2005 GMC ENVOY XL service

Airbag Readiness Light
There is an airbag readiness light on the instrument
panel, which shows the airbag symbol. The system
checks the airbag’s electrical system for malfunctions.
The light tells you if there is an electrical problem.
The system check includes the airbag sensors, the
airbag modules, the wiring and the crash sensing and
diagnostic module. For more information on the
airbag system, seeAirbag System on page 1-52.
This light will come on
when you start your
vehicle, and it will ash
for a few seconds.
Then the light should
go out. This means
the system is ready.
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.
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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. SeeAirbag Readiness Light
on page 3-35.
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 a generator drive belt,
or another electrical problem. Have it checked
right away. Driving while this light is on could drain
your battery.
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.
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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. 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 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.You can only drive for a short time with the reading in
either warning zone. If you must drive, turn off all
unnecessary accessories.
Readings in either warning zone indicate a possible
problem in the electrical system. Have the vehicle
serviced as soon as possible.
Brake System Warning Light
When the ignition is on, the brake system warning light
will come on when you set your parking brake. The
light will stay on if your parking brake doesn’t release
fully. If it stays on after your parking brake is fully
released, it means you have a brake problem. A chime
may also sound when the light comes on.
Your vehicle’s hydraulic brake system is divided into
two parts. If one part isn’t 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, there could be a brake
problem. Have your brake system inspected right away.
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This light should come on briey when you turn the
ignition key to RUN. If it doesn’t 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, the pedal 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 4-50.
{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 States
Canada
3-39

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. A chime
may also sound when
the light comes on.
If the light stays on, or comes on when you’re driving,
your vehicle needs service. If the regular brake
system warning light isn’t on, you still have brakes,
but you don’t have anti-lock brakes. If the regular
brake system warning light is also on, you don’t have
anti-lock brakes and there’s a problem with your regular
brakes. SeeBrake System Warning Light on page 3-38
earlier in this section.
The anti-lock brake system warning light should come
on briey 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.
Engine Coolant Temperature Gage
This gage shows the engine coolant temperature. If the
gage pointer moves into the red area, it means that
your engine coolant has overheated. If you have been
operating your vehicle under normal driving conditions,
you should pull off the road, stop your vehicle and
turn off the engine as soon as possible.
SeeEngine Overheating on page 5-26for more
information.
United StatesCanada
3-40

Malfunction Indicator Lamp
Check Engine Light
Your vehicle is equipped
with 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.
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.
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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.
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 the 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.
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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).
{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.
Oil pressure may vary with engine speed, outside
temperature and oil viscosity, but readings above the
low pressure zone indicate the normal operating range.
A reading in the low pressure zone may be caused
by a dangerously low oil level or other problems causing
low oil pressure. United States
Canada
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