2004 ISUZU TF SERIES fuse diagram

ELECTRICAL-BODY AND CHASSIS 8A-1
SECTION 8A
ELECTRICAL-BODY AND CHASSIS
TABLE OF CONTENTS
PAGE
General Information ........................................................................................................ 8A- 4
Notes for Working on Electrical Items .......................................................................... 8A- 5
Symbols and Abbreviations ........................................................................................... 8A- 11
Symbols ...................................................................................................................... 8A- 11
Abbreviations ............................................................................................................. 8A- 12
Parts for Electrical Circuit .............................................................................................. 8A- 13
Wiring .......................................................................................................................... 8A- 13
Fuse ............................................................................................................................. 8A- 15
Fusible Link ................................................................................................................ 8A- 15
Relay ............................................................................................................................ 8A- 16
Diode ........................................................................................................................... 8A- 17
Connector ................................................................................................................... 8A- 18
Battery ......................................................................................................................... 8A- 19
Reading the Circuit Diagram .......................................................................................... 8A- 22
Parts Location ............................................................................................................ 8A- 22
Circuit Diagram ........................................................................................................... 8A- 23
Connector List ............................................................................................................. 8A- 23
Main Data and Specifications ........................................................................................ 8A- 24
Bulb Specifications .................................................................................................... 8A- 24
Relay and Fuse ................................................................................................................ 8A- 26
Relay and Fuse Box Location ................................................................................... 8A- 26
Relay Location ............................................................................................................ 8A- 28

8A-4 ELECTRICAL-BODY AND CHASSIS
GENERAL INFORMATION
The body and chassis electrical system operates on a twelve volt power supply with negative ground polarity.
The main harness consists of the engine harness, the instrument harness, the body harness, and the chassis
harness.
The harnesses use a split corrugated tube to protect the wires from the elements.
Wire size is determined by current flow, circuit length, and voltage drop.
All wires have color-coded insulation.
Wire color-codes are shown in the circuit diagrams.
This makes it easier to trace circuits and to make the proper connections.
Each circuit consists of the following:
1. Power source - The battery and the alternator
2. Wires - To carry electrical current through the circuit
3. Fuses - To protect the circuit against current overload
4. Relays - To protect voltage drop between the battery and the circuit parts and to protect the switch points against
burning
5. Switches - To open and close the circuit
6. Load - Any device, such as a light or motor, which converts the electrical current into useful work
7. Ground - To allow the current to flow back to the power source

ENGINE ELECTRICAL 6D – 33
PRE-HEATING SYSTEM
INSPECTION AND REPAIR
Make the necessary adjustments, repairs, and part replacement if excessive wear of damage is discovered during
inspection.

VISUAL CHECK
Check the main fuses and glow indicator for damage.
Replace the part(s) if required.
GLOW RELAY
The glow relay is located in the relay box the engine
compartment.



825R300046




Use an ohmmeter to measure the resistance between
terminals No.2 and No.3.
If the measured value is outside the specified range, the
glow relay must be replaced.
Glow Relay Resistance Ohms
94  114

GLOW PLUG


LNW21KSH001401
Use a circuit tester to test the glow plugs for continuity.
Glow Plug Resistance (Reference) Ohms
Approximately 0.9

EGR SYSTEM 4JA1T (L)
Refer to 6F-9. (EGR system diagram)

