warning GMC YUKON 2020 Owner's Manual

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 263
3. Drive slowly until the trailer isclear of the chocks.
4. Stop and have someone pick up and store the chocks.
Launching and Retrieving
a Boat
Backing the Trailer into the Water
{Warning
.Have all passengers get out
of the vehicle before
backing onto the sloped part
of the ramp. Lower the
driver and passenger side
windows before backing
onto the ramp. This will
provide a means of escape
in the unlikely event the
vehicle slides into the water.
. If the boat launch surface is
slippery, have the driver
remain in the vehicle with
the brake pedal applied
while the boat is being
launched. The boat launch
(Continued)
Warning (Continued)
can be especially slippery at
low tide when part of the
ramp was previously
submerged at high tide. Do
not back onto the ramp to
launch the boat if you are
not sure the vehicle can
maintain traction.
. Do not move the vehicle if
someone is in the path of
the trailer. Some parts of the
trailer might be underwater
and not visible to people
who are assisting in
launching the boat.
Disconnect the wiring to the trailer
before backing the trailer into the
water to prevent damage to the
electrical circuits on the trailer.
Reconnect the wiring to the trailer
after removing the trailer from the
water. If the trailer has electric
brakes that can function when the
trailer is submerged, it might help to leave the electrical trailer connector
attached to maintain trailer brake
functionality while on the boat ramp.
To back the trailer into the water:
1. If equipped, place the vehicle in four-wheel-drive high.
2. Slowly back down the boat ramp until the boat is floating,
but no further than necessary.
3. Press and hold the brake pedal, but do not shift into
P (Park) yet.
4. Have someone place chocks under the front wheels of the
vehicle.
5. Gradually release the brake pedal to allow 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 1. Press and hold the brake pedal.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
264 Driving and Operating
2. Start the engine and shift intoa 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
(Continued)
Caution (Continued)
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 0379. 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
0 300.
Trailer Towing
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.
Trailer Weight
{Warning
Never exceed the towing capacity
for your vehicle.
Safe trailering requires monitoring
the weight, speed, altitude, road
grades, outside temperature,
dimensions of the front of the trailer,
and how frequently the vehicle is
used to tow a trailer.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 265
Trailering 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
Adjustment” underTowing
Equipment 0270 to determine if
equalizer bars are required to obtain
the maximum trailer weight rating.
See “Trailer Brakes” underTowing
Equipment 0270 to determine if
brakes are required based on your
trailer's weight. The only way to be sure the weight
is not exceeding any of these
ratings is to weigh the tow vehicle
and trailer combination, fully loaded
for the trip, getting individual
weights for each of these items.
{Warning
You and others could be seriously
injured or killed if the trailer is too
heavy or the trailer brakes are
inadequate for the load. The
vehicle may be damaged, and the
repairs would not be covered by
the vehicle warranty.
Only tow a trailer if all the steps in
this section have been followed.
Ask your dealer for advice and
information about towing a trailer.
Gross Combined Weight
Rating (GCWR)
GCWR is the total allowable weight
of the completely loaded vehicle
and trailer including any fuel,
passengers, cargo, equipment, and
accessories. Do not exceed theGCWR for your vehicle. The GCWR
for the vehicle is on the Tow Rating
Chart following.
To check that the weight of the
vehicle and trailer are within the
GCWR for the vehicle, follow these
steps:
.
Start with the "curb weight" from
the trailering information label
. Add the weight of the trailer
loaded with cargo and ready for
the trip
. Add the weight of all passengers
. Add the weight of all cargo in the
vehicle
. Add the weight of hitch hardware
such as a draw bar, ball, load
equalizer bars, or sway bars
. Add the weight of any
accessories or aftermarket
equipment added to the vehicle
The resulting weight cannot exceed
the GCWR value shown on the
Trailering Information Label.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 275
{Warning
Connecting a trailer that has an
air brake system may result in
reduced or complete loss of trailer
braking, including increased
stopping distance or trailer
instability which could result in
serious injury, death, or property
damage. Only use the ITBC
system with electric or electric
over hydraulic trailer brake
systems.
Trailer Brake Control Panel
1. Manual Trailer Brake Apply Lever
2. Trailer Gain Adjustment Buttons
The ITBC control panel is on the
instrument panel to the left of the
steering column. The control panel
allows adjustment to the amount of
output, referred to as Trailer Gain,
available to the trailer brakes and
allows manual application of the
trailer brakes. Use the ITBC control
panel and the DIC trailer brake
display page to adjust and display
power output to the trailer brakes.
Trailer Brake DIC Display Page
The ITBC display page indicates:
.Trailer Gain setting
. Output to the trailer brakes
. Trailer connection
. System operational status.
