ISUZU 4HK1 Service Manual
WORKSHOP MANUAL
727 (N SERIES)
ENGINE CONTROL SYSTEM
(4HK1 ENGINE)
SECTION 1A
International Service & Parts
Tokyo, Japan
N O T I C E
Before using this Workshop Manual to assist you in performing
vehicle service and maintenance operations, it is recommended
that you carefully read and thoroughly understand the information
contained in Section - 0A under the headings “GENERAL REPAIR
INSTRUCTIONS” and “HOW TO USE THIS MANUAL”.
All material contained in this Manual is based on the latest product
information available at the time of publication.
All rights are reserved to make changes at any time without prior
notice.
Engine Control System 1A-1
ENGINE
Engine Control System
CONTENTS
Engine Control System . . . . . . . . . . . . . . . . . . . . 1A-2
Precautions on Service . . . . . . . . . . . . . . . . . . . 1A-2
Function and Operation. . . . . . . . . . . . . . . . . . . 1A-4
Component Layout . . . . . . . . . . . . . . . . . . . . . 1A-20
Circuit diagram . . . . . . . . . . . . . . . . . . . . . . . . 1A-25
Strategy-Based Diagnostics . . . . . . . . . . . . . . 1A-31
Functional Check List . . . . . . . . . . . . . . . . . . . 1A-37
Hearing Diagnostic . . . . . . . . . . . . . . . . . . . . . 1A-37
On-Board Diagnostic (OBD) System Check . . 1A-39
Inactive CHECK ENGINE Lamp (MIL) . . . . . . 1A-41
CHECK ENGINE Lamp (MIL) Remains Active 1A-44
Engine Cranks But Will Not Run. . . . . . . . . . . 1A-46
Diagnosis with Tech 2 Scan Tool. . . . . . . . . . . 1A-48
Diagnostic Chart . . . . . . . . . . . . . . . . . . . . . . . 1A-67
DTC11 - No Signal CKP Sensor . . . . . . . . . . . 1A-73
DTC13 - TCV Fault . . . . . . . . . . . . . . . . . . . . . 1A-75
DTC14 - Pump ROM Fault . . . . . . . . . . . . . . . 1A-78
DTC15 - Pump Cam Sensor (NE Sensor)
Short Break Fault . . . . . . . . . . . . . . . . . . . . . . 1A-80
DTC16 - No Signal from Pump Cam Sensor
(NE Sensor) . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-82
DTC21 - ECT Sensor Fault. . . . . . . . . . . . . . . 1A-84
DCT23 - IAT Sensor Fault. . . . . . . . . . . . . . . . 1A-88
DTC24 - AP Sensor Output Fault . . . . . . . . . . 1A-91
DTC25 - VS Sensor Circuit Fault . . . . . . . . . . 1A-95
DTC31 - Idle Up Volume Fault . . . . . . . . . . . . 1A-98
DTC32 - MAP Sensor Fault . . . . . . . . . . . . . 1A-101
DTC34 - Exhaust Brake Open Wiring Fault . 1A-104
DTC35 - Neutral Switch Signal Fault . . . . . . 1A-106
DTC36 - Clutch Switch Signal Fault
(M/T Vehicle only) . . . . . . . . . . . . . . . . . . . . . 1A-108
DTC41 - FT Sensor Cir cuit High Voltage . . . 1A-110
DTC51 - Atmospheric Pressure Sensor Fault 1A-113
DTC52 - ECM Internal Fault . . . . . . . . . . . . . 1A-114
DTC53 - Engine Driver Unit Fault . . . . . . . . . 1A-116
DTC55 - Pump Unmatched
(Difference from ECM Specifications). . . . . . 1A-118
DTC65 - Idle Position Switch Fault . . . . . . . . 1A-120
Symptom Diagnosis Chart . . . . . . . . . . . . . . 1A-122
Hard Starting. . . . . . . . . . . . . . . . . . . . . . . . . 1A-123
Vehicle Speed Variation . . . . . . . . . . . . . . . . 1A-127
Lack Power or Faulty Response . . . . . . . . . . 1A-130
Unstable Idling . . . . . . . . . . . . . . . . . . . . . . . 1A-134
Engine Not Stall . . . . . . . . . . . . . . . . . . . . . . 1A-137
Starter Motor does Not Run . . . . . . . . . . . . . 1A-139
Quick On Start (QOS) System does Not
Operate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-142
Excessive Black Smoke in Exhaust Gas. . . . 1A-144
Excessive White Smoke in Exhaust Gas . . . 1A-147
Noisy Engine. . . . . . . . . . . . . . . . . . . . . . . . . 1A-149
Nasty Smell. . . . . . . . . . . . . . . . . . . . . . . . . . 1A-152
Poor Fuel Economy. . . . . . . . . . . . . . . . . . . . 1A-155
