2004 ISUZU TF SERIES ECU

6E–82 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL SERVICE INFORMATION
Serviceability Issues
Non-OEM Parts
All of the OBD diagnostics have been calibrated to run
with OEM parts. Accordingly, if commercially sold
sensor or switch is installed, it makes a wrong diagnosis
and turns on the check engine lamp.
Aftermarket electronics, such as cellular phones,
stereos, and anti-theft devices, may radiate EMI into the
control system if they are improperly installed. This may
cause a false sensor reading and turn on the check
engine lamp.
Poor Vehicle Maintenance
The sensitivity of OBD diagnostics will cause the check
engine lamp to turn on if the vehicle is not maintained
properly. Restricted oil filters, fuel filters, and crankcase
deposits due to lack of oil changes or improper oil
viscosity can trigger actual vehicle faults that were not
previously monitored prior to OBD. Poor vehicle
maintenance can not be classified as a “non-vehicle
fault”, but with the sensitivity of OBD diagnostics,
vehicle maintenance schedules must be more closely
followed.
Related System Faults
Many of the OBD system diagnostics will not run if the
ECM detects a fault on a related system or component.
Visual/Physical Engine Compartment
Inspection
Perform a careful visual and physical engine
compartment inspection when performing any
diagnostic procedure or diagnosing the cause of an
emission test failure. This can often lead to repairing a
problem without further steps. Use the following
guidelines when performing a visual/physical
inspection:
Inspect all vacuum hoses for punches, cuts,
disconnects, and correct routing.
Inspect hoses that are difficult to see behind other
components.
Inspect all wires in the engine compartment for
proper connections, burned or chafed spots, pinched
wires, contact with sharp edges or contact with hot
exhaust manifolds or pipes.
Basic Knowledge of Tools Required
NOTE: Lack of basic knowledge of this powertrain
when performing diagnostic procedures could result in
an incorrect diagnosis or damage to powertrain
components. Do not attempt to diagnose a powertrain
problem without this basic knowledge.
A basic understanding of hand tools is necessary to
effectively use this section of the Service Manual.
ON-BOARD DIAGNOSTIC (OBD)
On-Board Diagnostic (Self Diagnosis
System) Tests
A diagnostic test is a series of steps, the result of which
is a pass or fail reported to the diagnostic ex ecutive.
When a diagnostic test reports a pass result, the
diagnostic ex ecutive records the following data:
The diagnostic test has been completed since the
last ignition cycle.
The diagnostic test has passed during the current
ignition cycle.
The fault identified by the diagnostic test is not
currently active.
When a diagnostic test reports a fail result, the
diagnostic ex ecutive records the following data:
The diagnostic test has been completed since the
last ignition cycle.
The fault identified by the diagnostic test is currently
active.
The fault has been active during this ignition cycle.
The operating conditions at the time of the failure.
The Diagnostic Executive
The Diagnostic Executive is a unique segment of
software which is designed to coordinate and prioritize
the diagnostic procedures as well as define the protocol
for recording and displaying their results. The main
responsibilities of the Diagnostic Ex ecutive are listed as
follow s:
Commanding the check engine lamp on and off
DTC logging and clearing
Current status information on each diagnostic
Diagnostic Information
The diagnostic charts and functional checks are
designed to locate a faulty circuit or component through
a process of logical decisions. The charts are prepared
with the requirement that the vehicle functioned
correctly at the time of assembly and that there are not
multiple faults present.
There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complemented
by the diagnostic procedures contained in this manual.
The language of communicating the source of the
malfunction is a system of diagnostic trouble codes.
When a malfunction is detected by the control module, a
diagnostic trouble code is set and the check engine
lamp is illuminated.
Check Engine Lamp
The check engine lamp looks the same as the check
engine lamp you are already familiar with, the “Check
Engine” lamp.
Basically, the check engine lamp is turned on when the