To display:
. Scroll through the DIC menu
pages
. Press a Trailer Gain (+) or (−)
button .
Activate the Manual Trailer
Brake Apply Lever
TRAILER GAIN:
Press a Trailer Gain button to recall
the current Trailer Gain setting.
Each press and release of the gain
buttons will then change the Trailer
Gain setting. Press the Trailer
Gain (+) or (−) to adjust. Press and
hold to continuously adjust the
Trailer Gain. To turn the output to
the trailer off, adjust the Trailer Gain
setting to 0.0. This setting can be
adjusted from 0.0 to 10.0 with a
trailer connected or disconnected.
TRAILER OUTPUT: This displays
anytime a trailer with electric brakes
is connected. Output to the trailer
brakes is based on the amount of
vehicle braking present and relative
to the Trailer Gain setting. Output is
displayed from 0 to 100% for each
gain setting.
The Trailer Output will indicate “- - -
- - -” on the Trailer Brake Display
Page whenever the following occur:
. No trailer is connected.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
276 Driving and Operating
.A trailer without electric brakes
is connected, no DIC message
will display
. A trailer with electric brakes has
become disconnected, a CHECK
TRAILER WIRING message
displays on the DIC
. There is a fault present in the
wiring to the trailer brakes, a
CHECK TRAILER WIRING
message displays on the DIC
. The ITBC system is not working
due to a fault, a SERVICE
TRAILER BRAKE SYSTEM
message displays in the DIC
Manual Trailer Brake Apply Lever
Slide this lever left to apply the
trailer ’s electric brakes independent
of the vehicle’s brakes. Use this
lever to adjust Trailer Gain to
achieve the proper power output to
the trailer brakes. The trailer's and
the vehicle's brake lamps will come
on when either vehicle brakes or
manual trailer brakes are applied
and properly connected. Trailer Gain Adjustment Procedure
Trailer Gain should be set for a
specific trailering condition and it
must be readjusted anytime vehicle
loading, trailer loading, or road
surface conditions change.
{Warning
Trailer brakes that are
over-gained or under-gained may
not stop the vehicle and the trailer
as intended and can result in a
crash. Always follow the
instructions to set the Trailer Gain
for the proper trailer stopping
performance.
To adjust Trailer Gain for each
towing condition: 1. Drive the vehicle with the trailer attached on a level road
surface representative of the
towing condition and free of
traffic at about 32 to 40 km/h
(20 to 25 mph) and fully apply
the Manual Trailer Brake apply
lever. Note
Adjusting Trailer Gain at speeds
lower than 32 to 40 km/h (20 to
25 mph) may result in an incorrect
gain setting.
2. Adjust the Trailer Gain, using the Trailer Gain adjustment
buttons, to just below the point
of trailer wheel lock-up,
indicated by trailer wheel
squeal or tire smoke when a
trailer wheel locks.
Note
Trailer wheel lock-up may not occur
if towing a heavily loaded trailer. In
this case, adjust the Trailer Gain to
the highest allowable setting for the
towing condition.
3. Readjust Trailer Gain any time vehicle loading, trailer loading,
or road surface conditions
change or if trailer wheel
lock-up is noticed at any time
while towing.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
278 Driving and Operating
Contact your trailer dealer for
assistance with trailer repairs and
trailer warranty information.
Trailer Sway
Control (TSC)
Vehicles with StabiliTrak have a
Trailer Sway Control (TSC) feature.
Trailer sway is unintended
side-to-side motion of a trailer while
towing. If the vehicle is towing a
trailer and the TSC detects that
sway is increasing, the vehicle
brakes are selectively applied at
each wheel, to help reduce
excessive trailer sway. If equipped
with the Integrated Trailer Brake
Control (ITBC) system, and the
trailer has an electric brake system,
StabiliTrak may also apply the trailer
brakes.If TSC is enabled, the Traction
Control System (TCS)/StabiliTrak
warning light will flash on the
instrument cluster. Reduce vehicle
speed by gradually removing your
foot from the accelerator. If trailer
sway continues, StabiliTrak can
reduce engine torque to help slow
the vehicle. TSC will not function if
StabiliTrak is turned off. See
Traction Control/Electronic Stability
Control0226.
{Warning
Trailer sway can result in a crash
and in serious injury or death,
even if the vehicle is equipped
with TSC.
(Continued)
Warning (Continued)
If the trailer begins to sway,
reduce vehicle speed by
gradually removing your foot from
the accelerator. Then pull over to
check the trailer and vehicle to
help correct possible causes,
including an improperly or
overloaded trailer, unrestrained
cargo, improper trailer hitch
configuration, or improperly
inflated or incorrect vehicle or
trailer tires. SeeTowing
Equipment 0270 for trailer ratings
and hitch setup
recommendations.
