service GMC YUKON 2021 Repair Manual

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 241
Before leaving the vehicle, check the red
parking brake status light to ensure that the
parking brake is applied.
EPB Apply
To apply the EPB:1. Be sure the vehicle is at a complete stop.
2. Press the EPB switch momentarily.
The red parking brake status light will flash
and then stay on once the EPB is fully
applied. If the red parking brake status light
flashes continuously, then the EPB is only
partially applied or there is a problem with
the EPB. A DIC message will display. Release
the EPB and try to apply it again. If the
light does not come on, or keeps flashing,
have the vehicle serviced. Do not drive the
vehicle if the red parking brake status light
is flashing. See your dealer.
If the amber service parking brake warning
light is on, press the EPB switch. Continue to
hold the switch until the red parking brake
status light remains on. If the amber service
parking brake warning light is on, see your
dealer. If the EPB is applied while the vehicle is
moving, the vehicle will decelerate as long
as the switch is pressed. If the switch is
pressed until the vehicle comes to a stop,
the EPB will remain applied.
The vehicle may automatically apply the EPB
in some situations when the vehicle is not
moving. This is normal, and is done to
periodically check the correct operation of
the EPB system, or at the request of other
safety functions that utilize the EPB.
If the EPB fails to apply, block the rear
wheels to prevent vehicle movement.
EPB Release
To release the EPB:
1. Turn the ignition on or to ACC/ ACCESSORY.
2. Apply and hold the brake pedal.
3. Press the EPB switch momentarily.
The EPB is released when the red parking
brake status light is off.
If the amber service parking brake warning
light is on, release the EPB by pressing and
holding the EPB switch. Continue to hold the
switch until the red parking brake status
light is off. If either light stays on after
release is attempted, see your dealer.
Caution
Driving with the parking brake on can
overheat the brake system and cause
premature wear or damage to brake
system parts. Make sure that the parking
brake is fully released and the brake
warning light is off before driving.
If you are towing a trailer and parking on a
hill, see Driving Characteristics and Towing
Tips 0280.
Automatic EPB Release
The EPB will automatically release if the
vehicle is running, placed into gear, and an
attempt is made to drive away. Avoid rapid
acceleration when the EPB is applied, to
preserve parking brake lining life.
Brake Assist
Brake Assist detects rapid brake pedal
applications due to emergency braking
situations and provides additional braking to
activate the Antilock Brake System (ABS) if
the brake pedal is not pushed hard enough
to activate ABS normally. Minor noise, brake
pedal pulsation, and/or pedal movement
during this time may occur. Continue to

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
250 Driving and Operating
Aerodynamic Height is 20 mm (0.75 in)
lower than Normal Height. This ride height
lowers the vehicle at higher vehicle speeds
to improve aerodynamics.
The vehicle will lower to Aerodynamic
Height when vehicle speed exceeds
105 km/h (65 mph) for a period of time. The
vehicle will raise to Normal Height when the
vehicle slows to less than 48 km/h
(30 mph).
Aerodynamic Height is automatically
disabled when a trailer is connected to the
vehicle or Tow/Haul Driver Mode is active.
Suspension Modes
The air suspension has two special modes
located in the infotainment screen under
Settings/Vehicle/Suspension. When either is
active, the following amber icon will be
illuminated in the instrument cluster.
SeeFour Corner Air Suspension Light 0117. Service Mode
Service Mode will disable all air suspension
operation including raising and lowering the
vehicle and operation of the air compressor.
This mode is useful when the vehicle is
being towed on a flat bed or when any
work under the vehicle is being performed.
Service Mode is automatically enabled when
the vehicle is put on a hoist or a floor jack
is used to raise a corner. Service Mode may
temporarily enable during intense off-road
situations to prevent damaging air
suspension activity. Service Mode
automatically disables when vehicle speed
exceeds 16 km/h (10 mph).
Alignment Mode
Alignment Mode will optimize the vehicle
height to provide the most accurate wheel
alignment. This mode should be enabled
once the vehicle is driven onto the
alignment station.
To enable Alignment Mode, ensure the
vehicle is at Normal Height and shift the
vehicle to Neutral. Alignment Mode
automatically disables when vehicle speed
exceeds 16 km/h (10 mph).
Air Suspension Operation with Door(s) or
Hood Open
The air suspension will temporarily suspend
all height changes while the hood or any
door is open.
System Over-Temperature
If the air suspension is under heavy use, the
system may temporarily suspend all height
changes to allow compressor cooldown.
When this occurs and a height change is
requested, a
‘Leveling System Unavailable’
message will be displayed in the instrument
cluster.
