2003 CHEVROLET TAHOE check engine

Turn off the engine and give the oil several minutes to
drain back into the oil pan. If you don't, the oil
dipstick might not show the actual level.
Pull out the dipstick and clean it with a paper towel or
cloth, then push it back in all the way. Remove it again,
keeping the tip down, and check the level.When to Add Engine Oil
If the oil is at or below the cross-hatched area at the tip
of the dipstick, then you'll need to add at least one
quart of oil. But you must use the right kind. This part
explains what kind of oil to use. For engine oil crankcase
capacity, see
Capacities and Speci®cations on
page 5-118.
Notice:Don't add too much oil. If your engine has
so much oil that the oil level gets above the
cross-hatched area that shows the proper operating
range, your engine could be damaged.
8.1L Engine
All Other Engines
5-19

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 ®lter. 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 ENGINE OIL message 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 ®lter must be changed at least once a year
and at this time the system must be reset. Your dealer
has GM-trained service people who will perform this work
using genuine GM parts and reset the system. It is also
important to check your oil regularly and keep it at the
proper level.
If the system is ever reset accidentally, you must
change your oil at 3,000 miles (5 000 km) since your
last oil change. Remember to reset the oil life system
whenever the oil is changed.
How to Reset the CHANGE ENGINE OIL
Message
The GM Oil Life System calculates when to change
your engine oil and ®lter based on vehicle use. Anytime
your oil is changed, reset the system so it can
calculate when the next oil change is required. If a
situation occurs where you change your oil prior to a
CHANGE ENGINE OIL message being turned on, reset
the system.
To reset the CHANGE ENGINE OIL message, see ªGM
Oil Life Systemº under
DIC Operation and Displays
on page 3-54for vehicles equipped with the DIC, or do
the following:
1. Turn the ignition key to RUN with the engine off.
2. Fully press and release the accelerator pedal three
times within ®ve seconds.
If the OIL LIFE RESET message ¯ashes for 10 seconds,
the system is reset.
If the system does not reset, try the procedure once
again. If it still does not reset, see your dealer for service.
5-22

Automatic Transmission Fluid
When to Check and Change
A good time to check your automatic transmission ¯uid
level is when the engine oil is changed.
Change both the ¯uid and ®lter every 50,000 miles
(83 000 km) if the vehicle's GVWR is over 8,600 or if
the vehicle is mainly driven under one or more of these
conditions:
·In heavy city traffic where the outside temperature
regularly reaches 90ÉF (32ÉC) or higher.
·In hilly or mountainous terrain.
·When doing frequent trailer towing.
·Uses such as found in taxi, police or delivery
service.
If your vehicle's GVWR is not over 8,600 and you do
not use your vehicle under any of these conditions,
change the ¯uid and ®lter every 100,000 miles
(166 000 km).
See
Part A: Scheduled Maintenance Services on
page 6-4.
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 ¯uid can damage
your transmission. Too much can mean that some
of the ¯uid could come out and fall on hot engine
part or exhaust system parts, starting a ®re.
Too little ¯uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission ¯uid.
Wait at least 30 minutes before checking the
transmission ¯uid level if you have been driving:
·When outside temperatures are above 90ÉF (32ÉC).
·At high speed for quite a while.
·In heavy traffic ± especially in hot weather.
·While pulling a trailer.
To get the right reading, the ¯uid should be at normal
operating temperature, which is 180ÉF to 200ÉF
(82ÉC to 93ÉC).
5-26

Get the vehicle warmed up by driving about 15 miles
(24 km) when outside temperatures are above 50ÉF
(10ÉC). If it's colder than 50ÉF (10ÉC), drive the vehicle
in THIRD (3) until the engine temperature gage
moves and then remains steady for 10 minutes.
A cold ¯uid check can be made after the vehicle has
been sitting for eight hours or more with the engine off,
but this is used only as a reference. Let the engine
run at idle for ®ve minutes if outside temperatures are
50ÉF (10ÉC) or more. If it's colder than 50ÉF (10ÉC), you
may have to idle the engine longer. Should the ¯uid
level be low during this cold check, you
mustcheck the
¯uid hot before adding ¯uid. Checking the ¯uid hot
will give you a more accurate reading of the ¯uid level.
Checking the Fluid Level
Prepare your vehicle as follows:
·Park your vehicle on a level place. Keep the engine
running.
·With the parking brake applied, place the shift lever
in PARK (P).
·With your foot on the brake pedal, move the shift
lever through each gear range, pausing for about
three seconds in each range. Then, position the shift
lever in PARK (P).
·Let the engine run at idle for three minutes or more.
5-27