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–1
ENGINE
CONTENTS
4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
ABBREVIATION CHARTS ........................ 6E-9
4JA1-TC .................................................... 6E-10
4JH1-TC .................................................... 6E-11
ECM CIRCUIT DIAGRAM (4JA1-TC) ........ 6E-14
ECM CIRCUIT DIAGRAM (4JA1-TC) ........ 6E-15
ECM CIRCUIT DIAGRAM (4JH1-TC) ........ 6E-16
ECM CIRCUIT DIAGRAM (4JH1-TC) ........ 6E-17
GROUND POINT CHART GENERAL EXPORT
(LHD) (1/4) ............................................... 6E-18
LOCATION ................................................ 6E-34
PARTS LOCATION ................................... 6E-39
CONNECTOR LIST ................................... 6E-40
RELAY AND FUSE .................................... 6E-43
RELAY AND FUSE BOX LOCATION
(LHD & RHD) ........................................... 6E-43
RELAY AND FUSE BOX LOCATION
(LHD & RHD) ........................................... 6E-44
FUSE AND RELAY LOCATION (LHD & RHD) 6E-45
ECM WIRING DIAGRAM (1/7) .................. 6E-46
ECM WIRING DIAGRAM (2/7) .................. 6E-47
ECM WIRING DIAGRAM (3/7) .................. 6E-48
ECM WIRING DIAGRAM (4/7) .................. 6E-49
ECM WIRING DIAGRAM (5/7) .................. 6E-50
ECM WIRING DIAGRAM (6/7) .................. 6E-51
ECM WIRING DIAGRAM (7/7) .................. 6E-52
ECM CONNECTOR PIN ASSIGNMENT &
OUTPUT SIGNAL .................................... 6E-53
GENERAL DESCRIPTION FOR ECM AND
SENSORS ............................................... 6E-64
Engine Control Module (ECM) ................... 6E-64
Pump Control Unit (PSG) & Data Ex change
Between Control Module ......................... 6E-64
Mass Air Flow (MAF) Sensor & Intake Air
Temperature (IAT) Sensor ....................... 6E-65
Throttle Position Sensor (TPS) .................. 6E-66
Crankshaft Position (CKP) Sensor ............ 6E-66
Engine Coolant Temperature (ECT) Sensor 6E-67
Vehicle Speed Sensor (VSS) .................... 6E-67
GENERAL DESCRIPTION FOR EGR
(EXHAUST GAS RE-CIRCULATION) ..... 6E-68
GENERAL DESCRIPTION FOR
INJECTION PUMP .................................. 6E-70Outline ....................................................... 6E-70
Cross-section View .................................... 6E-70
Low Pressure Fuel Circuit .......................... 6E-71
High Pressure Fuel Circuit ......................... 6E-72
Pump Camshaft Speed Sensor ................. 6E-72
High Pressure Solenoid Valve ................... 6E-73
Timing Control Valve (TCV) ....................... 6E-74
ISUZU Strategy Based Diagnostics .............. 6E-76
Overview .................................................... 6E-76
STRATEGY BASED DIAGNOSTICS CHART 6E-76
Diagnostic Thought Process ...................... 6E-77
1. Verify the Complaint .............................. 6E-77
2. Perform Preliminary Checks .................. 6E-77
3. Check Bulletins and Troubleshooting Hints 6E-78
4. Perform Service Manual Diagnostic Checks 6E-78
5a and 5b. Perform Service Manual Diagnostic
Procedures .............................................. 6E-78
5c. Technician Self Diagnoses .................. 6E-78
5d. Intermittent Diagnosis .......................... 6E-79
5e. Vehicle Operates as Designed ............ 6E-80
6. Re-examine the complaint ..................... 6E-81
7. Repair and Verify Fix ............................. 6E-81
GENERAL SERVICE INFORMATION ....... 6E-82
ON-BOARD DIAGNOSTIC (OBD) ............. 6E-82
TECH 2 OPERATING FLOW CART
(START UP) ............................................. 6E-86
TYPICAL SCAN DATA & DEFINITIONS
(ENGINE DATA) ................................... 6E-88
TYPICAL SCAN DATA & DEFINITIONS
(ENGINE DATA) ................................... 6E-90
MISCELLANEOUS TEST .......................... 6E-92
Plotting Snapshot Graph ............................ 6E-93
Plotting Graph Flow Chart (Plotting graph
after obtaining vehicle information) .......... 6E-94
Flow Chart for Snapshot Replay
(Plotting Graph) ....................................... 6E-95
SNAPSHOT DISPLAY WITH TIS2000 ...... 6E-96
ON-BOARD DIAGNOSTIC (OBD) SYSTEM
CHECK .................................................... 6E-105
Circuit Description ...................................... 6E-105
Diagnostic Aids .......................................... 6E-105
Test Description ......................................... 6E-105