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–87
F0: Diagnostic Trouble Code
The purpose of the “Diagnostic Trouble Codes” mod e i s
to display stored trouble code in the ECM.
When “Clear DTC Information” is selected, a “Clear
DTC Information”, warning screen appears.
This screen informs you that by cleaning DTC's “all
stored DTC information in the ECM will be erased”.
After clearing codes, confirm system operation by test
driving the vehicle.
Symptom Code:
This number or alphabet means identification of the
malfunction. Each DTC includes plural symptoms, such
as DTC P0100 has four kinds of symptom code (7), (9),
(B) and (C). DTC chart (check procedure) is separated
depending on the symptom code.F1: Data Display
The purpose of the “Data Display” mode is to
continuously monitor data parameters.
The current actual values of all important sensors and
signals in the system are display through F1 mode.
See the “Typical Scan Data” section.
F2: Snapshot
“Snapshot” allows you to focus on making the condition
occur, rather than trying to view all of the data in
anticipation of the fault.
The snapshot will collect parameter information around
a trigger point that you select.
F3: Miscellaneous Test:
The purpose of “Miscellaneous Test” mode is to check
for correct operation of electronic system actuators.
F4: Programming (Factory Use Only)
The purpose of “Programming” is to program VIN in the
ECM and lock the programmed data. F0: Diagnostic Trouble Codes
F0: Read DTC Infor As Stored By ECU
F1: Clear DTC Information
F1: Data Display
F2: Snapshot
F3: Miscellaneous Test
F0: Lamps
F0: Glow Time Telltale Test
F1: Relays
F0: Glow Time Relay Test
F2: Solenoids
F0: EGR Solenoid Test
F3: Engine Speed (RPM) Control
F4: Programming
F0: Program VIN
F1: Lock ECU
Read DTC Infor A s Stored By ECU

P0100 Present
(7) Mass Air Flow (MAF) Sensor
Voltage Supply Circuit High Input
DTC No.
Symptom Code

6E–96 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
SNAPSHOT DISPLAY WITH TIS2000
Procedures for transferring and displaying Tech2
snapshot data by using TIS2000 [Snapshot Upload]
function is described below.
Snapshot data can be displayed with [Snapshot Upload]
function included in TIS2000.
1. Record the snapshot data, in Tech2.
2. Transfer the snapshot data to PC.By analyzing these data in various methods, trouble
conditions can be checked.
Snapshot data is displayed by ex ecuting the three steps
below shown:

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–97
After recording the snapshot in Tech2, transfer the data
from Tech2 to PC by the below procedures.
1. Start TIS2000.
2. Select [Snapshot Upload] on the TIS2000 start
screen.
3. Select [Upload from trouble diagnosis tool (transfer
from diagnosis tester)] or click the corresponding
icon of the tool bar.
4. Select Tech2, and transfer the recorded snapshot
information.
5. Select the transferred snapshot.
6. After ending transfer of the snapshot, data
parameter list is displayed on the screen.3. Snapshot data is displayed with TIS2000
[Snapshot Upload] function.
Snapshot is stored in the PC hard disk or floppy disk,
and can be displayed any time.
Stored snapshot can be displayed by the below
procedures.
1. Start TIS2000.
2. Select [Snapshot Upload] on the TIS2000 start
screen.
3. Select [Open the existing files] or click the
corresponding icon of the tool bar.
4. Select the transferred snapshot.
5. Open the snapshot, to display the data parameter
list on the screen.
Graph display Values and graphs (Max. 3 graphs):
1. Click the icon for graph display. [Graph Parameter]
window opens.
2. Click the first graph icon of the window upper part,
and select one parameter from the list of the window
lower part. Selected parameter is displayed nest to
the graph icon. Graph division can be selected in
the field on the parameter right side.
3. Repeat the same procedures with the 2nd and 3rd
icons.
4. After selecting all parameters to be displayed (Max .
3 parameters), click [OK] button.
5. Parameter selected is displayed in graph form on
the right of the data parameter on the screen.
6. Graph display can be moved with the navigation
icon.
7. For displaying another parameter by graph, click the
parameter of the list, drug the mouse to the display
screen while pressing the mouse button and release
the mouse button. New parameter is displayed at
the position of the previous parameter. For
displaying the graph display screen in full size,
move the cursor upward on the screen. When thecursor is changed to the magnifying glass form, click
the screen. Graph screen is displayed on the whole
screen.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–101
5. After choosing the data, click the “Nex t” button.
6. When all the necessary information is entered, the
“details” of software within the database that match
the entered data will appear for confirmation. Click
the “Program” switch and then download the new
software onto Tech-2.
7.“Data Transfer” comes on display. The progress of
downloading will be displayed on the screen in the
form of bar graph.
8. Upon finishing the data transfer, turn off the power
of Tech-2, removing from P/C.4. Programming of ECM
1. Check to see if batteries are fully charged, while
ABS connectors shall be removed from the vehicle.
2. Connect Tech-2 to Vehicle Diagnostic Connectors.
3. Turn on the power of Tech-2 and the title screen
comes on display.
4. Turn on the ignition (without allowing the engine to
start)
5. On the title screen of Tech-2, push the “Enter”
button.
6. Choose “F1: Service Programming System” on the
main screen and then choose “Fl: Program ECU”.
7. While data is being transferred, “Programming in
Progress” will be displayed on the Tech-2 screen.
8. Upon finishing the data transfer, Tech-2 will display
“Reprogramming Was Successful”. Push the “Exit”
button to bring program to completion
9. Following “Procedure 2: Demand of Data”, try over
again “Information Obtaining” and check to confirm
if the data has been correctly re-loaded.
10. Upon finishing confirmation, turn off the ignition of
the vehicle and then turn off the power of Tech-2,
removing from the vehicle.

