GMC ENVOY 2002 Owner's Manual

4-41
What's the worst time for this? ªWet ice.º Very cold
snow or ice can be slick and hard to drive on. But wet
ice can be even more trouble because it may offer the
least traction of all. You can get wet ice when it's about
freezing (32
F; 0
C) and freezing rain begins to fall.
Try to avoid driving on wet ice until salt and sand crews
can get there.Whatever the condition
-- smooth ice, packed, blowing
or loose snow
-- drive with caution.
If you have traction assist, keep the system on. It will
improve your ability to accelerate when driving on a
slippery road. But you can turn the traction system
off if you ever need to. You should turn the system off
if your vehicle ever gets stuck in sand, mud, ice or snow.
See ªRocking Your Vehicleº in the Index. Even though
your vehicle has a traction system, you'll want to slow
down and adjust your driving to the road conditions.
See ªTraction Assist Systemº in the Index.
If you don't have a traction system, accelerate gently.
Try not to break the gentle traction. If you accelerate
too fast, the drive wheels will spin and polish the surface
under the tires even more.

4-42
Your anti-lock brakes improve your vehicle's stability
when you make a hard stop on a slippery road. Even
though you have an anti
-lock braking system, you'll
want to begin stopping sooner than you would on dry
pavement. See ªAnti
-Lockº in the Index.

Allow greater following distance on any
slippery road.

Watch for slippery spots. The road might be fine
until you hit a spot that's covered with ice. On an
otherwise clear road, ice patches may appear in
shaded areas where the sun can't reach: around
clumps of trees, behind buildings or under bridges.
Sometimes the surface of a curve or an overpass may
remain icy when the surrounding roads are clear. If
you see a patch of ice ahead of you, brake before you
are on it. Try not to brake while you're actually on
the ice, and avoid sudden steering maneuvers.
If You're Caught in a Blizzard
If you are stopped by heavy snow, you could be in a serious
situation. You should probably stay with your vehicle
unless you know for sure that you are near help and you can
hike through the snow. Here are some things to do to
summon help and keep yourself and your passengers safe:

Turn on your hazard flashers.

Tie a red cloth to your vehicle to alert police that
you've been stopped by the snow.

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Put on extra clothing or wrap a blanket around you.
If you have no blankets or extra clothing, make body
insulators from newspapers, burlap bags, rags, floor
mats
-- anything you can wrap around yourself or
tuck under your clothing to keep warm.
You can run the engine to keep warm, but be careful.
CAUTION:
Snow can trap exhaust gases under your vehicle.
This can cause deadly CO (carbon monoxide) gas
to get inside. CO could overcome you and kill
you. You can't see it or smell it, so you might not
know it is in your vehicle. Clear away snow from
around the base of your vehicle, especially any
that is blocking your exhaust pipe. And check
around again from time to time to be sure snow
doesn't collect there.
Open a window just a little on the side of the
vehicle that's away from the wind. This will help
keep CO out.
Run your engine only as long as you must. This saves
fuel. When you run the engine, make it go a little faster
than just idle. That is, push the accelerator slightly. This
uses less fuel for the heat that you get and it keeps the
battery charged. You will need a well
-charged battery to
restart the vehicle, and possibly for signaling later on
with your headlamps. Let the heater run for a while.

4-44
Then, shut the engine off and close the window almost
all the way to preserve the heat. Start the engine again
and repeat this only when you feel really uncomfortable
from the cold. But do it as little as possible. Preserve the
fuel as long as you can. To help keep warm, you can get
out of the vehicle and do some fairly vigorous exercises
every half hour or so until help comes.
Recreational Vehicle Towing
Recreational vehicle towing means towing your vehicle
behind another vehicle
-- such as behind a motorhome.
The two most common types of recreational vehicle
towing are known as ªdinghy towingº (towing your
vehicle with all four wheels on the ground) and ªdolly
towingº (towing your vehicle with two wheels on
the ground and two wheels up on a device know as
a ªdollyº).
With the proper preparation and equipment, many
vehicles can be towed in these ways. See ªDinghy
Towingº and ªDolly Towing,º following.Here are some important things to consider before you
do recreational vehicle towing:

What's the towing capacity of the towing
vehicle? Be sure you read the tow vehicle
manufacturer's recommendations.

