ECU GMC YUKON 2021 Service Manual

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
190 Infotainment System
To move, touch and hold the favorite, and
then drag up or down to rearrange the
position.
.Set Number of Audio Favorites: Touch to
select how many favorites pages can be
viewed from the audio application. The
Auto setting will automatically adjust this
number based on the number of favorites
you have saved. Touch Auto, 5, 10, 15, 20,
25, 30, 35, or 40.
Updates
If equipped, the vehicle can download and
install select software updates over a
wireless connection. The system will prompt
for certain updates to be downloaded and
installed. There is also an option to check
for updates manually.
To manually check for updates, touch
Settings on the Home Page and select the
System tab. Go to the Vehicle Software
section and touch Updates. Follow the
on-screen prompts. The steps to check for,
download, and install updates may vary by
vehicle.
The vehicle can be used normally during the
software download. Once the download is
complete, there may be a prompt to accept
the installation of the update upon the next ignition cycle or the next time the vehicle is
shifted into P (Park). For most updates, the
vehicle will be disabled and cannot be driven
during the installation. The system will
deliver messages indicating success or error
during and after the download and
installation processes.
Downloading Over-the-Air vehicle software
updates requires Internet connectivity, which
can be accessed through the vehicle’s
built-in 4G LTE connection, if equipped and
active. If required, data plans are provided
by a third party. Optionally, a secure Wi-Fi
hotspot such as a compatible mobile device
hotspot, home hotspot, or public hotspot
can be used. Applicable data rates may
apply.
To connect the infotainment system to a
secured mobile device hotspot, home
hotspot, or public hotspot, touch Settings on
the Home Page, select the System tab,
followed by Wi-Fi Networks. Select the
appropriate Wi-Fi network, and follow the
on-screen prompts. Download speeds
may vary.
On most compatible mobile devices,
activation of the Wi-Fi hotspot is in the
Settings menu under Mobile Network
Sharing, Personal Hotspot, Mobile Hotspot,
or similar.
Availability of Over-the-Air software updates
varies by vehicle and country. Features are
subject to change. For more information on
this feature, see my.gmc.com/learn.
Preferences
Touch the controls on the infotainment
display to disable or enable the download of
new updates in the background.
About
Touch to view the infotainment system
software information.
Running Applications
Touch to see a complete list of applications
that are currently running on the
infotainment system.
Return to Factory Settings
Touch and the following may display:
.Reset Vehicle Settings: Resets all vehicle
settings for the current user.
Touch Reset or Cancel.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Infotainment System 193
Touch Disable or Enable.
Vehicle
This menu allows adjustment of different
vehicle features. SeeVehicle Personalization
0 126.
Personal
If equipped, this menu allows adjustment of
different user profile settings. See “Users”in
Using the System 0145 for information on
setting up user profiles.
The menu may contain the following:
Name
Touch to edit your user name that will be
displayed in the vehicle.
Vehicle Account Information
Touch to view the vehicle account
information and to change the account
password.
An “unverified user account” pop-up will
display until the account information
verification process has been completed on
the Internet. Check your registered e-mail
account for an activation e-mail to complete
the verification process. Profile Picture
Touch to choose or change your profile
picture.
Profile Identifiers
Touch to have the vehicle recognize the
identifier you choose.
Touch Vehicle Key 1 and/or Vehicle Key 2.
If the Remote Key is lost or stolen, see your
dealer.
Security
Touch to have your profile secured with
a PIN.
Touch No or Yes.
Vehicle Name
Touch to edit your vehicle name.
Vehicle Account
Touch to view the vehicle account
information and to change the account
password.
Delete Profile
Touch to remove the profile from the
vehicle.
Touch Remove or Cancel.
Teen Driver
If equipped, this allows multiple keys to be
registered for beginner drivers to encourage
safe driving habits. When the vehicle is
started with a Teen Driver key, it will
automatically activate certain safety
systems, allow setting of some features, and
limit the use of others. The Report Card will
record vehicle data about driving behavior
that can be viewed later. When the vehicle
is started with a registered key, the Driver
Information Center (DIC) displays a message
that Teen Driver is active.
To access:
1. Touch Settings on the Home Page, then touch Vehicle, and then Teen Driver.
2. Create a Personal Identification Number (PIN) by choosing a four-digit PIN.
Re-enter the PIN to confirm. To change
the PIN, touch Change PIN.
The PIN is required to:
.Register or unregister keys.
.Change Teen Driver settings.
.Change or clear the Teen Driver PIN.
