1999 GMC ENVOY check engine

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2-74 Security Warning 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.
This light should also flash as you open the door (if your
ignition is off). This is a reminder to activate the
theft
-deterrent system. See ªContent Theft-Deterrentº in
the Index for more information.
Service Four-Wheel-Drive Warning Light
Your vehicle is equipped with the Automatic
Four
-Wheel-Drive Transfer Case. It has a computer
which controls the four
-wheel-drive system.
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 Automatic Four
-Wheel
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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2-75 Tow/Haul Mode Light
This light will come on
when the tow/haul mode has
been selected.
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
When the ignition is on,
the fuel gage tells you
about how much fuel you
have remaining.
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3-25
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, 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.
Care of Your Cassette Tape Player
A tape player that is not cleaned regularly can cause
reduced sound quality, ruined cassettes or a damaged
mechanism. Cassette tapes should be stored in their
cases away from contaminants, direct sunlight and
extreme heat. If they aren't, they may not operate
properly or may cause failure of the tape player.
Your tape player should be cleaned regularly after every
50 hours of use. Your radio may display CLN to indicate
that you have used your tape player for 50 hours without
resetting the tape clean timer. If this message appears on
the display, your cassette tape player needs to be
cleaned. It will still play tapes, but you should clean it as
soon as possible to prevent damage to your tapes and
player. If you notice a reduction in sound quality, try a
known good cassette to see if it is the tape or the tape
player at fault. If this other cassette has no improvement
in sound quality, clean the tape player.
The recommended cleaning method for your cassette
tape player is the use of a scrubbing action,
non
-abrasive cleaning cassette with pads which scrub
the tape head as the hubs of the cleaner cassette turn.
The recommended cleaning cassette is available through
your dealership (GM Part No. 12344789).
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4-7
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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4-26 Driving in Water
Light rain causes no special off-road driving problems.
But heavy rain can mean flash flooding, and flood
waters demand extreme caution.
Find out how deep the water is before you drive through
it. If it's deep enough to cover your wheel hubs, axles or
exhaust pipe, don't try it
-- you probably won't get
through. Also, water that deep can damage your axle
and other vehicle parts.
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.
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4-33
The exit speed is usually posted.
Reduce your speed according to your speedometer, not
to your sense of motion. After driving for any distance
at higher speeds, you may tend to think you are going
slower than you actually are.
Before Leaving on a Long Trip
Make sure you're ready. Try to be well rested. If you
must start when you're not fresh
-- such as after a day's
work
-- don't plan to make too many miles that first part
of the journey. Wear comfortable clothing and shoes you
can easily drive in.
Is your vehicle ready for a long trip? If you keep it
serviced and maintained, it's ready to go. If it needs
service, have it done before starting out. Of course,
you'll find experienced and able service experts in GM
dealerships all across North America. They'll be ready
and willing to help if you need it.Here are some things you can check before a trip:

Windshield Washer Fluid: Is the reservoir full? Are
all windows clean inside and outside?

Wiper Blades: Are they in good shape?

Fuel, Engine Oil, Other Fluids: Have you checked
all levels?

Lamps: Are they all working? Are the lenses clean?

Tires: They are vitally important to a safe,
trouble-free trip. Is the tread good enough for
long
-distance driving? Are the tires all inflated to the
recommended pressure?

Weather Forecasts: What's the weather outlook
along your route? Should you delay your trip a short
time to avoid a major storm system?

Maps: Do you have up
-to-date maps?
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4-34
Highway Hypnosis
Is there actually such a condition as ªhighway
hypnosisº? Or is it just plain falling asleep at the wheel?
Call it highway hypnosis, lack of awareness,
or whatever.
There is something about an easy stretch of road with
the same scenery, along with the hum of the tires on the
road, the drone of the engine, and the rush of the wind
against the vehicle that can make you sleepy. Don't let it
happen to you! If it does, your vehicle can leave the
road in less than a second, and you could crash and
be injured.
What can you do about highway hypnosis? First, be
aware that it can happen.
Then here are some tips:

Make sure your vehicle is well ventilated, with a
comfortably cool interior.

Keep your eyes moving. Scan the road ahead and
to the sides. Check your mirrors and your
instruments frequently.

If you get sleepy, pull off the road into a rest, service
or parking area and take a nap, get some exercise, or
both. For safety, treat drowsiness on the highway as
an emergency.
Hill and Mountain Roads
Driving on steep hills or mountains is different from
driving in flat or rolling terrain.
If you drive regularly in steep country, or if you're
planning to visit there, here are some tips that can make
your trips safer and more enjoyable. (See ªOff
-Road
Drivingº in the Index for information about driving
off
-road.)
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4-35

Keep your vehicle in good shape. Check all fluid
levels and also the brakes, tires, cooling system and
transmission. These parts can work hard on
mountain roads.

Know how to go down hills. The most important
thing to know is this: let your engine do some of the
slowing down. Shift to a lower gear when you go
down a steep or long hill.
CAUTION:
If you don't shift down, your brakes could get so
hot that they wouldn't work well. You would then
have poor braking or even none going down a
hill. You could crash. Shift down to let your
engine assist your brakes on a steep
downhill slope.
CAUTION:
Coasting downhill in NEUTRAL (N) or with the
ignition off is dangerous. Your brakes will have to
do all the work of slowing down. They could get so
hot that they wouldn't work well. You would then
have poor braking or even none going down a hill.
You could crash. Always have your engine running
and your vehicle in gear when you go downhill.

Know how to go uphill. You may want to shift down
to a lower gear. The lower gears help cool your engine
and transmission, and you can climb the hill better.

Stay in your own lane when driving on two
-lane
roads in hills or mountains. Don't swing wide or cut
across the center of the road. Drive at speeds that let
you stay in your own lane.

As you go over the top of a hill, be alert. There could be
something in your lane, like a stalled car or an accident.

You may see highway signs on mountains that warn of
special problems. Examples are long grades, passing or
no
-passing zones, a falling rocks area or winding
roads. Be alert to these and take appropriate action.
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