2021 GMC YUKON service indicator

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Instruments and Controls 109
the normal operating range, the charging
system light comes on. SeeCharging System
Light 0111. The voltmeter gauge may also
read lower when in fuel economy mode.
This is normal.
Readings outside the normal operating
range can also occur when a large number
of electrical accessories are operating in the
vehicle and the engine is left idling for an
extended period. This condition is normal
since the charging system is not able to
provide full power at engine idle. As engine
speeds are increased, this condition should
correct itself as higher engine speeds allow
the charging system to create maximum
power.
The vehicle can only be driven for a short
time with the readings outside the normal
operating range. If the vehicle must be
driven, turn off all accessories, such as the
radio and air conditioner.
Readings outside the normal operating
range indicate a possible problem in the
electrical system. Have the vehicle serviced
as soon as possible.Seat Belt Reminders
Driver Seat Belt Reminder Light
There is a driver seat belt reminder light on
the instrument cluster.
When the vehicle is started, this light
flashes and a chime may come on to remind
the driver to fasten their seat belt.
Then the light stays on solid until the belt is
buckled. This cycle may continue several
times if the driver remains or becomes
unbuckled while the vehicle is moving.
If the driver seat belt is buckled, neither the
light nor the chime comes on.
Front Passenger Seat Belt Reminder
Light
The vehicle may have a front passenger seat
belt reminder light near the passenger
airbag status indicator. See Passenger
Sensing System 066.
When the vehicle is started, this light
flashes and a chime may come on to remind
passengers to fasten their seat belt.
Then the light stays on solid until the belt is
buckled. This cycle continues several times if
the front passenger remains or becomes
unbuckled while the vehicle is moving.
If the front passenger seat belt is buckled,
neither the chime nor the light comes on.
The front passenger seat belt reminder light
and chime may come on if an object is put
on the seat such as a briefcase, handbag,
grocery bag, laptop, or other electronic
device. To turn off the reminder light and/or
chime, remove the object from the seat or
buckle the seat belt.
Airbag Readiness Light
This light shows if there is an electrical
problem with the airbag system. The system
check includes the airbag sensor(s),
passenger sensing system (if equipped), the

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
110 Instruments and Controls
pretensioners, the airbag modules, the
wiring, and the crash sensing and diagnostic
module. For more information on the airbag
system, seeAirbag System 060.
The airbag readiness light comes on for
several seconds when the vehicle is started.
If the light does not come on then, have it
fixed immediately.
{Warning
If the airbag readiness light stays on
after the vehicle is started or comes on
while driving, it means the airbag system
might not be working properly. The
airbags in the vehicle might not inflate in
a crash, or they could even inflate
without a crash. To help avoid injury,
have the vehicle serviced right away.
If there is a problem with the airbag
system, a Driver Information Center (DIC)
message may also come on.
Passenger Airbag Status Indicator
The vehicle has a passenger sensing system.
See Passenger Sensing System 066 for
important safety information. The overhead
console has a passenger airbag status
indicator.
United States and Canada
When the vehicle is started, the passenger
airbag status indicator will light ON and OFF,
and the symbols for on and off, for several
seconds as a system check. Then, after
several more seconds, the status indicator
will light either ON or OFF, and the symbol
for on or off, to let you know the status of
the front outboard passenger frontal airbag.
If the word ON, and the on symbol, are lit
on the passenger airbag status indicator, it
means that the front outboard passenger
frontal airbag is allowed to inflate. If the word OFF, and the off symbol, are lit
on the passenger airbag status indicator, it
means that the passenger sensing system
has turned off the front outboard passenger
frontal airbag.
If, after several seconds, both status
indicator lights remain on, if there are no
lights at all, or if the airbag readiness light
is on, there may be a problem with the
lights or the passenger sensing system. See
your dealer for service right away.{Warning
If the airbag readiness light ever comes
on and stays on, it means that
something may be wrong with the airbag
system. To help avoid injury to yourself
or others, have the vehicle serviced right
away. See
Airbag Readiness Light 0109
for more information, including important
safety information.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Instruments and Controls 111
Charging System Light
The charging system light comes on briefly
when the ignition is turned on, but the
engine is not running, as a check to show
the light is working. It should go out when
the engine is started.
If the light stays on, or comes on while
driving, there may be a problem with the
electrical charging system. Have it checked
by your dealer. Driving while this light is on
could drain the battery.
When this light comes on, or is flashing, the
Driver Information Center (DIC) also displays
a message.
If a short distance must be driven with the
light on, be sure to turn off all accessories,
such as the radio and air conditioner.
Malfunction Indicator Lamp
(Check Engine Light)
This light is part of the vehicle’s emission
control on-board diagnostic system. If this
light is on while the engine is running, a
malfunction has been detected and the
vehicle may require service. The light should
come on to show that it is working when
the ignition is in Service Mode. SeeIgnition
Positions 0226.