Suspension Lowered for Stability
In the event of a loss of Electronic Stability
Control, the air suspension will lower the
vehicle at higher speeds to provide increased
stability. This will be accompanied by a
‘Vehicle Lowering for Stability’ message in
the instrument cluster.
Excessive Vehicle Loading
If the air suspension detects excessive
vehicle loading, it will not raise above
Normal Height.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 251
Air Suspension Service
If a‘Service Leveling System’ message is
displayed in the instrument cluster, see your
authorized dealer immediately.
Cruise Control
{
Warning
Cruise control can be dangerous where
you cannot drive safely at a steady
speed. Do not use cruise control on
winding roads or in heavy traffic.
Cruise control can be dangerous on
slippery roads. On such roads, fast
changes in tire traction can cause
excessive wheel slip, and you could lose
control. Do not use cruise control on
slippery roads.
If equipped with cruise control, a speed of
about 40 km/h (25 mph) or more can be
maintained without keeping your foot on
the accelerator. Cruise control does not work
at speeds below about 40 km/h (25 mph).
If the cruise control is being used and the
Traction Control System (TCS) or StabiliTrak/
Electronic Stability Control (ESC) begins to
limit wheel spin, the cruise control will automatically disengage. See
Traction
Control/Electronic Stability Control 0242.
If a collision alert occurs when cruise control
is activated, cruise control is disengaged. See
Forward Collision Alert (FCA) System 0267.
When road conditions allow you to safely
use it again, cruise control can be turned
back on.
Turning off the TCS or StabiliTrak/ESC
system will disengage the cruise control.
If the brakes are applied, cruise control
disengages.
5: Press to turn cruise control on or off.
A white indicator comes on or off in the
instrument cluster. +RES :
If there is a set speed in memory,
press the control up briefly to resume to
that speed or press and hold to accelerate.
If cruise control is already engaged, use to
increase vehicle speed.
SET− :Press the control down briefly to set
the speed and activate cruise control.
If cruise control is already engaged, use to
decrease vehicle speed.
*: Press to disengage cruise control
without erasing the set speed from memory.
Setting Cruise Control
If
5is on when not in use, SET− or +RES
could get pressed and go into cruise when
not desired. Keep
5off when cruise is not
being used.
1. Press
5to turn the cruise system on.
2. Get up to the desired speed.
3. Press and release SET−.
4. Remove your foot from the accelerator.
The cruise control indicator on the
instrument cluster turns green after cruise
control has been set to the desired speed.
See Instrument Cluster 0104.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 259
{Warning
The ACC will not automatically apply the
brakes if your foot is resting on the
accelerator pedal. You could crash into a
vehicle ahead of you.
Curves in the Road
{Warning
On curves, ACC may not detect a vehicle
ahead in your lane. You could be startled
if the vehicle accelerates up to the set
speed, especially when following a vehicle
exiting or entering exit ramps. You could
lose control of the vehicle or crash. Do
not use ACC while driving on an entrance
or exit ramp. Always be ready to use the
brakes if necessary.
{Warning
On curves, ACC may respond to a vehicle
in another lane, or may not have time to
react to a vehicle in your lane. You could
crash into a vehicle ahead of you, or lose
control of your vehicle. Give extra (Continued)
Warning (Continued)
attention in curves and be ready to use
the brakes if necessary. Select an
appropriate speed while driving in curves.
ACC may operate differently in a sharp
curve. It may briefly reduce the vehicle
speed if the curve is too sharp.
ACC automatically slows the vehicle down
while navigating the curve and may increase
speed out of the curve, but will not exceed
the set speed.
When following a vehicle and entering a
curve, ACC may not detect the vehicle ahead
and accelerate to the set speed. When this
happens, the vehicle ahead indicator will not
appear.
ACC may detect a vehicle that is not in your
lane and apply the brakes.
ACC may occasionally provide an alert and/
or braking that is considered unnecessary.
It could respond to vehicles in different
lanes or stationary objects when entering or
exiting a curve. This is normal operation.
The vehicle does not need service.
Other Vehicle Lane Changes

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 269
Following Distance Indicator
The following distance to a moving vehicle
ahead in your path is indicated in following
time in seconds on the Driver Information
Center (DIC). SeeDriver Information Center
(DIC) 0120. The minimum following time is
0.5 seconds away. If there is no vehicle
detected ahead, or the vehicle ahead is out
of sensor range, dashes will be displayed.
Unnecessary Alerts
FCA may provide unnecessary alerts for
turning vehicles, vehicles in other lanes,
objects that are not vehicles, or shadows.
These alerts are normal operation and the
vehicle does not need service.
