2012 GMC YUKON service indicator

Black plate (4,1)GMC Yukon/Yukon XL Owner Manual - 2012
iv Introduction
Using this Manual
To quickly locate information about
the vehicle, use the Index in the
back of the manual. It is an
alphabetical list of what is in the
manual and the page number where
it can be found.
Danger, Warnings, and
Cautions
Warning messages found on vehicle
labels and in this manual describe
hazards and what to do to avoid or
reduce them.
Dangerindicates a hazard with a
high level of risk which will result in
serious injury or death.
Warning orCaution indicates a
hazard that could result in injury or
death.
{WARNING
These mean there is something
that could hurt you or other
people.
Notice: This means there is
something that could result in
property or vehicle damage. This
would not be covered by the
vehicle's warranty.
A circle with a slash through it is a
safety symbol which means “Do
Not,” “Do not do this,” or“Do not let
this happen.”
Symbols
The vehicle has components and
labels that use symbols instead of
text. Symbols are shown along with
the text describing the operation or
information relating to a specific
component, control, message,
gauge, or indicator.
M: This symbol is shown when
you need to see your owner manual
for additional instructions or
information.
*: This symbol is shown when
you need to see a service manual
for additional instructions or
information.

Black plate (40,1)GMC Yukon/Yukon XL Owner Manual - 2012
3-40 Seats and Restraints
For some children, including
children in child restraints, and for
very small adults, the passenger
sensing system may or may not
turn off the right front passenger
frontal airbag, depending upon the
person's seating posture and body
build. Everyone in the vehicle
who has outgrown child restraints
should wear a safety belt
properly—whether or not there is
an airbag for that person.
{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 on page 5‑18 for more
information, including important
safety information.
If the On Indicator is Lit for a
Child Restraint
If a child restraint has been installed
and the on indicator is lit:
1. Turn the vehicle off.
2. Remove the child restraint from the vehicle.
3. Remove any additional items from the seat such as blankets,
cushions, seat covers, seat
heaters, or seat massagers.
4. Reinstall the child restraint following the directions
provided by the child restraint
manufacturer and refer to
Securing Child Restraints (Rear
Seat Position) on page 3‑60 or
Securing Child Restraints
(Center Front Seat Position) on
page 3‑63 orSecuring Child
Restraints (Right Front Seat
Position) on page 3‑63. 5. If, after reinstalling the child
restraint and restarting the
vehicle, the on indicator is still lit,
turn the vehicle off. Then slightly
recline the vehicle seatback
and adjust the seat cushion,
if adjustable, to make sure that
the vehicle seatback is not
pushing the child restraint into
the seat cushion.
Also make sure the child
restraint is not trapped under the
vehicle head restraint. If this
happens, adjust the head
restraint. See Head Restraints
on page 3‑2.
6. Restart the vehicle.
The passenger sensing system
may or may not turn off the
airbag for a child in a child
restraint depending upon the
child’s seating posture and body
build. It is better to secure the
child restraint in a rear seat.

Black plate (42,1)GMC Yukon/Yukon XL Owner Manual - 2012
3-42 Seats and Restraints
A thick layer of additional material,
such as a blanket or cushion,
or aftermarket equipment such as
seat covers, seat heaters, and seat
massagers, can affect how well
the passenger sensing system
operates. We recommend that you
not use seat covers or other
aftermarket equipment except when
approved by GM for your specific
vehicle. SeeAdding Equipment to
the Airbag-Equipped Vehicle on
page 3‑42 for more information
about modifications that can affect
how the system operates.
The on indicator may be lit if an
object, such as a briefcase,
handbag, grocery bag, laptop,
or other electronic device, is put on
an unoccupied seat. If this is not
desired, remove the object from
the seat.{WARNING
Stowing of articles under the
passenger seat or between the
passenger seat cushion and
seatback may interfere with the
proper operation of the passenger
sensing system.
Servicing the
Airbag-Equipped Vehicle
Airbags affect how the vehicle
should be serviced. There are parts
of the airbag system in several
places around the vehicle. Your
dealer and the service manual have
information about servicing the
vehicle and the airbag system. To
purchase a service manual, see
Service Publications Ordering
Information on page 13‑12.
{WARNING
For up to 10 seconds after the
vehicle is turned off and the
battery is disconnected, an airbag
can still inflate during improper
service. You can be injured if you
are close to an airbag when it
inflates. Avoid yellow connectors.
They are probably part of the
airbag system. Be sure to follow
proper service procedures, and
make sure the person performing
work for you is qualified to do so.
Adding Equipment to the
Airbag-Equipped Vehicle
Q: Is there anything I might add to or change about the vehicle
that could keep the airbags
from working properly?
A: Yes. If you add things that
change your vehicle's frame,
bumper system, height, front end
or side sheet metal, they may

Black plate (16,1)GMC Yukon/Yukon XL Owner Manual - 2012
5-16 Instruments and Controls
A reading in the low pressure zone
may be caused by a dangerously
low oil level or some other problem
causing low oil pressure. Check the
oil as soon as possible.
{WARNING
Do not keep driving if the oil
pressure is low. The engine can
become so hot that it catches fire.
Someone could be burned. Check
the oil as soon as possible and
have the vehicle serviced.
Notice: Lack of proper engine oil
maintenance can damage the
engine. The repairs would not be
covered by the vehicle warranty.
Always follow the maintenance
schedule for changing engine oil.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Engine Coolant
Temperature Gauge
Metric
English
This gauge shows the engine
coolant temperature.
It also provides an indicator of how
hard the vehicle is working. During a
majority of the operation, the gauge
reads 100°C (210°F) or less. If you
are pulling a load or going up hills, it
is normal for the temperature to
fluctuate and approach the 122°C
(250°F) mark. If the gauge reaches
the 125°C (260°F) mark, it indicates
that the cooling system is working
beyond its capacity.