Malfunctions are often indicated by the
system before any problem is noticeable.
Being aware of the light and seeking service
promptly when it comes on may prevent
damage.
Caution
If the vehicle is driven continually with
this light on, the emission control system
may not work as well, the fuel economy
may be lower, and the vehicle may not
(Continued)
Caution (Continued)
run smoothly. This could lead to costly
repairs that might not be covered by the
vehicle warranty.
Caution
Modifications to the engine, transmission,
exhaust, intake, or fuel system, or the
use of replacement tires that do not
meet the original tire specifications, can
cause this light to come on. This could
lead to costly repairs not covered by the
vehicle warranty. This could also affect
the vehicle’s ability to pass an Emissions
Inspection/Maintenance test. See
Accessories and Modifications 0309.
If the light is flashing : A malfunction has
been detected that could damage the
emission control system and increase vehicle
emissions. Diagnosis and service may be
required.
To help prevent damage, reduce vehicle
speed and avoid hard accelerations and
uphill grades. If towing a trailer, reduce the
amount of cargo being hauled as soon as
possible.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Instruments and Controls 115
Vehicle Ahead Indicator
If equipped, this indicator will display green
when a vehicle is detected ahead and amber
when you are following a vehicle ahead
much too closely.
SeeForward Collision Alert (FCA) System
0 267.
Pedestrian Ahead Indicator
If equipped, this indicator will display amber
when a nearby pedestrian is detected in
front of the vehicle.
See Front Pedestrian Braking (FPB) System
0 270.
Traction Off Light
This light comes on briefly while starting
the engine. If it does not, have the vehicle
serviced by your dealer. If the system is
working normally, the indicator light then
turns off.
The traction off light comes on when the
Traction Control System (TCS) has been
turned off by pressing and releasing the
TCS/StabiliTrak/ESC button.
This light and the StabiliTrak/ESC OFF light
come on when StabiliTrak/Electronic Stability
Control (ESC) is turned off.
If the TCS is off, wheel spin is not limited.
Adjust driving accordingly.
See Traction Control/Electronic Stability
Control 0242.
Traction Control System (TCS)/
Electronic Stability Control Light
If equipped, the Electronic Stability Control
(ESC) or TCS indicator/warning light comes
on briefly when the engine is started.
If the light does not come on, have the
vehicle serviced by your dealer. If the
system is working normally, the indicator
light turns off.
If the light is on and not flashing, the TCS,
and potentially the ESC system have been
disabled.
If the indicator/warning light is on and
flashing, the TCS and/or the ESC system is
actively working.
See Traction Control/Electronic Stability
Control 0242.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
116 Instruments and Controls
Trailer Sway Control Light
This light will flash when Trailer Sway
Control is active. SeeTrailer Sway Control
(TSC) 0295.
Electronic Stability Control (ESC)
Off Light
This light comes on briefly while starting
the engine. If it does not, have the vehicle
serviced by your dealer.
This light comes on when the ESC system is
turned off. If ESC is off, the Traction Control
System (TCS) is also off. If the ESC and TCS are off, the system does
not assist in controlling the vehicle. Turn on
the TCS and the ESC systems and the
warning light turns off.
See
Traction Control/Electronic Stability
Control 0242.
Engine Coolant Temperature
Warning Light
This light comes on briefly while starting
the vehicle.
If it does not, have the vehicle serviced by
your dealer. If the system is working
normally the indicator light goes off.
Caution
The engine coolant temperature warning
light indicates that the vehicle has
overheated. Driving with this light on can
(Continued)
Caution (Continued)
damage the engine and it may not be
covered by the vehicle warranty. See
Engine Overheating 0322.
The engine coolant temperature warning
light comes on when the engine has
overheated.
If this happens, pull over and turn off the
engine as soon as possible. See Engine
Overheating 0322.
Driver Mode Control Light
This light comes on when Sport Mode is
selected.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
118 Instruments and Controls
Tire Pressure Light
For vehicles with the Tire Pressure Monitor
System (TPMS), this light comes on briefly
when the engine is started. It provides
information about tire pressures and
the TPMS.
When the Light Is On Steady
This indicates that one or more of the tires
are significantly underinflated.
A Driver Information Center (DIC) tire
pressure message may also display. Stop as
soon as possible, and inflate the tires to the
pressure value shown on the Tire and
Loading Information label. SeeTire Pressure
0 344.
When the Light Flashes First and Then Is On
Steady
If the light flashes for about a minute and
then stays on, there may be a problem with
the TPMS. If the problem is not corrected, the light will come on at every ignition
cycle. See
Tire Pressure Monitor Operation
0 347.