Excessive Engine Oil Consumption . . . . . . . 1A-159
Large Engine Vibration . . . . . . . . . . . . . . . . . 1A-161
Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . 1A-164
Wiring Harness Repair: Shielded Cable. . . . . . 1A-165
Removal Procedure . . . . . . . . . . . . . . . . . . . 1A-165
Installation Procedure . . . . . . . . . . . . . . . . . . 1A-165
Twisted Leads . . . . . . . . . . . . . . . . . . . . . . . . . 1A-166
Removal Procedure . . . . . . . . . . . . . . . . . . . 1A-166
Installation Procedure . . . . . . . . . . . . . . . . . . 1A-166
Weather-Pack Connector. . . . . . . . . . . . . . . . . 1A-168
Removal Procedure . . . . . . . . . . . . . . . . . . . 1A-168
Installation Procedure . . . . . . . . . . . . . . . . . . 1A-168
Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . 1A-169
Com-Pack III. . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-170
General Information . . . . . . . . . . . . . . . . . . . 1A-170
Metri-Pack . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-171
Removal Procedure . . . . . . . . . . . . . . . . . . . 1A-171
Installation Procedure . . . . . . . . . . . . . . . . . . 1A-171
Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . 1A-171
1A-2 Engine Control System
Engine Control System
Precautions on Servic e
Circuit Test Tools
Unless otherwise specified in diagnostic procedures,
do not use Test Light to diagnose the powertrain
electrical system. When diagnostic procedures need
probe connector, use Connector Test Adapter Kit 58840-0385-0.
On-Market Electrical Equipment and Vacuum
Devices
On-market electrical equipment and vacuum devices
refer to those components that will be installed to
vehicles after shipme nt from manufacturing plants. Be
careful that installation of these components is not
considered during the process of vehicle design.
CAUTION:
Do not install on-market vacuum devices to
vehicles.
CAUTION:
Connect on-market electrical equipment, as well as
its power supplies and grounds, to the circuits
isolated from the electronic control system.
The on-market electrical equipment, even when
installed to vehicles in normal manner, may bring
functional troubles to the electronic control system.
Affected devices include those not connected to the
vehicle electrical equipment system, for example,
mobile phones or radios. Therefore, when you intend to
diagnose the powertrain, check such the on-market
electrical equipment has not been installed to the
vehicle and, if installed, remove it. If faults still occur
even after removal of on-market electric al equipment,
diagnose the vehicle according to normal procedures.
List of Abbreviations
Damage by Electrostatic Discharge
Electronic components used in the electronic control
system are designed to wor k at very low volt ages and,
for this reason, they are susceptible to damage by
electrostatic discharge and some types of electronic
components may be damaged even by the static
electricity of less than 100 V that is usua lly not sens ed
by persons. Persons’ sensitivity level is 4,000 V.
Persons are electrostatically charged in various ways
and the most typical el ectrification sources are fric tion
and induction. Shown below are examples.
• Electrification by friction occurs when a person
slides on the seat in the vehicle.
• Electrification by i nduction occurs when a person
with insulating shoes is standing near a highly
electrifiable substance and touches a ground
momentarily. Electric charges with the same
polarity flow out and resultantly the person is
charged at high opposite polarity. Since static
electric charges cause damages, it is important
when you handle or test electronic components.
