fuses ISUZU TF SERIES 2004 Workshop Manual

9A1-12 RESTRAINT CONTROL SYSTEM

Chart B “AIR BAG” Warning Lamp Comes “ON” Steady


RTW49JLF000101

Circuit Description
When the ignition switch is first turned “ON”, “Ignition 1”
voltage is applied from the “METER” fuse to “AIR
BAG”, warning lamp which is connected to “SRS
Warning Lamp”, terminal “39”. The “SRS” fuses appl
y
system voltage to the “Ignition 1” inputs, terminals “35”.
The SRS control unit responds by flashing the “AIR
BAG” warning lamp 7 times. If “Ignition 1” is less than
9 volts, the “AIR BAG” warning lamp will come “ON”
solid with no DTCs set.
Chart Test Description
Number(s) below refer to step number(s) on the
diagnostic chart:
2.
This test checks for an open in the “Ignition 1” circuit
to the SRS control unit.
3.
This test checks for the voltage of “Ignition 1”.
4.
This test determines whether the malfunction is a
short to ground in SRS waring lamp circuit.

BRAKE CONTROL SYSTEM 5A-21

Computer System Service Precautions
The Anti-lock Brake System and Electronic Brake-force
Distribution interfaces directly with the Electronic
Hydraulic Control Unit (EHCU) which is a control
computer that is similar in some regards to the Engine
Control Module. These modules are designed to
withstand normal current draws associated with vehicle
operation. However, care must be taken to avoid
overloading any of the EHCU circuits. In testing for
opens or shorts, do not ground or apply voltage to any
of the circuits unless instructed to do so by the
appropriate diagnostic procedure. These circuits should
only be tested with a high impedance multimeter
5-8840-0366-0 or special tools as described in this
section. Power should never be removed or applied to
any control module with the ignition in the “ON”
position.
Before removing or connecting battery cables, fuses or
connectors, always turn the ignition switch to the “OFF”
position.

General Service Precautions
The following are general precautions which should be
observed when servicing and diagnosing the Anti-lock
Brake System and/or other vehicle systems. Failure to
observe these precautions may result in Anti-lock Brake
System and Electronic Brake-force Distribution
damage.
 If welding work is to be performed on the vehicle
using an electric arc welder, the EHCU and valve
block connectors should be disconnected before
the welding operation begins.
 The EHCU and valve block connectors should
never be connected or disconnected with the
ignition “ON”.
Note:
 If only rear wheels are rotated using jacks or drum
tester, the system will diagnose a speed sensor
malfunction and the “ABS and Brake” warning lamp
will illuminate. But actually no trouble exists. When
the DTC is not detected and the ABS and BRAKE
warning lamp is on, “How to erase code” is
performed and a ABS and BRAKE warning lamp
are off.
If the battery has been discharged
The engine may stall if the battery has been completely
discharged and the engine is started via jumper cables.
This is because the Anti-lock Brake System (ABS) and
Electronic Brake-force Distribution (EBD) System
requires a large quantity of electricity. In this case, wait
until the battery is recharged, or set the ABS and EBD
to a non-operative state by removing the fuse for the
ABS. After the battery has been recharged, stop the
engine and install the ABS fuse. Start the engine again,
and confirm that the ABS warning Lamp does not light.
Note on Intermittents
As with virtually any electronic system, it is difficult to
identify an intermittent failure. In such a case
duplicating the system malfunction during a test drive or
a good description of vehicle behavior from the
customer may be helpful in locating a “most likely”
failed component or circuit. The symptom diagnosis
chart may also be useful in isolating the failure. Most
intermittent problems are caused by faulty electrical
connections or wiring. When an intermittent failure is
encountered, check suspect circuits for:
 Suspected harness damage.
 Poor mating of connector halves or terminals not
fully seated in the connector body (backed out).
 Improperly formed or damaged terminals.

