2003 CHEVROLET C/K wiring

2-58
The exterior lamp control has four positions:
OFF: Turning the control to this position turns off all
lamps except the Daytime Running Lamps (DRL).
(Parking Lamps): Turning the control to this
position turns on the parking lamps, together with the
following:

Marker Lamps

Taillamps

License Plate Lamps

Instrument Panel Lights
(Headlamps): Turning the control to this position
turns on the headlamps, together with the previously
listed lamps and lights.
You can switch your headlamps from low to high
beam by pulling the turn signal/multifunction lever
toward you. Pull the lever toward you again to return
to low beam.
A circuit breaker protects your headlamps. If you have
an electrical overload, your headlamps will flicker on
and off. Have your headlamp wiring checked right away
if this ever happens.
Headlamps On Reminder (If Equipped)
If you have this system, a tone will sound when your
headlamps and/or parking lamps are turned on and your
ignition is in LOCK or ACCESSORY.
Daytime Running Lamps
Daytime Running Lamps (DRL) can make it easier for
others to see the front of your vehicle during the day.
DRL can be helpful in many different driving
conditions, but they can be especially helpful in the
short periods after dawn and before sunset. Fully
functional daytime running lamps are required on all
vehicles first sold in Canada.
The DRL system will make your headlamps come
on at reduced brightness when the following conditions
are met:

The ignition is on,

the exterior lamp control is off, and

the parking brake is released.
When the DRL are on, only your headlamps will be on.
The taillamps, sidemarker and other lamps won't be on.
Your instrument panel won't be lit up either.

2-66
Certain electrical accessories may not be compatible
with the accessory power outlet and could result in
blown vehicle or adapter fuses. If you experience a
problem, see your dealer for additional information on
accessory power outlets.
NOTICE:
Adding some electrical equipment to your vehicle
can damage it or keep other things from working
as they should. This wouldn't be covered by your
warranty. Check with your dealer before adding
electrical equipment, and never use anything that
exceeds the amperage rating.
When adding electrical equipment, be sure to follow the
proper installation instructions included with the equipment.
NOTICE:
Power outlets are designed for accessory plugs
only. Do not hang any type of accessory or
accessory bracket from the plug. Improper use of
the power outlet can cause damage not covered
by your warranty.
Trailer Connections (C4/C5 Models
Only) (If Equipped)
Heavy-Duty Trailer Wiring Package
Your vehicle may be equipped with an eight-wire trailer
towing harness. This harness, with a seven
-pin universal
heavy
-duty trailer connector, is attached to a bracket on
the platform hitch.
The Center High
-Mounted Stoplamp (CHMSL) wire is
tied next to the trailer wiring harness for use with a trailer.

2-75 Air Bag Readiness Light
There is an air bag readiness light on the instrument
panel, which shows the airbag 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 sensors, the air bag
modules, the wiring, the passenger air bag suppression
circuit and the crash sensing and diagnostic module. For
more information on the air bag system, see ªAir Bagº
in the Index.
This light will come on
when you start your vehicle,
and it will flash 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 inflate in a crash, or they
could even inflate 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 flash for a few
seconds when you turn the ignition key to RUN or
START. If the light doesn't come on then, have it fixed
so it will be ready to warn you if there is a problem.

3-5 Defogging and Defrosting
Turn the mode knob to defrost to remove fog or ice from
the windshield quickly in extremely cold conditions.
The temperature knob should be in the red area with the
fan knob toward high.
To keep the windshield clear and send heated air
through the floor vents, turn the mode knob to defog.
The air conditioning compressor may operate in this
setting to dehumidify the air.
Rear Window Defogger (If Equipped)
If you see lines running across the rear windows, you
have a rear window defogger. The lines warm the glass.
For best results, clear the windows of as much snow or
ice as possible before using the rear window defogger.
To turn on the rear window
defogger, press this button
located near the fan control.
An indicator light in the
button will come on when
the rear window defogger
is working.The rear window defogger will only work when the
ignition is in RUN.
The rear window defogger will turn itself off after
several minutes. If you need additional warming time,
press the button again. Pressing the button when the
indicator light is illuminated will turn the defogger off.
NOTICE:
Don't use a razor blade or something else sharp
on the inside of the rear window. If you do, you
could cut or damage the warming grid, and the
repairs wouldn't be covered by your warranty.
Do not attach a temporary vehicle license, tape or decals
across the defogger grid on the rear windows. Use care
not to damage the wiring bands that connect the rear
window defogger grid when operating the rear
swing
-out windows (if equipped).

