2021 GMC YUKON engine overheat

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
44 Seats and Restraints
Obstructions
If something has blocked the driver seat
while recalling a memory position, the recall
may stop. Remove the obstruction and try
the recall again. If the memory position still
does not recall, see your dealer.
Heated and Ventilated Front
Seats
{Warning
If temperature change or pain to the skin
cannot be felt, the seat heater may cause
burns. To reduce the risk of burns, use
care when using the seat heater,
especially for long periods of time. Do
not place anything on the seat that
insulates against heat, such as a blanket,
cushion, cover, or similar item. This may
cause the seat heater to overheat. An
overheated seat heater may cause a burn
or may damage the seat.Heated and Ventilated Seat Buttons Shown,Heated Seat Buttons Similar
If equipped, the buttons are near the
climate controls on the center stack. To
operate, the engine must be on.
Press
Ior+to heat the driver or
passenger seatback.
Press
Jorzto heat the driver or
passenger seatback and cushion.
Press
Cor{, if available, to ventilate the
driver or passenger seat. A ventilated seat
has a fan that pulls or pushes air through
the seat. The air is not cooled. When this feature is off, the heated and
ventilated seat symbols on the buttons are
white. When a heated seat is turned on, the
symbol turns red. When a ventilated seat is
turned on, the symbol turns blue.
Press the button once for the highest
setting. With each press of the button, the
seat will change to the next lower setting,
and then to the off setting. The indicator
lights next to the buttons indicate three for
the highest setting and one for the lowest.
If the heated seats are on high, the level
may automatically be lowered after
approximately 30 minutes.
The passenger seat may take longer to
heat up.
Auto Heated and Ventilated Seats
When the vehicle is on, this feature will
automatically activate the heated or
ventilated seats at the level required by the
vehicle’s interior temperature.
The active high, medium, low, or off heated
or ventilated seat level will be indicated by
the manual heated or ventilated seat
buttons on the center stack. Use the manual
heated or ventilated seat buttons on the
center stack to turn auto heated or
ventilated seats off. If the passenger seat is

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
116 Instruments and Controls
Trailer Sway Control Light
This light will flash when Trailer Sway
Control is active. SeeTrailer Sway Control
(TSC) 0295.
Electronic Stability Control (ESC)
Off Light
This light comes on briefly while starting
the engine. If it does not, have the vehicle
serviced by your dealer.
This light comes on when the ESC system is
turned off. If ESC is off, the Traction Control
System (TCS) is also off. If the ESC and TCS are off, the system does
not assist in controlling the vehicle. Turn on
the TCS and the ESC systems and the
warning light turns off.
See
Traction Control/Electronic Stability
Control 0242.
Engine Coolant Temperature
Warning Light
This light comes on briefly while starting
the vehicle.
If it does not, have the vehicle serviced by
your dealer. If the system is working
normally the indicator light goes off.
Caution
The engine coolant temperature warning
light indicates that the vehicle has
overheated. Driving with this light on can
(Continued)
Caution (Continued)
damage the engine and it may not be
covered by the vehicle warranty. See
Engine Overheating 0322.
The engine coolant temperature warning
light comes on when the engine has
overheated.
If this happens, pull over and turn off the
engine as soon as possible. See Engine
Overheating 0322.
Driver Mode Control Light
This light comes on when Sport Mode is
selected.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
218 Driving and Operating
Warning (Continued)
case overrides the transmission. You or
someone else could be injured. If leaving
the vehicle, set the parking brake and
shift the transmission to P (Park). Shift
the transfer case to any position but
N (Neutral).
.When driving down a hill, keep the
vehicle headed straight down. Use a low
gear because the engine will work with
the brakes to slow the vehicle and help
keep the vehicle under control.
{Warning
Heavy braking when going down a hill
can cause your brakes to overheat and
fade. This could cause loss of control and
you or others could be injured or killed.
Apply the brakes lightly when descending
a hill and use a low gear to keep vehicle
speed under control.
If the vehicle stalls on a hill: 1. Apply the brakes to stop the vehicle, and then apply the parking brake. 2. Shift into P (Park) and then restart the
engine.
.If driving uphill when the vehicle
stalls, shift to R (Reverse), release the
parking brake, and back
straight down.
.Never try to turn the vehicle around.
If the hill is steep enough to stall the
vehicle, it is steep enough to cause it
to roll over.
.If you cannot make it up the hill,
back straight down the hill.
.Never back down a hill in N (Neutral)
using only the brake. The vehicle can
roll backward quickly and you could
lose control.
.If driving downhill when the vehicle
stalls, shift to a lower gear, release
the parking brake, and drive straight
down the hill.
3. If the vehicle cannot be restarted after stalling, set the parking brake, shift into
P (Park), and turn the vehicle off.
