2021 GMC YUKON overheating

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
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
244 Driving and Operating
For vehicles with four corner air suspension
StabiliTrak/ESC will automatically turn on if
the vehicle exceeds 32 km/h (20 mph).
The vehicle has a Trailer Sway Control (TSC)
feature and a Hill Start Assist (HSA) feature.
SeeTrailer Sway Control (TSC) 0295 or
Hill Start Assist (HSA) 0242.
Adding accessories can affect the vehicle
performance. See Accessories and
Modifications 0309.
Hill Descent Control (HDC)
If equipped, Hill Descent Control (HDC) sets
and maintains vehicle speed while driving
down steep grades in a forward or reverse
gear. The HDC switch is on the instrument
panel to the left of the steering wheel.Press5to enable or disable HDC. Vehicle
speed must be below 60 km/h (37 mph).
When enabled, the HDC light displays on
the instrument cluster.
A blinking HDC light indicates the system is
actively applying the brakes to maintain
vehicle speed. HDC can maintain vehicle
speeds between 1 and 30 km/h (1 and
19 mph) on grades greater than or equal
to 5%. If HDC is to be used for more than
three minutes or on grades steeper than
25%, the transfer case should be put into
Four-Wheel Drive Low (4
n) to reduce the
possibility of brake overheating.
Noise from the hydraulic brake control
module is normal when HDC is active.
When HDC is activated, the initial HDC
speed is set to the current driving speed.
It can be increased or decreased by pressing
+RES or SET- on the steering wheel, or by
applying the accelerator or brake pedal. This
adjusted speed becomes the new set speed.
HDC will remain enabled between 30 and
60 km/h (19 and 37 mph); however, vehicle
speed cannot be set or maintained in this
range. HDC will automatically disable if the
vehicle speed is above 80 km/h (50 mph) or
above 60 km/h (37 mph) for at least
30 seconds.
5must be pressed again to re-enable HDC.
HDC may disable after an extended period
of use. If this happens, HDC will require
time to cool down. The length of time HDC
remains active depends on road conditions,
grade, set speed, vehicle loading, and
outside temperature.

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.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
284 Driving and Operating
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. SeeMaintenance
Schedule 0384. It is especially important to
check the automatic transmission fluid,
engine oil, axle lubricant, belts, cooling
system, and brake system before and during
each trip.
Check periodically 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 0322.
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, durability,
and fuel economy. 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.
Trailer Weight
{Warning
Never exceed the towing capacity for
your vehicle. Safe trailering requires monitoring the
weight, speed, altitude, road grades, outside
temperature, and how frequently the vehicle
is used to tow a trailer.
Trailer Weight Ratings
When towing a trailer, the combined weight
of the vehicle, vehicle contents, trailer, and
trailer contents must be below all of the
maximum weight ratings for the vehicle,
including:
.GCWR: Gross Combined Weight Rating
.GVWR: Gross Vehicle Weight Rating
.Maximum Trailer Weight Rating
.GAWR-RR: Gross Axle Weight Rating-Rear
.Maximum Trailer Tongue Weight Rating
See “Weight-Distributing Hitch and
Adjustment” underTowing Equipment 0287
to determine if equalizer bars are required
to obtain the maximum trailer weight
rating.