Test Driving ABS Complaint Vehicles
In case that there has been an abnormality in the
lighting pattern of “ABS” warning lamp, the fault can be
located in accordance with the “DIAGNOSIS BY “ABS”
WARNING LAMP ILLUMINATION PATTERN”. In case
of such trouble as can be detected by the driver as a
vehicle symptom, however, it is necessary to give a test
drive following the test procedure mentioned below,
thereby reproducing the symptom for trouble diagnosis
on a symptom basis:
1.
Start the engine and make sure that the “ABS” W/L
goes OFF. If the W/L remains ON, it means that
the Diagnostic Trouble Code (DTC) is stored.
Therefore, read the code and locate the fault.
Note: The DTC cannot be cleared if the vehicle speed
does not exceed about 6km/h (4mph) at DTC, even
though the repair operation is completed.
2. Start the vehicle and accelerate to about 30 km/h
(19 mph) or more.
3. Slowly brake and stop the vehicle completely.
4. Then restart the vehicle and accelerate to about 40
km/h (25 mph) or more.
5. Brake at a time so as to actuate the ABS and stop
the vehicle.
6. Be cautious of abnormality during the test. If the
W/L is actuated while driving, read the DTC and
locate the fault.
7. If the abnormality is not reproduced by the test,
make best efforts to reproduce the situation
reported by the customer.
8. If the abnormality has been detected, repair in
accordance with the “SYMPTOM DIAGNOSIS” .
Note:

Be sure to give a test drive on a wide, even road
with a small traffic.
 If an abnormality is detected, be sure to suspend
the test and start trouble diagnosis at once.

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

ELECTRICAL-BODY AND CHASSIS 8A-15
Normal Blown

FUSE
Fuses are the most common form of circuit protection used in
vehicle wiring.
A fuse is a thin piece of wire or strip of metal encased in a
glass or plastic housing.
It is wired in series with the circuit it protects.
When there is an overload of current in a circuit, such as a
short of a ground, the wire or metal strip is designed to burn
out and interrupt the flow of current.
This prevents a surge of high current from reaching and
damaging other components in the circuit.
Determine the cause of the overloaded before replacing the
fuse.
Never replace a blown fuse with a fuse of a different amperage
specification.
Doing so can result in an electrical fire or other serious circuit
damage.
A blown fuse is easily identified.
Normal Blown


FUSIBLE LINK
The fusible link is primarily used to protect circuits where high
amounts of current flow and where is would not be practical to
use a fuse.
For example, the starter circuit.
When a current overload occurs, the fusible link melts open
and interrupts the flow of current so as to prevent the rest of
the wiring harness from burning.
Determine the cause of the overload before replacing the
fusible link.
The replacement fusible link must have the same amperage
specification as the original fusible link.
Never replace a blown fusible link with fusible link of a different
amperage specification.
Doing so can result in an electrical fire or other serious circuit
damage.
A blown fusible link is easily identified.


Fusible Link Specifications
Type Rating Case Color Maximum Circuit Current (A)
Connector 20A 10
Connector 30A Pink 15
Connector 40A Green 20
Bolted 50A Red 25
Bolted 60A Yellow 30
Bolted 80A Black 40

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–77
Diagnostic Thought Process
As you follow a diagnostic plan, every box on the
Strategy Based Diagnostics chart requires you to use
the diagnostic thought process. This method of thinking
optimizes your diagnosis in the following ways:
Improves your understanding and definition of the
customer complaint
Saves time by avoiding testing and/or replacing good
parts
Allows you to look at the problem from different
perspectives
Guides you to determine what level of understanding
about system operation is needed:
–Owner’s manual level
–Service manual level
–In-depth (engineering) level
–Owner’s manual level
–Service manual level
–In-depth (engineering) level
1. Verify the Complaint
What you should do
To verify the customer complaint, you need to know the
correct (normal) operating behavior of the system and
verify that the customer complaint is a valid failure of the
system.
The following information will help you verify the
complaint:
WHAT the vehicle model/options are
WHAT aftermarket and dealer-installed accessories
exist
WHAT related system(s) operate properly
WHEN the problem occurs
WHERE the problem occurs
HOW the problem occurs
HOW LONG the condition has ex isted (and if the
system ever worked correctly)
HOW OFTEN the problem occurs
Whether the severity of the problem has increased,
decreased or stayed the same
What resources you should use
Whenever possible, you should use the following
resources to assist you in verifying the complaint:
Service manual Theory or Circuit Description
sections
Service manual “System Performance Check”
Owner manual operational description
Technician ex perience
Identical vehicle for comparisonCircuit testing tools
Vehicle road tests
Complaint check sheet
Contact with the customer
2. Perform Preliminary Checks
NOTE: An estimated 10 percent of successful vehicle
repairs are diagnosed with this step!
What you should do
You perform preliminary checks for several reasons:
To detect if the cause of the complaint is VISUALLY
OBVIOUS
To identify parts of the system that work correctly
To accumulate enough data to correctly and
accurately search for a ISUZU Service Bulletin on
ISUZU Web site.
The initial checks may vary depending on the
complex ity of the system and may include the following
actions:
Operate the suspect system
Make a visual inspection of harness routing and
accessible/visible power and ground circuits
Check for blown fuses
Make a visual inspection for separated connectors
Make a visual inspection of connectors (includes
checking terminals for damage and tightness)
Check for any DTCs stored by the on-board
computers
Sense unusual noises, smells, vibrations or
mov ements
Investigate the vehicle service history (call other
dealerships, if appropriate)
What resources you should use
Whenever appropriate, you should use the following
resources for assistance in performing preliminary
checks:
Tech II or other technical equipment for viewing DTCs
Service manual information:
–Component locations
–Harness routing
–Wiring schematics
–Procedures for viewing DTCs
Dealership service history file
Vehicle road test
Identical vehicle or system for comparison