Engine Oil Pressure Light
Caution
Lack of proper engine oil maintenance
can damage the engine. Driving with the
engine oil low can also damage the
engine. The repairs would not be covered
by the vehicle warranty. Check the oil
level as soon as possible. Add oil if
required, but if the oil level is within the
operating range and the oil pressure is
still low, have the vehicle serviced.
Always follow the maintenance schedule
for changing engine oil.
This light should come on briefly as the
engine is started. If it does not come on,
have the vehicle serviced by your dealer. If the light comes on and stays on, it means
that oil is not flowing through the engine
properly. The vehicle could be low on oil
and might have some other system
problem. See your dealer.
Low Fuel Warning Light
A Low Fuel Warning Light near the fuel
gauge comes on briefly when the ignition is
turned on as a check to show it is working.
For vehicles with a reconfigurable cluster,
this light is in the display area and may not
come on when the ignition is turned on.
It also comes on when the fuel gauge
indicator nears empty. The light turns off
when fuel is added. If it does not, have the
vehicle serviced.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Instruments and Controls 119
Security Light
The security light should come on briefly as
the engine is started. If it does not come on,
have the vehicle serviced by your dealer.
If the system is working normally, the
indicator light turns off.
If the light stays on and the engine does
not start, there could be a problem with the
theft-deterrent system. SeeImmobilizer
Operation 027.
High-Beam On Light
This light comes on when the high-beam
headlamps are in use. See
Headlamp High/Low-Beam Changer
0 136.
IntelliBeam Light
This light comes on when the IntelliBeam
system, if equipped, is enabled.
See Exterior Lamp Controls 0134.
Front Fog Lamp Light
For vehicles with fog lamps, this light comes
on when the fog lamps are on.
The light goes out when the fog lamps are
turned off. See Fog Lamps0138.
Lamps On Reminder
This light comes on when the exterior lamps
are in use, except when only the Daytime
Running Lamps (DRL) are active. See Exterior
Lamp Controls 0134.
Cruise Control Light
The cruise control light is white when the
cruise control is on and ready, and turns
green when the cruise control is set and
active.
See Cruise Control 0251.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Driving and Operating 227
interference to the Keyless Access system.
SeeRemote Keyless Entry (RKE) System
Operation 08.
To shift out of P (Park), the ignition must be
on or in Service Mode, and the brake pedal
must be applied.
{Warning
Turning off the vehicle while moving may
cause loss of power assist in the brake
and steering systems and disable the
airbags. While driving, only shut the
vehicle off in an emergency.
Stopping the Engine/LOCK/OFF (No Indicator
Lights) : When the vehicle is stopped, press
ENGINE START/STOP once to turn the
engine off.
If the vehicle is in P (Park), the ignition will
turn off, and Retained Accessory Power (RAP)
will remain active. See Retained Accessory
Power (RAP) 0229.
If the vehicle is not in P (Park), the ignition
will return to ACC/ACCESSORY and display
the message SHIFT TO PARK in the Driver
Information Center (DIC). When the vehicle is
shifted into P (Park), the ignition system will
turn off. The vehicle may have an electric steering
column lock. The lock is activated when the
ignition is turned off and either front door is
opened. A sound may be heard as the lock
actuates or releases. The steering column
lock may not release with the wheels turned
off center. If this happens, the vehicle may
not start. Move the steering wheel from left
to right while attempting to start the
vehicle. If this does not work, the vehicle
needs service.
If the vehicle must be shut off in an
emergency:
1. Brake using a firm and steady pressure. Do not pump the brakes repeatedly. This
may deplete power assist, requiring
increased brake pedal force.
2. Shift the vehicle to N (Neutral). This can be done while the vehicle is moving.
After shifting to N (Neutral), firmly apply
the brakes and steer the vehicle to a
safe location.
3. Come to a complete stop. Hold the brake pedal down and shift to P (Park). The
vehicle must be in P (Park) to turn the
ignition off.
4. Continue to hold the brake pedal down. 5. Set the parking brake. See
Electric
Parking Brake 0240.
6. Press ENGINE START/STOP once to turn the ignition off.
7. Release the brake pedal.
If the vehicle cannot be pulled over, and
must be shut off while driving, press and
hold ENGINE START/STOP for longer than
two seconds, or press twice in five seconds.
ACC/ACCESSORY (Amber Indicator Light) :
This mode allows some electrical accessories
to be used when the engine is off.
With the ignition off, pressing the button
one time without the brake pedal applied
will place the ignition system in ACC/
ACCESSORY.
The ignition will switch from ACC/
ACCESSORY to off after five minutes to
prevent battery rundown.
ON/RUN/START (Green Indicator Light) : This
mode is for driving and starting. With the
ignition off, and the brake pedal applied,
pressing the button once will turn the
ignition on. Once engine cranking begins,
release the button. Engine cranking will
continue until the engine starts. See Starting
the Engine 0228.