2003 CHEVROLET EXPRESS check engine

Brakes
Brake Fluid
Your brake master cylinder
reservoir is lled with
DOT-3 brake uid. See
Engine Compartment
Overview on page 5-12for
the location of the
reservoir.
There are only two reasons why the brake uid level in
the reservoir might go down. The rst is that the
brake uid goes down to an acceptable level during
normal brake lining wear. When new linings are put in,
the uid level goes back up. The other reason is
that uid is leaking out of the brake system. If it is, you
should have your brake system xed, since a leak
means that sooner or later your brakes will not work
well, or will not work at all.So, it is not a good idea to top off your brake uid.
Adding brake uid will not correct a leak. If you add uid
when your linings are worn, then you will have too
much uid when you get new brake linings. You should
add or remove brake uid, as necessary, only when
work is done on the brake hydraulic system.
{CAUTION:
If you have too much brake uid, it can spill on
the engine. The uid will burn if the engine is
hot enough. You or others could be burned,
and your vehicle could be damaged. Add brake
uid only when work is done on the brake
hydraulic system. See “Checking Brake Fluid”
in this section.
Refer to the Maintenance Schedule to determine when
to check your brake uid. SeeScheduled Maintenance
on page 6-4.
5-34

Checking Brake Fluid
You can check the brake uid without taking off the cap.
Look at the brake uid
reservoir. The uid level
should be above MIN. If it
is not, have your brake
system checked to
see if there is a leak.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not over the
MAX mark.
What to Add
When you do need brake uid, use only DOT-3 brake
uid. Use new brake uid from a sealed container
only. SeeRecommended Fluids and Lubricants on
page 6-13.Always clean the brake uid reservoir cap and the area
around the cap before removing it. This will help
keep dirt from entering the reservoir.
{CAUTION:
With the wrong kind of uid in your brake
system, your brakes may not work well, or they
may not even work at all. This could cause a
crash. Always use the proper brake uid.
Notice:
Using the wrong uid can badly damage brake
system parts. For example, just a few drops of
mineral-based oil, such as engine oil, in your
brake system can damage brake system parts so
badly that they will have to be replaced. Do not
let someone put in the wrong kind of uid.
If you spill brake uid on your vehicle’s painted
surfaces, the paint nish can be damaged. Be
careful not to spill brake uid on your vehicle. If
you do, wash it off immediately. SeeAppearance
Care on page 5-82.
5-35

5. Check that the jumper cables do not have loose or
missing insulation. If they do, you could get a
shock. The vehicles could be damaged too.
Before you connect the cables, here are some
basic things you should know. Positive (+) will go to
positive (+) or to a remote positive (+) terminal if
the vehicle has one. Negative (−) will go to a heavy,
unpainted metal engine part or to a remote
negative (−) terminal if the vehicle has one.
Do not connect positive (+) to negative (−)oryou
will get a short that would damage the battery
and maybe other parts too. And do not connect the
negative (−) cable to the negative (−) terminal on
the dead battery because this can cause sparks.
6. Connect the red positive (+) cable to the positive (+)
terminal of the dead battery. Use a remote
positive (+) terminal if the vehicle has one.
7. Do not let the other end touch metal. Connect it to
the positive (+) terminal of the good battery. Use a
remote positive (+) terminal if the vehicle has one.
5-41

ApplicationCapacities
English Metric
Fuel Tank
Standard Tank (Passenger and Cargo)
Standard Tank (Cab and Chassis)
Optional Tank (Cab and Chassis)*
* 159 inch (4 039 mm) wheelbase or 177 inch (4 496 mm)
wheel base only31.0 gallons
33.0 gallons
57.0 gallons117.3 L
124.9 L
215.7 L
Wheel Nut Torque 140 ft lb 190Y
All capacities are approximate. When adding, be sure to ll to the approximate level, as recommended in this
manual. Recheck uid level after lling.
Engine Specications
Engine VIN Code Transmission Spark Plug Gap
VORTEC™ 4300 V6 W Automatic 0.040 inches (1.01 mm)
VORTEC™ 4800 V8 V Automatic 0.040 inches (1.01 mm)
VORTEC™ 5300 V8 T Automatic 0.040 inches (1.01 mm)
VORTEC™ 6000 V8 U Automatic 0.040 inches (1.01 mm)
5-98

