2004 ISUZU TF SERIES ESP

BRAKE CONTROL SYSTEM 5A-27

Actuator Test (Tech 2)
There are 5 different menus available for this test. The
state of each circuit can be tested by using these
menus. Especially when DTC cannot be detected, a
faulty circuit can be diagnosed by testing each circuit by
means of these menus.
Even when DTC has been detected, the circuit tests
using these menus could help discriminate between a
mechanical trouble and an electrical trouble.
In all cases test condition; Engine stops with the key
turned to the “ON” position. To be more specific, the
test is conducted with the brake pedal stepped on after
stepping once and releasing.
 Engine: Stop
 Ignition SW: ON

060L300002

ABS Check Light Test
Test condition: Engine stops with the key turned to the
“ON” position. To be more specific, the test is
conducted with the brake pedal stepped on after
stepping once and releasing.
 The circuit is normal if the warning light (lamp) in
the meter panel comes on and goes out in
accordance with Tech2’s instruction.

060L300002

Return Pump Test
Test condition: Engine stops with the key turned to the
“ON” position. To be more specific, the test is
conducted with the brake pedal stepped on after
stepping once and releasing.
Make sure of the working sound of the return pump
relay and return pump.
The circuit is normal if the working sound of the return
pump relay and return pump are made in accordance
with Tech2’s instruction.

060L300002

8A-18 ELECTRICAL-BODY AND CHASSIS


CONNECTOR
The connector pin shape determines whether the connector is
male or female.
The connector housing configuration does not determine
whether a connector is male or female.



The symbol illustrated in the figure is used as connector in the
circuit this section.



Connector is identified with a number.



The applicable terminal number is shown for each connector.



Connector terminal numbers are clearly shown.
Male side connector terminal numbers are in sequence from
upper right to lower left.
Female side connector terminal numbers are in sequence from
upper left to lower right.
NOTE:
For those connectors on which specific terminal numbers
on symbols are shown, the terminal numbers or symbols
are used in the circuit diagram, irrespective of the above
rule.

ENGINE MECHANICAL 6A – 31
VALVE CLEARANCE ADJUSTMENT
1. Bring the piston in either the No. 1 cylinder or the No. 4
cylinder to TDC on the compression stroke by turning
the crankshaft until the crankshaft damper pulley TDC
line is aligned with the timing pointer.

014RY00014











2. Check the rocker arm shaft bracket nuts for
looseness.
Tighten any loose rocker arm shaft bracket nuts
before adjusting the valve clearance.

Rocker Arm Shaft Bracket Nut Torque N·m (kg·m /lb·ft)
54 (5.5/40)


014RY00015
8. Check for play in the No. 1 intake and exhaust valve
push rods.
If the No. 1 cylinder intake and exhaust valve push
rods have play, the No. 1 piston is at TDC on the
compression stroke.
If the No. 1 cylinder intake and exhaust valve push
rods are depressed, the No. 4 piston is at TDC on the
compression stroke.

014RY00016
Adjust the No.1 or the No. 4 cylinder valve clearances
while their respective cylinders are at TDC on the
compression stroke.
Valve Clearance (At Cold) mm (in)
0.4 (0.016)

9. Loosen each valve clearance adjusting screw as
shown in the illustration.
10. Insert a feeler gauge of the appropriate thickness
between the rocker arm and the valve stem end.


014RY00017


11. Turn the valve clearance adjusting screw until a slight
drag can be felt on the feeler gauge.
12. Tighten the lock nut securely.
13. Rotate the crankshaft 360.
14. Realign the crankshaft damper pulley TDC notched
line with the timing pointer.
15. Adjust the clearances for the remaining valves as
shown in the illustration.

FUEL SYSTEM 6C – 7
INJECTION PUMP


RTW46CLF000201

4JA1T(L):
A Bosch Distributor Type Injection Pump is used. A single reciprocating/revolving plunger delivers the fuel uniformly
to the injection nozzles, regardless of the number of cylinders.
The governor, the injection timer, and the feed pump are all contained in the injection pump housing. The injection
pump is compact, light weight, and provides reliable high-speed operation.
The vacuum-type fast idle actuator increases the engine idling speed to provide the additional power required to
operate the air conditioner.
Fast idler diaphragm movement is caused by changes in the negative pressure created by the engine’s vacuum
pump.
The diaphragm motion is transferred to the injection pump control lever to increase or decrease the idling speed.

