when to use 2 wheel dr GMC ENVOY 2004 Owner's Manual

{CAUTION:
If something is between an occupant and an
air bag, the bag might not inate properly or it
might force the object into that person causing
severe injury or even death. The path of an
inating air bag must be kept clear. Don’t put
anything between an occupant and an air bag,
and don’t attach or put anything on the
steering wheel hub or on or near any other air
bag covering. Don’t let seat covers block the
ination path of a side impact air bag.
When Should an Air Bag Inate?
The driver’s and right front passenger’s frontal air bags
are designed to inate in moderate to severe frontal
or near-frontal crashes. But they are designed to inate
only if the impact speed is above the system’s
designed “threshold level.”
In addition, your vehicle has “dual stage” frontal air
bags, which adjust the amount of restraint according to
crash severity. For moderate frontal impacts, these
air bags inate at a level less than full deployment.
For more severe frontal impacts, full deployment occurs.
If the front of your vehicle goes straight into a wall
that doesn’t move or deform, the threshold level for the
reduced deployment is about 12 to 16 mph
(19 to 26 km/h), and the threshold level for a full
deployment is about 16 to 25 mph (26 to 40 km/h).
The threshold level can vary, however, with specic
vehicle design, so that it can be somewhat above
or below this range.
If your vehicle strikes something that will move or
deform, such as a parked car, the threshold level will be
higher. The driver’s and right front passenger’s frontal
air bags are not designed to inate in rollovers, rear
impacts, or in many side impacts because ination
would not help the occupant.
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primarily because an occupant’s motion is not toward
those air bags. Air bags should never be regarded
as anything more than a supplement to safety belts, and
then only in moderate to severe frontal or near-frontal
collisions for the driver’s and right front passenger’s
frontal air bags, and only in moderate to severe
side collisions for vehicles with a driver’s and right front
passenger’s side impact air bag.
What Will You See After an Air Bag
Inates?
After the air bag inates, it quickly deates, so quickly
that some people may not even realize the air bag
inated. Some components of the air bag module will be
hot for a short time. These components include the
steering wheel hub for the driver’s frontal air bag and the
instrument panel for the right front passenger’s frontal
air bag. For vehicles with side impact air bags, the side
of the seatback closest to the driver’s and/or right
front passenger’s door will be hot. The parts of the bag
that come into contact with you may be warm, but
not too hot to touch. There will be some smoke and dust
coming from the vents in the deated air bags. Air
bag ination doesn’t prevent the driver from seeing or
being able to steer the vehicle, nor does it stop
people from leaving the vehicle.
{CAUTION:
When an air bag inates, there is dust in the
air. This dust could cause breathing problems
for people with a history of asthma or other
breathing trouble. To avoid this, everyone in
the vehicle should get out as soon as it is safe
to do so. If you have breathing problems but
can’t get out of the vehicle after an air bag
inates, then get fresh air by opening a
window or a door. If you experience breathing
problems following an air bag deployment, you
should seek medical attention.
Your vehicle has a feature that will automatically unlock
the doors and turn the interior lamps on when the air
bags inate (if battery power is available). You can lock
the doors again and turn the interior lamps off by
using the door lock and interior lamp controls.
In many crashes severe enough to inate an air bag,
windshields are broken by vehicle deformation.
Additional windshield breakage may also occur from the
right front passenger air bag.
1-59