CAUTION:
To prevent damages by electrostatic discharge,
follow the guidelines shown below.
• Do not touch ECM connector pins as well as
electronic components soldered to the ECM
circuit board.
• Do not unpack each replacement component
until preparations are completed for the
component.
• Before taking out a component from the
package, connect the package to the normal
grounding line of the vehicle.
• When you intend to slide on the seat, change
the posture from standing to sitting, or wa lk by
a certain distance to handle a component,
touch an appropriate grounding material.
Abbreviation Original form Meaning in this manual
A/C Air Conditioner Air conditioning units (cooler, heater, etc.)
AP Accelerate Position Depressing stroke of accelerator pedal
CKP Crankshaft Position Rotating reference signal of crankshaft
CMP Camshaft Position Rotating reference signal of pump camshaft
DLC Data Link Connector DLC connector (Tech 2 communication connector)
DTC Diagnosis Trouble Code DTC code
DVM Digital Volt Meter Special service tool (part No. 5-8840-0366-0)
ECT Engine Coolant Temperature Coolant temperature
ECM Engine Control Modulle Engine control computer
EDU Engine Driver Unit Fuel pump spill valve drive unit
Engine Control System 1A-3
Abbreviation Original form Meaning in this manual
EGR Exhaust Gas Recirculation Exhaust gas recirculation
ISM Intake Step Motor Intake throttle valve drive motor
ITP Intake Throttle Position Intake throttle valve opening
MIL Malfunction Indicator Lamp CHECK ENGINE Lamp
SPV Spill Control Valve Valve for high pressure circuit in the fuel pump
SW Switch
TCV Timing Control Valve Injection timing control valve in the fuel pump
Key SW Key switch Starter switch
Wire Color
All wiring harnes ses are i den tifi ed us in g c ol ored jacket.
The wiring harness used for the main circuit in an
electrical system is i den tif ied wi th sin gl e c olor whi le the
wiring harness us ed for th e sub -circui t is id entifi ed with
color stripe. The following rule is used in each wiring
diagram to indicate size and color of a wiring harness.
eg. : 0.5 GRN / RED
Legend
1. Red (stripe color)
2. Green (base color)
3. Harness size (0.5 mm
Symbol Color Symbol Color
B Black BR Brown
W White LG Light green
RRedGRGray
1
2
3
LNW21ASH000101-X
2
)
G Green P P ink
Y Yellow LB Light blue
L Blue V Violet
O Orange
1A-4 Engine Control System
Function and Operation
Electronic Control System
The electronic control system processes the data,
which has been collected with various types of sensors,
by means of the control program installed to ECM
(engine control module) to totally control engine
parameters such as fuel injection amount, injection
timing, engine startup, altitude compensation, and
EGR.
Sensor Actuator Control
Engine Rotating Speed
(Built-in Injection Pump)
Crankshaft Position
Accelerator Position
Coolant Temperature
Fuel Temperature
(Built-in Injection Pump)
Intake Air Pressure
Vehicle Speed
ECM
Engine Driver Unit
Injection Pump
Spill Control Valve
Timing Control Valve
EGR Valve
Engine
Control
Module
Intake Throttle Valve
Exhaust Magnetic Valve
Fuel Injection Volume
Control
Fuel Injection Timing
Control
Idle Rotating Speed
Control
Starting Control
Altitude Control
EGR Control
Intake Air Throttle
Control
Exhaust Brake Control
Idle Up Volume
Intake Air Temperature
Atmospheric Pressure
(Built-in ECU)
ECM
ECM Description
The ECM is mounted in the glove box. The ECM
monitors va ri ou s da ta se n t fr om d iv e rsi fi e d se ns or s a n d
controls systems in the powertrain. The ECM
diagnoses these s ystems to detect faults with resp ect
to system operations and inform the driver of faulty
condition via the CHECK ENGINE Lamp (MIL) and
stores DTCs (diagnosti c trouble codes ). DTC identifi es
the trouble generation area to aid repairs by service
operators.
