2003 CHEVROLET EXPRESS CARGO VAN wiring

i(Daytime Running Lamps (DRL)):Turning the
control to this position selects the DRLs. When the
vehicle is shifted out of PARK (P), the instrument panel
lamps will illuminate and the DRLs will turn on, unless
defeated. When the DRLs are active, the DRL indicator
will illuminate.
;(Parking Lamps):Turn the control to this position
to turn on the parking lamps, together with the
following:
·Instrument Panel Lights
·Daytime Running Lamps
·Sidemarker Lamps
·Taillamps
·License Plate Lamps
·Ashtray Lamp
If the DRLs are active when the control is turned to this
position, the DRLs will turn off.
For vehicles ®rst sold in Canada, the DRLs will remain
active along with the lamps mentioned above.
5(Headlamps):Turn the control to this position to
turn on the headlamps together with the parking
lamps and turn off the daytime running lamps.
You can switch your headlamps from high to
low-beam by pulling the turn signal/high-beam lever
toward you.
A circuit breaker protects your headlamps. If you have
an electrical overload, your headlamps will ¯icker on and
off. Have your headlamp wiring checked right away if
this happens.
Lamps On Reminder
A reminder chime will sound when your control is turned
to the headlamps or parking lamps position, your key
is out of the ignition, and your driver's door is open. To
disable the chime, turn the control to the Daytime
Running Lamp (DRL) position and then back to the
parking lamps or headlamps position.
3-14

Air Bag Readiness Light
There is an air bag readiness light on the instrument
panel, which shows the air bag symbol. The system
checks the air bag's electrical system for malfunctions.
The light tells you if there is an electrical problem.
The system check includes the air bag sensor, the air
bag modules, the wiring and the crash sensing and
diagnostic module. For more information on the air bag
system, see
Air Bag System on page 1-63.
This light will come on
when you start your
vehicle, and it will ¯ash for
a few seconds. Then
the light should go out.
This means the system
is ready.
If the air bag readiness light stays on after you start the
vehicle or comes on when you are driving, your air
bag system may not work properly. Have your vehicle
serviced right away.
{CAUTION:
If the air bag readiness light stays on after you
start your vehicle, it means the air bag system
may not be working properly. The air bags in
your vehicle may not in¯ate in a crash, or they
could even in¯ate without a crash. To help
avoid injury to yourself or others, have your
vehicle serviced right away if the air bag
readiness light stays on after you start your
vehicle.
The air bag readiness light should ¯ash for a few
seconds when you turn the ignition key to RUN. If the
light doesn't come on then, have it ®xed so it will
be ready to warn you if there is a problem.
3-27

·If you'll be pulling a trailer that, when loaded, will
weigh more than 4,000 lbs (1 800 kg), be sure to
use a properly mounted, weight-distributing
hitch and sway control of the proper size. This
equipment is very important for proper vehicle
loading and good handling when you're driving.
·Will you have to make any holes in the body of
your vehicle when you install a trailer hitch?
If you're using the wiring provided by the
factory-installed hitch, you should not need to make any
holes in the body of your vehicle. However, if you
have an aftermarket hitch installed, you may need to
make holes in the body.
If you do, then be sure to seal the holes later when you
remove the hitch. If you don't seal them, deadly
carbon monoxide (CO) from your exhaust can get into
your vehicle. Dirt and water can, too.
Safety Chains
You should always attach chains between your
vehicle and your trailer. Cross the safety chains under
the tongue of the trailer to help prevent the tongue from
contacting the road if it becomes separated from the
hitch. Instructions about safety chains may be provided
by the hitch manufacturer or by the trailer manufacturer.Follow the manufacturer's recommendation for attaching
safety chains and do not attach them to the bumper.
Always leave just enough slack so you can turn with your
rig. Never allow safety chains to drag on the ground.
Trailer Brakes
If your trailer weighs more than 1,000 lbs (450 kg)
loaded, then it needs its own brakes ± and they must be
adequate. Be sure to read and follow the instructions
for the trailer brakes so you'll be able to install,
adjust and maintain them properly.
Your trailer brake system can tap into your vehicle's
hydraulic brake system, except:
·Don't tap into your vehicle's brake system if the
trailer's brake system will use more than 0.02 cubic
inch (0.3 cc) of ¯uid from your vehicle's master
cylinder. If it does, both braking systems won't work
well. You could even lose your brakes.
·Will the trailer parts take 3,000 psi (20 650 kPa) of
pressure? If not, the trailer brake system must not
be used with your vehicle.
·If everything checks out this far, then make the
brake ¯uid tap at the port on the master cylinder that
sends ¯uid to the rear brakes. But don't use
copper tubing for this. If you do, it will bend and
®nally break off. Use double-walled steel tubing.
4-40

Passing
You'll need more passing distance up ahead when
you're towing a trailer. And, because you're a good deal
longer, you'll need to go much farther beyond the
passed vehicle before you can return to your lane.
Backing Up
Hold the bottom of the steering wheel with one hand.
Then, to move the trailer to the left, just move that hand
to the left. To move the trailer to the right, move your
hand to the right. Always back up slowly and, if possible,
have someone guide you.
Making Turns
Notice:Making very sharp turns while trailering
could cause the trailer to come in contact with the
vehicle. Your vehicle could be damaged. Avoid
making very sharp turns while trailering.
When you're turning with a trailer, make wider turns than
normal. Do this so your trailer won't strike soft shoulders,
curbs, road signs, trees or other objects. Avoid jerky or
sudden maneuvers. Signal well in advance.
Turn Signals When Towing a Trailer
When you tow a trailer, your vehicle has to have extra
wiring and a heavy-duty turn signal ¯asher (included
in the optional trailering package).The arrows on your instrument panel will ¯ash whenever
you signal a turn or lane change. Properly hooked up,
the trailer lamps will also ¯ash, telling other drivers
you're about to turn, change lanes or stop.
When towing a trailer, the arrows on your instrument
panel will ¯ash for turns even if the bulbs on the trailer
are burned out. Thus, you may think drivers behind
you are seeing your signal when they are not. It's
important to check occasionally to be sure the trailer
bulbs are still working.
Driving On Grades
Reduce speed and shift to a lower gearbeforeyou 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.
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
Engine Overheating on
page 5-24.
4-42