4JA1TC/4JH1TC:
The Bosch VP44 injection pump is electronically controlled. The pump controller combine to injection pump.
Signals from the pump controller are sent to the engine control module (ECM). In response to these signals, the
ECM selects the optimum fuel injection timing and volume for the existing driving conditions.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–5
DIAGNOSTIC TROUBLE CODE (DTC) P0400
(SYMPTOM CODE 8) (FLASH CODE 32)
EXHAUST GAS RECIRCULATION CIRCUIT
SHORT TO BATTERY ............................ 6E-227
Circuit Description ..................................... 6E-228
Diagnostic Aids .......................................... 6E-228
Diagnostic Trouble Code (DTC) P0400
(Symptom Code 3) (Flash Code 32) Ex haust
Gas Recirculation Flow Ex cessive Detected 6E-228
Diagnostic Trouble Code (DTC) P0400
(Symptom Code 4) (Flash Code 32) Ex haust
Gas Recirculation Circuit Short to Ground or
Open Circuit ............................................. 6E-232
Diagnostic Trouble Code (DTC) P0400
(Symptom Code 5) (Flash Code 32) Ex haust
Gas Recirculation Flow Insufficient Detected 6E-235
Diagnostic Trouble Code (DTC) P0400
(Symptom Code 8) (Flash Code 32) Ex haust
Gas Recirculation Circuit Short to Battery 6E-238
DIAGNOSTIC TROUBLE CODE (DTC) P0500
(SYMPTOM CODE 1) (FLASH CODE 24)
VEHICLE SPEED SENSOR CIRCUIT HIGH
INPUT ...................................................... 6E-240
DIAGNOSTIC TROUBLE CODE (DTC) P0500
(SYMPTOM CODE A) (FLASH CODE 24)
VEHICLE SPEED SENSOR INPUT SIGNAL
FREQUENCY TOO HIGH ....................... 6E-240
DIAGNOSTIC TROUBLE CODE (DTC) P0500
(SYMPTOM CODE B) (FLASH CODE 24)
VEHICLE SPEED SENSOR INCORRECT
SIGNAL ................................................... 6E-240
Circuit Description ..................................... 6E-241
Diagnostic Aids .......................................... 6E-241
Diagnostic Trouble Code (DTC) P0500
(Symptom Code 1) (Flash Code 24) Vehicle
Speed Sensor Circuit High Input ............. 6E-241
Diagnostic Trouble Code (DTC) P0500
(Symptom Code A) (Flash Code 24)
Vehicle Speed Sensor Input Signal
Frequency Too High ................................ 6E-245
Diagnostic Trouble Code (DTC) P0500
(Symptom Code B) (Flash Code 24)
VehicleSpeed Sensor Incorrect Signal .... 6E-248
DIAGNOSTIC TROUBLE CODE (DTC) P0560
(SYMPTOM CODE 1) (FLASH CODE 35)
SYSTEM VOLTAGE TOO HIGH ............. 6E-253
DIAGNOSTIC TROUBLE CODE (DTC) P0560
(SYMPTOM CODE 2) (FLASH CODE 35)
SYSTEM VOLTAGE TOO LOW .............. 6E-253
DIAGNOSTIC TROUBLE CODE (DTC) P0560
(SYMPTOM CODE A) (FLASH CODE 35)
SYSTEM VOLTAGE MALFUNCTION ..... 6E-253
Circuit Description ..................................... 6E-253Diagnostic Aids .......................................... 6E-254
Diagnostic Trouble Code (DTC) P0560
(Symptom Code 1) (Flash Code 35)
System Voltage Too High ........................ 6E-254
Diagnostic Trouble Code (DTC) P0560
(Symptom Code 2) (Flash Code 35)
System Voltage Too Low ......................... 6E-256
Diagnostic Trouble Code (DTC) P0560
(Symptom Code A) (Flash Code 35)
System Voltage Malfunction .................... 6E-258
DIAGNOSTIC TROUBLE CODE (DTC) P0561
(SYMPTOM CODE A) (FLASH CODE 18)
IGNITION SWITCH CIRCUIT
MALFUNCTION ....................................... 6E-260
DIAGNOSTIC TROUBLE CODE (DTC) P0561
(SYMPTOM CODE B) (FLASH CODE 18)
IGNITION SWITCH CIRCUIT
MALFUNCTION ....................................... 6E-260
Circuit Description ...................................... 6E-261
Diagnostic Aids .......................................... 6E-261
Diagnostic Trouble Code (DTC) P0561
(Symptom Code A) (Flash Code 18)
Ignition Switch Circuit Malfunction ........... 6E-261
Diagnostic Trouble Code (DTC) P0561
(Symptom Code B) (Flash Code 18)
Ignition Switch Circuit Malfunction ........... 6E-261
DIAGNOSTIC TROUBLE CODE (DTC) P0602
CONTROL MODULE PROGRAMMING
ERROR .................................................... 6E-264
Circuit Description & Diagnostic Aids ........ 6E-264
Diagnostic Trouble Code (DTC) P0602
Control Module Programming Error ......... 6E-264
DIAGNOSTIC TROUBLE CODE (DTC) P0606
(SYMPTOM CODE A) (FLASH CODE 28)
ECU MALFUNCTION .............................. 6E-265
DIAGNOSTIC TROUBLE CODE (DTC) P0606
(SYMPTOM CODE B) (FLASH CODE 28)
ECU MALFUNCTION .............................. 6E-265
Circuit Description & Diagnostic Aids ........ 6E-265
Diagnostic Trouble Code (DTC) P0606
(Symptom Code A) (Flash Code 28)
ECU Malfunction ...................................... 6E-265
Diagnostic Trouble Code (DTC) P0606
(Symptom Code B) (Flash Code 28)
ECU Malfunction ...................................... 6E-267
DIAGNOSTIC TROUBLE CODE (DTC) P0645
(SYMPTOM CODE 4) (FLASH CODE 46)
A/C COMPRESSOR RELAY CIRCUIT
VOLTAGE LOW ...................................... 6E-268
DIAGNOSTIC TROUBLE CODE (DTC) P0645
(SYMPTOM CODE 8) (FLASH CODE 46)
A/C COMPRESSOR RELAY CIRCUIT
VOLTAGE HIGH ...................................... 6E-268

