2021 GMC YUKON tow

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 291
MeasurementHeight Example 1500 (mm)
H1 1 000
H2 1 060
H2−H1 60
(H2−H1)/3 20
H2−[(H2−H1)/3] 1 040
Tires
.Do not tow a trailer while using a
compact spare tire on the vehicle.
.Tires must be properly inflated to support
loads while towing a trailer. SeeTires
0 339 for instructions on proper tire
inflation.
Safety Chains
Always attach chains between the vehicle
and the trailer, and attach the chains to the
holes on the trailer hitch platform.
Instructions about safety chains may be
provided by the hitch manufacturer or by
the trailer manufacturer.
If the trailer being towed weighs up to
2 271 kg (5,000 lb) with a factory-installed
step bumper, safety chains may be attached to the attaching points on the bumper;
otherwise, safety chains should be attached
to holes on the trailer hitch.
Cross the safety chains under the tongue of
the trailer to help prevent the tongue from
contacting the road if it becomes separated
from the hitch. Always leave just enough
slack so the combination can turn. Never
allow safety chains to drag on the ground.Trailer Brakes
Loaded trailers over 900 kg (2,000 lb) must
be equipped with brake systems and with
brakes for each axle. Trailer braking
equipment conforming to Canadian
Standards Association (CSA) requirement
CAN3-D313, or its equivalent, is
recommended.State or local regulations may require
trailers to have their own braking system if
the loaded weight of the trailer exceeds
certain minimums that can vary from state
to state. Read and follow the instructions for
the trailer brakes so they are installed,
adjusted, and maintained properly. Never
attempt to tap into your vehicle's hydraulic
brake system. If you do, both the vehicle
anti-lock brakes and the trailer brakes may
not function, which could result in a crash.
Trailer Wiring Harness
The seven-pin trailer connector is mounted
in the bumper. This connector can be
plugged into a seven-pin universal
heavy-duty trailer connector available
through your dealer.
Use only a round, seven-wire connector with
flat blade terminals meeting SAE J2863
specifications for proper electrical
connectivity.
The seven-wire harness contains the
following trailer circuits:
.Yellow/Grey: Left Stop/Turn Signal
.Green/Violet: Right Stop/Turn Signal
.Grey/Brown: Taillamps
.White: Ground

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
292 Driving and Operating
.White/Green: Back-up Lamps
.Red/Green: Battery Feed
.Dark Blue: Trailer Brake
To help charge a remote (non-vehicle)
battery change drive mode to Tow Haul.
If the trailer is too light for Tow/Haul Mode,
turn on the headlamps to help charge the
battery.
Electric Brake Control Wiring Provisions
These wiring provisions are included with
the vehicle as part of the trailer wiring
package. These provisions are for an electric
brake controller.
The harness should be installed by your
dealer or a qualified service center.
Refer to the aftermarket electric trailer brake
controller owner's manual to determine wire
color coding of the electric trailer brake
controller. The wire colors on the brake
controller may be different from the vehicle.
Trailer Lamps
Always check all trailer lamps are working at
the beginning of each trip, and periodically
on longer trips.
Turn Signals When Towing a Trailer
When properly connected, the trailer turn
signals should will illuminate to indicate the
vehicle is turning, changing lanes,
or stopping. When towing a trailer, the
arrows on the instrument cluster will
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, see Tow/Haul Mode 0235.
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 0284.
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.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
294 Driving and Operating
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.
.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 right 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. This lever may also be used to request additional trailer braking at any
time. 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.
Other ITBC-Related DIC Messages
TRAILER 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.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 295
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 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 ignition 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. 2. Turn the ignition off.
3. Wait 10 seconds, then turn the ignition
back 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.
SERVICE TRAILER BRAKE SYSTEM: This
message will display when there is a
problem with the ITBC system. If this
message continues over multiple ignition
cycles, there is a problem with the ITBC
system. Have the vehicle serviced.
If either the CHECK TRAILER WIRING or
SERVICE TRAILER BRAKE SYSTEM 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 ignition off. Check the
wiring connection to the trailer and turn the
ignition 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 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.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
296 Driving and Operating
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 Control
0242.
{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,
(Continued)
Warning (Continued)
unrestrained cargo, improper trailer hitch
configuration, or improperly inflated or
incorrect vehicle or trailer tires. See
Towing Equipment0287 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
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, (Continued)