6E–106 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
6. The Tech2 parameters which is not within the typical
range may help to isolate the area which is causing the
problem.12. This vehicle is equipped with ECM which utilizes an
electrically erasable programmable read only memory
(EEPROM).
On-Board Diagnostic (OBD) System Check
Step Action Value(s) Yes No
11. Ignition “On”, engine “Off”.
2. Check the “CHECK ENGINE” lamp (MIL).
Does the “CHECK ENGINE” lamp turn “On”?—Go to Step 2Go to No
CHECK
ENGINE Lamp
21. Using the Tech 2, ignition “On” and engine “Off”.
2. Attempt to display “Data Display” with the Tech 2.
Does the Tech 2 display engine data? —Go to Step 3Go to Step 7
31. Using the Tech 2, ignition “On” and engine “Off”.
2. Select the “Miscellaneous Test” and perform the
“Check Light” in “Lamps”.
3. Operate the Tech 2 in accordance with the Tech 2
instructions.
Does the “CHECK ENGINE” lamp turn “Off”? —Go to Step 4Go to CHECK
ENGINE LAMP
On Steady
4Attempt to start the engine.
Does the engine start and continue to “Run”?
—Go to Step 5Go to Engine
Cranks But Will
Not Run
51. Using the Tech 2, ignition “On” and engine “Off”.
2. Select the “Read DTC Infor As Stored By ECU” in
“Diagnostic Trouble Code”.
3. Are any DTCs stored?—Go to DTC
ChartGo to Step 6
6Compare typical scan data values displayed on the
Te c h 2 “Data Display”.
Are the displayed values within the range?—Refer to
SYMPTOM
DIAGNOSISRefer to
TYPICAL
SCAN DATA
7Using the DVM and check the data link connector
power supply circuit.
1. Ignition “Off”, engine “Off”.
2. Check the circuit for open circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 8
V
B-58

