light GMC YUKON DENALI 2005 Workshop Manual

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.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
3-40

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.
If the Light Is On Steady
You may be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If so, reinstall the fuel cap, making sure to fully install
the cap. SeeFilling Your Tank on page 5-8. The
diagnostic system can determine if the fuel cap has
been left off or improperly installed. A loose or missing
fuel cap will allow fuel to evaporate into the atmosphere.
A few driving trips with the cap properly installed
should turn the light off.Did you just drive through a deep puddle of water?
If so, your electrical system may be wet. The condition
will usually be corrected when the electrical system
dries out. A few driving trips should turn the light off.
Have you recently changed brands of fuel?
If so, be sure to fuel your vehicle with quality fuel. See
Gasoline Octane on page 5-5. Poor fuel quality will
cause your engine not to run as efficiently as designed.
You may notice this as stalling after start-up, stalling
when you put the vehicle into gear, misring, hesitation
on acceleration, or stumbling on acceleration. (These
conditions may go away once the engine is warmed up.)
This will be detected by the system and cause the
light to turn on.
If you experience one or more of these conditions,
change the fuel brand you use. It will require at least
one full tank of the proper fuel to turn the light off.
If none of the above steps have made the light turn off,
your dealer can check the vehicle. Your dealer has
the proper test equipment and diagnostic tools to x any
mechanical or electrical problems that may have
developed.
3-41

Emissions Inspection and Maintenance
Programs
Some state/provincial and local governments have or
may begin programs to inspect the emission control
equipment on your vehicle. Failure to pass this
inspection could prevent you from getting a vehicle
registration.
Here are some things you need to know to help your
vehicle pass an inspection:
Your vehicle will not pass this inspection if the check
engine light is on or not working properly.
Your vehicle will not pass this inspection if the OBD
(on-board diagnostic) system determines that critical
emission control systems have not been completely
diagnosed by the system. The vehicle would be
considered not ready for inspection. This can happen if
you have recently replaced your battery or if your
battery has run down. The diagnostic system is
designed to evaluate critical emission control systems
during normal driving. This may take several days
of routine driving. If you have done this and your vehicle
still does not pass the inspection for lack of OBD
system readiness, your GM dealer can prepare the
vehicle for inspection.
Oil Pressure Gage
The oil pressure gage shows the engine oil pressure
in psi (pounds per square inch) when the engine
is running. Canadian vehicles indicate pressure in
kPa (kilopascals).
Oil pressure may vary with engine speed, outside
temperature and oil viscosity, but readings above the
low pressure zone indicate the normal operating range.United States
Canada
3-42

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 your oil as soon as
possible. SeeEngine Oil on page 5-14.
{CAUTION:
Do not keep driving if the oil pressure is low. If
you do, your engine can become so hot that it
catches re. You or others could be burned.
Check your oil as soon as possible and have
your vehicle serviced.
Notice:Lack of proper engine oil maintenance may
damage the engine. The repairs would not be
covered by your warranty. Always follow the
maintenance schedule in this manual for changing
engine oil.
Security Light
This light will come on
briey when you turn the
key toward START.
The light will stay on until
the engine starts.
If the light ashes, the Passlock
®system has entered a
tamper mode. If the vehicle fails to start, seePasslock®
on page 2-19.
If the light comes on continuously while driving and
stays on, there may be a problem with the Passlock
®
system. Your vehicle will not be protected by Passlock®,
and you should see your dealer.
Also, seeContent Theft-Deterrent on page 2-17for
additional information regarding the security light.
3-43

Cruise Control Light
This light comes on
whenever you set your
cruise control.
The light will go out when the cruise control is turned
off. SeeCruise Control on page 3-11for more
information.
Highbeam On Light
This light will come on
when the high-beam
headlamps are in use.
SeeHeadlamp High/Low-Beam Changer on page 3-8.
Tow/Haul Mode Light
This light is displayed
when the Tow/Haul mode
has been activated.
For more information, seeTow/Haul Mode on page 2-26.
3-44