3.1. Leave the vehicle and seek help.
3.2. Stay clear of the path the vehicle would take if it rolled downhill.
.Avoid turns that take the vehicle across
the incline of the hill. A hill that can be
driven straight up or down might be too
steep to drive across. Driving across an
incline puts more weight on the downhill
wheels, which could cause a downhill
slide or a rollover.
.Surface conditions can be a problem.
Loose gravel, muddy spots, or even wet
grass can cause the tires to slip sideways,
downhill. If the vehicle slips sideways, it
can hit something that will trip it —a
rock, a rut, etc. —and roll over.
.Hidden obstacles can make the steepness
of the incline more severe. If a rock is
driven across with the uphill wheels, or if
the downhill wheels drop into a rut or
depression, the vehicle can tilt even more.
.If an incline must be driven across, and
the vehicle starts to slide, turn downhill.
This should help straighten out the
vehicle and prevent the side slipping.
{Warning
Getting out of the vehicle on the
downhill side when stopped across an
incline is dangerous. If the vehicle rolls
over, you could be crushed or killed.
(Continued)

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
220 Driving and Operating
types of driving conditions and avoid driving
through large puddles and deep-standing or
flowing water.
{Warning
Wet brakes can cause crashes. They
might not work as well in a quick stop
and could cause pulling to one side. You
could lose control of the vehicle.
After driving through a large puddle of
water or a car/vehicle wash, lightly apply
the brake pedal until the brakes work
normally.
Flowing or rushing water creates strong
forces. Driving through flowing water
could cause the vehicle to be carried
away. If this happens, you and other
vehicle occupants could drown. Do not
ignore police warnings and be very
cautious about trying to drive through
flowing water.
Hydroplaning
Hydroplaning is dangerous. Water can build
up under the vehicle's tires so they actually
ride on the water. This can happen if theroad is wet enough and you are going fast
enough. When the vehicle is hydroplaning, it
has little or no contact with the road.
There is no hard and fast rule about
hydroplaning. The best advice is to slow
down when the road is wet.
Other Rainy Weather Tips
Besides slowing down, other wet weather
driving tips include:
.Allow extra following distance.
.Pass with caution.
.Keep windshield wiping equipment in
good shape.
.Keep the windshield washer fluid reservoir
filled.
.Have good tires with proper tread depth.
See
Tires 0339.
.Turn off cruise control.
Hill and Mountain Roads
Driving on steep hills or through mountains
is different than driving on flat or rolling
terrain. Tips include:
.Keep the vehicle serviced and in good
shape.
.Check all fluid levels and brakes, tires,
cooling system, and transmission.
.Shift to a lower gear when going down
steep or long hills.
{Warning
Using the brakes to slow the vehicle on a
long downhill slope can cause brake
overheating, can reduce brake
performance, and could result in a loss of
braking. Shift the transmission to a lower
gear to let the engine assist the brakes
on a steep downhill slope.
{Warning
Coasting downhill in N (Neutral) or with
the ignition off is dangerous. This can
cause overheating of the brakes and loss
of steering assist. Always have the engine
running and the vehicle in gear.
.Drive at speeds that keep the vehicle in
its own lane. Do not swing wide or cross
the center line.
.Be alert on top of hills; something could
be in your lane (e.g., stalled car, crash).
.Pay attention to special road signs (e.g.,
falling rocks area, winding roads, long
grades, passing or no-passing zones) and
take appropriate action.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
222 Driving and Operating
If stuck too severely for the traction system
to free the vehicle, turn the traction system
off and use the rocking method. See
Traction Control/Electronic Stability Control
0242.
{Warning
If the vehicle's tires spin at high speed,
they can explode, and you or others
could be injured. The vehicle can
overheat, causing an engine compartment
fire or other damage. Spin the wheels as
little as possible and avoid going above
56 km/h (35 mph).
Rocking the Vehicle to Get it Out
Turn the steering wheel left and right to
clear the area around the front wheels. Turn
off any traction system. Shift back and forth
between R (Reverse) and a low forward gear,
spinning the wheels as little as possible. To
prevent transmission wear, wait until the
wheels stop spinning before shifting gears.
Release the accelerator pedal while shifting,
and press lightly on the accelerator pedal
when the transmission is in gear. Slowly
spinning the wheels in the forward and
reverse directions causes a rocking motion
that could free the vehicle. If that does not get the vehicle out after a few tries, it
might need to be towed out. If the vehicle
does need to be towed out, see
Towing the
Vehicle 0370.
Recovery Hooks
{Warning
Never pull on recovery hooks from the
side. The hooks could break and you and
others could be injured. When using
recovery hooks, always pull the vehicle
from the front.
Caution
Never use recovery hooks to tow the
vehicle. The vehicle could be damaged,
and the repairs would not be covered by
the vehicle warranty.