Aftermarket Electronic Trailer
Sway Control Devices
Some trailers may come equipped
with an electronic device designed
to reduce or control trailer sway.
Aftermarket equipment
manufacturers also offer similar
devices that connect to the wiring
between the trailer and the vehicle.
These devices may interfere with

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 279
the vehicle’s trailer brake systems
or other systems, including
integrated anti-sway systems,
if equipped. Messages related to
trailer connections or trailer brakes
could appear on the DIC. The
effects of these aftermarket devices
on vehicle handling or trailer brake
performance is not known.
{Warning
Use of aftermarket electronic
trailer sway control devices could
result in reduced trailer brake
performance, loss of trailer
brakes, or other malfunctions, and
result in a crash. You or others
could be seriously injured or
killed. Before using one of these
devices:
. Ask the device or trailer
manufacturer if the device
has been thoroughly tested
for compatibility with the
make, model, and year of
(Continued)
Warning (Continued)
your vehicle and any
optional equipment installed
on your vehicle.
. Before driving, check the
trailer brakes are working
properly, if equipped. Drive
the vehicle with the trailer
attached on a level road
surface that is free of traffic
at about 32-40 km/h
(20-25 mph) and fully apply
the manual trailer brake
apply lever. Also, check the
trailer brake lamps and
other lamps are functioning
correctly.
. If the trailer brakes are not
operating properly at any
time, or if a DIC message
indicates problems with the
trailer connections or trailer
brakes, carefully pull the
vehicle over to the side of
the road when traffic
conditions allow.
Trailer Tires
Special Trailer (ST) tires differ from
vehicle tires. Trailer tires are
designed with stiff sidewalls to help
prevent sway and to support heavy
loads. These features can make it
difficult to determine if the trailer tire
pressures are low only based on a
visual inspection.
Always check all trailer tire
pressures before each trip when the
tires are cool. Low trailer tire
pressure is a leading cause of trailer
tire blow-outs.
Trailer tires deteriorate over time.
The trailer tire sidewall will show the
week and year the tire was
manufactured. Many trailer tire
manufacturers recommend
replacing tires more than six
years old.
Overloading is another leading
cause of trailer tire blow-outs. Never
load your trailer with more weight
than the tires are designed to
support. The load rating is located
on the trailer tire sidewall.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
280 Driving and Operating
Always know the maximum speed
rating for the trailer tires before
driving. This may be significantly
lower than the vehicle tire speed
rating. The speed rating may be on
the trailer tire sidewall. If the speed
rating is not shown, the default
trailer tire speed rating is 105 km/h
(65 mph).Conversions and
Add-Ons
Add-On Electrical
Equipment
{Warning
The Data Link Connector (DLC) is
used for vehicle service and
Emission Inspection/Maintenance
testing. SeeMalfunction Indicator
Lamp (Check Engine Light) 0136
. A device connected to the DLC
— such as an aftermarket fleet or
driver-behavior tracking device —
may interfere with vehicle
systems. This could affect vehicle
operation and cause a crash.
Such devices may also access
information stored in the vehicle’s
systems.
Caution
Some electrical equipment can
damage the vehicle or cause
components to not work and
would not be covered by the
vehicle warranty. Always check
with your dealer before adding
electrical equipment.
Add-on equipment can drain the
vehicle's 12-volt battery, even if the
vehicle is not operating.
The vehicle has an airbag system.
