Surge Tank
Pressure Cap
3. Engine Cooling Fan
{ Warning
An electric engine cooling fan can
start even when the engine is not
running. To avoid injury, always
keep hands, clothing, and tools
away from any engine
cooling fan.

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 (21,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-21
Light-Duty
Coolant Surge
Tank
Pressure Cap Heavy-Duty
Coolant Surge
Tank
Pressure Cap
1. Remove the coolant surge tank
pressure cap when the cooling
system, including the coolant
surge tank pressure cap and
upper radiator hose, is no
longer hot.
Turn the pressure cap slowly
counterclockwise about one full
turn. If a hiss is heard, wait for
that to stop. A hiss means there
is still some pressure left.
2. Keep turning the pressure cap
slowly, and remove it.
3. Fill the coolant surge tank with
the proper mixture to the FULL
COLD mark. 4. With the coolant surge tank
pressure cap off, start the
engine and let it run until the
engine coolant temperature
gauge indicates approximately
90°C (195°F).
By this time, the coolant level
inside the coolant surge tank
may be lower. If the level is
lower, add more of the proper
mixture to the coolant surge tank
until the level reaches the FULL
COLD mark.
5. Replace the pressure cap tightly.
6. Verify coolant level after the
engine is shut off and the
coolant is cold. If necessary,
repeat coolant fill procedure
Steps 1-6. { CautionIf the pressure cap is not tightly
installed, coolant loss and
possible engine damage may
occur. Be sure the cap is properly
and tightly secured.
Engine Overheating If the vehicle has the Duramax
diesel engine, see the Duramax
diesel supplement.
The vehicle has several indicators
to warn of engine overheating.
There is a coolant temperature
gauge in the vehicle's instrument
cluster. See Engine Coolant
Temperature Gauge on page 5-13 .

Black plate (23,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-23If No Steam is Coming from
the Engine Compartment The ENGINE OVERHEATED STOP
ENGINE or the ENGINE
OVERHEATED IDLE ENGINE
message, along with a low coolant
condition, can indicate a serious
problem.
If there is an engine overheat
warning, but no steam is seen or
heard, the problem may not be too
serious. Sometimes the engine can
get a little too hot when the vehicle: .
Climbs a long hill on a hot day. .
Stops after high-speed driving. .
Idles for long periods in traffic. .
Tows a trailer; see Trailer Towing
on page 9-71 .
If the ENGINE OVERHEATED
STOP ENGINE or the ENGINE
OVERHEATED IDLE ENGINE
message appears with no sign of
steam, try this for a minute or so:
1. Turn the air conditioning off. 2. Turn the heater on to the highest
temperature and to the highest
fan speed. Open the windows as
necessary.
3. When it is safe to do so, pull off
the road, shift to P (Park) or
N (Neutral) and let the
engine idle.
If the temperature overheat gauge is
no longer in the overheat zone or an
overheat warning no longer
displays, the vehicle can be driven.
Continue to drive the vehicle slowly
for about 10 minutes. Keep a safe
vehicle distance from the vehicle in
front. If the warning does not come
back on, continue to drive normally
and have the cooling system
checked for proper fill and function.
If the warning continues, pull over,
stop, and park the vehicle
right away.
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. Also, see “ Overheated
Engine Protection Operating Mode ”
following.
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

Black plate (24,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-24 Vehicle Care distances and/or towing a trailer in
the overheat protection mode
should be avoided.
{ CautionAfter 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 on page 10-8 .
Engine Fan If the vehicle has a clutched engine
cooling fan, when the clutch is
engaged, the fan spins faster to
provide more air to cool the engine.
In most everyday driving conditions,
the fan is spinning slower and the
clutch is not fully engaged. This
improves fuel economy and reduces fan noise. Under heavy vehicle
loading, trailer towing, and/or high
outside temperatures, the fan speed
increases as the clutch more fully
engages, so an increase in fan
noise may be heard. This is normal
and should not be mistaken as the
transmission slipping or making
extra shifts. It is merely the cooling
system functioning properly. The fan
will slow down when additional
cooling is not required and the
clutch disengages.
This fan noise may also be heard
when starting the engine. It will go
away as the fan clutch partially
disengages.
If the vehicle has electric cooling
fans, 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.
Power Steering Fluid
(1500 Series) The vehicle has electric power
steering and does not use power
steering fluid.
Power Steering Fluid
(2500/3500 Series)