There are recovery hooks at the front of the
vehicle. Use them if the vehicle is stuck
off-road and needs to be pulled some place
to continue driving.
Vehicle Load Limits
It is very important to know how much
weight the vehicle can carry. This
weight is called the vehicle capacity
weight and includes the weight of all
occupants, cargo, and all
nonfactory-installed options. Two labels
on the vehicle may show how much
weight it was designed to carry, the
Tire and Loading Information label and
the Certification/Tire label.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
228 Driving and Operating
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 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 ignition is
on, but the vehicle will not be able to be
driven. The engine will not start in Service
Mode. Press the button again to turn the
ignition 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.
SeeAdd-On Electrical Equipment 0306. Shift the vehicle into 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 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 the ENGINE START/
STOP position to continue engine
cranking.
Caution
Cranking the engine for long periods of
time, by trying to start the engine
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
pushing the accelerator pedal all the way
to the floor and holding it there while
pressing ENGINE START/STOP for up to a
maximum of 15 seconds. Wait at least
15 seconds between each try, to allow
the cranking motor to cool down. When
the engine starts, let go of the button
and accelerator. If the vehicle starts
briefly but then stops again, do the
same thing. This clears the extra gasoline
from the engine. Do not race the engine
immediately after starting it. Operate
the engine and transmission gently until
the oil warms up and lubricates all
moving parts.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
230 Driving and Operating
.Infotainment System
.Power Windows (during RAP this
functionality will be lost when any door
is opened)
.Sunroof (during RAP this functionality will
be lost when any door is opened)
.Auxiliary Power Outlet
.Audio System
.OnStar System
Shifting Into Park
{Warning
It can be dangerous to get out of the
vehicle if the vehicle is not in P (Park)
with the parking brake 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 you are pulling a
trailer, seeDriving Characteristics and
Towing Tips 0280.
1. Hold the brake pedal down and set the parking brake. See Electric Parking Brake
0 240. 2. Press the P (Park) switch on the center
stack.
3. Press ENGINE START/STOP to turn the engine off.
If the vehicle is shifted into P (Park) on a
hill, the Electric Parking Brake (EPB) may
apply automatically. The driver may not be
able to release the EPB using the EPB
switch. It should automatically release when
the vehicle is shifted out of P (Park).
Leaving the Vehicle with the Engine
Running
{Warning
It can be dangerous to leave the vehicle
with the engine running. It could
overheat and catch fire.
It is dangerous to get out of the vehicle
if the vehicle is not in P (Park) with the
parking brake set. The vehicle can roll.
Do not leave the vehicle when the engine
is running. 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, (Continued)
Warning (Continued)
always set the parking brake and shift
the vehicle to P (Park). SeeShifting Into
Park 0230. If you are towing a trailer,
see Driving Characteristics and Towing
Tips 0280.
If you have to leave the vehicle with the
engine running, the vehicle must be in
P (Park) with the parking brake set.
Confirm that the vehicle is in P (Park).
Shifting out of Park
This vehicle is equipped with an electronic
transmission.
To shift out of P (Park): 1. Ensure the engine is running.
2. Apply the brake pedal.
3. Press or pull the desired shift switch. For N (Neutral) press and hold the N (Neutral)
switch until the N indicator
illuminates red.
4. The P indicator will turn white and the gear indicator will turn red when the
vehicle is no longer in P (Park).

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
282 Driving and Operating
beyond the passed vehicle before returning
to the lane. Pass on level roadways. Avoid
passing on hills if possible.
Backing Up
Hold the bottom of the steering wheel with
one hand. To move the trailer to the left,
move that hand to the left. To move the
trailer to the right, move that hand to the
right. Always back up slowly and, if possible,
have someone guide you.
Making TurnsCaution
Turn more slowly and make wider arcs
when towing a trailer to prevent damage
to your vehicle. Making very sharp turns
could cause the trailer to contact the
vehicle.
Make wider turns than normal when towing,
so trailer will not go over soft shoulders,
over curbs, or strike road signs, trees,
or other objects. Always signal turns well in
advance. Do not steer or brake suddenly.
Driving on Grades
Reduce speed and shift to a lower gear
before starting down a long or steep
downhill grade. If the transmission is not
shifted down, the brakes may overheat and
result in reduced braking efficiency.
The vehicle 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.
When towing at higher altitudes, engine
coolant will boil at a lower temperature
than at lower altitudes. If the engine is
turned off immediately after towing at high
altitude on steep uphill grades, the vehicle
could show signs similar to engine
overheating. To avoid this, let the engine
run, 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 0322.
Parking on Hills
{Warning
To prevent serious injury or death,
always park your vehicle and trailer on a
level surface when possible.
When parking your vehicle and your trailer
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, gradually release the brake pedal to
allow the chocks to absorb the load of
the trailer.
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.
.Start the engine.
.Shift into a gear.
.Release the parking brake.