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. SeeDriver Information
Center (DIC) on page 3-46.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
The light next to the fuel gage will come on briey when
you are starting the engine.
This light comes on when the fuel tank is low on fuel.
To turn it off, add fuel to the fuel tank. SeeFuel on
page 5-5. United States
Canada
3-45

DIC Warnings and Messages
Warning messages are displayed on the Driver
Information Center (DIC) to notify the driver that the
status of the vehicle has changed and that some action
may be needed by the driver to correct the condition.
If there is more than one message that needs to
be displayed they will appear one after another. Some
messages may not require immediate action, but
you should press any of the four DIC buttons on the
steering wheel, if equipped, to acknowledge that
you received the messages and clear them from the
display. If your vehicle is not equipped with DIC buttons
on the steering wheel, press the trip odometer reset
stem located on the instrument panel cluster to
acknowledge messages and clear them from the display.
Some messages cannot be cleared from the display
because they are more urgent. These messages require
action before they can be removed from the DIC
display. You should take any messages that appear on
the display seriously and remember that clearing the
messages will only make the messages disappear, not
correct the problem. The following are the possible
messages that can be displayed and some information
about them.
BATTERY NOT CHARGING
On some vehicles, if the battery is not charging during
operation, this message will appear on the DIC. Driving
with this problem could drain your battery. Have the
electrical system checked by your GM dealer as soon as
possible. Pressing any of the four DIC buttons, if
equipped, will clear the message from the DIC display. If
your vehicle is not equipped with the four DIC buttons,
pressing the trip odometer reset stem will clear the
message from the DIC display. SeeCharging System
Light on page 3-33andVoltmeter Gage on page 3-34.
BUCKLE PASSENGER
If your vehicle is equipped with the passenger sensing
system, this message reminds you to buckle the
passenger’s seat belt. SeePassenger Sensing System
on page 1-79.
This message will display and a chime will sound when
the ignition is on, the driver’s seat belt is buckled, the
passenger’s seat belt is unbuckled with the passenger
airbag enabled and the vehicle is in motion. You should
have the passenger buckle their seat belt.
3-50

This reminder will be repeated if the ignition is on, the
vehicle is in motion, the driver is buckled and the
passenger is still unbuckled and the passenger airbag is
enabled. If the passenger’s seat belt is already
buckled, this message and chime will not come on.
Pressing any of the four DIC buttons, if equipped, will
acknowledge the message and clear it from the DIC
display. If your vehicle is not equipped with the four DIC
buttons, pressing the trip odometer reset stem will
acknowledge the message and clear it from the DIC
display.
BUCKLE SEATBELT
If your vehicle is equipped with the passenger sensing
system, this message reminds you to buckle the
driver’s seat belt. SeePassenger Sensing System on
page 1-79.
This message will display and a chime will sound when
the ignition is on, the driver’s seat belt is unbuckled
and the vehicle is in motion. You should buckle
your seat belt.
If the driver remains unbuckled when the ignition is on
and the vehicle is in motion, the reminder will be
repeated. If the driver’s seat belt is already buckled, this
message and chime will not come on.This message is an additional reminder to the Safety
Belt Reminder Light in the instrument panel cluster. See
Safety Belt Reminder Light on page 3-30.
Pressing any of the four DIC buttons, if equipped, will
acknowledge the message and clear it from the
DIC display. If your vehicle is not equipped with the
four DIC buttons, pressing the trip odometer reset stem
will acknowledge the message and clear it from the
DIC display.
CHANGE ENGINE OIL
This message is displayed when the engine oil needs to
be changed. SeeEngine Oil Life System on page 5-17for
information on how to reset the message. This message
will clear itself after 10 seconds until the next ignition
cycle. SeeScheduled Maintenance on page 6-4and
Engine Oil on page 5-14for more information.
CHARGING SYSTEM FAILURE
On some vehicles, if there is a problem with the generator
and battery charging system, this message will appear on
the DIC, a chime will sound and the charging system light
on the instrument panel cluster will come on. See
Charging System Light on page 3-33andVoltmeter Gage
on page 3-34for more information. Driving with this
problem could drain your battery. Turn off all unnecessary
accessories. Stop and turn off the vehicle as soon as it is
safe to do so. Have the electrical system checked by your
GM dealer immediately.
3-51