6E–78 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
3. Check Bulletins and
Troubleshooting Hints
NOTE: As estimated 30 percent of successful vehicle
repairs are diagnosed with this step!
What you should do
You should have enough information gained from
preliminary checks to accurately search for a bulletin
and other related service information. Some service
manual sections provide troubleshooting hints that
match symptoms with specific complaints.
What resources you should use
You should use the following resources for assistance in
checking for bulletins and troubleshooting hints:
Printed bulletins
Access ISUZU Bulletin Web site.
Videotapes
Service manual
4. Perform Service Manual
Diagnostic Checks
What you should do
The “System Checks” in most service manual sections
and in most cells of section 8A (electrical) provide you
with:
A systematic approach to narrowing down the
possible causes of a system fault
Direction to specific diagnostic procedures in the
service manual
Assistance to identify what systems work correctly
What resources you should use
Whenever possible, you should use the following
resources to perform service manual checks:
Service manual
Technical equipment (for viewing DTCs and
analyzing data)
Digital multimeter and circuit testing tools
Other tools as needed
5a and 5b. Perform Service Manual
Diagnostic Procedures
NOTE: An estimated 40 percent of successful vehicle
repairs are diagnosed with these steps!
What you should do
When directed by service manual diagnostic checks,
you must then carefully and accurately perform the
steps of diagnostic procedures to locate the fault relatedto the customer complaint.
What resources you should use
Whenever appropriate, you should use the following
resources to perform service manual diagnostic
procedures:
Service manual
Technical equipment (for analyzing diagnostic data)
Digital multimeter and circuit testing tools
Essential and special tools
5c. Technician Self Diagnoses
When there is no DTC stored and no matching
symptom for the condition identified in the service
manual, you must begin with a thorough understanding
of how the system(s) operates. Efficient use of the
service manual combined with you ex perience and a
good process of elimination will result in accurate
diagnosis of the condition.
What you should do
Step 1: Identify and understand the suspect
circuit(s)
Having completed steps 1 through 4 of the Strategy
Based Diagnostics chart, you should have enough
information to identify the system(s) or sub-system(s)
involved. Using the service manual, you should
determine and investigate the following circuit
characteristics:
Electrical:
–How is the circuit powered (power distribution
charts and/or fuse block details)?
–How is the circuit grounded (ground distribution
charts)?
–How is the circuit controlled or sensed (theory of
operation):
–If it is a switched circuit, is it normally open or
normally closed?
–Is the power switched or is the ground
switched?
–Is it a variable resistance circuit (ECT sensor
or TP sensor, for ex ample)?
–Is it a signal generating device (MAF sensor of
VSS, for example)?
–Does it rely on some mechanical/vacuum
device to operate?
Physical:
–Where are the circuit components (component
locators and wire harness routing diagrams):
–Are there areas where wires could be chafed
or pinched (brackets or frames)?
–Are there areas subjected to ex treme
temperatures?

6E–362 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
ENGINE CRANKS BUT WILL NOT RUN
DEFINITIONS: Engine cranks, but will not run. (The engine never start.)
NOTE: The vehicle with immobilizer system, this system may be activated. Check the immobilizer system diagnosis.
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?—Verify repair Go to Step 3
3 Was a visually/physical check performed?
—Go to Step 4Go to Visual /
physical Check
4 Is the fuel amount enough?
—Go to Step 5Add fuel to the
tank
5 Is the customer using the incorrect fuel type? Diesel fuel
onlyReplace with
diesel fuel Go to Step 6
6 Check the “ECM” fuse (10A) and “Engine” fuse (15A).
If the fuse is burnt out, repair as necessary.
Was the problem found?—Verify repair Go to Step 7
7 Visually/physically inspect for the following conditions.
Restrict air intake system. Check for a restricted air
filter element, or foreign objects blocking the air
intake system
Check for objects blocking or ex cessive deposits in
the throttle bore and on the throttle plate
Check for a condition that causes a large vacuum
leak, such as an incorrectly installed or faulty
crankcase ventilation hose.
Restrict air intake system at the turbocharger.
Check for objects blocking the turbocharger
compressor wheel or turbine shaft sticking.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 8
8 Check the ECM & PSG grounds to verify that they are
clean and tight. Refer to the ECM wiring diagrams.
Was a problem found?—Verify repair Go to Step 9
9 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Neutral Switch” in the data display.
Does the Tech 2 indicate correct “Neutral Switch”
status depending on any shift positions?
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 10