Automatic Transmission Operation
There are several different positions for your gear
shift lever.
PARK (P):This position locks the rear wheels. It’s the
best position to use when you start the engine
because your vehicle can’t move easily.
{CAUTION:
It is dangerous to get out of your vehicle if the
shift lever is not fully in PARK (P) with the
parking brake rmly set. Your vehicle can roll.
Do not leave your vehicle when the engine is
running unless you have to. If you have left the
engine running, the vehicle can move
suddenly. You or others could be injured.
To be sure your vehicle will not move, even
when you are on fairly level ground, always set
your parking brake and move the shift lever to
PARK (P). SeeShifting Into Park (P) on
page 2-31. If you are pulling a trailer, see
Towing a Trailer on page 4-55.
{CAUTION:
If you have four-wheel drive, your vehicle will
be free to roll — even if your shift lever is in
PARK (P) — if your transfer case is in
NEUTRAL. So, be sure the transfer case is in a
drive gear — not in NEUTRAL. SeeFour-Wheel
Drive on page 2-26. SeeShifting Into Park (P)
on page 2-31.
Ensure the shift lever is fully in PARK (P) before starting
the engine. Your vehicle has an automatic transmission
shift lock control system. You have to fully apply the
regular brakes before you can shift from PARK (P) when
the ignition key is in RUN. If you cannot shift out of
PARK (P), ease pressure on the shift lever, press the
button on the shift lever and push the shift lever all
the way into PARK (P) as you maintain brake
application. Move the shift lever into the gear you wish.
SeeShifting Out of Park (P) on page 2-33.
2-24

REVERSE (R):Use this gear to back up.
Notice:Shifting to REVERSE (R) while your vehicle
is moving forward could damage the transmission.
The repairs would not be covered by your warranty.
Shift to REVERSE (R) only after your vehicle is
stopped.
To rock your vehicle back and forth to get out of snow,
ice or sand without damaging your transmission,
see If You Are Stuck: In Sand, Mud, Ice or Snow on
page 4-42.
NEUTRAL (N):In this position, the engine doesn’t
connect with the wheels. To restart when you’re already
moving, use NEUTRAL (N) only.
{CAUTION:
Shifting into a drive gear while your engine is
running at high speed is dangerous. Unless
your foot is rmly on the brake pedal, your
vehicle could move very rapidly. You could
lose control and hit people or objects. Do not
shift into a drive gear while your engine is
running at high speed.Notice:Shifting out of PARK (P) or NEUTRAL (N)
with the engine racing may damage the
transmission. The repairs would not be covered by
your warranty. Be sure the engine is not racing
when shifting your vehicle.
DRIVE (D):This position is for normal driving. If you
need more power for passing, and you’re:
Going less than about 35 mph (55 km/h), push the
accelerator pedal about halfway down.
Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
You’ll shift down to the next gear and have more power.
DRIVE (D) can be used when towing a trailer, carrying
a heavy load, driving on steep hills or for off-road driving.
You may want to shift the transmission to THIRD (3)
or, if necessary, a lower gear selection if the
transmission shifts too often.
2-25

THIRD (3):This position is also used for normal driving.
However, it offers more power and lower fuel economy
than DRIVE (D).
SECOND (2):This position gives you more power but
lower fuel economy than THIRD (3). You can use
SECOND (2) on hills. It can help control your speed as
you go down steep mountain roads, but then you
would also want to use the brakes off and on.
You can also use SECOND (2) for starting the vehicle
from a stop on slippery road surfaces.
FIRST (1):This position gives you even more power
but lower fuel economy than SECOND (2). You can use
it on very steep hills, or in deep snow or mud. If the
selector lever is put in FIRST (1) while the vehicle
is moving forward, the transmission won’t shift into rst
gear until the vehicle is going slowly enough.
Notice:Spinning the tires or holding the vehicle in
one place on a hill using only the accelerator
pedal may damage the transmission. If you are
stuck, do not spin the tires. When stopping on a hill,
use the brakes to hold the vehicle in place.Four-Wheel Drive
If your vehicle has four-wheel drive, you can send your
engine’s driving power to all four wheels for extra
traction. To get the most satisfaction out of four-wheel
drive, you must be familiar with its operation. Read
the part that follows before using four-wheel drive. You
should use two-wheel drive high (2HI) for most
normal driving conditions.
Notice:Driving on pavement in four-wheel drive for
an extended period of time may cause premature
wear on your vehicle’s powertrain. Do not drive
in four-wheel drive on pavement for extended
periods of time.
2-26

