2006 GMC ENVOY DENALI wheel

Highway Hypnosis
Is there actually such a condition as highway hypnosis?
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. Do
not 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 at or rolling terrain.
If you drive regularly in steep country, or if you are
planning to visit there, here are some tips that can make
your trips safer and more enjoyable. SeeOff-Road
Driving on page 4-19for information about driving off-road.
Keep your vehicle in good shape. Check all uid
levels and also the brakes, tires, cooling system, and
transmission. These parts can work hard on
mountain roads.
4-38

What is the worst time for this? Wet ice. 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 is 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.
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 Brake System (ABS) improves your
vehicle’s stability when you make a hard stop on
a slippery road. Even though you have ABS, you will
want to begin stopping sooner than you would on
dry pavement. SeeAnti-Lock Brake System (ABS)
on page 4-7.
Allow greater following distance on any slippery road.
Watch for slippery spots. The road might be ne until
you hit a spot that is covered with ice. On an
otherwise clear road, ice patches may appear in
shaded areas where the sun cannot reach, such as
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 are actually on the ice, and avoid sudden
steering maneuvers.
4-41

If Your Vehicle is Stuck in Sand,
Mud, Ice, or Snow
In order to free your vehicle when it is stuck, you will
need to spin the wheels, but you do not want to
spin your wheels too fast. The method known as rocking
can help you get out when you are stuck, but you
must use caution.
{CAUTION:
If you let your tires spin at high speed, they can
explode, and you or others could be injured.
And, the transmission or other parts of the
vehicle can overheat. That could cause an
engine compartment re or other damage.
When you are stuck, spin the wheels as little as
possible. Do not spin the wheels above 35 mph
(55 km/h) as shown on the speedometer.Notice:Spinning your wheels can destroy parts of
your vehicle as well as the tires. If you spin the
wheels too fast while shifting your transmission
back and forth, you can destroy your transmission.
For more information about using tire chains on your
vehicle, seeTire Chains on page 5-71.
Rocking Your Vehicle to Get It Out
First, turn your steering wheel left and right. That
will clear the area around your front wheels. If you have
a four-wheel-drive vehicle, shift into Four-Wheel
High. Then shift back and forth between REVERSE (R)
and a forward gear, spinning the wheels as little as
possible. Release the accelerator pedal while you shift,
and press lightly on the accelerator pedal when the
transmission is in gear. By slowly spinning your wheels
in the forward and reverse directions, you will cause
a rocking motion that may free your vehicle. If that does
not get you out after a few tries, you may need to be
towed out. If you do need to be towed out, seeTowing
Your Vehicle on page 4-50.
4-44

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 would
not be covered by warranty. Do not install a snow
plow or similar equipment on your vehicle.
Towing
Towing Your Vehicle
Consult your dealer or a professional towing service if
you need to have your disabled vehicle towed. See
Roadside Assistance Program on page 7-6.
If you want to tow your vehicle behind another vehicle
for recreational purposes (such as behind a motorhome),
see “Recreational Vehicle Towing” following.
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 “dinghy towing” (towing your
vehicle with all four wheels on the ground) and “dolly
towing” (towing your vehicle with two wheels on
the ground and two wheels up on a device known
as a “dolly”).
With the proper preparation and equipment, many
vehicles can be towed in these ways. See “Dinghy
Towing” and “Dolly Towing,” following. You may
also need brakes for the vehicle being towed. See your
dealer for additional trailering information.
4-50

Here are some important things to consider before you
do recreational vehicle towing:
What’s the trailering 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
be towed.
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. SeeBefore Leaving on a Long Trip on
page 4-37.
Dinghy Towing
Two-Wheel-Drive Vehicles
Notice:If you tow your vehicle with all four wheels
on the ground, the drivetrain components could
be damaged. The repairs would not be covered by
your warranty. Do not tow your vehicle with all
four wheels on the ground.
Two-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.
4-51

Four-Wheel-Drive Vehicles
Four-wheel-drive vehicles can be dinghy towed if you
follow the proper procedures. The transmission has no
provisions for internal lubrication while being towed, so it
is important that you follow all the steps listed in this
manual to dinghy tow your four-wheel-drive vehicle.
Use the following procedure to tow your vehicle:
1. Shift the transmission to PARK (P).
2. Turn the engine off, but leave the ignition on.
3. Firmly set the parking brake.
4. Securely attach the vehicle being towed to the
tow vehicle.
{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 rmly set before you shift the
transfer case to NEUTRAL.
5. Shift the transfer case to NEUTRAL (N). See
Four-Wheel Drive on page 2-27for the proper
procedure to select the NEUTRAL (N) position for
your vehicle.
6. Release the parking brake only after the vehicle
being towed is rmly attached to the towing
vehicle.
7. Turn the ignition off.
After towing, see “Shifting Out of Neutral” under
Four-Wheel Drive on page 2-27.
4-52

Dolly Towing
Front Towing
(Front Wheels Off the Ground)
Two-Wheel-Drive Vehicles
Notice:If you tow a two-wheel-drive vehicle with
the rear wheels on the ground, the transmission
could be damaged. The repairs would not be
covered by your warranty. Never tow your vehicle
with the rear wheels on the ground.
Four-Wheel-Drive Vehicles
Four-wheel-drive vehicles can be dolly towed with the
rear wheels on the ground.
Use the following procedure to tow your vehicle:
1. Drive the vehicle onto the tow dolly.
2. Shift the automatic transmission to PARK (P).
3. Turn the engine off, but leave the ignition on.
4. Firmly set the parking brake.
5. Securely attach the vehicle being towed to
the dolly.
{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 rmly set before you shift the
transfer case to NEUTRAL.
6. Shift the transfer case to NEUTRAL (N). See
Four-Wheel Drive on page 2-27for the proper
procedure to select the NEUTRAL (N) position for
your vehicle.
7. Release the parking brake only after the
vehicle being towed is rmly attached to the
towing vehicle.
8. Turn the ignition off.
After towing, see “Shifting Out of Neutral” under
Four-Wheel Drive on page 2-27.
4-53

Rear Towing
(Rear Wheels Off the Ground)
(Two-Wheel or Four-Wheel-Drive Vehicles)
Use the following procedure to tow your vehicle from
the rear:
1. Drive the vehicle onto the dolly.
2. Firmly set the parking brake. SeeParking Brake on
page 2-31for more information.
3. Shift the transmission in PARK (P).4. Follow the dolly manufacturer’s instructions to
attach and secure the vehicle being towed to
the dolly and then the loaded dolly to the tow
vehicle. Use an adequate clamping device to
ensure that the front wheels are locked into the
straight position.
5. Release the parking brake only after the vehicle
being towed is rmly attached to the towing
vehicle.
6. Turn the ignition to LOCK.
If the tow vehicle will not be started or driven for
six weeks or more, remove the battery cable
from the negative terminal (post) of the battery.
4-54