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-1
ENGINE
3.5L ENGINE DRIVEABILITY AND EMISSIONS
CONTENTS


ABBREVIATION CHARTS ................................ 6E-5
COMPONENT LOCATOR ................................. 6E-6
ENGINE COMPONENT LOCATOR TABLE .. 6E-6
ECM CIRCUIT DIAGRAM ................................. 6E-10
GROUND POINT CHART G.EXP (LHD)
WITHOUT EUROPE, ISRAEL, TURKEY (1/4). 6E-13
GROUND POINT CHART G.EXP (LHD) (2/4) .. 6E-14
GROUND POINT CHART G.EXP (LHD) (3/4) .. 6E-15
GROUND POINT CHART G.EXP (LHD) (4/4) .. 6E-16
GROUND POINT CHART G.EXP (RHD) (1/4) . 6E-17
GROUND POINT CHART G.EXP (RHD) (2/4) . 6E-18
GROUND POINT CHART G.EXP (RHD) (3/4) . 6E-19
GROUND POINT CHART G.EXP (RHD) (4/4) . 6E-20
LOCATION ........................................................ 6E-21
CABLE HARNESS & CONNECTOR
LOCATION ....................................................... 6E-22
CONNECTOR LIST ........................................... 6E-27
RELAY AND FUSE ............................................ 6E-30
RELAY AND FUSE BOX LOCATION
(LHD&RHD) ................................................... 6E-30
RELAY AND FUSE BOX LOCATION
(LHD&RHD) ................................................... 6E-31
FUSE AND RELAY LOCATION
(LHD&RHD) ................................................... 6E-32
ECM WIRING DIAGRAM (1/10) ........................ 6E-33
ECM WIRING DIAGRAM (2/10) ........................ 6E-34
ECM WIRING DIAGRAM (3/10) ........................ 6E-35
ECM WIRING DIAGRAM (4/10) ........................ 6E-36
ECM WIRING DIAGRAM (5/10) ........................ 6E-37
ECM WIRING DIAGRAM (6/10) ........................ 6E-38
ECM WIRING DIAGRAM (7/10) ........................ 6E-39
ECM WIRING DIAGRAM (8/10) ........................ 6E-40
ECM WIRING DIAGRAM (9/10) ........................ 6E-41
ECM WIRING DIAGRAM (10/10) ...................... 6E-42
ECM CONNECTOR PIN ASSIGNMENT
& OUTPUT SIGNAL ......................................... 6E-43
GENERAL DESCRIPTION FOR ECM AND
SENSORS ........................................................ 6E-51

Mass Air Flow (MAF) Sensor & Intake Air
Temperature (IAT) Sensor ............................. 6E-52
Throttle Position Sensor (TPS)....................... 6E-52
Idle Air Control (IAC) Valve ............................ 6E-53
Camshaft Position (CMP) Sensor .................. 6E-53
Crankshaft Position (CKP) Sensor ................. 6E-54
Engine Coolant Temperature (ECT) Sensor .. 6E-54
Vehicle Speed Sensor (VSS) ......................... 6E-55
Heated Oxygen (O
2) Sensor........................... 6E-55
GENERAL DESCRIPTION FOR FUEL
METERING....................................................... 6E-56
GENERAL DESCRIPTION FOR ELECTRONIC
IGNITION SYSTEM IGNITION
COILS & CONTROL ......................................... 6E-58
GENERAL DESCRIPTION FOR EVAPORATIVE
EMISSION SYSTEM ........................................ 6E-61
GENERAL DESCRIPRION FOR EXHAUST
GAS RECIRCULATION (EGR) SYSTEM......... 6E-62
ISUZU STRATEGY BASED DIAGNOSTICS .... 6E-63
Diagnostic Thought Process .......................... 6E-64
1. Verify the Complaint ................................... 6E-64
2. Perform Preliminary Checks....................... 6E-64
3. Check Bulletins and Troubleshooting
Hints ........................................................... 6E-65
4. Perform Service Manual Diagnostic
Checks ....................................................... 6E-65
5a and 5b. Perform Service Manual
Diagnostic Procedures ............................... 6E-65
5c. Technician Self Diagnoses ....................... 6E-65
5d. Intermittent Diagnosis............................ 6E-66
Symptom Simulation Tests.......................... 6E-67
5e. Vehicle Operates as Designed ................. 6E-68
6. Re-Examine the Complaint ........................ 6E-68
7. Repair and Verify Fix .................................. 6E-68
GENERAL SERVICE INFORMATION .............. 6E-69
Aftermarket Electrical and Vacuum
Equipment ..................................................... 6E-69
Electrostatic Discharge Damage .................... 6E-69

