2002 GMC ENVOY Engine

2-21
When starting your engine in very cold weather
(below 0
F or
-18
C), do this:
1. With your foot off the accelerator pedal, turn the
ignition key to START and hold it there up to
15 seconds. When the engine starts, let go of the key.
2. If your engine still won't start (or starts but then stops),
it could be flooded with too much gasoline. Try
pushing your accelerator pedal all the way to the floor
and holding it there as you hold the key in START for
about three seconds. When the engine starts, let go of
the key and accelerator. If the vehicle starts briefly but
then stops again, do the same thing, but this time keep
the pedal down for five or six seconds. This clears the
extra gasoline from the engine.NOTICE:
Your engine is designed to work with the
electronics in your vehicle. If you add electrical
parts or accessories, you could change the way
the engine operates. Before adding electrical
equipment, check with your dealer. If you don't,
your engine might not perform properly.

2-22
Engine Coolant Heater (If Equipped)
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 underhood fuse block.
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 fire. You could be seriously injured. Plug the
cord into a properly grounded three
-prong
11 0
-volt AC outlet. If the cord won't 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 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 firmly set. Your vehicle can roll.
Don't 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 won't move, even when you're on fairly
level ground, always set your parking brake and
move the shift lever to PARK (P).
CAUTION: (Continued)
CAUTION: (Continued)
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. See ªFour-Wheel
Drive (Automatic Transfer Case)º in the Index.
See ªShifting Into PARK (P)º in the Index. If
you're pulling a trailer, see ªTowing a Trailerº in
the Index.
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. Then move the shift lever into the
gear you wish. See ªShifting Out of PARK (P)º in
the Index.

2-24
REVERSE (R): Use this gear to back up.
NOTICE:
Shifting to REVERSE (R) while the vehicle is
moving forward could damage the transmission.
Shift to REVERSE (R) only after the vehicle
is stopped.
To rock your vehicle back and forth to get out of snow,
ice or sand without damaging your transmission, see
ªStuck In Sand, Mud, Ice or Snowº in the Index.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 out of PARK (P) or NEUTRAL (N) while
your engine is ªracingº (running at high speed) is
dangerous. Unless your foot is firmly on the
brake pedal, your vehicle could move very
rapidly. You could lose control and hit people or
objects. Don't shift out of PARK (P) or
NEUTRAL (N) while your engine is racing.
NOTICE:
Damage to your transmission caused by shifting
out of PARK (P) or NEUTRAL (N) with the
engine racing isn't covered by your warranty.

2-26
Shift Lock Release
This vehicle is equipped with a shift lock release
system. If your vehicle has a dead battery and you
need to have your vehicle towed, there is a shift lock
release lever that will allow you to move the shift lever
out of PARK (P).
To access the shift lock release lever, do the following:
1. Press on the sides of the boot around the shift lever
to release the boot.
2. Lift up the boot on the shift lever and you will see an
orange lever.
3. Press the orange lever down and move the shift lever
out of PARK (P).
4. Snap the shift lever boot back in place.
Four-Wheel Drive (If Equipped)
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 (2HI) for most normal
driving conditions.
NOTICE:
Driving in the 4HI or 4LO positions for a long
time on dry or wet pavement could shorten the
life of your vehicle's drivetrain.

2-29
Shifting to 4HI or A4WD
Turn the knob to 4HI or A4WD. This can be done at any
speed and the indicator light will flash while shifting. It
will remain illuminated when the shift is complete.
Shifting to 2HI
Turn the knob to 2HI. This can be done at any speed.
Shifting to 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 flashing and remain illuminated before shifting
your transmission into gear.
If you knob to 4LO when your vehicle is in gear
and/or moving, the 4LO indicator light will flash 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 flashing and remain illuminated before shifting
your transmission into gear.
If the 4HI, A4WD or 2HI knob is turned when your
vehicle is in gear and/or moving, the 4HI, A4WD or
2HI indicator light will flash for 30 seconds but will
not complete the shift unless your vehicle is moving
less than 2 mph (3.2 km/h) with the transmission
in NEUTRAL (N).

2-32
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 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. 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. See ªFour-Wheel
Drive (Automatic Transfer Case)º in the Index.
Always put the shift lever fully in PARK (P) with
the parking brake firmly set. If you're pulling a
trailer, see ªTowing a Trailerº in the Index.
1. Hold the brake pedal down with your right foot and
set the parking brake.
2. Move the shift lever into
PARK (P) like this:

Press the button in on
the front of the lever.

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. If you
can leave your vehicle with the key, your vehicle is
in PARK (P).

2-33
Leaving Your Vehicle With the
Engine Running
CAUTION:
It can be dangerous to leave your vehicle with the
engine running. Your vehicle could move
suddenly if the shift lever is not fully in PARK (P)
with the parking brake firmly set. 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. See ªFour
-Wheel Drive (Automatic
Transfer Case)º in the Index. And, if you leave
the vehicle with the engine running, it could
overheat and even catch fire. You or others could
be injured. Don't leave your vehicle with the
engine running unless you have to.
If you have to leave your vehicle with the engine
running, be sure your vehicle is in PARK (P) and your
parking brake is firmly set before you leave it. After
you've moved the shift lever into PARK (P), hold the
regular brake pedal down. Then, see if you can move the
shift lever away from PARK (P) without pressing the
button on the shift lever. If you can, it means that the
shift lever wasn't fully locked into PARK (P).