How far will you tow? Some vehicles have
restrictions on how far and how long they can tow.

Do you have the proper towing equipment? See your
dealer or trailering professional for additional advice
and equipment recommendations.

Is your vehicle ready to be towed? Just as you would
prepare your vehicle for a long trip, you'll want to
make sure your vehicle is prepared to be towed. See
ªBefore Leaving on a Long Tripº in the Index.

4-45 Dinghy Towing
When towing your vehicle, turn the ignition off.
To prevent your battery from draining while towing,
remove the Ignition A and the Ignition B fuses from the
engine compartment fuse block. Be sure to reinstall the
fuse when you reach your destination. See ªFuses and
Circuit Breakersº in the Index.
Tw o
-Wheel-Drive Vehicles
Tw o
-wheel-drive vehicles, should not be towed with
all four wheels on the ground. Two
-wheel-drive
transmissions have no provisions for internal lubrication
while being towed. To properly tow these vehicles,
they should be placed on a platform trailer with all
four wheels off the ground.
In rare cases when it's unavoidable that a
two
-wheel-drive vehicle is to be towed with all
four wheels on the ground, the propeller shaft to
axle yoke orientation should be marked and the
propeller shaft removed following the applicable
service manual removal/installation procedure.
Dust or dirt can enter the back of the transmission
through the opening created by removing the propeller
shaft if proper protection is not provided. Also, check
the transmission fluid level before driving the truck.Four
-Wheel-Drive Vehicles
Use the following procedure to tow your vehicle:
1. Firmly set the parking brake.
2. Shift the transmission to PARK (P).
3. Securely attach the vehicle being towed to the
tow vehicle.

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4. Shift the transfer case to NEUTRAL (N).
See ªFour
-Wheel Driveº in the Index for the
proper procedure to select the NEUTRAL position
for your vehicle.
5. Release the parking brake only after the vehicle
being towed is firmly attached to the towing vehicle.
6. Turn the ignition off. This unlocks the steering
column and reduces battery drain as long as the
Ignition A and Ignition B fuses are removed.
Unlocking the steering column will allow the
proper movement of the front wheels and tires
during towing.
CAUTION:
Shifting a four-wheel-drive vehicle's transfer
case into NEUTRAL can cause your vehicle to
roll even if the transmission is in Park (P). You or
others could be injured. Make sure the parking
brake is firmly set before you shift the transfer
case to NEUTRAL.
Dolly Towing
Your vehicle was not designed to be dolly towed. If you
need to tow your vehicle see ªDinghy Towingº earlier in
this section.
CAUTION:
Shifting a four-wheel-drive vehicle's transfer
case into NEUTRAL can cause your vehicle to
roll even if the transmission is in PARK (P).
You or others could be injured. Make sure the
parking brake is firmly set before you shift the
transfer case into NEUTRAL.

4-47
Loading Your Vehicle
The Certification/Tire label is found on the driver's door
edge, above the door latch. The label shows the size of
your original tires and the inflation pressures needed to
obtain the gross weight capacity of your vehicle. This is
called the Gross Vehicle Weight Rating (GVWR). The
GVWR includes the weight of the vehicle, all occupants,
fuel, cargo and trailer tongue weight, if pulling a trailer.
The Certification/Tire label also tells you the maximum
weights for the front and rear axles, called Gross Axle
Weight Rating (GAWR). To find out the actual loads onyour front and rear axles, you need to go to a weigh
station and weigh your vehicle. Your dealer can help
you with this. Be sure to spread out your load equally
on both sides of the centerline.
Never exceed the GVWR for your vehicle, or the
GAWR for either the front or rear axle.
And, if you do have a heavy load, you should spread
it out.
Similar appearing vehicles may have different GVWRs
and payloads. Please note the Certification/Tire label on
your truck or consult your dealer for additional details.
CAUTION:
Do not load your vehicle any heavier than the
GVWR, or either the maximum front or rear
GAWR. If you do, parts on your vehicle can
break, and it can change the way your vehicle
handles. These could cause you to lose control
and crash. Also, overloading can shorten the life
of your vehicle.