Cleaning the System
If the FCA system does not seem to operate
properly, this may correct the issue:
.Clean the outside of the windshield in
front of the rearview mirror.
.Clean the entire front of the vehicle.
.Clean the headlamps.
For cleaning instructions, see “Washing the
Vehicle” underExterior Care 0374.
System operation may also be limited under
snow, heavy rain, or road spray conditions.
Automatic Emergency
Braking (AEB)
If the vehicle has Forward Collision Alert
(FCA), it also has AEB, which includes
Intelligent Brake Assist (IBA). When the
system detects a vehicle ahead in your path
that is traveling in the same direction that
you may be about to crash into, it can
provide a boost to braking or automatically
brake the vehicle. This can help avoid or
lessen the severity of crashes when driving
in a forward gear. Depending on the
situation, the vehicle may automatically
brake moderately or hard. This automatic
emergency braking can only occur if a
vehicle is detected. This is shown by the FCA
vehicle ahead indicator being lit. See
Forward Collision Alert (FCA) System 0267.
The system works when driving in a forward
gear between 8 km/h (5 mph) and 80 km/h
(50 mph), or on vehicles with Adaptive
Cruise Control (ACC), above 4 km/h (2 mph).
It can detect vehicles up to approximately
60 m (197 ft).
{Warning
AEB is an emergency crash preparation
feature and is not designed to avoid
crashes. Do not rely on AEB to brake the
vehicle. AEB will not brake outside of its
operating speed range and only responds
to detected vehicles.
AEB may not:
.Detect a vehicle ahead on winding or
hilly roads.
.Detect all vehicles, especially vehicles
with a trailer, tractors, muddy
vehicles, etc.
.Detect a vehicle when weather limits
visibility, such as in fog, rain, or snow.
.Detect a vehicle ahead if it is partially
blocked by pedestrians or other
objects.
Complete attention is always required
while driving, and you should be ready to
take action and apply the brakes and/or
steer the vehicle to avoid crashes.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
270 Driving and Operating
AEB may slow the vehicle to a complete
stop to try to avoid a potential crash. The
vehicle will only hold at a stop briefly.
A firm press of the accelerator pedal will
also release AEB.
{Warning
AEB may automatically brake the vehicle
suddenly in situations where it is
unexpected and undesired. It could
respond to a turning vehicle ahead,
guardrails, signs, and other non-moving
objects. To override AEB, firmly press the
accelerator pedal, if it is safe to do so.
Intelligent Brake Assist (IBA)
IBA may activate when the brake pedal is
applied quickly by providing a boost to
braking based on the speed of approach and
distance to a vehicle ahead.
Minor brake pedal pulsations or pedal
movement during this time is normal and
the brake pedal should continue to be
applied as needed. IBA will automatically
disengage only when the brake pedal is
released.
{Warning
IBA may increase vehicle braking in
situations when it may not be necessary.
You could block the flow of traffic. If this
occurs, take your foot off the brake pedal
and then apply the brakes as needed.
AEB and IBA can be disabled through vehicle
personalization. See “Collision/Detection
Systems” underVehicle Personalization
0 126.
{Warning
Using AEB or IBA while towing a trailer
could cause you to lose control of the
vehicle and crash. Turn the system to
Alert or Off when towing a trailer.
A system unavailable message may
display if:
.The front of the vehicle or windshield is
not clean.
.Heavy rain or snow is interfering with
object detection.
.There is a problem with the StabiliTrak/
Electronic Stability Control (ESC) system.
The AEB system does not need service.
Front Pedestrian Braking (FPB)
System
If equipped, the FPB system may help avoid
or reduce the harm caused by front-end
crashes with nearby pedestrians when
driving in a forward gear. FPB displays an
amber indicator,
~, when a nearby
pedestrian is detected ahead. When
approaching a detected pedestrian too
quickly, FPB provides a red flashing alert on
the windshield and rapidly beeps or pulses
the driver seat. FPB can provide a boost to
braking or automatically brake the vehicle.
This system includes Intelligent Brake Assist
(IBA), and the Automatic Emergency Braking
(AEB) system may also respond to
pedestrians. See Automatic Emergency
Braking (AEB) 0269.
The FPB system can detect and alert to
pedestrians in a forward gear at speeds
between 8 km/h (5 mph) and 80 km/h
(50 mph). During daytime driving, the
system detects pedestrians up to a distance
of approximately 40 m (131 ft). During
nighttime driving, system performance is
very limited.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
272 Driving and Operating
8 km/h (5 mph) and 80 km/h (50 mph).
Automatic braking levels may be reduced
under certain conditions, such as higher
speeds.