Glow Plug
Glow Lamp
CHECK ENGINE Lamp
Swirl Change-Over Valve
Warm-Up System
Control
Starting Aid Control
Self Diagnosis
Intake Air Swirl Control
LNW21ALF000301-X
Function of ECM
ECM supplies 5 V and 12 V voltages to various sensors
and switches. Since powers are supplied via high
resistances in ECM , Test Light, eve n when connected
to the circuit, will not be lit. In a spe cial case, a normal
voltmeter does not indicate correct values since the
resistance of the instru ment is to o low. To get accu rate
readings, you need a digital voltmeter whose input
impedance is at least 10 M Ω. The special tool 5-88400366-0 is a pro per ch oice fo r this m easurement. In t he
ECM, the output circuit is con trolled by regulating the
Engine Control System 1A-5
grounding system or power circuit via transistor or
either of the devices listed below.
• Output driver module (ODM)
• Quad drive module (QDM)
ECM and Components
The ECM is designed to offer excellent drivability and
fuel economy while achieving exhaust gas emission
control requirements. The ECM monitors engine and
vehicle functions via various electronic sensors such as
CKP (crank position) and VS (vehicle speed) sensors.
Voltages from ECM
The ECM supplies reference voltages to various
switches and sensors. Resistances of the ECM are
very high and this allows the ECM to supply voltages to
these devices, and voltag es actually applied to circuits
are low and even connecting Test Light to individual
circuits may fail turn-on. Since the voltmeter normal ly
used in service factories has low input impedance,
correct readings may not be obtained . To get a ccurate
readings, a digi tal voltm eter whose i nput impeda nce is
10 MΩ (for example, 5-8840-0366-0) should be used.
Input/output devices of the ECM include analog-todigital converter, signal buffer, counter, and special
driver. By using electronic switches, th e ECM controls
most system components and turning off a switch
closes the ground circuit. These switches are divided
into four-switch or seven-s wit ch groups, and the former
group is called quad dr i ver m odu le ( QD M) an d c ontro ls
up to four output pins respectively while the latter group
is called output driver module (ODM) and controls up to
seven outputs respectively . Note that all the outputs are
necessarily not used in the control.
Electrically Erasable Programmable ROM
(EEPROM)
EEPROM is a permanent memory chip and soldered to
the board in the ECM. EEPROM stores program and
calibration data, both of which are necessary for the
ECM to control the powertrain. Different from
conventional ROMs, EEPROM cannot be replaced with
new component. If EEP ROM fails, the complete ECM
assembly must be replaced with new one.
engine fault to the user.
In a service factory, 4 pins and 6 pins of DLC (data link
connector) can be short to check the DTC while the
CHECK ENGINE Lamp (MIL) is flashing.
LNW21ASH000201
87654321
161514131211109
LNW21ASH000301
Precautions on ECM Service
The ECM is designed to withstand ordinary currents
used in operations of a vehicle. Be careful that the
circuits must not be overloaded. To test the ECM to
check open wiring or short, ECM circuits must be
connected to the ground or voltages must not be
applied to the ECM. To test ECM circuits, the digital
voltmeter 5-8840-0366-0 should always be used.
CHECK ENGINE Lamp (MIL)
Used as a means of communication between ECM and
user usually in the user mode, by light on and off. If this
lamp illuminates during operation, it warns some
1A-6 Engine Control System
Electronically Controlled Distributor Injection Pump
12
11
10
12
4
5
6
3
9
8
7
Legend
1. Spill control valve
2. Pump cam position sensor (engine speed
sensor)
3. Inlet pipe
4. Fuel temperature sensor
5. Accumulator
6. Bearing cover
An electronically contr olled distribu tor inj ectio n pump is
employed to meet the requirements of the long-term
exhaust gas control without impairing the fuel efficiency
and output. These features allow finer particles of
injected fuel, and optimum injection timing and injection
amount while the vehicle is traveling, which was
impossible with the former injection pump.
