2023 GMC YUKON DENALI warning

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-16417394) - 2023 - CRC - 5/16/22
Driving and Operating 291
towing a trailer, the arrows on the
instrument cluster illuminate even if the
trailer is not properly connected or the bulbs
are burned out.
Tow/Haul Mode
For instructions on how to enter Tow/Haul
mode, seeDriver Mode Control 0217.
Tow/Haul assists when pulling a heavy
trailer or a large or heavy load.
Tow/Haul Mode is designed to be most
effective when the vehicle and trailer
combined weight is at least 75% of the
vehicle's Gross Combined Weight Rating
(GCWR). See “Maximum Trailer Weight”
under Trailer Towing 0281.
Tow/Haul Mode is most useful when towing
a heavy trailer or carrying a large or
heavy load:
.through rolling terrain
.in stop-and-go traffic
.in busy parking lots
Operating the vehicle in Tow/Haul Mode
when lightly loaded or not towing will not
cause damage; however, it is not
recommended and may result in unpleasant
engine and transmission driving
characteristics and reduced fuel economy.
Integrated Trailer Brake Control System
The vehicle may have an Integrated Trailer
Brake Control (ITBC) system for use with
electric trailer brakes or most electric over
hydraulic trailer brake systems. These
instructions apply to both types of electric
trailer brakes.
This symbol is on the Trailer Brake Control
Panel on vehicles with an ITBC system. The
power output to the trailer brakes is
proportional to the amount of vehicle
braking. This available power output to the
trailer brakes can be adjusted to a wide
range of trailering situations.
The ITBC system is integrated with the
vehicle’s brake, anti-lock brake, and
StabiliTrak/Electronic Stability Control (ESC)
systems. In trailering conditions that cause
the vehicle’s anti-lock brake or StabiliTrak/
ESC systems to activate, power sent to the
trailer's brakes will be automatically adjusted to minimize trailer wheel lock-up.
This does not imply that the trailer has
StabiliTrak/ESC.
If the vehicle’s brake, anti-lock brake,
or StabiliTrak/ESC systems are not
functioning properly, the ITBC system may
not function fully or at all. Make sure all of
these systems are fully operational to allow
the ITBC system to function properly.
The ITBC system is powered through the
vehicle's electrical system. Turning the
ignition off will also turn off the ITBC
system. The ITBC system is fully functional
only when the ignition is in ON/RUN.
{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.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-16417394) - 2023 - CRC - 5/16/22
Driving and Operating 293
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.
Other ITBC-Related DIC Messages
TRAILER BRAKES CONNECTED: This message
will briefly display when a trailer with
electric brakes is first connected to the
vehicle. This message will automatically turn
off in about 10 seconds. This message can
be acknowledged before it automatically
turns off. CHECK TRAILER WIRING: This message will
display if:
.The ITBC system first determines
connection to a trailer with electric brakes
and then the trailer harness becomes
disconnected from the vehicle.
If the disconnect occurs while the vehicle
is stationary, this message will
automatically turn off in about
30 seconds. This message will also turn
off if it is acknowledged or if the trailer
harness is reconnected.
If the disconnect occurs while the vehicle
is moving, this message will continue
until the vehicle is turned off. This
message will also turn off if it is
acknowledged or if the trailer harness is
reconnected.
.There is an electrical fault in the wiring to
the trailer brakes. This message will
continue as long as there is an electrical
fault in the trailer wiring. This message
will also turn off if it is acknowledged.
To determine whether the electrical fault is
on the vehicle side or trailer side of the
trailer wiring harness connection: 1. Disconnect the trailer wiring harness from the vehicle.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-16417394) - 2023 - CRC - 5/16/22
294 Driving and Operating
2. Turn the vehicle off.
3. Wait 10 seconds, then turn the vehicleback to RUN.
4. If the CHECK TRAILER WIRING message reappears, the electrical fault is on the
vehicle side.
If the CHECK TRAILER WIRING message only
reappears when connecting the trailer wiring
harness to the vehicle, the electrical fault is
on the trailer side.
TRAILER BRAKES DISABLED SERVICE
REQUIRED: This message will display when
there is a problem with the ITBC system.
If this message continues over multiple
restarts, have the vehicle serviced.