6E–122 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
35 P0560 A OFF System Voltage Malfunction System voltage of PSG
(pump control unit) is below
4.5V or more than 27V.PSG uses default voltage as
substitute.System voltage of PSG is
between 4.5V and 27V.1. Battery power feed
harness open circuit or
short to ground circuit.
2. PSG (pump control unit)
ground harness open or
p o o r c o n n e c t i o n .
3. Poor connector
c o n n e c t i o n .
4 . B a t t e r y m a l f u n c t i o n .
5. Charge system
m a l f u n c t i o n .
6. Battery jump start cable
misconnect.
7. PSG (pump control unit)
malfunction.——
18 P0561 A OFF Ignition Switch Circuit
MalfunctionThe ECM recognized ignition
switch turn off signal during
ECM is activated.ECM stops engine. No recovery until condition
match in the next ignition key
cycle.1. Ignition switch circuit
open or short to ground
c i r c u i t .
2. Poor connector
c o n n e c t i o n .
3. Ignition switch
m a l f u n c t i o n .
4. ECM malfunction.39 —
B OFF Ignition Switch Circuit
MalfunctionIgnition switch circuit is
malfunction.1. Ignition switch circuit
open or short to ground
c i r c u i t .
2. Poor connector
c o n n e c t i o n .
3. Ignition switch
m a l f u n c t i o n .
4. ECM malfunction.39 —
- P0602 - Control Module
Programming ErrorECM memory area error. Engine control disabled. Memory are is OK. ECM is not programmed.
——
28 P0606 A ON ECU Malfunction Gate Array communication
error.1. MAB (fuel cutoff solenoid
v a l v e ) i s o p e r a t e d .
2. Desired injection quantity
becomes 0mg/strk.No recovery. ECM malfunction.
——
B ON ECU Malfunction 1. Throttle position is below
1 % .
2. Desired injection quantity
is more than 0mg/strk.
3. Engine speed is more
t h a n 2 0 0 0 r p m . MAB (fuel cutoff solenoid
v a l v e ) i s o p e r a t e d . Desired injection quantity is
b e l o w 0 m g / s t r k . 1 . E C M m a l f u n c t i o n .
2. PSG (pump control unit)
malfunction.
—— Flash
CodeCodeSymptom
CodeMILDTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure PartsRelated
ECM Pin
No.Related
Multiple
DTC4JA1-TC
(MT)4JH1-TC
(MT)4JH1-TC
(AT)

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–125
43 P1335 A ON Engine Speed Output Circuit
MalfunctionThe PSG (pump control unit)
is recognized defective
engine speed signal form the
ECM.Fuel injection quantity is
reduced.Correct engine speed signal. 1. CKP sensor harness
open circuit, short to
ground or short to
voltage.
2. CKP sensor output
harness open circuit,
short to ground or short
t o v o l t a g e .
3. Poor connector
c o n n e c t i o n .
4. CKP sensor malfunction.
5. Pulse sensing gap
i n c o r r e c t .
6 . P u l s e r m a l f u n c t i o n .
7. Electrical interference.
8. Magnetic interference.
9. ECM malfunction.
10. PSG (pump control unit)
malfunction.9 0 /
9 1 /
9 8 /
101P0335(B)/











P0335(D)
45 P1345 A ON Camshaft Speed Malfunction The PSG (pump control unit)
is recognized incorrect
camshaft speed signal.No fail-safe function. Correct camshaft speed. 1. Pump camshaft speed
s e n s o r m a l f u n c t i o n .
2. Pulse sensing gap
i n c o r r e c t .
3 . P u l s e r m a l f u n c t i o n .
4. Electrical interference.
5. Magnetic interference.
6. ECM malfunction.
7. PSG (pump control unit)
malfunction.——
47 P1520 A ON Neutral Switch ON Error Neutral switch signal is
inputted "On" three times
consecutively under driving
conditions.No fail-safe function. Correct neutral switch signal
is inputted two times
consecutively under driving
conditions.1. Neutral switch circuit
short to voltage circuit.
2. Neutral switch
m a l f u n c t i o n .
3. ECM malfunction.87 —
B ON Neutral Switch OFF Error Neutral switch signal is
inputted "Off" three times
consecutively under driving
conditions.1. Neutral switch circuit
open, short to ground
c i r c u i t .
2. Poor connector
c o n n e c t i o n .
3. Neutral switch
m a l f u n c t i o n .
4. ECM malfunction.87 — —
55 P1605 C ON Seed and Key File Destroyed Seed or key file in EEPROM
is destroyed.No fail-safe function. No recovery. ECM malfunction.
——
D ON EEPROM Defect Write and read from the
EEPROM are failed during
initialization of the ECM.ECM uses default values
from the EPROM.Write and read from the
EEPROM are correct during
initialization of the ECM.ECM malfunction.
—— Flash
CodeCodeSymptom
CodeMILDTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure PartsRelated
ECM Pin
No.Related
Multiple
DTC4JA1-TC
(MT)4JH1-TC
(MT)4JH1-TC
(AT)