Black plate (3,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
INDEX i-3Child Restraints
Infants and Young
Children . . . . . . . . . . . . . . . . . . . . . 3-32
Lower Anchors and
Tethers for Children . . . . . . . . . 3-38
Older Children . . . . . . . . . . . . . . . . 3-30
Securing . . . . . . . . . . . . . . . . 3-45, 3-47
Systems . . . . . . . . . . . . . . . . . . . . . . 3-35
Cleaning
Exterior Care . . . . . . . . . . . . . . . 10-96
Interior Care . . . . . . . . . . . . . . . 10-101
Climate Control Systems
Dual Automatic . . . . . . . . . . . . . . . . 8-1
Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
Cluster, Instrument . . . . . . . . . . . . . 5-9
Collision Damage Repair . . . . . . 13-9
Compartments
Storage . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Compass . . . . . . . . . . . . . . . . . . . . . . . 5-4
Messages . . . . . . . . . . . . . . . . . . . . 5-32
Connections
OnStar ®
. . . . . . . . . . . . . . . . . . . . . . 14-4
Control . . . . . . . . . . . . . . . . . . . . . . . . 9-51
Traction and Electronic
Stability . . . . . . . . . . . . . . . . . . . . . 9-49 Control Light
Hill Descent . . . . . . . . . . . . . . . . . . 5-22
Control of a Vehicle . . . . . . . . . . . . . 9-3
Convex Mirrors . . . . . . . . . . . . . . . . 2-14
Coolant
Engine . . . . . . . . . . . . . . . . . . . . . . 10-18
Engine Temperature
Gauge . . . . . . . . . . . . . . . . . . . . . . 5-13
Engine Temperature
Warning Light . . . . . . . . . . . . . . . 5-24
Cooling System . . . . . . . . . . . . . . . 10-17
Engine Messages . . . . . . . . . . . . 5-33
Courtesy Transportation
Program . . . . . . . . . . . . . . . . . . . . . . 13-8
Cruise Control . . . . . . . . . . . . . . . . . 9-52
Light . . . . . . . . . . . . . . . . . . . . . . . . . . 5-27
Cupholders . . . . . . . . . . . . . . . . . . . . . 4-1
Customer Assistance . . . . . . . . . . 13-4
Offices . . . . . . . . . . . . . . . . . . . . . . . . 13-3
Text Telephone (TTY)
Users . . . . . . . . . . . . . . . . . . . . . . . 13-4
Customer Information
Service Publications
Ordering Information . . . . . . .13-11
Customer Satisfaction
Procedure . . . . . . . . . . . . . . . . . . . . 13-1 D Damage Repair, Collision . . . . . . 13-9
Danger, Warnings, and
Cautions . . . . . . . . . . . . . . . . . . . . . . . . iv
Data Recorders, Event . . . . . . . 13-14
Daytime Running
Lamps (DRL) . . . . . . . . . . . . . . . . . . 6-3
Defensive Driving . . . . . . . . . . . . . . . 9-3
Delayed Locking . . . . . . . . . . . . . . . . 2-9
Distracted Driving . . . . . . . . . . . . . . . 9-2
Dome Lamps . . . . . . . . . . . . . . . . . . . 6-7
Door
Ajar Light . . . . . . . . . . . . . . . . . . . . . 5-27
Ajar Messages . . . . . . . . . . . . . . . 5-33
Delayed Locking . . . . . . . . . . . . . . . 2-9
Locks . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Power Locks . . . . . . . . . . . . . . . . . . . 2-9
Drive Belt Routing, Engine . . . . . 12-4
Driver Assistance Systems . . . . 9-55
Driver Information
Center (DIC) . . . . . . . . . . . . . . . . . 5-27
Driving
Assistance Systems . . . . . . . . . . 9-59
Characteristics and
Towing Tips . . . . . . . . . . . . . . . . . 9-68
Defensive . . . . . . . . . . . . . . . . . . . . . . 9-3