Then, without shutting off the engine, follow these steps:
The transmission dipstick
handle with the graphic is
located at the rear of
the engine compartment,
on the passenger's side.
See
Engine Compartment Overview on page 5-14for
more information on location.
1. Flip the handle up and then pull out the dipstick
and wipe it with a clean rag or paper towel.
2. Push it back in all the way, wait three seconds and
then pull it back out again.3. Check both sides of the dipstick, and read the lower
level. The ¯uid level must be in the COLD area,
below the cross-hatched area, for a cold check or in
the HOT area or cross-hatched area for a hot check.
4. If the ¯uid level is in the acceptable range, push the
dipstick back in all the way; then ¯ip the handle
down to lock the dipstick in place.
5-28

How to Add Fluid
Refer to the Maintenance Schedule to determine what
kind of transmission ¯uid to use. SeePart D:
Recommended Fluids and Lubricants on page 6-18.
Add ¯uid only after checking the transmission ¯uid while
it is hot. (A cold check is used only as a reference.) If
the ¯uid level is low, add only enough of the proper ¯uid
to bring the level up to the HOT area for a hot check.
It doesn't take much ¯uid, generally less than one
pint (0.5 L).
Don't over®ll.
Notice:
We recommend you use only ¯uid labeled
DEXRONž-III, because ¯uid with that label is
made especially for your automatic transmission.
Damage caused by ¯uid other than DEXRON
ž-III is
not covered by your new vehicle warranty.
·After adding ¯uid, recheck the ¯uid level as
described under
How to Check.
·When the correct ¯uid level is obtained, push the
dipstick back in all the way; then ¯ip the handle
down to lock the dipstick in place.
Engine Coolant
The cooling system in your vehicle is ®lled with
DEX-COOLžengine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs ®rst, if you add only
DEX-COOL
žextended life coolant.
The following explains your cooling system and how to
add coolant when it is low. If you have a problem
with engine overheating, see
Engine Overheating on
page 5-33.
5-29

Notice:If you use an improper coolant mixture,
your engine could overheat and be badly damaged.
The repair cost wouldn't be covered by your
warranty. Too much water in the mixture can freeze
and crack the engine, radiator, heater core and
other parts.
If you have to add coolant more than four times a year,
have your dealer check your cooling system.
Notice:If you use the proper coolant, you don't
have to add extra inhibitors or additives which claim
to improve the system. These can be harmful.
Checking Coolant
The coolant surge tank is
located in the engine
compartment on the
passenger's side of the
vehicle. See
Engine
Compartment Overview on
page 5-14
for more
information on location.
{CAUTION:
Turning the surge tank pressure cap when the
engine and radiator are hot can allow steam
and scalding liquids to blow out and burn you
badly. Never turn the surge tank pressure
cap Ð even a little Ð when the engine and
radiator are hot.
The vehicle must be on a level surface. When your
engine is cold, the coolant level should be at the FULL
COLD mark.
If your vehicle is equipped with a low coolant sensor,
and the LOW COOLANT LEVEL message comes
on and stays on, it means you're low on engine coolant.
See ªLow Coolant Levelº under
DIC Warnings and
Messages on page 3-64.
5-31

How to Add Coolant to the Coolant
Surge Tank
If you haven't found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level isn't at or above the FULL
COLD mark, add a 50/50 mixture of
clean, drinkable
waterand DEX-COOLžcoolant at the coolant
surge tank, but be sure the cooling system, including
the coolant surge tank pressure cap, is cool before you
do it. See
Engine Coolant on page 5-29for more
information.If no coolant is visible in the surge tank, add coolant as
follows:
{CAUTION:
Steam and scalding liquids from a hot cooling
system can blow out and burn you badly. They
are under pressure, and if you turn the coolant
surge tank pressure cap Ð even a little Ð they
can come out at high speed. Never turn the
cap when the cooling system, including the
coolant surge tank pressure cap, is hot. Wait
for the cooling system and coolant surge tank
pressure cap to cool if you ever have to turn
the pressure cap.
5-38