wheel GMC ENVOY 2001 Workshop Manual

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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4-36
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.
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4-39
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 (32F; 0C) 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.
Accelerate gently. Try not to break the fragile traction.
If you accelerate too fast, the drive wheels will spin and
polish the surface under the tires even more.
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.
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4-42 Two-Wheel Drive Vehicles and Vehicles
with the Electronic Shift Transfer Case
Tw o-wheel-drive vehicles and vehicles with the
Electronic Shift Transfer Case should not be towed
with all four wheels on the ground. These 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. Towing with all four wheels on the ground
should be avoided.
In rare cases when it's unavoidable and your vehicle
has 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. See ªService and Owner Publicationsº in
the Index.
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 vehicle.
Four-Wheel-Drive Vehicles
(Automatic Transfer Case)
Use the following procedure to correctly tow your
vehicle on all four wheels:
1. Firmly set the parking brake.
2. Place the transmission in PARK (P).
3. Securely attach the vehicle being towed to the
tow vehicle.
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4-43
4. With the engine running, shift the transfer case to
NEUTRAL. See ªFour
-Wheel Driveº in the Index
for the proper procedure to select the NEUTRAL
position for your vehicle.
CAUTION:
Shifting the transfer case into NEUTRAL can
cause your vehicle to roll even if the transmission
is in PARK (P), for an automatic transmission,
or if your vehicle is in gear, for a manual
transmission. You or others could be injured.
Make sure the parking brake is firmly set
before you shift the transfer case into NEUTRAL.
See ªFour
-Wheel Drive (Automatic Transfer Case)º
in the Index.
5. Release the parking brake only after the vehicle
being towed is firmly attached to the towing vehicle.
6. Turn the ignition to OFF. The OFF position unlocks
the steering column and reduces battery drain.
Unlocking the steering column will allow the proper
movement of the front wheels and tires during towing.
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).
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4-50 Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For example,
speed, altitude, road grades, outside temperature and
how much your vehicle is used to pull a trailer are all
important. And, it can also depend on any special
equipment that you have on your vehicle.
The following chart shows how much your trailer can
weigh, based upon your vehicle model and options.
VehicleAxle
Ratio Max. Trailer Wt.
2
-Wheel Drive,
2 Door
Auto. Trans.3.08
3.424,700 lbs. (2 133 kg)
5,700 lbs. (2 587 kg)
2
-Wheel Drive,
2 Door
Manual Trans.3.42 4,200 lbs. (1 906 kg)
2
-Wheel Drive,
4 Door
Auto. Trans.3.08
3.424,500 lbs. (2 043 kg)
5,500 lbs. (2 497 kg)
4
-Wheel Drive,
2 Door
Auto. Trans.3.08
3.42
3.734,400 lbs. (1 997 kg)
5,400 lbs. (2 451 kg)
5,400 lbs. (2 451 kg)VehicleAxle
Ratio Max. Trailer Wt.
4
-Wheel Drive,
2 Door
Manual Trans.3.42 3,900 lbs. (1 770 kg)
ZR2
Auto. Trans. 3.73 4,800 lbs. (2 179 kg)
Manual Trans. 3.73 4,300 lbs. (1 952 kg)
4
-Wheel Drive,
4 Door
Auto. Trans.3.08
3.42
3.734,200 lbs. (1 906 kg)
5,200 lbs. (2 360 kg)
5,200 lbs. (2 360 kg)
4
-Wheel Drive,
4 Door
Manual Trans.3.42 3,700 lbs. (1 679 kg)
Maximum trailer weight is calculated assuming the
driver and one passenger are in the tow vehicle and it
has all the required trailering equipment. The weight of
additional optional equipment, passengers and cargo in
the tow vehicle must be subtracted from the maximum
trailer weight. The weight of the trailer tongue also
affects the maximum trailer weight. See ªWeight of the
Trailer Tongueº later in this section.
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4-54
Before you start, check the trailer hitch and platform
(and attachments), safety chains, electrical connector,
lamps, tires and mirror adjustment. If the trailer has
electric brakes, start your vehicle and trailer moving
and then apply the trailer brake controller by hand to
be sure the brakes are working. This lets you check
your electrical connection at the same time.
During your trip, check occasionally to be sure that the
load is secure, and that the lamps and any trailer brakes
are still working.
Following Distance
Stay at least twice as far behind the vehicle ahead as
you would when driving your vehicle without a trailer.
This can help you avoid situations that require heavy
braking and sudden turns.
Passing
You'll need more passing distance up ahead when
you're towing a trailer. And, because you're a good
deal longer, you'll need to go much farther beyond the
passed vehicle before you can return to your lane.
