2004 GMC ENVOY XL Owners Manual

Engine Coolant Heater
Your vehicle may have this feature. In very cold
weather, 0°F (-18°C) or colder, the engine coolant
heater can help. You’ll get easier starting and better
fuel economy during engine warm-up. Usually, the
coolant heater should be plugged in a minimum of
four hours prior to starting your vehicle. At temperatures
above 32°F (0°C), use of the coolant heater is not
required.
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord.
The cord is located on the driver’s side of the
engine compartment, behind the battery.
3. Plug it into a normal, grounded 110-Volt
AC outlet.
{CAUTION:
Plugging the cord into an ungrounded outlet
could cause an electrical shock. Also, the
wrong kind of extension cord could overheat
and cause a re. You could be seriously
injured. Plug the cord into a properly grounded
three-prong 110-volt AC outlet. If the cord will
not reach, use a heavy-duty three-prong
extension cord rated for at least 15 amps.
4. Before starting the engine, be sure to unplug and
store the cord as it was before to keep it away
from moving engine parts. If you don’t, it could be
damaged.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature,
the kind of oil you have, and some other things. Instead
of trying to list everything here, we ask that you
contact your dealer in the area where you’ll be parking
your vehicle. The dealer can give you the best advice
for that particular area.
2-23

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, seeIf
You Are Stuck: In Sand, Mud, Ice or Snow on page 4-44.
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 running at high speed may damage
the transmission. The repairs would not be covered
by your warranty. Be sure the engine is not running
at high speed 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.
THIRD (3):This position is also used for normal driving.
However, it offers more power and lower fuel economy
than DRIVE (D).
2-25

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.
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.
2-26

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 2-29.
NEUTRAL:Shift the vehicle’s transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 4-45for more
information.
An indicator light in the knob will show you which position
the transfer case is in. The indicator lights will come on
briey when you turn on the ignition and one will stay on.
If the lights do not come on, you should take your vehicle
to your dealer for service. An indicator light will ash while
shifting the transfer case. It will remain illuminated when
the shift is complete. If for some reason the transfer case
cannot make a requested shift, it will return to the last
chosen setting.
2-27

If the service four-wheel drive light on the instrument
panel cluster stays on, you should take your vehicle
to your dealer for service. SeeService Four-Wheel Drive
Warning Light on page 3-48for further information.
Shifting into 4HI or A4WD
Turn the knob to 4HI or A4WD. This can be done at any
speed unless you are shifting out of 4LO. The indicator
light will ash while shifting. It will remain illuminated
when the shift is complete.
Shifting into 2HI
Turn the knob to 2HI. This can be done at any speed
unless you are shifting out of 4LO.
Shifting into 4LO
To shift to 4LO, the vehicle’s engine must be running
and the vehicle must be stopped or moving less than
2 mph (3.2 km/h) with the transmission in NEUTRAL (N).
The preferred method for shifting into 4LO is to have your
vehicle moving 1 or 2 mph (1.6 to 3.2 km/h). Turn the
knob to 4LO. You must wait for the 4LO indicator light to
stop ashing and remain illuminated before shifting your
transmission into gear.If you turn the knob to 4LO when your vehicle is in
gear and/or moving, the 4LO indicator light will ash
for 30 seconds and not complete the shift unless your
vehicle is moving less than 2 mph (3.2 km/h) and
the transmission is in NEUTRAL (N). After 30 seconds,
the transfer case will return to the setting last chosen.
Shifting Out of 4LO
To shift from 4LO to 4HI, A4WD or 2HI your vehicle must
be stopped or moving less than 2 mph (3.2 km/h) with the
transmission in NEUTRAL (N) and the engine running.
The preferred method for shifting out of 4LO is to have
your vehicle moving 1 or 2 mph (1.6 to 3.2 km/h). Turn
the knob to 4HI, A4WD or 2HI. You must wait for the 4HI,
A4WD or 2HI indicator light to stop ashing and remain
illuminated before shifting your transmission into gear.
If the knob is turned to 4HI, A4WD or 2HI when your
vehicle is in gear and/or moving, the 4HI, A4WD or 2HI
indicator light will ash for 30 seconds. It will not
complete the shift unless your vehicle is moving less
than 2 mph (3.2 km/h) with the transmission in
NEUTRAL (N).
2-28

Shifting into NEUTRAL
Before shifting the transfer case to NEUTRAL, rst
make sure the vehicle is parked so that it will not roll.
1. Set the parking brake.
2. Start the vehicle.
3. Put the transmission in NEUTRAL (N).
4. Shift the transfer case to 2HI.
5. Turn the transfer case knob all of the way past
4LO and hold it there for a minimum of 10 seconds.
The neutral indicator light will come on.
6. Shift the transmission to REVERSE (R) for one
second, then shift the transmission to DRIVE (D)
for one second.
7. Place the transmission shift lever in PARK (P).
8. Turn the ignition to LOCK.
9. Release the parking brake prior to towing.
Shifting Out of NEUTRAL
To shift the transfer case out of NEUTRAL, do the
following:
1. Set the parking brake and apply the regular brake
pedal.
2. Start the vehicle with the transmission in PARK (P).
3. Turn the transfer case knob to the desired shift
position (2HI, 4HI or A4WD).
4. Put the transmission in NEUTRAL (N).
5. Release the parking brake.
6. After the transfer case has shifted out of NEUTRAL,
the indicator light will go out. Shift the transmission
lever to the desired position.
A re-engagement sound is normal when shifting out of
NEUTRAL.
Parking Brake
To set the parking brake, hold the regular brake pedal
down with your foot and pull up on the parking brake
lever. If the ignition is on, the brake system warning light
will come on.
2-29

To release the parking brake, hold the regular brake
pedal down. Pull the parking brake lever up until you can
press in the button at the end of the lever. Hold the
button in as you move the parking brake lever all the
way down.
Notice:Driving with the parking brake on can
overheat the brake system and cause premature
wear or damage to brake system parts. Verify that
the parking brake is fully released and the brake
warning light is off before driving.
If you are towing a trailer and you must park on a hill,
seeTowing a Trailer on page 4-55. That section
shows what to do rst to keep the trailer from moving.
2-30