2001 GMC ENVOY check engine

2-95
NOTICE:
If you keep driving your vehicle with this light
on, after a while, 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:
Modifications 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 the SERVICE ENGINE SOON
OR CHECK ENGINE light to come on.
Modifications 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 doesn't come on, have it repaired.
This light will also come on during a malfunction in one
of two ways:

Light Flashing
-- A misfire condition has been
detected. A misfire increases vehicle emissions and
may damage the emission control system on your
vehicle. Dealer or qualified service center diagnosis
and service may be required.

Light On Steady
-- An emission control
system malfunction has been detected on your
vehicle. Dealer or qualified service center 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 flashing and remains on steady,
see ªIf the Light Is On Steadyº following.
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If the light continues to flash, 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 ªIf the Light
Is On Steadyº following. If the light is still flashing,
follow the previous steps, and drive the vehicle to your
dealer or qualified service center for service.
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. See ªFilling Your Tankº in the Index.
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 ªFuelº in the Index. 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, misfiring, 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,
have your dealer or qualified service center check the
vehicle. Your dealer has the proper test equipment and
diagnostic tools to fix any mechanical or electrical
problems that may have developed.
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2-97
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 in order to help
your vehicle pass an inspection:
Your vehicle will not pass this inspection if the
SERVICE ENGINE SOON or 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, see your dealer or qualified service center to
prepare the vehicle for inspection.
Oil Pressure Gage
United States Canada
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:
Don't keep driving if the oil pressure is low.
If you do, your engine can become so hot that
it catches fire. You or others could be burned.
Check your oil as soon as possible and have
your vehicle serviced.
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NOTICE:
Damage to your engine from neglected oil problems
can be costly and is not covered by your warranty.
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.
Security Light
This light will come on
briefly when you turn
the key toward START.
The light will stay on
until the engine starts.
If the light flashes, the Passlock

system has entered a
tamper mode. If the vehicle fails to start, see ªPasslockº
in the Index.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, see ªContent Theft
-Deterrentº in the Index for
additional information regarding the SECURITY light.
Service Four-Wheel-Drive Warning Light
(If Equipped)
This light should come on
briefly when you turn on
the ignition, as a check to
show you it is working.
The SERVICE 4WD light comes on to indicate that
there may be a problem with the drive system and
service is required. Malfunctions can be indicated by the
system before any problem is apparent, which may
prevent serious damage to the vehicle. This system is
also designed to assist your service technician in
correctly diagnosing a malfunction.
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Tow/Haul Mode Light (If Equipped)
This light should come on
when the tow/haul mode
has been selected.
For more information, see ªTow/Haul Modeº in
the Index.
Check Gages Light
The CHECK GAGES light
will come on briefly when
you are starting the engine.
If the light comes on and stays on while you are driving,
check your coolant temperature and engine oil pressure
gages to see if they are in the warning zones.
Gate Ajar Light
If this light comes on, your
liftgate or liftglass is ajar.
Try closing the liftgate or
liftglass again. Never drive
with the liftgate or liftglass
even partially open.
Fuel Gage
United States Canada
When the ignition is on, the fuel gage tells you about
how much fuel you have remaining.
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3-45 Understanding Radio Reception
AM
The range for most AM stations is greater than for FM,
especially at night. The longer range, however, can
cause stations to interfere with each other. AM can
pick up noise from things like storms and power lines.
Try reducing the treble to reduce this noise if you
ever get it.
FM Stereo
FM stereo will give you the best sound, but FM signals
will reach only about 10 to 40 miles (16 to 65 km). Tall
buildings or hills can interfere with FM signals, causing
the sound to come and go.
Tips About Your Audio System
Hearing damage from loud noise is almost undetectable
until it is too late. Your hearing can adapt to higher
volumes of sound. Sound that seems normal can be
loud and harmful to your hearing. Take precautions by
adjusting the volume control on your radio to a safe
sound level before your hearing adapts to it.To help avoid hearing loss or damage:

Adjust the volume control to the lowest setting.

Increase volume slowly until you hear comfortably
and clearly.
NOTICE:
Before you add any sound equipment to your
vehicle
-- like a tape player, CB radio, mobile
telephone or two
-way radio -- be sure you
can add what you want. If you can, it's very
important to do it properly. Added sound
equipment may interfere with the operation of
your vehicle's engine, Delphi Delco Electronics
radio or other systems, and even damage them.
Your vehicle's systems may interfere with the
operation of sound equipment that has been
added improperly.
So, before adding sound equipment, check with
your dealer and be sure to check Federal rules
covering mobile radio and telephone units.
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4-8
Avoid needless heavy braking. Some people drive
in spurts
-- heavy acceleration followed by heavy
braking
-- rather than keeping pace with traffic.
This is a mistake. Your brakes may not have time
to cool between hard stops. Your brakes will wear
out much faster if you do a lot of heavy braking.
If you keep pace with the traffic and allow realistic
following distances, you will eliminate a lot of
unnecessary braking. That means better braking
and longer brake life.
If your engine ever stops while you're driving, brake
normally but don't pump your brakes. If you do,
the pedal may get harder to push down. If your engine
stops, you will still have some power brake assist.
But you will use it when you brake. Once the power
assist is used up, it may take longer to stop and the
brake pedal will be harder to push.
Anti-Lock Brakes (ABS)
Your vehicle has anti-lock brakes (ABS). ABS is
an advanced electronic braking system that will help
prevent a braking skid.
When you start your engine and begin to drive away,
your anti
-lock brake system will check itself. You may
hear a momentary motor or clicking noise while this test
is going on. This is normal.
If there's a problem with
the anti
-lock brake system,
this warning light will stay
on. See ªAnti
-Lock Brake
System Warning Lightº in
the Index.
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4-28
If the water isn't too deep, then drive through it slowly.
At fast speeds, water splashes on your ignition system
and your vehicle can stall. Stalling can also occur if you
get your tailpipe under water. And, as long as your
tailpipe is under water, you'll never be able to start your
engine. When you go through water, remember that
when your brakes get wet, it may take you longer to stop.
CAUTION:
Driving through rushing water can be dangerous.
Deep water can sweep your vehicle downstream
and you and your passengers could drown.
If it's only shallow water, it can still wash away
the ground from under your tires, and you could
lose traction and roll the vehicle over. Don't drive
through rushing water.
See ªDriving Through Waterº in the Index for more
information on driving through water.
After Off-Road Driving
Remove any brush or debris that has collected on
the underbody, chassis or under the hood.
These accumulations can be a fire hazard.
After operation in mud or sand, have the brake linings
cleaned and checked. These substances can cause
glazing and uneven braking. Check the body structure,
steering, suspension, wheels, tires and exhaust system
for damage. Also, check the fuel lines and cooling
system for any leakage.
Your vehicle will require more frequent service due to
off
-road use. Refer to the Maintenance Schedule for
additional information.
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