Backing Up
Hold the bottom of the steering wheel with one hand.
Then, to move the trailer to the left, just move that
hand to the left. To move the trailer to the right, move
your hand to the right. Always back up slowly and,
if possible, have someone guide you.
Making Turns
NOTICE:
Making very sharp turns while trailering
could cause the trailer to come in contact with
the vehicle. Your vehicle could be damaged.
Avoid making very sharp turns while trailering.
When you're turning with a trailer, make wider
turns than normal. Do this so your trailer won't
strike soft shoulders, curbs, road signs, trees or other
objects. Avoid jerky or sudden maneuvers. Signal well
in advance.
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4-56 Parking on Hills
CAUTION:
You really should not park your vehicle, with a
trailer attached, on a hill. If something goes
wrong, your rig could start to move. People can
be injured, and both your vehicle and the trailer
can be damaged.
But if you ever have to park your rig on a hill,
here's how to do it:
1. Apply your regular brakes, but don't shift into
PARK (P) yet, or into gear for a manual
transmission. Then turn your wheels into the curb
if facing downhill or into traffic if facing uphill.
2. Have someone place chocks under the trailer wheels.
3. When the wheel chocks are in place, release the
regular brakes until the chocks absorb the load.
4. Reapply the regular brakes. Then apply your
parking brake, and then shift into PARK (P), or
REVERSE (R) for a manual transmission.5. If you have a four
-wheel-drive vehicle with an
automatic transfer case, be sure the transfer case is
in a drive gear
-- not in NEUTRAL.
6. Release the regular brakes.
CAUTION:
It can be dangerous to get out of your vehicle if
the shift lever is not fully in PARK (P) with the
parking brake firmly set. Your vehicle can roll.
If you have left the engine running, the vehicle
can move suddenly. You or others could be
injured. To be sure your vehicle won't move,
even when you're on fairly level ground,
use the steps that follow.
Always put the shift lever fully in PARK (P) with
the parking brake firmly set.
If the transfer case on four-wheel drive vehicles
is in NEUTRAL, your vehicle will be free to
roll, even if your shift lever is in PARK (P).
So, be sure the transfer case is in a drive
gear
-- not in NEUTRAL. See ªFour-Wheel
Drive (Automatic Transfer Case)º in the Index.
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5-17
Engine Fan Noise
This vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the clutch is not engaged. This improves
fuel economy and reduces fan noise. Under heavy
vehicle loading, trailer towing and/or high outside
temperatures, the fan speed increases when the clutch
engages. So you may hear an increase in fan noise.
This is normal and should not be mistaken as the
transmission slipping or making extra shifts. It is merely
the cooling system functioning properly. The fan will
slow down when additional cooling is not required and
the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
If a Tire Goes Flat
It's unusual for a tire to ªblow outº while you're driving,
especially if you maintain your tires properly. If air goes
out of a tire, it's much more likely to leak out slowly.
But if you should ever have a ªblowout,º here are a
few tips about what to expect and what to do:
If a front tire fails, the flat tire will create a drag that
pulls the vehicle toward that side. Take your foot off
the accelerator pedal and grip the steering wheel firmly.
Steer to maintain lane position, and then gently brake
to a stop well out of the traffic lane.
A rear blowout, particularly on a curve, acts much like
a skid and may require the same correction you'd use
in a skid. In any rear blowout, remove your foot from
the accelerator pedal. Get the vehicle under control by
steering the way you want the vehicle to go. It may be
very bumpy and noisy, but you can still steer. Gently
brake to a stop
-- well off the road if possible.
If a tire goes flat, the next part shows how to use your
jacking equipment to change a flat tire safely.
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5-18
Changing a Flat Tire
If a tire goes flat, avoid further tire and wheel damage
by driving slowly to a level place. Turn on your hazard
warning flashers.
CAUTION:
Changing a tire can cause an injury. The vehicle
can slip off the jack and roll over you or other
people. You and they could be badly injured.
Find a level place to change your tire. To help
prevent the vehicle from moving:
1. Set the parking brake firmly.
2. Put an automatic transmission shift lever in
PARK (P) or shift a manual transmission
to FIRST (1) or REVERSE (R).
3. If you have a four
-wheel-drive vehicle,
be sure the transfer case is in a drive
gear
-- not in NEUTRAL.
CAUTION: (Continued)
CAUTION: (Continued)
4. Turn off the engine.
5. Put the wheel blocks at the front and rear
of the tire farthest away from the one being
changed. That would be the tire on the other
side of the vehicle, at the opposite end.
The following steps will tell you how to use the jack and
change a tire.
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