ignition GMC YUKON XL 2007 Service Manual

If the airbag readiness light stays on after you
start the vehicle or comes on when you are driving,
your airbag system may not work properly.
Have your vehicle serviced right away.
{CAUTION:
If the airbag readiness light stays on after
you start your vehicle, it means the airbag
system may not be working properly. The
airbags in your vehicle may not inate in
a crash, or they could even inate without
a crash. To help avoid injury to yourself
or others, have your vehicle serviced right
away if the airbag readiness light stays on
after you start your vehicle.
The airbag readiness light should ash for a few
seconds when you turn the ignition key to RUN.
If the light doesn’t come on then, have it xed so it
will be ready to warn you if there is a problem.
Passenger Airbag Status Indicator
Your vehicle has the passenger sensing system.
Your overhead console has a passenger airbag
status indicator.
When the ignition key is turned to RUN or START,
the passenger airbag status indicator will light
ON and OFF, or the symbol 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, or either the on
or off symbol to let you know the status of the
right front passenger’s frontal airbag.
Passenger
Airbag Status
Indicator – United
StatesPassenger
Airbag Status
Indicator – Canada
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If, after several seconds, all 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.
{CAUTION:
If the off indicator and the airbag
readiness light ever come on together, it
means that something may be wrong with
the airbag system. If this ever happens,
have the vehicle serviced promptly,
because an adult-size person sitting in the
right front passenger seat may not have
the protection of the frontal airbag. See
Airbag Readiness Light on page 227.
Charging System Light
The charging system
light will come on briey
when you turn on the
ignition, but the
engine is not running,
as a check to show you
it is working.
It should go out once the engine is running.
If it stays on, or comes on while you are driving,
you may have a problem with the charging system.
It could indicate that you have problems with the
generator, the generator drive belt, or another
electrical problem. Have it checked right away.
Driving while this light is on could drain your
battery.
When this light comes on, the DIC will also display
the SERVICE BATTERY NOT CHARGING
SYSTEM message. SeeDIC Warnings and
Messages on page 254for more information.
If you must drive a short distance with the light on,
be certain to turn off all your accessories, such as
the radio and air conditioner, to reduce the drain on
your battery.
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Voltmeter Gage
When your engine is not
running, but the ignition
is in RUN, this gage
shows your battery’s
state of charge in
DC volts.
When the engine is running, the gage shows the
condition of the charging system. The charging
system regulates voltage based on the state of the
battery for improved fuel economy and battery
life. The gage may transition from a higher to lower
or a lower to higher reading, this is normal.
Readings between the low and high warning zones
indicate the normal operating range.Readings in the low warning zone may occur
when a large number of electrical accessories are
operating in the vehicle and the engine is left at
an idle 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 full power. If there is a problem
with the battery charging system, this light
will come on or the SERVICE BATTERY
CHARGING SYSTEM DIC message will display.
SeeDIC Warnings and Messages on page 254
andCharging System Light on page 230for more
information.
231

Brake System Warning Light
With the ignition on, the brake system warning
light will come on when you set the parking brake.
If you try to drive with the parking brake engaged,
a chime will sound when the vehicle speed is
greater than 3 mph (5 km/h).
Your vehicle’s hydraulic brake system is divided
into two parts. If one part is not working, the other
part can still work and stop you. For good
braking, though, you need both parts working well.
If the warning light comes on and a chime sounds
there could be a brake problem. Have your brake
system inspected right away.
This light may also come on due to low brake uid.
SeeBrakes on page 463for more information.This light should come on briey when you turn
the ignition key to RUN. If it does not come
on then, have it xed so it will be ready to warn
you if there’s a problem.
If the light comes on while you are driving, pull off
the road and stop carefully. You may notice
that the pedal is harder to push or may go closer
to the oor. It may take longer to stop. If the
light is still on, have the vehicle towed for service.
SeeTowing Your Vehicle on page 400.
{CAUTION:
Your brake system may not be working
properly if the brake system warning light
is on. Driving with the brake system
warning light on can lead to an accident.
If the light is still on after you have pulled
off the road and stopped carefully, have
the vehicle towed for service.
United StatesCanada
232

Anti-Lock Brake System Warning
Light
With the anti-lock brake
system, this light will
come on when you start
your engine and may
stay on for several
seconds.
That’s normal. If the light does not come on then,
have it xed so it will be ready to warn you if
there is a problem.If the light stays on, or comes on when you are
driving, your vehicle needs service. You will
also hear a chime sound when the light is on
steady. If the regular brake system warning light is
not on, you still have brakes, but you do not
have anti-lock brakes. If the regular brake system
warning light is also on you do not have anti-lock
brakes and there is a problem with your regular
brakes. In addition to both lights, you will also hear
a chime sound on the rst occurrence of a
problem and each time the vehicle is shut off and
then restarted. SeeBrake System Warning
Light on page 232.
The anti-lock brake system warning light should
come on briey when you turn the ignition
key to RUN. If the light does not come on then,
have it xed so it will be ready to warn you if there
is a problem.
233