ENGINE COOLANT HOT
If the cooling system temperature gets hot, this message
will appear in the DIC. Stop the vehicle and let the engine
idle in PARK (P) to allow the coolant to reach a safe
temperature. This message will clear when the coolant
temperature drops to a safe operating temperature.
ENGINE OVERHEATED
If the engine cooling system reaches unsafe
temperatures for operation, this message will appear in
the DIC and you will hear a chime. Stop and turn off
the vehicle as soon as it is safe to do so to avoid severe
damage. This message will clear when the engine
has cooled to a safe operating temperature.
Notice:If you drive your vehicle while the engine is
overheating, severe engine damage may occur. If
an overheat warning appears on the instrument
panel cluster and/or DIC, stop the vehicle as soon
as possible. Do not increase the engine speed above
normal idling speed. SeeEngine Overheating on
page 5-28for more information.
FUEL LEVEL LOW
If the fuel level is low, this message will appear on the
DIC and you will hear a chime. Refuel as soon as
possible. Pressing any of the four DIC buttons, if
equipped, will clear the message from the DIC display.
If your vehicle is not equipped with the four DIC
buttons, pressing the trip odometer reset stem will clear
the message from the DIC display. It will also clear
itself after 10 seconds until the next ignition cycle. The
low fuel light near the fuel gage will still remain on
in either case. SeeFuel Gage on page 3-45,Fuel on
page 5-5andLow Fuel Warning Light on page 3-45.
KEYFOB X BATTERY LOW
If a remote keyless entry transmitter battery is low, this
message will appear on the DIC. The battery needs
to be replaced in the transmitter. See “Battery
Replacement” underRemote Keyless Entry System
Operation on page 2-6. Pressing any of the four
DIC buttons, if equipped, will clear the message from
the DIC display. If your vehicle is not equipped with the
four DIC buttons, pressing the trip odometer reset
stem will clear the message from the DIC display.
3-53

SERVICE 4WD
If a problem occurs with the all-wheel-drive system, this
message will appear on the DIC. If this message
appears, stop as soon as possible and turn off the
vehicle. Restart the vehicle and check for the message
on the DIC display. If the message is still displayed
or appears again when you begin driving, the
four-wheel-drive system needs service. See your
GM dealer.
SERVICE AIR BAG
If there is a problem with the airbag system, this
message will be displayed on the DIC. Have your
GM dealer inspect the system for problems. SeeAirbag
Readiness Light on page 3-31andAirbag System on
page 1-70for more information. Pressing any of the four
DIC buttons, if equipped, will clear the message from
the DIC display. If your vehicle is not equipped with the
four DIC buttons, pressing the trip odometer reset
stem will clear the message from the DIC display.
SERVICE BRAKE SYSTEM
If a problem occurs with the brake system, this message
will appear on the DIC. If this message appears, stop
as soon as possible and turn off the vehicle. Restart the
vehicle and check for the message on the DIC display.
If the message is still displayed or appears again
when you begin driving, the brake system needs service.
See your GM dealer.
SERVICE CHARGING SYSTEM
On some vehicles, if there is a problem with the battery
charging system, this message will appear on the
DIC. Under certain conditions, the charging system light
may also turn on in the instrument panel cluster. See
Charging System Light on page 3-33. The battery
will not be charging at an optimal rate and the vehicle
will lose the ability to enter the fuel economy mode. The
vehicle is safe to drive, however you should have the
electrical system checked by your GM dealer. Pressing
any of the four DIC buttons, if equipped, will clear
the message from the DIC display. If your vehicle is not
equipped with the four DIC buttons, pressing the trip
odometer reset stem will clear the message from
the DIC display.
3-56