If this happens, Automatic Braking may
engage the Electric Parking Brake (EPB) to
hold the vehicle at a stop. Release the EPB.
A firm press of the accelerator pedal will
also release Automatic Braking and the EPB.
{Warning
FPB may alert or automatically brake the
vehicle suddenly in situations where it is
unexpected and undesired. It could falsely
alert or brake for objects similar in shape
or size to pedestrians, including shadows.
This is normal operation and the vehicle
does not need service. To override
Automatic Braking, firmly press the
accelerator pedal, if it is safe to do so.
Automatic Braking can be disabled through
vehicle personalization. See “Front Pedestrian
Detection” in“Collision/Detection Systems”
under Vehicle Personalization 0126.
{Warning
Using the Front Pedestrian Braking
system while towing a trailer could cause
you to lose control of the vehicle and
crash. Turn the system to Alert or Off
when towing a trailer.
Cleaning the System
If FPB does not seem to operate properly,
cleaning the outside of the windshield in
front of the rearview mirror may correct the
issue.
Side Blind Zone Alert (SBZA)
If equipped, the SBZA system is a
lane-changing aid that assists drivers with
avoiding crashes that occur with moving
vehicles in the side blind zone, or blind spot
areas. When the vehicle is in a forward gear,
the left or right side mirror display will light
up if a moving vehicle is detected in that
blind zone. If the turn signal is activated and
a vehicle is also detected on the same side,
the display will flash as an extra warning
not to change lanes. Since this system is
part of the Lane Change Alert (LCA) system,
read the entire LCA section before using this
feature.
Lane Change Alert (LCA)
If equipped, the Lane Change Alert (LCA)
system is a lane-changing aid that can assist
drivers with avoiding lane change crashes
with moving vehicles in the side blind zone,
or blind spot areas or with vehicles rapidly
approaching these areas from behind. When
a vehicle is detected in the blind zone, the
LCA warning display will light up in the
corresponding side mirror and will flash if
the turn signal is on. The Side Blind Zone
Alert (SBZA) system is included as part of
the LCA system.
{Warning
LCA does not alert the driver to vehicles
outside of the system detection zones,
pedestrians, bicyclists, or animals. It may
not provide alerts when changing lanes
under all driving conditions. Failure to use
proper care when changing lanes may
result in injury, death, or vehicle damage.
Before making a lane change, always
check mirrors, glance over your shoulder,
and use the turn signals.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
274 Driving and Operating
making a lane change, check the SBZA
display, check mirrors, glance over your
shoulder, and use the turn signals.
Left Side MirrorDisplayRight Side Mirror Display
When the vehicle is started, both outside
mirror LCA/ESBZA displays will briefly come
on to indicate the system is operating.
When the vehicle is in a forward gear, the
left- or right-side mirror display will light up
if a moving vehicle is detected in that blind
zone. If the turn signal is activated in the
same direction as a detected vehicle, this
display will flash as an extra warning not to
change lanes.
LCA/ESBZA displays may not come on when
passing a vehicle quickly, or when passing a
stopped vehicle. LCA/ESBZA may alert to
objects attached to the vehicle, such as a
bicycle, or object extending out to either side of the vehicle or trailer. This is normal
system operation; the vehicle does not need
service.
LCA/ESBZA can be disabled through vehicle
personalization. See
“Collision/Detection
Systems” underVehicle Personalization
0 126. If SBZA is disabled by the driver, the
ESBZA mirror displays will not light up.When the System Does Not Seem to
Work Properly
LCA/ESBZA displays may not come on when
passing a vehicle quickly, or when passing a
stopped vehicle. The LCA/ESBZA 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. LCA/ESBZA may
alert to objects attached to the vehicle, such
as a trailer, bicycle, or object extending out
to either side of the vehicle or trailer. This is
normal system operation; the vehicle does
not need service.
LCA/ESBZA may not always alert the driver
to vehicles in the side blind zone, especially
in wet conditions. The system does not need
to be serviced. The system may light up due to guardrails, signs, trees, shrubs, and other
non-moving objects. This is normal system
operation; the vehicle does not need service.
LCA/ESBZA may not operate when the LCA/
ESBZA sensors in the left or right corners of
the rear bumper are covered with mud, dirt,
snow, ice, or slush, or in heavy rainstorms.
For cleaning instructions, see "Washing the
Vehicle" under
Exterior Care0374. If the DIC
displays the system unavailable message
after cleaning both sides of the vehicle
toward the rear corners of the vehicle, see
your dealer.
If the DIC displays the system unavailable
message after cleaning both sides of the
vehicle toward the rear corners of the
vehicle, see your dealer
If the LCA/ESBZA displays do not light up
when vehicles are in the blind zone and the
system is clean, the system may need
service. Take the vehicle to your dealer.
