2002 GMC ENVOY oil temperature

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.

2-86
Oil Pressure Gage
United States Canada
The oil pressure gage shows the engine oil pressure in
psi (pounds per square inch) when the engine is running.
Canadian vehicles indicate pressure in kPa (kilopascals).
CAUTION:
Don't keep driving if the oil pressure is low. If
you do, your engine can become so hot that it
catches fire. You or others could be burned.
Check your oil as soon as possible and have
your vehicle serviced.
NOTICE:
Damage to your engine from neglected oil
problems can be costly and is not covered by
your warranty.
Oil pressure may vary with engine speed, outside
temperature and oil viscosity, but readings above the
low pressure zone indicate the normal operating range.
A reading in the low pressure zone may be caused by a
dangerously low oil level or other problems causing low
oil pressure.

2-89
Service Four-Wheel-Drive Warning Light
(If Equipped)
United States Canada
This light should come on briefly when you turn on the
ignition, as a check to show you it is working.
The SERVICE 4WD light comes on to indicate that
there may be a problem with the drive system and
service is required. Malfunctions can be indicated by the
system before any problem is apparent, which may
prevent serious damage to the vehicle. This system is
also designed to assist your service technician in
correctly diagnosing a malfunction.
Check Gages Light
United States Canada
The CHECK GAGES light will come on briefly when
you are starting the engine.
If the light comes on and stays on while you are driving,
check your coolant temperature and engine oil pressure
gages to see if they are in the warning zones.

2-102
DIC Warnings and Messages
Warning 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 select button to acknowledge that you
received the message and clear it from the display.
Some messages cannot be cleared from the display
because they are more urgent. These message required
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.
ENGINE COOLANT HOT/IDLE ENGINE
If the cooling system temperature gets hot this message
will appear in the DIC and you will hear a chime. Stop
the vehicle and let the engine idle in PARK (P) to allow
the coolant to reach a safe temperature. This message
will clear when the coolant temperature drops to a safe
operating temperature.ENGINE OVERHEATED/STOP ENGINE
(If Equipped)
If the engine cooling system reaches unsafe
temperatures for operation, this message will appear
in the DIC and you will hear a chime. Stop and turn off
the vehicle as soon as it is safe to do so to avoid severe
damage. This message will clear when the engine has
cooled to a safe operating temperature.
OIL PRESSURE LOW/STOP ENGINE
If low oil pressure levels occur this message will be
displayed on the DIC. Stop the vehicle as soon as safely
possible and do not operate it until the cause of the low
oil pressure has been corrected. Check your oil as soon
as possible and have your vehicle serviced.
BATTERY NOT CHARGING
If the battery is not charging during operation this
message will appear on the DIC. Driving with this
problem could drain your battery. Have the electrical
system checked as soon as possible. Pressing the select
button will acknowledge this message and clear it from
the DIC display.

2-104
CHECK OIL LEVEL
If the oil level in the vehicle is low this message will
appear on the DIC. Check the oil level and correct it as
necessary. You may need to need to let the vehicle cool
or warm up and cycle the ignition to be sure this
message will clear. Once the problem is corrected,
pressing the select button will clear this message from
the DIC display.
CHECK WASHER FLUID
If the washer fluid level is low this message will appear
on the DIC. Adding washer fluid will clear the message.
Pressing the select button will acknowledge this
message and clear it from the DIC display.
TRANS HOT IDLE ENGINE
If the transmission fluid in the vehicle gets hot this
message will appear on the DIC. Driving with the
transmission fluid temperature high can cause damage to
the vehicle. Stop the vehicle and let it idle to allow the
transmission to cool. This message will clear when the
fluid temperature reaches a safe level.ICE POSSIBLE
If the outside temperature reaches a level where ice
could form on the roadway, this message may appear
on the DIC. If the temperature rises to a safe level the
message will clear. Pressing the select button will
acknowledge this message and clear it from the
DIC display.
DRIVER DOOR AJAR
If the driver's door is not fully closed this message will
appear on the display and you will hear a chime. Stop
and turn off the vehicle, check the door for obstacles,
and close the door again. Check to see if the message
still appears on the DIC. Pressing the select button
will acknowledge this message and clear it from the
DIC display.