If either the CHECK TRAILER WIRING, TRAILER
BRAKES DISABLED SERVICE REQUIRED,
SERVICE TRAILER BRAKES, HOLD LAST KNOWN
GAIN, or REDUCED TRAILER BRAKING
message displays while driving, the ITBC
system may not be fully functional or may
not function at all. When traffic conditions
allow, carefully pull the vehicle over to the
side of the road and turn the vehicle off.
Check the wiring connection to the trailer
and turn the vehicle back on. If either of
these messages continues, either the vehicle
or trailer needs service. A GM dealer may be able to diagnose and
repair problems with the trailer. However,
any diagnosis and repair of the trailer is not
covered under the vehicle warranty. Contact
your trailer dealer for assistance with trailer
repairs and trailer warranty information.
Trailer Sway Control (TSC)
Vehicles with StabiliTrak/Electronic Stability
Control (ESC) 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 help slow the
vehicle down. TSC will not function if
StabiliTrak is turned off. See
Traction
Control/Electronic Stability Control 0214.
{Warning
Trailer sway can result in a crash and in
serious injury or death, even if the
vehicle is equipped with TSC.
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
(Continued)

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-16417394) - 2023 - CRC - 5/16/22
Driving and Operating 295
Warning (Continued)
configuration, or improperly inflated or
incorrect vehicle or trailer tires. See
Towing Equipment0285 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 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 (Continued)
Warning (Continued)
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 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.
If the vehicle is equipped with a trailer tire
pressure monitoring system, see the trailer
tire pressure monitoring system description
and the trailering app.
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-16417394) - 2023 - CRC - 5/16/22
296 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).
Trailering App
Trailer Lights App
If equipped, the Trailer Lights App is on the
home page of the infotainment screen.
Touch Start to cycle the trailer lamps on and
off to determine if they are working. The
test follows this sequence:1. The running lights turn on first and remain on throughout the sequence.
2. The brake lights turn on for about two seconds.
3. The left turn signal light flashes three times.
4. The right turn signal light flashes three times.
5. The reverse lights turn on for about two seconds. 6. Steps 2–5 repeat for approximately
one minute and 45 seconds, or until the
test deactivates.
Touch Stop to stop the test. The test will
automatically end after one minute and
45 seconds.
The sequence deactivates when any of the
following occur:
.The vehicle is turned off.
.The transmission is shifted out of P (Park).
.The brake pedal is pressed.
.The turn signal is activated.
.The hazard warning lights are activated.
Trailering App
If equipped, the Trailering App is on the
home page of the infotainment screen.
If equipped, this feature allows profiles for
connected trailers to be created to view
status, to store and track trailer usage
information, and to set up towing assist
features.
The Trailering App welcome page will appear
when the Trailering App is opened for the
first time from the Home Page. When a trailer is electrically connected and
a trailer profile has not been created, there
will be an option to create a profile, use a
guest profile, or select Accessory/No trailer.
When a trailer is electrically connected and
after a Trailer Profile has been created, the
trailer detection pop-up will appear with a
list of all of the custom Trailer Profiles made
on the vehicle. To load an existing Trailer
Profile, select one of the Trailer Profiles
listed, or load the Guest Trailer Profile by
selecting GUEST TRAILER. Touching
Accessory/No trailer will select Accessory/No
trailer as the active Trailer Profile and will
dismiss the pop-up. Shifting the vehicle from
P (Park) selects Guest Trailer as the active
Trailer Profile and will dismiss the pop-up.
Create a Trailer Profile
Touch Add Trailer on the trailer detection
pop-up or touch + Add Trailer in the
Trailering App.
Follow on-screen instructions to set up
profile.
After a profile is created, set up for
additional features may become available,
such as Tow/Haul mode reminder, Trailer
Tire Pressure Monitoring System,
maintenance reminders, or towing assist.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-16417394) - 2023 - CRC - 5/16/22
300 Driving and Operating
Trailering App System will not display a
Trailer Detection Alert to the user when a
trailer is connected.
When a trailer is connected and the vehicle
is off, the Trailering App System will
periodically pulse the lighting circuits of the
trailer to verify it is still connected. The
trailer lights may periodically flash as a
result of this trailer connection detection.
These flashes may be more visible in dark
ambient light environments. The flashing or
flickering lights are a normal condition and
the Trailering App System has built-in
protections to prevent the battery from
draining. When Theft Alert is enabled, the
frequency and pattern of this flashing will
change.