Black plate (19,1)GMC Yukon/Yukon XL Owner Manual - 2012
Instruments and Controls 5-19
{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 can also come on.
See Airbag System Messages on
page 5‑44 for more information.
Passenger Airbag Status
Indicator
If the vehicle has the airbag status
indicator pictured in the following
illustration, then the vehicle has a
passenger sensing system for the
right front passenger position. The
passenger airbag status indicator is
on the overhead console. See
Passenger Sensing System on
page 3‑38for important safety
information.
In addition, if the vehicle has a
passenger sensing system for the
right front passenger position, the
label on the vehicle's sun visors
refers to “ADVANCED AIRBAGS.”
United States
Canada
When the vehicle is started, the
passenger airbag status indicator
will light ON and OFF, or the
symbols for on and off, for several
seconds as a system check. If you
are using remote start, if equipped,
to start the vehicle from a distance,
you may not see the system check.

Black plate (20,1)GMC Yukon/Yukon XL Owner Manual - 2012
5-20 Instruments and Controls
Then, after several more seconds,
the status indicator will light either
ON or OFF, or either the on or off
symbol to let you know the status of
the right front passenger frontal
airbag.
If the word ON or the on symbol is
lit on the passenger airbag status
indicator, it means that the right
front passenger frontal airbag is
enabled (may inflate).
If the word OFF or the off symbol is
lit on the airbag status indicator, it
means that the passenger sensing
system has turned off the right front
passenger frontal airbag.
If, after several seconds, both status
indicator lights remain on, or if there
are no lights at all, there may be a
problem with the lights or the
passenger sensing system. See
your dealer for service.{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. SeeAirbag Readiness
Light on page 5‑18 for more
information, including important
safety information.
Charging System Light
This light comes on briefly when the
ignition key is turned to START, but
the engine is not running, as a
check to show it is working. If it does not, have the vehicle
serviced by your dealer.
The light should go out once the
engine starts. If it stays on,
or comes on while driving, there
could be a problem with the
charging system. A charging system
message in the Driver Information
Center (DIC) can also appear. See
Battery Voltage and Charging
Messages on page 5‑38
for more
information. This light could indicate
that there are problems with a
generator drive belt, or that there is
an electrical problem. Have it
checked right away. If the vehicle
must be driven a short distance with
the light on, turn off accessories,
such as the radio and air
conditioner.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.

Black plate (21,1)GMC Yukon/Yukon XL Owner Manual - 2012
Instruments and Controls 5-21
Malfunction
Indicator Lamp
A computer system called OBD II
(On-Board Diagnostics-Second
Generation) monitors the operation
of the vehicle to ensure emissions
are at acceptable levels, to produce
a cleaner environment. This light
comes on when the vehicle is
placed in ON/RUN, as a check to
show it is working. If it does not,
have the vehicle serviced by your
dealer. SeeIgnition Positions on
page 9‑22 for more information.
If the malfunction indicator lamp
comes on and stays on while the
engine is running, this indicates that
there is an OBD II problem and
service is required.
Malfunctions often are indicated by
the system before any problem is
apparent. Being aware of the light
can prevent more serious damage
to the vehicle. This system assists
the service technician in correctly
diagnosing any malfunction.
Notice:If the vehicle is
continually driven with this light
on, the emission controls might
not work as well, the vehicle fuel
economy might not be as good,
and the engine might not run as
smoothly. This could lead to
costly repairs that might not be
covered by the vehicle warranty. Notice:
Modifications made to the
engine, transmission, exhaust,
intake, or fuel system of the
vehicle or the replacement of the
original tires with other than
those of the same Tire
Performance Criteria (TPC) can
affect the vehicle's emission
controls and can cause this light
to come on. Modifications to
these systems could lead to
costly repairs not covered by the
vehicle warranty. This could also
result in a failure to pass a
required Emission Inspection/
Maintenance test. See
Accessories and Modifications on
page 10‑3.
This light comes on during a
malfunction in one of two ways:
Light Flashing: A misfire condition
has been detected. A misfire
increases vehicle emissions and
could damage the emission control
system on the vehicle. Diagnosis
and service might be required.

Black plate (24,1)GMC Yukon/Yukon XL Owner Manual - 2012
5-24 Instruments and Controls
This light can also come on due to
low brake fluid. SeeBrake Fluid on
page 10‑27 for more information.
MetricEnglish
This light comes on briefly when the
ignition key is turned to ON/RUN.
If it does not come on then, have it
fixed so it is ready to warn if there is
a problem.
{WARNING
The brake system might not be
working properly if the brake
system warning light is on.
Driving with the brake system
warning light on can lead to a
crash. If the light is still on after
the vehicle has been pulled off
the road and carefully stopped,
have the vehicle towed for
service.
If the light comes on while driving,
pull off the road and stop carefully.
The pedal might be harder to push
or might go closer to the floor. It can
take longer to stop. If the light is still
on, have the vehicle towed for
service. See Towing the Vehicle on
page 10‑93.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Antilock Brake System
(ABS) Warning Light
For vehicles with the Antilock Brake
System (ABS), this light comes on
briefly when the engine is started.
If it does not, have the vehicle
serviced by your dealer. If the
system is working normally the
indicator light then goes off.
If the ABS light stays on, turn the
ignition off. If the light comes on
while driving, stop as soon as it is
safely possible and turn the ignition
off. Then start the engine again to
reset the system. If the ABS light
stays on, or comes on again while
driving, the vehicle needs service.