When ESBZA is disabled for any reason
other than the driver turning it off, the
Extended Side Blind Zone Alert On option
will not be available on the
personalization menu.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
276 Driving and Operating
audible alert or the driver seat may pulse
indicating that a lane marking has been
crossed.
To turn LKA on and off, press
Ato the
left of the steering wheel. If equipped, the
indicator light on the button comes on
when LKA is on and turns off when LKA is
disabled.
When on,
Ais white, if equipped,
indicating that the system is not ready to
assist.
Ais green if LKA is ready to
assist. LKA may assist by gently turning the
steering wheel if the vehicle approaches a
detected lane marking.
Ais amber when
assisting. It may also provide a Lane
Departure Warning (LDW) alert by flashing
Aamber if the vehicle crosses a
detected lane marking. Additionally, there
may be three beeps, or the driver seat may
pulse three times, on the right or left,
depending on the lane departure direction.
Take Steering
The LKA system does not continuously steer
the vehicle. If LKA does not detect active
driver steering, an alert and chime may be
provided. Steer the vehicle to dismiss. LKA
may become temporarily unavailable after
repeated take steering alerts.
When the System Does Not Seem to
Work Properly
The system performance may be
affected by:
.Close vehicles ahead.
.Sudden lighting changes, such as when
driving through tunnels.
.Banked roads.
.Roads with poor lane markings, such as
two-lane roads.
If the LKA system is not functioning
properly when lane markings are clearly
visible, cleaning the windshield may help.
A camera blocked message may display if
the camera is blocked. Some driver
assistance systems may have reduced
performance or not work at all. An LKA or
LDW unavailable message may display if the
systems are temporarily unavailable. This
message could be due to a blocked camera.
The LKA system does not need service. Clean
the outside of the windshield behind the
rearview mirror.
LKA assistance and/or LDW alerts may occur
due to tar marks, shadows, cracks in the
road, temporary or construction lane
markings, or other road imperfections. This is normal system operation; the vehicle does
not need service. Turn LKA off if these
conditions continue.
Fuel
Top Tier Fuel
GM recommends the use of TOP TIER
Detergent Gasoline to keep the engine clean,
reduce engine deposits, and maintain
optimal vehicle performance. Look for the
TOP TIER Logo or see www.toptiergas.com
for a list of TOP TIER Detergent Gasoline
marketers and applicable countries.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
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Driving and Operating 277
Recommended Fuel (5.3L Engine)
For diesel engine vehicles, see“Fuel for
Diesel Engines” in the Duramax diesel
supplement.
Use regular unleaded gasoline meeting
ASTM specification D4814 with a posted
octane rating of 87 —(R+M)/2 —or higher.
Do not use gasoline with a posted octane
rating of less than 87, as this may cause
engine knock and will lower fuel economy.
Do not use any fuel labeled E85 or FlexFuel.
Do not use gasoline with ethanol levels
greater than 15% by volume.
Recommended Fuel (6.2L Engine)
For diesel engine vehicles, see “Fuel for
Diesel Engines” in the Duramax diesel
supplement.
Premium unleaded gasoline meeting ASTM
specification D4814 with a posted octane
rating of 93 —(R+M)/2 —is highly
recommended for best performance and fuel
economy. Unleaded gasoline with an octane
rated as low as 87 can be used. Using
unleaded gasoline rated below 93 octane,
however, will lead to reduced acceleration
and fuel economy. If knocking occurs, use a
gasoline rated at 93 octane as soon as
possible, otherwise, the engine could be
damaged. If heavy knocking is heard when
using gasoline with a 93 octane rating, the
engine needs service.
Do not use any fuel labeled E85 or FlexFuel.
Do not use gasoline with ethanol levels
greater than 15% by volume.
Prohibited Fuels
Caution
Do not use fuels with any of the
following conditions; doing so may
damage the vehicle and void its
warranty:
.For vehicles that are not FlexFuel, fuel
labeled greater than 15% ethanol by
volume, such as mid-level ethanol
blends (16–50% ethanol), E85,
or FlexFuel.
.Fuel with any amount of methanol,
methylal, ferrocene, and aniline. These
fuels can corrode metal fuel system
parts or damage plastic and rubber
parts.
.Fuel containing metals such as
methylcyclopentadienyl manganese
tricarbonyl (MMT), which can damage
the emissions control system and
spark plugs.
.Fuel with a posted octane rating of
less than the recommended fuel. Using
this fuel will lower fuel economy and
performance, and may decrease the
life of the emissions catalyst.