2005 GMC ENVOY XL engine

Engine Coolant Heater
Your vehicle may have an engine coolant heater. In
very cold weather, 0°F (−18°C) or colder, the engine
coolant heater can help. You will 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 do not, 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 will be
parking your vehicle. The dealer can give you the
best advice for that particular area.
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Displacement on Demand (DoD)
Your vehicle’s engine may be equipped with
Displacement on Demand (DoD). This system allows
the engine to operate on either four or eight cylinders,
depending on your driving demands.
The system determines when to switch into and out
of the four-cylinder mode by rst making sure that
certain enabling criteria are met, such as coolant and
oil temperatures, and the transmission being in
either THIRD (3) or FOURTH (4) gear.
When greater power demands are required, such as
accelerating from a stop, passing, or merging onto
a freeway, the system will maintain eight-cylinder
operation. When less power is required, such a
cruising at a constant vehicle speed, the system will
automatically enable the four-cylinder mode, allowing
your vehicle to achieve better fuel economy.
Automatic Transmission Operation
There are several different positions for your gear
shift lever.
PARK (P):This position locks the rear wheels. It is
the best position to use when you start the engine
because your vehicle cannot move easily.
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{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 2-32. 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 2-27. SeeShifting Into Park (P)
on page 2-32.
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 2-34.
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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 Your Vehicle is Stuck in Sand, Mud, Ice or
Snow on page 4-42.
NEUTRAL (N):In this position, the engine does
not connect with the wheels. To restart when you
are 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 are:
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 will 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).
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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 will not 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 2HI (two-wheel high) for most normal
driving conditions.
Notice:Driving on clean, dry pavement in
four-wheel drive for an extended period of time may
cause premature wear on your vehicle’s powertrain.
Do not drive on clean, dry pavement in four-wheel
drive for extended periods of time.
2-27

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 stay on 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.
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 3-47for further information.
Shifting Into 4HI (Four-Wheel High)
or A4WD (Automatic Four-Wheel Drive)
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 on when
the shift is complete.
Shifting Into 2HI (Two-Wheel High)
Turn the knob to 2HI. This can be done at any speed
unless you are shifting out of 4LO.
Shifting Into 4LO (Four-Wheel Low)
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 stay on before shifting the
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 (Four-Wheel Low)
To shift from 4LO to 4HI, A4WD drive, 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 stay off 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).
2-29

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
four-wheel low and hold it there for a minimum
of 10 seconds. The neutral indicator light will
come on.
6. With the engine running, shift the transmission
to REVERSE (R) for one second, then shift
the transmission to DRIVE (D) for one second,
to ensure transfer case is in NEUTRAL.
7. Turn the engine off, by turning the key to
ACCESSORY.
8. Place the transmission shift lever in PARK (P).
9. Turn the ignition to LOCK.
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. Turn the ignition to RUN with the engine off.
3. Put the transmission in NEUTRAL (N).
4. Turn the transfer case knob to the desired
position (2 HI, 4HI, or A4WD).
5. After the transfer case has shifted out of NEUTRAL,
the indicator light will go out.
6. Release the parking brake.
7. You may start the engine and shift the transmission
to the desired position.
2-30

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 2-27. 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) by pressing the
button on the side of the shift lever and pushing 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.
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