Maintenance Schedule
Introduction
Important: Keep engine oil at the proper level and
change as recommended.
Have you purchased the GM Protection Plan? The Plan
supplements your new vehicle warranties. See your
Warranty and Owner Assistance booklet or your dealer
for details.
Maintenance Requirements
Notice:Maintenance intervals, checks, inspections,
replacement parts and recommended uids and
lubricants as prescribed in this manual are
necessary to keep your vehicle in good working
condition. Any damage caused by failure to follow
scheduled maintenance may not be covered
by warranty.
Your Vehicle and the Environment
Proper vehicle maintenance not only helps to keep your
vehicle in good working condition, but also helps the
environment. All recommended maintenance is
important. Improper vehicle maintenance can even
affect the quality of the air we breathe. Improper uid
levels or the wrong tire ination can increase the level of
emissions from your vehicle. To help protect our
environment, and to keep your vehicle in good condition,
be sure to maintain your vehicle properly.
6-2

Owner Checks and Services on page 6-10tells you
what should be checked, when to check it and what
you can easily do to help keep your vehicle in
good condition.
The proper replacement parts, uids and lubricants to
use are listed inRecommended Fluids and Lubricants
on page 6-13andNormal Maintenance Replacement
Parts on page 6-15. When your vehicle is serviced,
make sure these are used. All parts should be replaced
and all necessary repairs done before you or anyone
else drives the vehicle. We recommend the use of
genuine GM parts.
Scheduled Maintenance
When the change engine oil light comes on, it means
that service is required for your vehicle. Have your
vehicle serviced as soon as possible within the next
600 miles (1 000 km). It is possible that, if you are
driving under the best conditions, the engine oil life
system may not indicate that vehicle service 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 GM
Goodwrench dealer has GM-trained service technicians
who will perform this work using genuine GM parts
and reset the system.If the engine oil life system is ever reset accidentally,
you must service your vehicle within 3,000 miles
(5 000 km) since your last service. Remember to reset
the oil life system whenever the oil is changed. See
Engine Oil Life System on page 5-16for information on
the Engine Oil Life System and resetting the system.
When the change engine oil light appears, certain
services, checks and inspections are required. Required
services are described in the following for
“MaintenanceI” and “MaintenanceII.” Generally, it is
recommended that your rst service be MaintenanceI,
your second service be MaintenanceIIand that you
alternate MaintenanceIand MaintenanceIIthereafter.
However, in some cases, MaintenanceIImay be
required more often.
MaintenanceI— Use MaintenanceIif the change
engine oil light comes on within 10 months since
the vehicle was purchased or MaintenanceIIwas
performed.
MaintenanceII— Use MaintenanceIIif the previous
service performed was MaintenanceI. Always use
MaintenanceIIwhenever the message comes on
10 months or more since the last service or if the
message has not come on at all for one year.
6-4

Scheduled Maintenance
Service MaintenanceIMaintenanceII
Change engine oil and lter. SeeEngine Oil on page 5-13. Reset oil
life system. SeeEngine Oil Life System on page 5-16.An Emission
Control Service.••
Lubricate chassis components.See footnote #.••
Visually check for any leaks or damage.See footnote (j).••
Inspect engine air cleaner lter or change indicator (if equipped). If necessary,
replace lter. SeeEngine Air Cleaner/Filter on page 5-17.An Emission Control
Service. See footnotes † and (l).•
Rotate tires and check ination pressures and wear. SeeTires on page 5-52.••
Inspect brake system.See footnote (a).••
Check engine coolant and windshield washer uid levels and add uid
as needed.••
Perform any needed additional services. See “Additional Required Services” in
this section.••
Inspect suspension and steering components.See footnote (b).•
Inspect engine cooling system.See footnote (c).•
Inspect wiper blades.See footnote (d).•
Inspect restraint system components.See footnote (e).•
Lubricate body components.See footnote (f).•
Check transmission uid level and add uid as needed.•
Inspect shields, vehicles with GVWR above 10,000 lbs (4 536 kg) only.See
footnote (g).•
Inspect throttle system.See footnote (m).•
6-5

(g)Vehicles with GVWR above 10,000 lbs (4 536 kg)
only: Inspect shields for damage or looseness. Adjust or
replace as required. This is a Noise Emission Control
Service. Applicable only to vehicles sold in the
United States.
(h)Change automatic transmission uid and lter if the
vehicle is mainly driven under one or more of these
conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police or delivery
service.
(i)Drain, ush and rell cooling system. See Engine
Coolant on page 5-22for what to use. Inspect hoses.
Clean radiator, condenser, pressure cap and ller neck.
Pressure test the cooling system and pressure cap.(j)A uid loss in any vehicle system could indicate a
problem. Have the system inspected and repaired and
the uid level checked. Add uid if needed.
(k)Inspect system. Check all fuel and vapor lines and
hoses for proper hook-up, routing and condition.
Check that the purge valve works properly (if equipped).
Replace as needed.
(l)If you drive regularly under dusty conditions, inspect
the lter at each engine oil change.
(m)Check system for interference or binding and for
damaged or missing parts. Replace parts as needed.
Replace any components that have high effort or
excessive wear. Do not lubricate accelerator or cruise
control cables.
6-9