6-78 Headlamp Wiring
The headlamp wiring is protected by a circuit breaker in
the light switch. An electrical overload will cause the
lights to go 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 inside the motor and a circuit breaker or fuse in
the fuse block. If the motor overheats, the wipers will
stop until the motor cools. If the overload is caused by
an electrical problem, be sure to get it fixed.
Fusible Links
A fusible link is a short piece of wire several gauge sizes
smaller than the circuit it protects. It will melt in an
overload situation, opening the circuit.
Your starter and other circuits have these fusible links.
The size is printed on the insulation. If the insulation is
burned beyond recognition, consult your GM dealer for
the proper size. Replace a fusible link with one of the
same size and insulation type. Fusible link insulation is a
special purpose high
-temperature material.
The hydraulic brake booster motor feed circuit and
starter circuit are protected by a fusible link. Vehicles
with a diesel engine have a fusible link for the intake
heater feed circuit.

6-79 Power Windows and Other Power Options
Circuit breakers in the fuse panel protect the power
windows and other power accessories. When the current
load is too heavy, the circuit breaker opens. This
protects the circuit until the current load returns to
normal or the problem is fixed.
Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected from
short circuits by a combination of fuses, circuit breakers,
maxi
-fuses and fusible links. This greatly reduces the
chance of a fire caused by an electrical problem. There
may be a fuse taped to the wiring harness near the
hydraulic brake booster.

6-81
Fuse Usage
RH PARK LP Right
-hand Parking Lamps
LH PARK LP Left
-hand Parking Lamps
RADIO U Radio
PWR WINDOW Power Windows
BRAKE ISO Brake Warning Lamp
SPARE Spare Fuse
L
-RR TRUCK Left Rear Trailer Wiring
SPARE Spare Fuse
SPARE Spare Fuse
SPARE Spare Fuse
R
-RR TRUCK Right Rear Trailer Wiring
SPARE Spare FuseRelay Usage
BRAKE LAMP C4/C5 Brake Lamps, C6/C7/C8
Tractor/Trailer Wiring
IGN 4 Ignition
MARKER LP Sidemarker and Clearance Lamps
HTD FUEL LB7/LG4 Heated Fuel
AIR HTR LG4 Air Heater
ECU
MAINTAINLG4 Electronic Control Unit
DRL Daytime Running Lamps
CHMSL ISO Center High Mounted Stop Lamp
HTD MIRR Heated Mirrors
R-TRN TLR Right Trailer Turn Signal
L
-TRN TLR Left Trailer Turn Signal
SPARE Spare Relay
SPARE Spare Relay
SPARE Spare Relay

6-82
Fuse Block 2
Circuit Breaker Usage
1 Stoplamps
2 Center High Mounted Stop Lamp
3 Parking Lamps
4 Powertrain Control Module
5 Auxiliary Wiring
6 Heater/Air ConditioningCircuit Breaker Usage
7 Hazard Warning Flashers
8 Power Post
9 Courtesy Lamps
10 Warning Lights, Gages
and Indicators
11 Crank
12 Rear Axle
13 Trailer Turn Signals/Hazard
Warning Flashers
14 Radio/Chime
15 Daytime Running Lamps
16 Air Bag System
17 Exterior/Interior Lamps
18 Parking Brake
19 Accessory Power
20 Ignition
21 Sidemarker Lamps
22 Turn Signal/Backup Lamps
23 Transmission
24 Chassis
A Spare
B Spare