6E-64 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Thought Process
As you follow a diagnostic plan, every box on the
Strategy Based Diagnostics chart requires you to use
the diagnostic thought process. This method of thinking
optimizes your diagnosis in the following ways:

Improves your understanding and definition of the
customer complaint

Saves time by avoiding testing and/or replacing
good parts


Allows you to look at the problem from different
perspectives

Guides you to determine what level o
f
understanding about system operation is needed:
 Owner’s manual level
 Service manual level
 In-depth (engineering) level
1. Verify the Complaint
What you should do
To verify the customer complaint, you need to know the
correct (normal) operating behavior of the system and
verify that the customer complaint is a valid failure o
f
the system.
The following information will help you verify the
complaint:

WHAT the vehicle model/options are

WHAT aftermarket and dealer-installed
accessories exist

WHAT related system(s) operate properly

WHEN the problem occurs

WHERE the problem occurs

HOW the problem occurs

HOW LONG the condition has existed (and if the
system ever worked correctly)

HOW OFTEN the problem occurs

Whether the severity of the problem has
increased, decreased or stayed the same
What resources you should use
Whenever possible, you should use the following
resources to assist you in verifying the complaint:
Service manual Theory or Circuit Description
sections

Service manual “System Performance Check”

Owner manual operational description

Technician experience

Identical vehicle for comparison


Circuit testing tools

Vehicle road tests

Complaint check sheet

Contact with the customer
2. Perform Preliminary Checks
NOTE: An estimated 10 percent of successful
vehicle repairs are diagnosed with this step!
What you should do
You perform preliminary checks for several reasons:

To detect if the cause of the complaint is
VISUALLY OBVIOUS

To identify parts of the system that work correctly

To accumulate enough data to correctly and
accurately search for a ISUZU Service Bulletin.
The initial checks may vary depending on the
complexity of the system and may include the following
actions:

Operate the suspect system

Make a visual inspection of harness routing and
accessible/visible power and ground circuits

Check for blown fuses

Make a visual inspection for separated connectors

Make a visual inspection of connectors (includes
checking terminals for damage and tightness)

Check for any DTCs stored by the on-board
computers

Sense unusual noises, smells, vibrations o
r
movements

Investigate the vehicle service history (call othe
r
dealerships, if appropriate)
What resources you should use
Whenever appropriate, you should use the following
resources for assistance in performing preliminary
checks:

Tech 2 or other technical equipment for viewing
DTCs

Service manual information:
 Component locations
 Harness routing
 Wiring schematics
 Procedures for viewing DTCs