Automatic Transfer Case
If your vehicle is equipped
with four-wheel drive, the
transfer case knob is
located to the right of the
steering wheel on the
instrument panel. Use this
knob to shift into and
out of four-wheel drive.
2HI (Two-Wheel High):This setting is for driving in
most street and highway situations. Your front axle is not
engaged in two-wheel drive. It also provides the best
fuel economy.
A4WD (Automatic Four-Wheel Drive):This setting is
ideal for use when road conditions are variable.
When driving your vehicle in A4WD, the front axle is
engaged, but the vehicle’s power is sent to the
rear wheels. When the vehicle senses a loss of traction,
the system will automatically engage four-wheel
drive. Driving in this mode results in slightly lower fuel
economy than 2HI.4HI (Four-Wheel High):Use 4HI when you need extra
traction, such as on snowy or icy roads or in most
off-road situations. This setting also engages your front
axle to help drive your vehicle.
4LO (Four-Wheel Low):This setting also engages
your front axle and delivers extra torque. It sends
maximum power to all four wheels. You might choose
4LO if you are driving off-road in deep sand, deep mud,
and climbing or descending steep hills.
{CAUTION:
Shifting the transfer case to NEUTRAL can
cause your vehicle to roll even if the
transmission is in PARK (P). You or someone
else could be seriously injured. Be sure to set
the parking brake before placing the transfer
case in NEUTRAL. SeeParking Brake on
page 2-30.
NEUTRAL:Shift the vehicle’s transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 4-44for more
information.
2-27

Shifting Into Park (P)
{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 rmly 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 will
not move, even when you are on fairly level
ground, use the steps that follow. With
four-wheel drive, your vehicle will be free to
roll — even if your shift lever is in PARK
(P) — if your transfer case is in NEUTRAL.
So, be sure the transfer case is in a drive
gear — not in NEUTRAL. SeeFour-Wheel Drive
on page 2-26. Always put the shift lever fully in
PARK (P) with the parking brake rmly set.
If you are pulling a trailer, seeTowing a Trailer
on page 4-55.To shift into PARK (P), do the following:
1. Hold the brake pedal down with your foot and set
the parking brake.
2. Move the shift lever
into PARK (P)
like this:
2.1. Press the button in on the side of the lever.
2.2. Push the lever all the way toward the
front of the vehicle.
3. Turn the ignition key to LOCK.
4. Remove the key and take it with you. You know
your vehicle is in PARK (P) if the key can be
removed from the ignition.
2-31

You can also turn the dome lamps on by turning the
thumbwheel, located next to the exterior lamps knob, all
the way up to the top detent position. In this position,
the dome lamps will remain on until they are turned off.
Battery Run-Down Protection
This feature shuts off the dome, courtesy, vanity, and
reading lamps if they are left on for more than
20 minutes when the ignition is off. This will keep your
battery from running down.
If the battery run-down protection shuts off the interior
lamps, it may be necessary to do one of the following to
return to normal operation:
Shut off all lamps and close all doors, or
turn the ignition key to RUN.
This feature will also turn off the parking lamps and
headlamps under most circumstances, if they are left on.
If you would like to turn them back on, turn the exterior
lamps knob.
Accessory Power Outlets
Your vehicle may have accessory power outlets. With
the accessory power outlets, you can plug in auxiliary
electrical equipment such as a cellular telephone or
CB radio.The rst two outlets are located below the cigarette
lighter and the rear wiper switch on the instrument panel.
The third outlet is located on the rear of the center
console.
Remove the cover from the outlet to use the outlet.
Be sure to put the cover back on when not using the
accessory power outlet.
Certain electrical accessories may not be compatible
with the accessory power outlet and could result
in blown vehicle or adaptor fuses. If you experience a
problem, see your dealer for additional information
on the accessory power outlets.
Notice:Adding any electrical equipment to your
vehicle may damage it or keep other components
from working as they should. The repairs would not
be covered by your warranty. Check with your
dealer before adding electrical equipment.
When adding electrical equipment, be sure to follow the
proper installation instructions included with the
equipment.
Notice:Improper use of the power outlet can cause
damage not covered by your warranty. Do not
hang any type of accessory or accessory bracket
from the plug because the power outlets are
designed for accessory power plugs only.
3-19