LNW21ALF000101
7. Timer
8. Timing control valve
9. Delivery valve holder
10. Compensation ROM
11 . Overflow pipe
12. Overflow valve
Fuel Dehumidifying Agent
Sliding parts in the in jec ti on p ump are lubricated by t he
fuel (light oil) as in the ex isting d istr ibutor ty pe in jecti on
pump. If dehumidifying agent is mixed in the fuel, it
may exert adverse influence on the sliding parts.
Particularly, dehumidifying agent of alcohol type is
characterized by introducing moisture into water,
causing rust generation. It should be explained to
customers not to use fu el dehumid ifying ag ent or other
fuel additives.
Structure and Operation
1. Higher pressure of injection fuel
An inner cam with a cam ring and radial plunger
are used to in crease the pressure o f the injection
fuel.
The cam ring is supported on th e pump body side
and provided with projections (cams) on the
internal periphery.
Four plungers are provided at an interval of 90°,
incorporated in the rotor i ntegrated with the drive
shaft, and in contact with the internal periphery of
the cam ring in the radial direction through the
roller.
When the drive shaft rotates, the plunger moves
on the cam ri ng int er nal s ur fac e throug h the rolling
of the roller, pushed out in the shaft center
direction with th e inner cam and compresses the
fuel.
Four plungers operate simultaneously. This
enables higher pr essure (75 ~ 130 M Pa) and high
rigidity is o btained since the lo ad bec om es rel ati ve
load in the radial direction.
Plunger diameter is ø7.5mm and the cam lift is
2.5mm.
1
Engine Control System 1A-7
3. Fuel injection amount control
Fuel injection amount is adjusted by opening or
closing the fuel high pressur e circuit with the high
response SPV (spill control valve).
EDU (engine driver unit; a high voltage driver) is
employed to drive the SPV at a high speed . EDU
can drive the SPV o f high fuel pressure at a high
speed by the high voltage and high speed
energizing system.
4. Pump ROM
In order to compensate the variation of correlation
between the fuel pump and engine, variation of the
injection amount in herent to the injection pump is
corrected.
5. Air bleeding of injection pump
a. Pumping until the pump is hard to operate.
b. Start the engine. If not started, repeat
pumping.
c. After the engine is started, keep the engine
speed at 1000 to 1500rpm for about 10
seconds.
d. Stop the engine.
e. Check for fuel leakage.
5
2
4
3
LNW21ASH000401
Legend
1. Cam ring
2. Rotor
3. Timer piston
4. Roller
5. Plunger
2. Injection timing control
Injection timi ng is ad ju sted by shifting the cam ring
phase with the fue l p ress ure app li ed t o th e back of
the timer piston. The fuel pressu re applied to the
timer piston is controlled with the ECM (engine
control module) through the timing control valve.
Legend
1. Priming pump
2. Plug
3. Sensor
4. Cartridge
1
4
3
2
LNW21ASH000501
1A-8 Engine Control System
EGR (Exhaust Gas Recirculation) Valve
In order to decrease NOx (nitrogen oxide) in the
exhaust gas, an EGR system is employed.
The EGR valve is vacuum control type.
LNW21ASF000101
Legend
1. Diaphragm
2. Valve
1
3
4
2
3
LNW21ASF000201
3. Exhaust gas
4. Vacuum
Injection Nozzle
Legend
1. Edge filter
Engine Control System 1A-9
1
LNW21ASF000301
A two-step valve opening pressure nozzle is used as
the injection no zzle. Spray pa rticle size i s reduced by
reducing the injection hole diameter.
To prevent clogging of the nozzle injection hole, an
edge filter is provided at the nozzle holder inlet.
Reference:
If the injection nozzle hole is clogged, ECM corrects the
cylinder inside condition.
The cylinder correction amount in the Tech 2 data list is
helpful to know the injection nozzle condition.
Item Engine 4HK1
Valve
opening
pressure
MPa(kg/cm
1st valve op ening
pressure
2nd valve
2
)
opening pressure
No. of injection holes - Injection
18.0 {185}
(Nominal value)
22.0 {225}
(Nominal value)
5 -ø0.25
hole diameter (mm)
Fuel Filter with Sedimentor
In order to secure the lubrication efficiency in the
injection pump, a fuel filter with sedimentor to remove
moisture in the fuel is provided.