.Access or delete Report Card data.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Infotainment System 195
Set Teen Driver Speed Warning :Displays a
warning in the DIC when exceeding a
selectable speed. Choose the desired speed
warning level. The speed warning does not
limit the speed of the vehicle.
SiriusXM Explicit Content Filter (if
equipped) : Allows the SiriusXM Explicit
Content Filter to be turned ON or OFF.
When ON, the teen driver will not be able
to listen to SiriusXM stations that contain
explicit content, and the Explicit Content
Filter selection in the Audio Settings will be
unavailable for change.
When Teen Driver is Active:
.If equipped with Buckle to Drive, shifting
out of P (Park) will be prevented if the
driver seat belt, and in some vehicles the
front passenger seat belt, is not buckled.
.The radio will mute when the driver seat
belt, and in some vehicles the front
passenger seat belt, is not buckled. The
audio from any device paired to the
vehicle will also be muted.
.An object placed on the front passenger
seat, such as a briefcase, handbag,
grocery bag, laptop, or other electronic
device, could cause the passenger sensing
system to falsely sense an unbuckled
front passenger and mute the radio. If this happens, remove the object from
the seat. See
Passenger Sensing System
0 66.
.Some safety systems, such as Forward
Collision Alert, if equipped, cannot be
turned off.
.The gap setting for the Forward Collision
Alert and Adaptive Cruise Control,
if equipped, cannot be changed.
.When trying to change a safety feature
that is not configurable in Teen Driver,
the DIC displays a message indicating
that Teen Driver is active and the action
is not available.
.Super Cruise, if equipped, is not available.
.Enhanced Low Fuel Warning (if equipped)
–When the vehicle is low on fuel, the
low fuel light on the instrument cluster
flashes and the DIC low fuel warning
cannot be dismissed.
.Do not tow a trailer.
Report Card
The vehicle owner must secure the driver’s
consent to record certain vehicle data when
the vehicle is driven with a registered Teen
Driver key. There is one Report Card per vehicle. Data is only recorded when a
registered Teen Driver key is used to
operate the vehicle.
The Report Card data is collected from the
time Teen Driver is activated or the last
time the Report Card was reset. The
following items may be recorded:
.Distance Driven
–the total distance
driven.
.Maximum Speed –the maximum vehicle
speed detected.
.Overspeed Warnings –the number of
times the speed warning setting was
exceeded.
.Wide Open Throttle –the number of
times the accelerator pedal was pressed
nearly all the way down.
.Forward Collision Alerts –the number of
times the driver was notified when
approaching a vehicle ahead too quickly
and at potential risk for a crash.
.Forward Automatic Braking, also called
Automatic Emergency Braking (if
equipped) –the number of times the
vehicle detected that a forward collision
was imminent and applied the brakes.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 217
Loading the Vehicle for Off-Road Driving
{Warning
.Unsecured cargo on the load floor can
be tossed about when driving over
rough terrain. You or your passengers
can be struck by flying objects. Secure
the cargo properly.
.Keep cargo in the cargo area as far
forward and as low as possible. The
heaviest things should be on the floor,
forward of the rear axle.
.Heavy loads on the roof raise the
vehicle's center of gravity, making it
more likely to roll over. You can be
seriously or fatally injured if the
vehicle rolls over. Put heavy loads
inside the cargo area, not on the roof.
For more information about loading the
vehicle, see Vehicle Load Limits 0222 and
Tires 0339.
Environmental Concerns
.Always use established trails, roads, and
areas that have been set aside for public
off-road recreational driving and obey all
posted regulations.
.Do not damage shrubs, flowers, trees,
or grasses or disturb wildlife.
.Do not park over things that burn. See
Parking over Things That Burn 0231.
Driving on Hills
Driving safely on hills requires good
judgment and an understanding of what the
vehicle can and cannot do.
{Warning
Many hills are simply too steep for any
vehicle. Driving up hills can cause the
vehicle to stall. Driving down hills can
cause loss of control. Driving across hills
can cause a rollover. You could be injured
or killed. Do not drive on steep hills.
Before driving on a hill, assess the
steepness, traction, and obstructions. If the
terrain ahead cannot be seen, get out of the
vehicle and walk the hill before driving
further.
When driving on hills:
.Use a low gear and keep a firm grip on
the steering wheel.
.Maintain a slow speed.
.When possible, drive straight up or down
the hill.
.Slow down when approaching the top of
the hill.
.Use headlamps even during the day to
make the vehicle more visible.