Trailer Wiring Harness
The optional heavy-duty trailer wiring package includes
a seven-wire harness assembly at the rear of the
vehicle and a four-wire harness assembly under the left
hand side of the instrument panel. The seven-wire
harness assembly is taped together and located in a
frame pocket at the driver side rear left corner of
the frame. The seven-wire harness includes a
30-amp feed wire. Both harnesses come without
connectors and should be wired by a quali®ed electrical
technician. The technician can use the following
color code chart when connecting the wiring harness to
your trailer and trailer brake controller.Seven-Wire Harness·Light Green: Back-up lamps
·Brown: Parking lamps
·Yellow: Left stoplamp and turn signal
·Dark Green: Right stoplamp and turn signal
·Dark Blue: Use for electric trailer brakes
·Orange: Trailer accessory
·White (heavy gage): Ground wire
Four-Wire Harness (Trailer Brake Controller)
·Black: Ground
·Red/White Stripe: Fused Battery
·Dark Blue: Trailer Brake Feed
·Light Blue: Fused Stop/CHMSL
4-44

Windshield Wiper Blade Replacement..............5-55
Tires..............................................................5-56
In¯ation -- Tire Pressure................................5-56
Dual Tire Operation.......................................5-57
Tire Inspection and Rotation...........................5-58
When It Is Time for New Tires.......................5-59
Buying New Tires.........................................5-60
Uniform Tire Quality Grading..........................5-61
Wheel Alignment and Tire Balance..................5-62
Wheel Replacement......................................5-62
Tire Chains..................................................5-63
If a Tire Goes Flat........................................5-64
Changing a Flat Tire.....................................5-65
Appearance Care............................................5-80
Cleaning the Inside of Your Vehicle.................5-80
Care of Safety Belts......................................5-83
Weatherstrips...............................................5-83Cleaning the Outside of Your Vehicle..............5-83
Sheet Metal Damage.....................................5-86
Finish Damage.............................................5-86
Underbody Maintenance................................5-87
Chemical Paint Spotting.................................5-87
Vehicle Care/Appearance Materials..................5-88
Vehicle Identi®cation......................................5-90
Vehicle Identi®cation Number (VIN).................5-90
Service Parts Identi®cation Label.....................5-90
Electrical System............................................5-91
Add-On Electrical Equipment..........................5-91
Headlamp Wiring..........................................5-91
Windshield Wiper Fuses................................5-91
Fuses and Circuit Breakers............................5-92
Capacities and Speci®cations..........................5-97
Normal Maintenance Replacement Parts.........5-100
Section 5 Service and Appearance Care
5-2

Electrical System
Add-On Electrical Equipment
Notice:Don't add anything electrical to your
vehicle unless you check with your dealer ®rst.
Some electrical equipment can damage your vehicle
and the damage wouldn't be covered by your
warranty. Some add-on electrical equipment can
keep other components from working as they
should.
Your vehicle has an air bag system. Before attempting
to add anything electrical to your vehicle, see
Servicing Your Air Bag-Equipped Vehicle on page 1-73.
Headlamp Wiring
The headlamp wiring is protected by a circuit breaker in
the lamp switch. An electrical overload will cause the
lamps to ¯icker on and off, or in some cases to remain
off. If this happens, have your headlamp wiring
checked right away.
Windshield Wiper Fuses
The windshield wiper motor is protected by a circuit
breaker and a fuse. If the motor overheats due to heavy
snow, etc., the wiper will stop until the motor cools.
Although the circuit is protected from electrical overload,
overload due to heavy snow, etc., may cause wiper
linkage damage. Always clear ice and heavy snow from
the windshield before using the windshield wipers. If
the overload is caused by some electrical problem and
not snow, etc., be sure to get it ®xed.
5-91

Fuse Usage
1 Radio Battery
2 Powertrain Control Module Battery
3 Left Rear Turn Lamp
4 Right Rear Turn Lamp
5 Backup Lamps Trailer Wiring
6 Ignition 0
7 Stop Lamp
8 Right Rear Defogger/Heated Mirror
9Right Daytime Running Lamp/Turn
Signal
10Left Daytime Running Lamp/Turn
Signal
11 Truck Body Control Module 4
12 Fuel Pump
13 Trailer
14 Flasher
15 Horn
16 Truck Body Control Module 3
17 Trailer Stop/Turn Signal
18 Truck Body Control Module 2
19 Truck Body Control Module
20 Remote Function Actuator
21 Engine 2Fuse Usage
22 Ignition E
23 Engine 1
24Truck Body Control Module
Ignition 1
25 Spare
26 RPA/Inside Rearview Mirror
27 Crankcase
28Brake Transmission Shift Interlock
System
29 Auxiliary Power Outlets
30 Cigarette Lighter
31 Instrument Panel Cluster
32 Air Conditioning
33 Spare
34 Vent
35 Spare
36 Vehicle Back Up
37Supplemental In¯atable Restraint
System
38 Powertrain Control Module Ignition 1
39 Oxygen Sensor B
40 Oxygen Sensor A
41 Windshield Wipers
5-95