This filter is pro vided with a priming pump to bleed th e
air from the injection pump.
1
2
LNW21ASH000601
Legend
1. Priming pump
2. Fuel filter & sedimentor
1A-10 Engine Control System
Pump CMP (Cam Position) Sensor (Engine Rotation
Sensor ) = NE Sensor
The pump CMP sensor is positioned on the outer
surface of the cam ring of the pump chamber. The
pulser installed to the injection pump drive shaft
interrupts the magnetic flux generated by the
permanent magnet and iron core of the sensor
according to the shaft rotation to generate AC wave
signal to the coil. This is transmitted to ECM (engine
control module) and converted to square wave signal .
engine speed and cam position are calculated by this
signal.
• Calculation of engine speed: No. of pulses per
hour is counted.
• Calculation of cam position: When the cam ring
slides, timing of sign al read from the pulse of the
sensor installed to the cam ring varies. ECM
calculates the time difference be tween this signal
and signal of the crank position sensor and
calculates the cam position.
CKP (Crank Position) Sensor
CKP sensor to detec t the crank position is installed to
the flywheel housin g. The sensor detec ts the rotating
angle of the crankshaft in non-contact condition with
the pointer installed to the flywheel and sends pulse
signal to ECM. ECM calc ulates the injection timin g at
the pump cam position based on this pulse signal.
Legend
1. Iron core
2. Magnetic flux
3. Permanent magnet
4. Coil
5. Pulser
12
21
34
5
LNW21AMH000101
Legend
LNW21ASH000701
1. (–) Pin
2. (+) Pin
Accelerator Position Sensor
The accelerator control is accelerator position sensor
type. This sensor is a potentiometer (variable
resistance) installed to the accelerator pedal.
Reference voltage i s constantly applied to the sens or
from ECM (engine control modul e) and the accelerat or
pedal stepping ang le is detected from varying voltage .
An accelerator switch (idle position switch) is also
installed to the accelerator pedal. The accelerator
switch is turned ON when the accelerator pedal is
released and OFF when the accelerator pedal is
stepped on.
Engine Control System 1A-11
1
(V)
5
(WOT)
4
3
2
Output Voltage
2
1
49
(Idle)
0
10 20 30
Stroke (on Pedal)
Legend
1. Accelerator position sensor 2. Accelerator switch operating point
Engine Coolant Temperature Sensor (Coolant
Temperature Sensor / ECT)
The engine coolant tempe ratur e s ensor se rves for both
the ECM and thermo m eter unit. The engine coolant
temperature sensor is of the thermistor type that the
electric resistance reduces with the increase of the
temperature. It is installed on the left front of the
cylinder head.
40 50 (mm)
LNW21AMF000701-X
1A-12 Engine Control System
Intake Air Temperature Sensor
AC
Intake air temperatur e sensor is installed to the i ntake
duct. Thermistor is used for the temperature detec tor
as in the thermo sensor to convert the changes of
temperature to changes of resistance values and
transmits to ECM.
ACB
Legend
1. Thermistor for ECM
2. Thermistor for thermo meter
[Thermistor Characteristics]
30
20
10
7.0
5.0
3.0
2.0
1.0
0.7
Resistance Value (k )
0.5
0.3
0.2
0.1
-20 1200 10020 8040 60
Engine Coolant Temperature ( C)
1
2
LNW21ASH000801
B
LNW21ASH001001
Atmospheric Pressure Sensor
The atmospheric pressure sensor is incorporated in
ECM.
MAP (Intake Air Pressure) Sensor
The MAP sensor is installed to the cylinder head cover.
The MAP sensor is composed of piezo type
semiconductor pressure element. Reference voltage is
constantly applied to the MAP sensor from ECM and
manifold pressure is detected by the changes of
voltage. When the manifol d pressure is low ( at idling),
low voltage signal is sent to ECM and when the
pressure is high (at ful l throttle), high voltage signa l is
LNW21ASH000901-X
transmitted to ECM.