Display Language
To select your personalization for display language,
press the select button while DISPLAY LANGUAGE is
displayed on the DIC. Pressing the select button
will scroll through the available languages:
Choosing a language will display all of the information
on the DIC in the desired language.
If your vehicle is equipped with an Information Center,
press and hold the trip stem while the odometer is
displayed. While holding down the trip stem button, the
Information Center will begin to list the available
languages. The name of each language will be
displayed in its native language (ENGLISH for English,
FRANCAIS for French and ESPANOL for Spanish).
When you see the language that you would like, release
the trip stem. The Information Center will then display
the information in the language you chose.
If you accidentaly choose a language you do not want
or understand, press and hold the trip information button
and the personalization button at the same time. After
a short time, the display will begin cycling through
the available languages. Release the buttons when you
see a language you would like. This will also reset
all of the current driver’s personalization features to their
factory default settings.
For vehicles with redundant steering wheel controls, see
“Personalization” under the DIC.
Select
The select button is used to reset certain functions and
turn off or acknowledge messages on the DIC display.
The select button also toggles through the options
available in each personalization menu. For example, this
button will reset the trip odometers, turn off the FUEL
LEVEL LOW message, and toggle through the languages
you can select the DIC to display information in.
DIC Warnings and Messages
Messages are displayed on the DIC to notify the driver
that the status of the vehicle has changed and that
some action may be needed by the driver to correct the
condition. More than one message may appear at
one time. They will appear one behind the other. Some
messages may not require immediate action but you
should press the trip stem to acknowledge that you
received the message and clear it from the display.
Pressing any of the DIC steering wheel buttons
(Trip Information, Fuel Information, Personalization or
Select button) will also acknowledge any warnings
or service messages. Some messages cannot be
cleared from the display because they are more urgent.
These messages require action before they can be
removed from the DIC display. The following are
the possible messages that can be displayed and some
information about them.
3-59

As you brake, your computer keeps receiving updates
on wheel speed and controls braking pressure
accordingly.
Remember: Anti-lock does not change the time you
need to get your foot up to the brake pedal or always
decrease stopping distance. If you get too close to
the vehicle in front of you, you will not have time to apply
your brakes if that vehicle suddenly slows or stops.
Always leave enough room up ahead to stop, even
though you have anti-lock brakes.
Using Anti-Lock
Do not pump the brakes. Just hold the brake pedal
down rmly and let anti-lock work for you. You may feel
the brakes vibrate, or you may notice some noise,
but this is normal.
Braking in Emergencies
With anti-lock, you can steer and brake at the same
time. In many emergencies, steering can help you more
than even the very best braking.
Traction Assist System (TAS)
Your two-wheel drive vehicle may have a Traction
Assist System (TAS) that limits wheel spin. This
is especially useful in slippery road conditions. The
system operates only if it senses that one or both of the
rear wheels are spinning or beginning to lose traction.
When this happens, the system reduces engine
power to limit wheel spin.
The low traction symbol next to the button will come on
when the TAS is limiting wheel spin. You may feel or
hear the system working, but this is normal.
The Traction Assist System may operate on dry roads
under some conditions. When this happens, you
may notice a reduction in acceleration. This is normal
and doesn’t mean there’s a problem with your vehicle.
Examples of these conditions include a hard
acceleration in a turn, an abrupt upshift or downshift of
the transmission or driving on rough roads.
If your vehicle is in cruise control when the TAS begins
to limit wheel spin, the cruise control will automatically
disengage. When road conditions allow you to safely
use it again, you may re-engage the cruise control.
See “Cruise Control” underTurn Signal/Multifunction
Lever on page 3-7. When the traction control off symbol
on the button is on, the TAS is off and will not limit
wheel spin. Adjust your driving accordingly.
4-8