4-48
Using heavier suspension components to get added
durability might not change your weight ratings. Ask
your dealer to help you load your vehicle the right way.
NOTICE:
Your warranty does not cover parts or
components that fail because of overloading.
If you put things inside your vehicle -- like suitcases,
tools, packages, or anything else
-- they will go as fast
as the vehicle goes. If you have to stop or turn quickly,
or if there is a crash, they'll keep going.
CAUTION:
Things you put inside your vehicle can strike
and injure people in a sudden stop or turn, or
in a crash.

Put things in the cargo area of your vehicle.
Try to spread the weight evenly.

Never stack heavier things, like suitcases,
inside the vehicle so that some of them are
above the tops of the seats.

Don't leave an unsecured child restraint in
your vehicle.

When you carry something inside the
vehicle, secure it whenever you can.

Don't leave a seat folded down unless you
need to.
There's also important loading information for off-road
driving in this manual. See ªLoading Your Vehicle for
Off
-Road Drivingº in the Index.

4-49 Electronically Controlled Air Suspension
System (If Equipped)
Your vehicle may be equipped with an electronically
controlled air suspension system that automatically
keeps your vehicle level as you load and unload. The
system includes a compressor, two height sensors and
two air springs supporting the rear axle.
The system also has an internal clock to prevent
overheating. If the system overheats, all leveling
function stops until the system cools down. During
this time, the indicator light on the air inflator system
will be flashing.
The ignition has to be on for the system to inflate, in
order to raise the vehicle to the standard ride height after
loading. The system can lower the vehicle to the
standard ride height after unloading with the ignition on
and also for up to 30 minutes after the ignition has been
turned off.
You may hear the compressor operating when you load
your vehicle, and periodically as the system adjusts the
vehicle to the standard ride height.
Load leveling will not function normally with the
inflator hose attached to the inflator outlet. Remove
the inflator hose from the outlet during loading
and unloading.Overload Protection
The air suspension system is equipped with overload
protection. Overload protection is designed to protect
the air suspension system, and it is an indicator to the
driver that the vehicle is overloaded. When the overload
protection mode is on, it will not allow damage to the
air compressor. However, do not overload the vehicle.
See ªLoading Your Vehicleº earlier in this section.
If the suspension remains at a low height, the rear axle
load has exceeded GAWR (Gross Axle Weight Rating).
When the overload protection mode is activated, the
compressor operates for about 30 seconds to one minute
without raising the vehicle depending on the amount
of overload. This will continue each time the ignition
is turned on until the rear axle load is reduced
below GAWR.
Indicator Light
The indicator light on the inflator switch in the rear
passenger compartment also serves as an indicator for
internal system error. If the indicator light is flashing
without the load leveling function or the inflator being
active, turn off the ignition. The next day turn on the
ignition and check the indicator light. The vehicle can
be driven with the light flashing, but if it is you should
have the vehicle serviced as soon as possible.

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Adding a Snow Plow or
Similar Equipment
Your vehicle was neither designed nor intended for a
snow plow.
NOTICE:
Adding a snow plow or similar equipment to
your vehicle can damage it, and the repairs
wouldn't be covered by warranty. Do not install a
snow plow or similar equipment on your vehicle.
Towing a Trailer
CAUTION:
If you don't use the correct equipment and drive
properly, you can lose control when you pull a
trailer. For example, if the trailer is too heavy,
the brakes may not work well
-- or even at all.
You and your passengers could be seriously
injured. Pull a trailer only if you have followed
all the steps in this section. Ask your dealer for
advice and information about towing a trailer
with your vehicle.