Fuel Temperature Sensor
Fuel temperature sensor is installed in the pump
chamber full of fuel. Thermistor is used for the
temperature detector as in the thermo sensor and
convert the changes of temperature to changes of
resistance and values transmits to ECM.
Vehicle Speed Sensor
The vehicle speed sensor is used commonly with the
speedometer. ECM receives signal from the
speedometer.
By one turn of the sp eedome ter driven gear, 25 pulses
are generated indicating 60 km/h at 637rpm.
LNW21ASH001101
MAP (Intake Air Pressure) Sensor
Engine Control System 1A-13
[MAP Sensor Characteristics]
Output Voltage (V)
6
5
4
3
Legend
1. Pressure at idling (low pressure)
2. Pressure at ratin g p oint (a bsolut e pre ssure (high
pressure))
3. Power pin
EDU (Engine Driver Unit)
EDU enables SPV high speed drive at high fuel
pressure by the high voltage and high speed energizing
system.
Maximum charging voltage is about 150V.
Absolute
Pressure
4. Output pin
5. Ground pin
6. Vacuum hose connected pipe
Legend
1. EDU
2. Left side cover
21
LNW21AMF000801-X
1
2
LNW21ASH001201
Connecting Diagram
Battery
ECM
ECM
A
B
C
High Voltage
Generating
Circuit
Control
Circuit
SPV+
D
E
SPV
F
Ground
LNW21ASH001601-X
1A-14 Engine Control System
SPV (Spill Control Valve)
Fuel injection amount is controlled with the highresponse SPV by opening and closing the fuel high
pressure circuit.
SPV is incorporated in the injection pump.
Legend
1. SPV drive signal
2. EDU
3. ECM
4. High pressure fuel
B
B
6
7
5
1
2
3
4
8
LNW21AMF000901
5. Valve
6. High pressure fuel passage
7. SPV
8. B-B section
TCV (Timing Control Valve)
TCV using a solenoid valve is installed to the oil
pressure timer. Duty (energizing rate) controlled
current with ECM increases or decreases the valve
opening time to control the oil pressure in the high
pressure chamber si de. The timer piston is mo ved by
the balance with the timer s pring. By sliding the cam
ring connected movably with the timer piston in the
rotating direction, the injection timing is controlled.
6
5
Engine Control System 1A-15
1
2
3
7
Legend
1. Cam ring
2. Low pressure chamber
3. Timer spring
4. TCV
Electronic Control Distributor Pump System
System Overview
The accelerator control uses an accelerator position
sensor. The accelerator sensor of the potentio meter
(variable resistanc e) type is installed to the ac celerator
pedal. Reference volta ge is constantly applied to the
sensor from the ECM (engin e con tr ol module) to det ec t
the accelerator ped al stepping angle from changes of
voltage. An idle posi tion switc h (acceler ator switch ) is
also installed to the accelerator pedal. The idle position
switch (accelerator switch ) is turned ON when the
accelerator pedal is released and OFF when the
accelerator is stepped on.
ECM detects the accelerator pedal stepping angle as
AP (accelerator position) signal and after calculating,
transmits SPV (spill controller valve) drive signal to
EDU (engine driver unit).
EDU enables high spee d drive of SPV which controls
fuel injection amount.
The fuel injectio n amount is contr olled by opening and
closing the fuel high pressure circuit with the high
response SPV.
SPV is incorporated in the injection pump.
The spill control valve and timing control valve are
4
LNW21ASF000401
5. High pressure chamber
6. Timer piston
7. From ECM
electronically controlled with ECM (engine control
module).
1A-16 Engine Control System
4
17
16
15
A
B
B
A
3
2
1
18
14
5
6
7
19
13
12
10
9
8
11
Legend
1. Timer piston
2. Plunger
3. Cam ring
4. Pump cam position signal (engine speed signal)
5. Spill control valve
6. Spill control valve drive signal
7. Engine driver unit
8. Engine control module
9. Accelerator pedal opening signal
10. Accelerator position signal
Fuel Injection Amount Control
The electromagnetic spi ll valve is o pened by the signal
from ECM (engine contr ol m odul e) , pres su r e in the fuel
forced feed unit (rotor unit) is decreased and injection is
completed. Injection amount is controlled at this timing.
