2003 CHEVROLET C/K engine

6-76
Vehicle Identification Number (VIN)
This is the legal identifier for your vehicle. It appears on
a plate in the front corner of the instrument panel, on the
driver's side. You can see it if you look through the
windshield from outside your vehicle. The VIN also
appears on the Vehicle Certification and Service Parts
labels and the certificates of title and registration.
Engine Identification
The 8th character in your VIN is the engine code. This
code will help you identify your engine, specifications
and replacement parts.
Service Statement
One of these statements is on your GVW Rating label.
Here is what each one means.
TRUCK SERVICE
-- A vehicle made to carry
property or special equipment. It is made for uniform
frame loading. That includes using the vehicle to pull a
full trailer.
TRUCK
-TRACTOR -- A vehicle made to draw other
vehicles. It's made to carry part of the load of the trailer.
It is made for point frame loading, usually for a
semi
-trailer (ªfifth wheelº).
MAX. VERT. CG
-- The highest allowable vertical
center of gravity, at the highest allowable GVWR. It's
measured from level ground in inches.
TRUCK
-CANADA -- A vehicle first sold in Canada
with a non
-school bus application, or cab models with
regular production option RQ2 (ªtruck serviceº).
TRACTOR
-CANADA -- A cab model with regular
production option RQ3 (ªtruck
-tractor serviceº).

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.

6-83
Underhood Fuse Block
When a circuit goes out, the problem could be in either
the primary or secondary underhood fuse blocks. These
blocks uses blade
-type fuses.
Both underhood
fuse blocks are
located in the engine
compartment, on the
passenger's side of
the vehicle.
Primary Underhood
Fuse BlockTo access the fuse blocks, gently squeeze both sides of
the cover to unlatch the tabs at the top. Then, unsnap
both attachments at the bottom and remove the cover.
Be sure to replace fuses with fuses of the same rating.
Do not use fuses of higher amperage than those
indicated on the fuse block.

6-84
Primary Underhood Fuse Block
Relay Usage
NOTE 1 LG4 Powertrain Control Valve,
L18/LB7 Fuel Pump,
LG5 Heated Fuel
IGN B Ignition
STARTER StarterRelay Usage
HORN Horn
IGN A Ignition
PTO Power Take
-Off
REVERSE Reverse
NEUTRAL
STARTNeutral Start
Fuse Usage
RR DEFOG Rear Defog
ENG 1 Engine 1
ENG 3 Engine 3
PCM
-B Powertrain Control Module
BLANK Empty
ENG 4 Engine 4
ENG 2 Engine 2
HTD FUEL Heated Fuel
BLANK Empty
BLANK Empty

6-85
Fuse Usage
BLANK Empty
A/C COMP Air Conditioning Compressor
ABS 1 Anti
-Lock Brake System 1
ABS 2 Anti
-Lock Brake System 2
ABS 3 Anti
-Lock Brake System 3
ENGINE Engine
E/A PUMP Electronic/Automatic Pump
HORN Horn
NOTE 2 L18/LB7 Fuel, LG4 Powertrain
Control Valve, LG5 Electronic
Control Module
BLANK Empty
STUD A Spare
STUD B Spare
Secondary Underhood Fuse Block
Fuse Usage
IGN 1 Ignition 1
IGN 4 Ignition 4
IGN 3 Ignition 3
BATT/HAZ Battery/Hazard Warning Flashers
HEADLAMP Headlamps
LIGHTING Interior/Exterior Lamps
HVAC Comfort Control System
NOTE C4/C5 Electric Brake,
C6/C7/C8 Brake Lamps

6-86
Replacement Bulbs
It is recommended that you use an ACDelco
type bulb whenever you need to replace one.
If you need a bulb replaced, contact your dealer.
Capacities and Specifications
Engine Specifications
Engine RPO LG5 L18 LG4 LB7
Engine Type 7.2L L6 8.1L V8 7.8L L6 6.6L V8
Fuel System HEUI SPFI Common Rail Common Rail
Firing Order
1
-5-3-6-2-41-8-7-2-6-5-4-31-5-3-6-2-41-2-7-8-4-5-6-3