{Warning
Driving to the top of a hill at high speed
can cause a crash. There could be a
drop-off, embankment, cliff, or even
another vehicle. You could be seriously
injured or killed. As you near the top of a
hill, slow down and stay alert.
.Never go downhill forward or backward
with either the transmission or transfer
case in N (Neutral). The brakes could
overheat and you could lose control.
{Warning
If the vehicle has the two-speed
automatic or electronic transfer case,
shifting the transfer case to N (Neutral)
can cause your vehicle to roll even if the
transmission is in P (Park). This is because
the N (Neutral) position on the transfer (Continued)

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
226 Driving and Operating
Warning (Continued)
.Never stack heavier things, like
suitcases, inside the vehicle so
that some of them are above the
tops of the seats.
.Do not leave an unsecured child
restraint in the vehicle.
.When you carry something inside
the vehicle, secure it whenever
you can.
.Do not leave a seat folded down
unless you need to.
There is also important loading
information for off-road driving in this
manual. See “Loading Your Vehicle for
Off-Road Driving” underOff-Road
Driving 0216.
Starting and Operating
New Vehicle Break-In
Caution
The vehicle does not need an elaborate
break-in. But it will perform better in the
long run if you follow these guidelines:
.Keep the vehicle speed at 88 km/h
(55 mph) or less for the first 805 km
(500 mi).
.Do not drive at any one constant
speed, fast or slow, for the first
805 km (500 mi). Do not make
full-throttle starts. Avoid downshifting
to brake or slow the vehicle.
.Avoid making hard stops for the first
322 km (200 mi) or so. During this
time the new brake linings are not yet
broken in. Hard stops with new linings
can mean premature wear and earlier
replacement. Follow this breaking-in
guideline every time you get new
brake linings.
(Continued)
Caution (Continued)
.Do not tow a trailer during break-in.
See Trailer Towing 0284 for the
trailer towing capabilities of the
vehicle and more information.
Following break-in, engine speed and load
can be gradually increased.
Ignition Positions
Vehicles equipped with Keyless Access have
pushbutton starting.
The Remote Key must be in the vehicle for
the system to operate. If the pushbutton
start is not working, the vehicle may be
near a strong radio antenna signal causing

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 281
.Automatic Parking Assist (APA)
.Reverse Automatic Braking (RAB)
If equipped, the following driver assistance
features should be turned to alert or off
when towing a trailer:
.Automatic Emergency Braking (AEB)
.Intelligent Brake Assist (IBA)
.Front Pedestrian Braking (FPB)
If equipped with Lane Change Alert (LCA),
the LCA detection zones that extend back
from the side of the vehicle do not move
further back when a trailer is towed. Use
caution while changing lanes when towing a
trailer.
If equipped with Rear Cross Traffic Alert
(RCTA), use caution while backing up when
towing a trailer, as the RCTA detection zones
that extend out from the back of the vehicle
do not move further back when a trailer is
towed.
{Warning
When towing a trailer, exhaust gases
may collect at the rear of the vehicle and
enter if the liftgate, trunk/hatch,
or rear-most window is open. (Continued)
Warning (Continued)
When towing a trailer:
.Do not drive with the liftgate, trunk/
hatch, or rear-most window open.
.Fully open the air outlets on or under
the instrument panel.
.Also adjust the climate control system
to a setting that brings in only outside
air. See“Climate Control Systems” in
the Index.
For more information about carbon
monoxide, see Engine Exhaust 0231.
Towing a trailer requires experience. The
combination of the vehicle and trailer is
longer and not as responsive as the vehicle
itself. Get used to the handling and braking
of the combination by driving on a level
road surface before driving on public roads.
The trailer structure, the tires, and the
brakes must be all be rated to carry the
intended cargo. Inadequate trailer
equipment can cause the combination to
operate in an unexpected or unsafe manner.
Before driving, inspect all trailer hitch parts
and attachments, safety chains, electrical connectors, lamps, tires, and mirrors. See
Towing Equipment
0287. If the trailer has
electric brakes, start the combination
moving and then manually apply the trailer
brake controller to check the trailer brakes
work. During the trip, occasionally check
that the cargo and trailer are secure and
that the lamps and any trailer brakes are
working.
Towing with a Stability Control System
When towing, the stability control system
might be heard. The system reacts to
vehicle movement caused by the trailer,
which mainly occurs during cornering. This is
normal when towing heavier trailers.
Following Distance
Stay at least twice as far behind the vehicle
ahead as you would when driving without a
trailer. This can help to avoid heavy braking
and sudden turns.