4-58 Driving On Grades
Reduce speed and shift to a lower gear before you start
down a long or steep downgrade. If you don't shift
down, you might have to use your brakes so much that
they would get hot and no longer work well.
You can tow in DRIVE (D). You may want to shift the
transmission to THIRD (3) or a lower gear, under heavy
loads or hilly conditions.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a
lower temperature than at normal altitudes. If you turn
your engine off immediately after towing at high altitude
on steep uphill grades, your vehicle may show signs
similar to engine overheating. To avoid this, let the
engine run while parked (preferably on level ground)
with the automatic transmission in PARK (P) for a
few minutes before turning the engine off. If you do
get the overheat warning, see ªEngine Overheatingº in
the Index.
Parking on Hills
CAUTION:
You really should not park your vehicle, with a
trailer attached, on a hill. If something goes
wrong, your rig could start to move. People can
be injured, and both your vehicle and the trailer
can be damaged.
But if you ever have to park your rig on a hill, here's
how to do it:
1. Apply your regular brakes, but don't shift into
PARK (P) yet. When parking uphill, turn your
wheels away from the curb. When parking downhill,
turn your wheels into the curb.
2. Have someone place chocks under the trailer wheels.
3. When the wheel chocks are in place, release the
regular brakes until the chocks absorb the load.
4. Reapply the regular brakes. Then apply your parking
brake, and then shift into PARK (P).
5. Release the regular brakes.

6-14
As in the chart shown previously, SAE 5W-30 is best for
your vehicle. However, you can use SAE 10W
-30 if it's
going to be 0F (
-18C) or above. These numbers on an
oil container show its viscosity, or thickness. Do not use
other viscosity oils, such as SAE 20W
-50.
NOTICE:
Use only engine oil with the American Petroleum
Institute Certified For Gasoline Engines
starburst symbol. Failure to use the
recommended oil can result in engine damage not
covered by your warranty.
GM Goodwrench
oil meets all the requirements for
your vehicle.
If you are in an area where the temperature falls below
-20F (-29C), consider using either an SAE 5W-30
synthetic oil or an SAE 0W
-30 oil. Both will provide
easier cold starting and better protection for your engine
at extremely low temperatures.
Engine Oil Additives
Don't add anything to your oil. The recommended oils
with the starburst symbol are all you will need for good
performance and engine protection.
When to Change Engine Oil
(GM Oil Life System )
Your vehicle has a computer system that lets you know
when to change the engine oil and filter. This is based on
engine revolutions and engine temperature, and not on
mileage. Based on driving conditions, the mileage at
which an oil change will be indicated can vary
considerably. For the oil life system to work properly,
you must reset the system every time the oil is changed.
When the system has calculated that oil life has been
diminished, it will indicate that an oil change is
necessary. A CHANGE ENG OIL light in the Driver
Information Center (DIC) will come on. Change your oil
as soon as possible within the next two times you stop
for fuel. It is possible that, if you are driving under the
best conditions, the oil life system may not indicate that
an oil change is necessary for over a year. However,
your engine oil and filter must be changed at least once
a year and at this time the system must be reset. It is also
important to check your oil regularly and keep it at the
proper level.

6-18
Automatic Transmission Fluid
When to Check and Change
A good time to check your automatic transmission fluid
level is when the engine oil is changed.
Change both the fluid and filter every 50,000 miles
(83 000 km) if the vehicle is mainly driven under one or
more of these conditions:

In heavy city traffic where the outside temperature
regularly reaches 90F (32C) or higher.

In hilly or mountainous terrain.

When doing frequent trailer towing.

Uses such as found in taxi, police or delivery service.
If you do not use your vehicle under any of these
conditions, change the fluid and filter every
100,000 miles (166 000 km).
See ªScheduled Maintenance Servicesº in the Index.
How to Check
Because this operation can be a little difficult, you
may choose to have this done at the dealership
service department.
If you do it yourself, be sure to follow all the
instructions here, or you could get a false reading
on the dipstick.
NOTICE:
Too much or too little fluid can damage your
transmission. Too much can mean that some of
the fluid could come out and fall on hot engine
parts or exhaust system parts, starting a fire.
Too little fluid could cause the transmission to
overheat. Be sure to get an accurate reading if
you check your transmission fluid.