6E–64 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR ECM AND
SENSORS
Engine Control Module (ECM)
The engine control module (ECM) is located flower
panel just under the passenger's seat.
The fuel quantity and injection timing related functions
are controlled by the pump control unit (PSG).
The engine control module (ECM) performs the
following functions.
Control of the ex haust gas re-circulation (EGR)
Control of the quick on start (QOS) glow control
system
Control of the A/C compressor
Ex ecution of the immobilizer function
Pump Control Unit (PSG) & Data Exchange
Between Control Module
The radial plunger distributor type injection pump uses
two control modules to ex ecute full control of the enginemanagement system.
Engine Control Module (ECM)
Pump Control Unit (PSG) = Pumpen Steuer Great
(German)
The pump control unit (PSG) receives signals from the
sensors inside the pump to determine the cam ring
rotation angle, the pump speed and the fuel
temperature .
These values are then compared to the desired values
sent by the engine control module (ECM) such as the
desired injection timing and the desired fuel injection
quantity.
The engine control module (ECM) processes all engine
data and data regarding the surrounding environment
received from ex ternal sensors to perform any engine
side adjustments.
Maps for both are encoded in both control units. The
control units input circuit process sensor data.
A Microprocessor then determines the operating
conditions and calculates set values for optimum
running.
The interchange of data between the engine control
module (ECM) and the pump control unit (PSG) is
perfumed via a CAN-bus system. The abbreviation CAN
stands for Controller Area Network. By having two
separate control modules, the high pressure solenoid
valve. This prevents the discharge of any disturbing
signals.
The information ex change between the two control
modules takes place via two means.
Via analogue signal leads
Via the CAN-bus
The analogue signal leads are used to ex change the
following information.
Engine speed signal (ECM terminal 91)
Pump Speed (ECM terminal 105)
Fuel Cutoff solenoid valve signal (MAB signal) (ECM
terminal 105)
The engine speed signal is sent from the ECM to PSG
based on the input from the crank shaft position (CKP)
sensor.
The analogue CKP sensor signal is converted by the
ECM into a square wave signal.
The fuel cutoff solenoid valve signal is also referred to
as MAB signal.
MAB in this case, refers to the German abbreviation
Magnet ventil ABschaltung that stands for high pressure
solenoid v alv e cut off.
The MAB signal wire is used for two purposes.
-As a reference for the engine control module (ECM) for
the pump speed (back up for the CKP sensor).
-To turn Off the engine.
Sel f Dia gn osis / Interfa ce / Si gn al
To High Pressure Solenoid
Engine Speed
Injection Timing
Accelerator Pedal
Injection Quantity
In ta ke Air Temperat ure
Response Signal
Ma ss Air Flow
Additional Signal
Others

Additional Operations To Timing Control Valve (TCV)
Engin e
Con trol
Modu le
(ECM) Cam Rin g Rota tiona l Angle
Fuel Temper atu re
High Pressure
Solenoid Valve
Pump
Con tr ol Fuel Inject ion
Unit (Mechanical)
(PSG)

Ti m i n
g Devi ce

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–75
When control current flows to the timing control valve
(TCV) coil, the valve needle opens and the fuel annular
chamber flows through the orifice to the feed pump inlet.
Consequently, the pressure of the annular chamber
decreases and the hydraulic stopper is moved to the
retard side.
The timing control valve (TCV) acts as a variable
throttle, using the rapid opening and closing (cycling) of
the valve needle in the timing control valve (TCV).
At normal operation, the TCV controls the pressure
acting on the annular chamber so that the hydraulic
stopper cam move to any position, from the retard
position to the advance position. At this time, the duty
ratio is set by the pump control unit (PSG).
Duty ratio is the ratio of the time that the timing control
valve (TCV) is opened to one complete timing control
valve (TCV) operating cycle. A duty ratio change of
100% to 0% is an advance in injection timing. (The
VP44 displays an ON duty ratio.)The engine control module (ECM) contains
characteristic maps of the start of injection,
corresponding to engine operating conditions (engine
load, engine speed and engine coolant temperature).
The pump control unit (PSG) is constantly comparing
the set start of injection timing and the actual start of
injection timing. If there is a difference, the timing
control valve (TCV) is controlled by the duty ratio. (The
actual start of injection timing is determined from the
pump camshaft speed sensor.) (1) Coil
(2) From Annular Chamber
(3) To Feed Pump
(4) Orifice
(5) Valve Needle
Engine Load
Engine Speed
Engine Coolant
TemperatureEngine
Control
Module
(ECM)Pump
Control
Unit
(PSG)
Pump Camshaft
Speed Sensor
Timing
Control
Valve
(TCV)

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