Passing
More passing distance is needed when
towing a trailer. The combination of the
vehicle and trailer will not accelerate as
quickly and is much longer than the vehicle
alone. It is necessary to go much farther

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 287
After loading the trailer, separately weigh
the trailer and then the trailer tongue and
calculate the trailer load balance percentage
to see if the weights and distribution are
appropriate for your vehicle. If the trailer
weight is too high, it may be possible to
transfer some of the cargo into your vehicle.
If the trailer tongue weight is too high or
too low, it may be possible to rearrange
some of the cargo inside of the trailer.
Do not exceed the maximum allowable
tongue weight for your vehicle. Use the
shortest hitch extension available to position
the hitch ball closer to your vehicle. This will
help reduce the effect of the trailer tongue
weight on the trailer hitch and the rear axle.
If a cargo carrier is used in the trailer hitch
receiver, choose a carrier that positions the
load as close to the vehicle as possible.
Make sure the total weight, including the
carrier, is no more than half of the
maximum allowable tongue weight for the
vehicle or 227 kg (500 lb), whichever is less.
Rear Gross Axle Weight Rating
(GAWR-RR)
The GAWR-RR is the total weight that can be
supported by the rear axle of the vehicle. Do
not exceed the GAWR-RR for the vehicle,with the tow vehicle and trailer fully loaded
for the trip including the weight of the
trailer tongue. If using a weight-distributing
hitch, do not exceed the GAWR-RR after
applying the weight distribution spring bars.
The GAWR-RR for the vehicle is on the
Trailering Information Label.
Ask your dealer for trailering information or
assistance.
Towing Equipment
Hitches
{Warning
In order to avoid serious injury or
property damage, always follow the hitch
manufacturer's instructions when securing
your draw bar/coupling device to the
vehicle's hitch receiver.
Ensure that the draw bar/coupling device
is secured with a locking retainer pin or
other means such that rotation of the pin
or locking mechanism will not cause the
pin to back out or loosen during use.
Failure to correctly secure the draw bar/
coupling device to the receiver can result
in separation of the hitch/receiver while
towing.
Always use the correct hitch equipment for
your vehicle. Crosswinds, large trucks going
by, and rough roads can affect the trailer
and the hitch.
Proper hitch equipment for your vehicle
helps maintain control of the vehicle-trailer
combination. Many trailers can be towed
using a weight-carrying hitch which has a

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
306 Driving and Operating
The setting will be on by default for each
profile. All Maintenance Alerts for that active
Trailer Profile will be received.
Turn a setting off to not receive any of the
Maintenance Alerts when that Trailer Profile
is active.
Theft Alert
A 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 in Settings to view the
Theft Alert settings page. These alerts are
based on the Trailer Profile, so the settings
for each Trailer Profile must be turned on or
off. Touch a profile to view more
information or adjust the setting for that
profile.
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 orconnected 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
Tow/Haul
Mode 0235.
Touch Tow/Haul Mode Reminder in Settings
to view the Tow/Haul Mode Reminder
settings page. These alerts are based on the
Trailer Profile, so the settings for each
Trailer Profile must be turned on or off.
Touch a profile to view more information or
to adjust the setting for that profile.
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
ignition 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) 0111.
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.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Vehicle Care 319
5.3L V8 Engine Shown, 6.2L V8 Engine Similar1. Remove the three screws, tilt the cover, and slide it out of the assembly.
{Warning
If part replacement is necessary, the part
must be replaced with one of the same
part number or with an equivalent part.
Use of a replacement part without the
same fit, form, and function may result
in personal injury or damage to the
vehicle.
2. Inspect or replace the engine air cleaner/ filter. 3. Lower the cover, slide it into the
assembly, then secure with the three
screws.
4. If equipped, reset the engine air filter life system after replacing the engine air
filter. See Engine Air Filter Life System
0 318.
{Warning
Operating the engine with the air
cleaner/filter off can cause you or others
to be burned. Use caution when working
on the engine. Do not start the engine or
drive the vehicle with the air cleaner/
filter off, as flames may be present if the
engine backfires.
Caution
If the air cleaner/filter is off, dirt can
easily get into the engine, which could
damage it. Always have the air cleaner/
filter in place when driving.
Cooling System
If the vehicle has the Duramax diesel
engine, see the Duramax diesel supplement. The cooling system allows the engine to
maintain the correct working temperature.
5.3L V8 Engine
1. Engine Electric Cooling Fans (Out
of View)
2. Coolant Surge Tank and Pressure Cap

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.