Dealership service history file

Vehicle road test

Identical vehicle or system for comparison

6E–62 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Thought Process
As you follow a diagnostic plan, every box on the
Strategy Based Diagnostics chart requires you to use
the diagnostic thought process. This method of thinking
optimizes your diagnosis in the following ways:
Improves your understanding and definition of the
customer complaint
Saves time by avoiding testing and/or replacing good
parts
Allows you to look at the problem from different
perspectives
Guides you to determine what level of understanding
about system operation is needed:
–Owner’s manual level
–Service manual level
–In-depth (engineering) level
–Owner’s manual level
–Service manual level
–In-depth (engineering) level
1. Verify the Complaint
What you should do
To verify the customer complaint, you need to know the
correct (normal) operating behavior of the system and
verify that the customer complaint is a valid failure of the
system.
The following information will help you verify the
complaint:
WHAT the vehicle model/options are
WHAT aftermarket and dealer-installed accessories
exist
WHAT related system(s) operate properly
WHEN the problem occurs
WHERE the problem occurs
HOW the problem occurs
HOW LONG the condition has ex isted (and if the
system ever worked correctly)
HOW OFTEN the problem occurs
Whether the severity of the problem has increased,
decreased or stayed the same
What resources you should use
Whenever possible, you should use the following
resources to assist you in verifying the complaint:
Service manual Theory or Circuit Description
sections
Service manual “System Performance Check”
Owner manual operational description
Technician ex perience
Identical vehicle for comparisonCircuit testing tools
Vehicle road tests
Complaint check sheet
Contact with the customer
2. Perform Preliminary Checks
NOTE: An estimated 10 percent of successful vehicle
repairs are diagnosed with this step!
What you should do
You perform preliminary checks for several reasons:
To detect if the cause of the complaint is VISUALLY
OBVIOUS
To identify parts of the system that work correctly
To accumulate enough data to correctly and
accurately search for a ISUZU Service Bulletin on
ISUZU Web site.
The initial checks may vary depending on the
complex ity of the system and may include the following
actions:
Operate the suspect system
Make a visual inspection of harness routing and
accessible/visible power and ground circuits
Check for blown fuses
Make a visual inspection for separated connectors
Make a visual inspection of connectors (includes
checking terminals for damage and tightness)
Check for any DTCs stored by the on-board
computers
Sense unusual noises, smells, vibrations or
mov ements
Investigate the vehicle service history (call other
dealerships, if appropriate)
What resources you should use
Whenever appropriate, you should use the following
resources for assistance in performing preliminary
checks:
Tech II or other technical equipment for viewing DTCs
Service manual information:
–Component locations
–Harness routing
–Wiring schematics
–Procedures for viewing DTCs
Dealership service history file
Vehicle road test
Identical vehicle or system for comparison

ENGINE DRIVEABILITY AND EMISSIONS 6E–233
ENGINE CRANKS BUT WILL NOT RUN
DEFINITIONS: Engine cranks, but will not run. (The engine never start.)
NOTE: The replacement ECM must be programmed. Refer to section of the Service Programming System (SPS) in
this manual. Following ECM programming, the immobilizer system (if equipped) must be linked to the ECM.
Refer to section 11 “Immobilizer System-ECM replacement” for the ECM/Immobilizer linking procedure.
NOTE: The vehicle with immobilizer system, this system may be activated. Check the immobilizer system diagosis.
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?—Go to Step 2Go to 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 Check the “Ignition coil” fuse (15A) and “ECM” fuse
(15A).
Was a fuse blown?—Verify repair Go to Step 5
5 1. Ignition ON
2. Use a DVM to verify that battery voltage at the
ignition coil fuse, and the ECM fuse.
Was battery voltage presented at the fuses?—Go to Step 6Verify & repair
6 1. Visually/physically inspect for the following
conditions:
Restriction of air intake system. Check for a
restricted air filter element, or foreign objects
blocking the air intake system.
Check for objects blocking the IAC passage or
throttle bore, excessive 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/brake booster
hose.
Was a problem found?—Verify repair Go to Step 7
7 1. Using a Tech 2, display the IAC value.
2. Check for a faulty, plugged, or sticking IAC
operation.
Was the problem found?—Verify repair Go to Step 8
8 1. Using a Tech 2, display the MAP sensor value.
2. Check for a faulty, plugged, or incorrectly installed
MAP sensor.
Was the problem found?—Verify repair Go to Step 9
9 If oscilloscope is available, check the wave form of the
CKP signal.
Was the correct wave form found?—Go to Step 12Go to Step 10
10 Check the CKP sensor wire for open or short circuit.
Was a problem found?—Verify repair Go to Step 11
11 Replace CKP sensor.
Is there still problem?—Replace pulsar
ring. Verify repair

1-90 HEATER AND AIR CONDITIONING

MAGNETIC CLUTCH DOES NOT RUN (4JA1L/4JH1-TC)



Replace
YES


Are the A/C thermo (X-15) and heater & A/C (X-11)
and A/C compressor (X-14) relay OK?

Are the No. SBF-8 fuse (30A) and the No. EB-13
(10A) fuses OK
YES


Is the pressure switch (C-24) OK?
YES


Are the A/C switch (B-57) and the fan switch (B-13)
OK?
NO
YES


Is there continuity between the engine harness
connector terminal No.1 (E-3) and engine room harness
connector terminal No.2 (X-14)?

Disconnect the A/C compressor relay.

Turn the ignition switch "ON" (Engine is running)


A/C switch and fan control knob (fan switch "ON")
NO
Replace
NO
Defective switch or insufficient
refrigerant
NO
NO
Does the magnetic clutch
operate?
YES
Replace


Disconnect the magnetic clutch connector.

Is there battery voltage between the engine room harness
connector terminal No.1 (E-3) and ground?
Defective compressor
YESNO
Defective magnetic clutch