Before attempting to add anything
electrical to the vehicle, see
Servicing the Airbag-Equipped
Vehicle 084 and
Adding Equipment to the
Airbag-Equipped Vehicle 084.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Vehicle Care 281
Vehicle Care
General Information
General Information . . . . . . . . . . 282
California Proposition65 Warning . . . . . . . . . . . . . . . . . 282
California Perchlorate Materials Requirements . . . . . 283
Accessories and Modifications . . . . . . . . . . . . . . . . 283
Vehicle Checks
Doing Your OwnService Work . . . . . . . . . . . . . . . 283
Hood . . . . . . . . . . . . . . . . . . . . . . . . . 284
Engine Compartment Overview . . . . . . . . . . . . . . . . . . . . 286
Engine Oil . . . . . . . . . . . . . . . . . . . . 289
Engine Oil Life System . . . . . . . 291
Automatic Transmission Fluid (6-Speed Transmission) . . . . . 292
Automatic Transmission Fluid (10-Speed Transmission) . . . 295
Engine Air Cleaner/Filter . . . . . . 296
Cooling System . . . . . . . . . . . . . . 297
Engine Overheating . . . . . . . . . . 300
Engine Fan . . . . . . . . . . . . . . . . . . . 302
Washer Fluid . . . . . . . . . . . . . . . . . 302
Brakes . . . . . . . . . . . . . . . . . . . . . . . 303 Brake Fluid . . . . . . . . . . . . . . . . . . . 304
Battery - North America . . . . . . 305
Four-Wheel Drive . . . . . . . . . . . . . 305
Front Axle . . . . . . . . . . . . . . . . . . . . 306
Rear Axle . . . . . . . . . . . . . . . . . . . . 306
Noise Control System . . . . . . . . 306
Starter Switch Check . . . . . . . . . 308
Automatic Transmission Shift
Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . . . 308
Ignition Transmission Lock Check . . . . . . . . . . . . . . . . . . . . . . . 308
Park Brake and P (Park) Mechanism Check . . . . . . . . . . 309
Wiper Blade Replacement . . . . 309
Glass Replacement . . . . . . . . . . 310
Windshield Replacement . . . . . 310
Gas Strut(s) . . . . . . . . . . . . . . . . . . 310
Headlamp Aiming
Headlamp Aiming . . . . . . . . . . . . 312
Bulb Replacement
Bulb Replacement . . . . . . . . . . . . 312
High Intensity Discharge (HID) Lighting . . . . . . . . . . . . . . . . . . . . . 312
LED Lighting . . . . . . . . . . . . . . . . . 312
Fog Lamps . . . . . . . . . . . . . . . . . . . 312
Back-Up Lamps . . . . . . . . . . . . . . 313
License Plate Lamp . . . . . . . . . . 314
Electrical System
Electrical System Overload . . . 314
Fuses and Circuit Breakers . . . 315
Engine Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . . . . 315
Instrument Panel Fuse Block
(Right) . . . . . . . . . . . . . . . . . . . . . . 320
Instrument Panel Fuse Block (Left) . . . . . . . . . . . . . . . . . 323
Rear Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . . . . 325
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . 326
All-Season Tires . . . . . . . . . . . . . . 327
Winter Tires . . . . . . . . . . . . . . . . . . 328
Low-Profile Tires . . . . . . . . . . . . . 328
All-Terrain Tires . . . . . . . . . . . . . . . 328
Tire Sidewall Labeling . . . . . . . . 329
Tire Designations . . . . . . . . . . . . . 330
Tire Terminology andDefinitions . . . . . . . . . . . . . . . . . . 331
Tire Pressure . . . . . . . . . . . . . . . . . 333
Tire Pressure for High-Speed Operation . . . . . . . . . . . . . . . . . . . 334
Tire Pressure Monitor System . . . . . . . . . . . . . . . . . . . . . . 335
Tire Pressure Monitor Operation . . . . . . . . . . . . . . . . . . . 336
Tire Inspection . . . . . . . . . . . . . . . . 340

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
282 Vehicle Care
Tire Rotation . . . . . . . . . . . . . . . . . 340
When It Is Time for NewTires . . . . . . . . . . . . . . . . . . . . . . . . 341
Buying New Tires . . . . . . . . . . . . . 342
Different Size Tires and Wheels . . . . . . . . . . . . . . . . . . . . . . 344
Uniform Tire Quality Grading . . . . . . . . . . . . . . . . . . . . . 344
Wheel Alignment and Tire Balance . . . . . . . . . . . . . . . . . . . . . 346
Wheel Replacement . . . . . . . . . . 346
Tire Chains . . . . . . . . . . . . . . . . . . . 347
If a Tire Goes Flat . . . . . . . . . . . . 347
Tire Changing . . . . . . . . . . . . . . . . 349
Full-Size Spare Tire . . . . . . . . . . 359
Jump Starting
Jump Starting - North America . . . . . . . . . . . . . . . . . . . . . 360
Towing the Vehicle
Towing the Vehicle . . . . . . . . . . . 363
Recreational VehicleTowing . . . . . . . . . . . . . . . . . . . . . . 364
Appearance Care
Exterior Care . . . . . . . . . . . . . . . . . 367
Interior Care . . . . . . . . . . . . . . . . . . 372
Floor Mats . . . . . . . . . . . . . . . . . . . . 375
General Information
For service and parts needs, visit
your dealer. You will receive
genuine GM parts and GM-trained
and supported service people.
Genuine GM parts have one of
these marks:
California Proposition
65 Warning
{Warning
Most motor vehicles, including
this one, as well as many of its
service parts and fluids, contain
and/or emit chemicals known to
the State of California to cause
cancer and birth defects or other
reproductive harm. Engine
exhaust, many parts and
systems, many fluids, and some
component wear by-products
contain and/or emit these
chemicals. For more information
go to www.P65Warnings.ca.gov/
passenger-vehicle.
See Battery - North America 0305
and
Jump Starting - North America
0 360 and the back cover.