See “Trailer Brakes” underTowing
Equipment 0287 to determine if brakes are
required based on your trailer's weight.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
308 Vehicle Care
Vehicle Care
General Information
General Information . . . . . . . . . . . . . . . . . . 309
California Proposition 65 Warning . . . . . 309
California Perchlorate MaterialsRequirements . . . . . . . . . . . . . . . . . . . . . . . 309
Accessories and Modifications . . . . . . . . . 309
Vehicle Checks
Doing Your Own Service Work . . . . . . . . . 310
Hood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
Engine Compartment Overview . . . . . . . . 312
Engine Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
Engine Oil Life System . . . . . . . . . . . . . . . . . 316
Automatic Transmission Fluid . . . . . . . . . . 317
Engine Air Filter Life System . . . . . . . . . . . 318
Engine Air Cleaner/Filter . . . . . . . . . . . . . . . 318
Cooling System . . . . . . . . . . . . . . . . . . . . . . . . 319
Engine Overheating . . . . . . . . . . . . . . . . . . . . 322
Engine Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Washer Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Brake Pad Life System . . . . . . . . . . . . . . . . . 325
Brake Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
Battery - North America . . . . . . . . . . . . . . . 327
Four-Wheel Drive . . . . . . . . . . . . . . . . . . . . . . 327
Front Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328
Rear Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328 Park Brake and P (Park) Mechanism
Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328
Wiper Blade Replacement . . . . . . . . . . . . . 329
Glass Replacement . . . . . . . . . . . . . . . . . . . . 330
Windshield Replacement . . . . . . . . . . . . . . 330
Gas Strut(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Headlamp Aiming
Front Headlamp Aiming . . . . . . . . . . . . . . . 331
Bulb Replacement
LED Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Electrical System
Electrical System Overload . . . . . . . . . . . . . 331
Fuses and Circuit Breakers . . . . . . . . . . . . . 331
Engine Compartment Fuse Block . . . . . . . 332
Instrument Panel Fuse Block . . . . . . . . . . . 335
Rear Compartment Fuse Block . . . . . . . . . 337
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
All-Season Tires . . . . . . . . . . . . . . . . . . . . . . . 340
Winter Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
Low-Profile Tires . . . . . . . . . . . . . . . . . . . . . . 340
All-Terrain Tires . . . . . . . . . . . . . . . . . . . . . . . 340
Tire Sidewall Labeling . . . . . . . . . . . . . . . . . . 341
Tire Designations . . . . . . . . . . . . . . . . . . . . . . 342
Tire Terminology and Definitions . . . . . . 342
Tire Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . 344
Tire Pressure for High-Speed Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 345 Tire Pressure Monitor System . . . . . . . . . 346
Tire Pressure Monitor Operation . . . . . . . 347
Tire Inspection . . . . . . . . . . . . . . . . . . . . . . . . 349
Tire Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . 350
When It Is Time for New Tires . . . . . . . . . 351
Buying New Tires . . . . . . . . . . . . . . . . . . . . . . 351
Different Size Tires and Wheels . . . . . . . . 352
Uniform Tire Quality Grading . . . . . . . . . . 353
Wheel Alignment and Tire Balance . . . . 354
Wheel Replacement . . . . . . . . . . . . . . . . . . . 354
Tire Chains . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
If a Tire Goes Flat . . . . . . . . . . . . . . . . . . . . . 355
Tire Changing . . . . . . . . . . . . . . . . . . . . . . . . . 356
Full-Size Spare Tire . . . . . . . . . . . . . . . . . . . . 366
Jump Starting
Jump Starting - North America . . . . . . . . 367
Towing the Vehicle
Towing the Vehicle . . . . . . . . . . . . . . . . . . . . 370
Recreational Vehicle Towing . . . . . . . . . . . 371
Appearance Care
Exterior Care . . . . . . . . . . . . . . . . . . . . . . . . . . 374
Interior Care . . . . . . . . . . . . . . . . . . . . . . . . . . . 378
Floor Mats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
320 Vehicle Care
6.2L V8 Engine
1. Engine Electric Cooling Fans (Outof View)
2. Coolant Surge Tank and Pressure Cap
{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.
{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, see Engine Overheating 0322.
What to Use
{Warning
Plain water, or other liquids such as
alcohol, can boil before the proper
coolant mixture will. With plain water or
(Continued)
Warning (Continued)
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.
.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.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
322 Vehicle Care
Caution
Failure to follow the specific coolant fill
procedure could cause the engine to
overheat and could cause system
damage. If coolant is not visible in the
surge tank, contact your dealer.
If no coolant is visible in the surge tank, add
coolant.
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 indicated 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.
Caution
If the pressure cap is not tightly installed,
coolant loss and engine damage may
occur. Be sure the cap is properly and
tightly secured.
Engine Overheating
Caution
Do not run the engine if there is a leak
in the engine cooling system. This can
cause a loss of all coolant and can
damage the system and vehicle. Have
any leaks fixed right away.
The vehicle has several indicators to warn of
engine overheating.
There is a coolant temperature gauge and a
engine coolant temperature warning light in
the vehicle's instrument cluster. See Engine
Coolant Temperature Gauge 0108 and
Engine Coolant Temperature Warning Light
0 116.
In addition, there are ENGINE OVERHEATED
STOP ENGINE, ENGINE OVERHEATED IDLE
ENGINE, and ENGINE POWER IS REDUCED
messages in the Driver Information
Center (DIC).
If the decision is made not to lift the hood
when this warning appears, get service help
right away. See Roadside Assistance Program
0 402.