6-87 Cooling System Capacity
The following approximate capacities are given in
English and metric conversions.
Please refer to ªRecommended Fluids and Lubricantsº
in the Index for more information.
C4/C5 Models Quarts (Liters). . . . . . . . . . . . . . . . .
8.1L with manual transmission 30.1 (28.5). . . . . . . .
8.1L with automatic transmission 29.8 (28.2). . . . . .
6.6L with manual transmission 27.6 (26.1). . . . . . . .
6.6L with automatic transmission 27.3 (25.8). . . . . .
C6/C7/C8 Models Quarts (Liters). . . . . . . . . . . . . .
8.1L with manual transmission 33.3 (31.5). . . . . . . .
8.1L with manual transmission,
air conditioning and increased
cooling 34.9 (33.0). . . . . . . . . . . . . . . . . . . . . . . . . . .
8.1L with automatic transmission 32.5 (30.8). . . . . .
7.8L 200
-230 hp engine with
manual transmission 31.6 (29.9). . . . . . . . . . . . . . . .
7.8L 200
-230 hp engine with manual
transmission, air conditioning and
increased cooling 35.3 (33.4). . . . . . . . . . . . . . . . . . . C6/C7/C8 Models Quarts (Liters). . . . . . . . . . . . . .
7.8L 200
-215 hp engine with
automatic transmission 33.7 (31.9). . . . . . . . . . . . . .
7.2L 175
-230 hp engine with
manual transmission 29.3 (27.7). . . . . . . . . . . . . . . .
7.2L 175
-230 hp engine with
manual transmission, air conditioning
and increased cooling 33.0 (31.2). . . . . . . . . . . . . . .
7.2L 175
-210 hp engine with
automatic transmission 31.4 (29.7). . . . . . . . . . . . . .
7.8L 250
-275 hp engine with
manual transmission 34.9 (33.0). . . . . . . . . . . . . . . .
7.8L 250
-275 hp engine with
manual transmission, air conditioning
and increased cooling 35.4 (33.5). . . . . . . . . . . . . . .
7.8L 230
-275 hp engine with automatic
transmission 33.3 (31.5). . . . . . . . . . . . . . . . . . . . . .
7.2L 250
-300 hp engine with manual
transmission 32.8 (31.0). . . . . . . . . . . . . . . . . . . . . .
7.2L 250
-300 hp engine with manual
transmission, air conditioning and
increased cooling 33.3 (31.5). . . . . . . . . . . . . . . . . . .
7.2L 250
-300 hp engine with automatic
transmission 31.2 (29.5). . . . . . . . . . . . . . . . . . . . . .

6-88 Engine Oil with Filter Capacity
Engine Quarts (Liters)
7.2L** 30.0 (28.4)*
8.1L** 6.5 (6.1)
7.8L** 23.8 (22.5 )
6.6L** 14.6 (13.8)
*Additional oil is required with auxiliary oil filter
systems. Make sure to add enough extra oil to fill the
auxiliary oil filter system. For vehicles equipped with
the LUBERFINER 750
-C, add 14 quarts (13.25 L).
** Check fill level on the oil indicator after initial fill to
make sure it is actually full. Oil level may vary
depending on vehicle option content.
Fuel Tank Capacity
C4/C5 Models Gallons (Liters). . . . . . . . . . . . . . . . .
Standard* 41 (155.2). . . . . . . . . . . . . . . . . . . . . . . .
Optional 40 (151.4). . . . . . . . . . . . . . . . . . . . . . . . . .
Optional 60 (227.1). . . . . . . . . . . . . . . . . . . . . . . . . .
Optional 80 (302.8). . . . . . . . . . . . . . . . . . . . . . . . . .
C6/C7/C8 Models Gallons (Liters). . . . . . . . . . . . . .
Standard 50 (189.2). . . . . . . . . . . . . . . . . . . . . . . . .
Optional 35 (132.4). . . . . . . . . . . . . . . . . . . . . . . . . .
Optional 50 (189.2). . . . . . . . . . . . . . . . . . . . . . . . . .
Optional
70 (264.8) . . . . . . . . . . . . . . . . . . . . . . . .
Optional75 (283.8) . . . . . . . . . . . . . . . . . . . . . . . .
Optional& 100 (378.5). . . . . . . . . . . . . . . . . . . . . . .
* One 25
-gallon (94.6 L) tank and one 16-gallon
(60.6 L) tank

Two 35
-gallon (132.4 L) tanks
One 25
-gallon (94.6 L) tank and One 50-gallon
(189.2 L) tank
&Two 50
-gallon (189.2 L) tanks