If a connected trailer becomes disconnected,
a message about the trailer disconnect will
appear on the DIC immediately (if vehicle is
on) or the next time the vehicle is turned on
(if trailer was disconnected while vehicle is
off). Check your trailer connection if needed.
Connection Problem
If any of the trailer connections are lost, a
message about the connection issue will
appear on the Driver Information Center(DIC). The infotainment display will also
show the connection issue in the Lights
Status view.
Connection Trailer Lighting Faults Detected
The Trailering App System monitors for
electrical faults on the trailer lights.
A message about the lighting issue will
appear on the DIC. The infotainment display
will also show the lighting issue in the
Lights Status view. Repair your trailer lights
if needed. A trailer lighting issue is not
covered by your GM warranty.
The Running Lights connection may not
detect partial outages. Activate the light test
to check all trailer lamps. See
“Light Test”
following.
Light Test
Touch Start Light Test to cycle the trailer
lights on and off to determine if they are
working. The test follows this sequence:
1. The running lights turn on first and remain on throughout the sequence.
2. The brake lights turn on for about two seconds.
3. The left turn signal light flashes three times. 4. The right turn signal light flashes three
times.
5. The reverse lights turn on for about two seconds.
6. Steps 2-5 repeat for approximately on minute and 45 seconds, or until the test
deactivates.
Touch Stop to stop the test. The test will
automatically end after one minute and
45 seconds.
The sequence also deactivates when any of
the following occur:
.The vehicle is turned off.
.The transmission is shifted out of
P (Park).
.The brake pedal is pressed.
.The turn signal is activated.
.The hazard warning lights are activated.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
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Driving and Operating 305
Maintenance Alerts
Touch Maintenance Alert to turn on/off
Maintenance Alerts for the selected profile.
These alerts are based on the Trailer Profile,
so the settings for each Trailer Profile must
be turned on or off.
The setting is on by default for each profile.
All Maintenance Alerts for that active Trailer
Profile will be received.
Turn this setting off to not receive any of
the Maintenance Alerts when the Trailer
Profile is active.
Theft Alert
Theft alert can be set if a trailer is
connected and the alert is enabled. When
the trailer is disconnected and the vehicle is
off, an alarm will sound.
Touch Theft Alert to turn on/off Theft Alerts
for the selected profile. These alerts are
based on the Trailer Profile, so the settings
for each Trailer Profile must be turned on
or off.
This setting will be off by default for each
Trailer Profile, including the Guest Trailer
Profile.A smartphone will receive a notification that
the trailer related to the selected Trailer
Profile is disconnected from the vehicle,
if the setting is on for the active Trailer
Profile, the vehicle has an OnStar or
connected service plan and the smartphone
number has been added to the account for
this notification.
If the setting is turned off for a given Trailer
Profile, the smartphone will not receive this
security notification even if the Trailer
Profile is active.
Tow/Haul Mode Reminder
This is a reminder to turn on the Tow/Haul
mode when towing a trailer. See
Driver
Mode Control 0217.
Touch Tow/Haul Mode Reminder to turn on/
off Tow/Haul Mode reminders for the
selected profile. These alerts are based on
the Trailer Profile, so the settings for each
Trailer Profile must be turned on or off.
This setting will default to OFF for each
Trailer Profile, including the Guest Trailer
Profile. If Tow/Haul Mode is off and this setting is
on for a Trailer Profile, each time the vehicle
is turned on, a reminder will appear to turn
on Tow/Haul Mode when the Trailer Profile
is active.
If Tow/Haul Mode is on and this setting is
on for a Trailer Profile, the reminder will not
appear when the Trailer Profile is active.
Conversions and Add-Ons
Add-On Electrical Equipment
{Warning
The Data Link Connector (DLC) is used for
vehicle service and Emission Inspection/
Maintenance testing. See
Malfunction
Indicator Lamp (Check Engine Light) 0113.
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.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
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306 Driving and Operating
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.
{Warning
Certain mobile radio equipment,
like amplifiers and antennas used for
two-way communication, can interfere
with some vehicle systems. Always
ensure this equipment is supplied with
proper local grounding. Follow all of the
instructions that came with the
equipment and see your GM dealer for
additional mobile radio installation
instructions.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 070 and
Adding Equipment to the Airbag-Equipped
Vehicle 070.