Tire Pressure Light
This light will come on
briey when you turn
the ignition to RUN.
This light will also come on when one or more of
your tires are signicantly underinated.If equipped, a CHECK TIRE PRESSURE DIC
message will accompany the light.
Stop and check your tires as soon as it is safe to
do so. If underinated, inate to the proper
pressure. SeeTires on page 482for more
information.
This light will ash for 60 seconds and then turn
on solid if a problem is detected with the Tire
Pressure Monitor system.
SeeTire Pressure Monitor System on page 492
for more information.
235

Malfunction Indicator Lamp
Check Engine Light
Your vehicle has a
computer which
monitors operation of
the fuel, ignition,
and emission control
systems.
This system is called OBD II (On-Board
Diagnostics-Second Generation) and is intended
to assure that emissions are at acceptable
levels for the life of the vehicle, helping to produce
a cleaner environment. The check engine light
comes on to indicate that there is a problem and
service is required. Malfunctions often will be
indicated by the system before any problem is
apparent. This may prevent more serious damage
to your vehicle. This system is also designed to
assist your service technician in correctly
diagnosing any malfunction.Notice:If you keep driving your vehicle with
this light on, after awhile, your emission
controls may not work as well, your fuel
economy may not be as good, and your engine
may not run as smoothly. This could lead to
costly repairs that may not be covered by your
warranty.
Notice:Modications made to the engine,
transmission, exhaust, intake, or fuel system
of your vehicle or the replacement of the
original tires with other than those of the same
Tire Performance Criteria (TPC) can affect
your vehicle’s emission controls and may
cause this light to come on. Modications to
these systems could lead to costly repairs not
covered by your warranty. This may also
result in a failure to pass a required Emission
Inspection/Maintenance test. SeeAccessories
and Modifications on page 426.
236

This light should come on, as a check to show
you it is working, when the ignition is on and the
engine is not running. If the light does not
come on, have it repaired. This light will also
come on during a malfunction in one of two ways:
Light Flashing— A misre condition has
been detected. A misre increases vehicle
emissions and may damage the emission
control system on your vehicle. Diagnosis and
service may be required.
Light On Steady— An emission control
system malfunction has been detected on your
vehicle. Diagnosis and service may be
required.
If the Light is Flashing
The following may prevent more serious damage
to your vehicle:
Reducing vehicle speed
Avoiding hard accelerations
Avoiding steep uphill grades
If you are towing a trailer, reduce the amount
of cargo being hauled as soon as it is
possible
If the light stops ashing and remains on steady,
see “If the Light Is On Steady” following.
If the light continues to ash, when it is safe to do
so, stop the vehicle. Find a safe place to park
your vehicle. Turn the key off, wait at least
10 seconds and restart the engine. If the light
remains on steady, see “If the Light Is On Steady”
following. If the light is still ashing, follow the
previous steps, and see your dealer for service as
soon as possible.
237

Fuel Gage
The fuel gage, when the ignition is on, tells you
about how much fuel you have left in your tank.
The gage will rst indicate empty before you
are out of fuel, and you should get more fuel as
soon as possible.
When the fuel tank is low, the FUEL LEVEL LOW
message will appear. SeeDIC Warnings and
Messages on page 254.
Here are some situations you may experience with
your fuel gage. None of these indicate a problem
with the fuel gage.
At the gas station, the fuel pump shuts off
before the gage reads full.
It takes a little more or less fuel to ll up than
the fuel gage indicated. For example, the
gage may have indicated the tank was half full,
but it actually took a little more or less than
half the tank’s capacity to ll the tank.
The gage goes back to empty when you turn
off the ignition.
Low Fuel Warning Light
This light, under the fuel
gage, will come on
briey when you
are starting the engine.
This light and a chime will come on when the fuel
tank is low on fuel. There will also be a “FUEL
LEVEL LOW” message on the Driver Information
Center, seeDIC Warnings and Messages on
page 254for more information. When you add fuel
this light and message should go off. If it does
not, have your vehicle serviced.United StatesCanada
243

Driver Information Center (DIC)
Your vehicle has a Driver Information Center (DIC).
The DIC displays information about your vehicle.
It also displays warning messages if a system
problem is detected.
All messages will appear in the DIC display
located below the tachometer in the instrument
panel cluster.
The DIC comes on when the ignition is on. After a
short delay, the DIC will display the information
that was last displayed before the engine was
turned off.
If your vehicle has DIC buttons, see “DIC
Operation and Displays (With DIC Buttons)” later
in this section andDIC Vehicle Customization
(With DIC Buttons) on page 264for the displays
available.
If your vehicle does not have DIC buttons, see
“DIC Operation and Displays (Without DIC
Buttons)” later in this section for the displays
available.
DIC Operation and Displays
(With DIC Buttons)
If your vehicle has DIC buttons, the information
below explains the operation of this system.
The DIC has different displays which can be
accessed by pressing the DIC buttons located on
the instrument panel, to the right of the steering
wheel.
The DIC displays trip, fuel, and vehicle system
information, and warning messages if a system
problem is detected.
The DIC also allows some features to be
customized. SeeDIC Vehicle Customization (With
DIC Buttons) on page 264for more information.
If your vehicle has DIC buttons, you can also use
the trip odometer reset stem to view some of
the DIC displays. See “DIC Operation and Displays
(Without DIC Buttons)” later in this section.
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