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 297
Warning (Continued)
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.
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 display.
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 also deactivates when any of
the following occur:
.The ignition 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 display.
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 assistance
features.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
298 Driving and Operating
The Trailering App Preview will appear when
the Trailering App is opened for the first
time from the Home Page. Touch GET
STARTED in the Trailering App to go into
the app.
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.
After the pop-up is displayed three times,
Don’t Remind Me will display and touching
that will turn off the trailer detection
pop-up. To turn the Trailer Detection Alert
on, select ON in the Settings tab.
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) will select Guest Trailer as the
active Trailer Profile and will dismiss the
pop-up.Create a Trailer Profile
1. Touch Create Profile on the trailer detection pop-up or touch + Add Trailer
Profile in the Trailering App.
2. Create a name for the trailer.
3. Select the trailer type.
4. Select Save Profile.
A pop-up will indicate the setup is complete.
Touch DONE to complete the process or
touch TRAILER FEATURE SETUP to set up the
Tow/Haul Mode reminder, Trailer Tire
Pressure Monitoring System, if equipped,
maintenance reminders, or towing
assistance, if equipped.
Import a Trailer Profile
A trailer profile saved to an OnStar account
can be imported to the vehicle. 1. Touch + Add Trailer Profile in the Trailering App
2. Touch Import Profile on the pop-up.
3. Select a trailer profile from the list.
4. Touch IMPORT.
A pop-up will indicate the import was
successful. Touch OK to return to the trailer
list and select the trailer profile. The Tow/ Haul Mode reminder, Brake Gain Setting and
Trailer Tire Pressure sensor learning,
if equipped, do not import.
Trailer Feature Setup
Tow/Haul Mode Reminder
To turn the Tow/Haul Mode Reminder
setting on, touch Yes. To turn it off,
touch No.
Trailer Tire Pressure Setup
If the Trailer Tire Pressure Monitoring
System (TTPMS) is detected, touch the Tire
Pressure Monitoring icon to set up tire
pressure monitoring. Touch Yes to set up
the sensors or touch No to return to the
previous screen.
The trailer tire pressure sensors can transmit
up to 7 m (23 feet) from the hitch receiver of
the vehicle.
A trailer must be electrically connected to
the vehicle before starting the
sensor-to-vehicle learn process.
After selecting Start from the Learn Sensors
screen, use the Tool Method or the Manual
Method (described below) to learn each tire
sensor, during which the current tire number
will be highlighted.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
302 Driving and Operating
Maintenance
1. List of Maintenance Reminders
2. Add a New Maintenance Reminder
The Maintenance Status view displays
reminders. Touch a reminder to edit.
Touch + New Maintenance Reminder to go
to the Select New Reminder view.
The progress bar turns yellow when the
maintenance item reaches 90% complete.
The progress bar turns red when the
maintenance item reaches 100% complete.
Maintenance Notifications
.Touch Service Complete to reset the
maintenance reminder.
.Touch Remind Me Later to delay the
reminder.
.Touch X next to Upcoming Alerts (90%)
to dismiss the alert. It will not appear
again.
.Touch X next to Maintenance Due (100%)
to delay the alert to the next ignition
cycle.
Always follow all of the maintenance
instructions that came with your trailer.
Guest Trailer Status View
Touch the Guest Trailer Profile for the status
views.
The Guest Trailer Profile Status view shows:
.Vehicle
.Connections
The Trailer Status view displays mileage
information. Touch to edit, and follow the
on-screen prompts. Mileage and fuel
economy will reset after the trailer
disconnects.
Accessory/No Trailer Status View
If the Accessory/No Trailer profile is active,
trailer status information is not available.
Checklist View
This view shows the recommended steps to
take before towing a trailer.
Touch the box next to each item if that step
has been completed.
Touch
pto access a detailed view of
each step. Within each detailed view, touch
Next and Previous to navigate between
steps.
Touch Clear All to clear the completed
statuses from all items in the current
checklist.