6E-66 3.5L ENGINE DRIVEABILITY AND EMISSIONS
 Does it rely on some mechanical/vacuum
device to operate?

Physical:
 Where are the circuit components (componen
t
locators and wire harness routing diagrams):

Are there areas where wires could be
chafed or pinched (brackets or frames)?

Are there areas subjected to extreme
temperatures?

Are there areas subjected to vibration or
movement (engine, transmission or
suspension)?

Are there areas exposed to moisture, road
salt or other corrosives (battery acid, oil o
r
other fluids)?

Are there common mounting areas with
other systems/components?
 Have previous repairs been performed to
wiring, connectors, components or mounting
areas (causing pinched wires between panels
and drivetrain or suspension components
without causing and immediate problem)?
 Does the vehicle have aftermarket or dealer-
installed equipment (radios, telephone, etc.)

Step 2: Isolate the problem
At this point, you should have a good idea of what could
cause the present condition, as well as could not cause
the condition. Actions to take include the following:

Divide (and separate, where possible) the system
or circuit into smaller sections

Confine the problem to a smaller area of the
vehicle (start with main harness connections while
removing panels and trim as necessary in order to
eliminate large vehicle sections from furthe
r
investigation)

For two or more circuits that do not share a
common power or ground, concentrate on areas
where harnesses are routed together o
r
connectors are shared (refer to the following hints)

Hints
Though the symptoms may vary, basic electrical failures
are generally caused by:

Loose connections:
 Open/high resistance in terminals, splices,
connectors or grounds

Incorrect connector/harness routing (usually in
new vehicles or after a repair has been made):

 Open/high resistance in terminals, splices,
connectors of grounds

Corrosion and wire damage:
 Open/high resistance in terminals, splices,
connectors of grounds

Component failure:
 Opens/short and high resistance in relays,
modules, switches or loads


Aftermarket equipment affecting normal operation
of other systems You may isolate circuits by:

Unplugging connectors or removing a fuse to
separate one part of the circuit from another part

Operating shared circuits and eliminating those
that function normally from the suspect circuit

If only one component fails to operate, begin
testing at the component

If a number of components do no operate, begin
tests at the area of commonality (such as powe
r
sources, ground circuits, switches or majo
r
connectors)
What resources you should use
Whenever appropriate, you should use the following
resources to assist in the diagnostic process:

Service manual

Technical equipment (for data analysis)

Experience

Technical Assistance

Circuit testing tools
5d. Intermittent Diagnosis
By definition, an intermittent problem is one that does
not occur continuously and will occur when certain
conditions are met. All these conditions, however, may
not be obvious or currently known. Generally,
intermittents are caused by:

Faulty electrical connections and wiring

Malfunctioning components (such as sticking
relays, solenoids, etc.)

EMI/RFI (Electromagnetic/radio frequency
interference)

Aftermarket equipment
Intermittent diagnosis requires careful analysis of
suspected systems to help prevent replacing good
parts. This may involve using creativity and ingenuity to
interpret customer complaints and simulating all
external and internal system conditions to duplicate the
problem.