LNW21ALF003101
11. Crankshaft position signal
12. Engine
13. High pressure fuel passage
14. Injection timing control si gna l
15. Timing control valve
16. Timer piston
17. Pump cam position sensor (engine speed
sensor)
18. A-A section
19. B-B section
Operation
ECM calculates the bas ic injection amount op timum to
the engine operating conditions and the maximum
injection amount at that engine condition, compares
and selects lower injection amount. By adding the
phase compensated with the compensation ROM to
that injection amount, the final injection amount is
determined.
Engine Control System 1A-17
At the time of start, the optimum fuel injection amount is
determined by the starter signal and coolant
temperature. (Injec tion amount increases more wh en
the coolant temperature is lower.)
Accelerator Position
Sensor
Basic Injection Amount
Select Lower Injection
Amount Side
Compen-
sation
Injection Amount
Determine
EDU
Engine Speed Sensor
Basic Max. Injection
Amount
Compen-
sation
Max. Injection Amount
Intake Air Pressure
Sensor
Increase When Higher
Intake Air Temperature
Sensor
Varying Depending on
Conditions
Fuel Temperature Sensor
Increases When Lower
Coolant Temperature
Sensor
Increases When Lower
Fuel Temperature Sensor
Compensates to Increasing
Side When Higher
Compensation ROM
Compensation Value
of Each Pump
Electromagnetic Spill Valve
LNW21AMF001001-X
1. Basic injection amount
Determined by accelerator opening and engine
speed.
2. Max. injection amount
Maximum injection amount is determined by
adding compensati on by signals of sen sors to the
basic maximum injection amount (amount which
can be theoretic ally in jec ted ) dete rm in ed ba se d on
the engine speed.
a. Intake air pressure compensation
When the intake air pressure is high, the air
amount is increased and the injection amount is
increased.
b. Intake air temperature compensation
Injection amount is increased or decreased
depending on the difference of density based
on the intake air temperature.
c. Fuel temperature compensation
When the fuel temperature decreases, the
injection amount is increased.
d. Coolant temperature compensation
When the coolant temperature is lower, the
injection amount is increased to secure the
operability immediately after the cold start.
3. Injection amount compensation
Since the actual injection amount decreases in
comparison with the des ignated value of injection
amount when the fuel temperature is higher,
designated injection amount value is increased.
Fuel Injection Timing Control
• Timing control valve is duty-controlled according to
a signal from ECM (engine control module) to
control the fuel injection start timing.
• Using the crankshaft angle feed back system,
highly precise control is effected.
1A-18 Engine Control System
Operation
ECM calculates the o ptimum target injection ti ming for
the engine condition, adding the compensation by
signals from sensors based on the basic target
injection timing.
At the time of start, the injection timing is determined by
the starter signal, coolant temperature and engine
speed (at the higher engine spee d, the injecti on timing
angle advances.)
Crank angle feed back system is emp loyed to c alculate
the actual inject ion timing and feed back the res ult at
the target injection timing.
Accelerator Position
Sensor
Basic Target Injection
Timing
Compen-
sation
Target Injection Timing
Comparison with Target
Injection Timing and
Actual Injection Timing
Calculation of Duty Ratio
Actual Injection Timing
Timing Control Valve
Speed Sensor
Compen-
sation
Crank Position Sensor
Intake Air Pressure
Sensor
Angle Advances
When Lower
Coolant Temperature
Sensor
Angle Advances
When Lower
Compensation ROM
Compensation Value
of Each Pump
1. Basic target injection timing
Determined based on the accel erator opening and
engine speed.
2. Injection timing compensation
a. Intake air pressure compensation
Basic target inje ction timing is compens ated by
the intake air pres sure. Whe n the at mospheric
pressure is low on a altitude, for instance, the
injection timing angle is advanced.
b. Coolant temperature compensation
Basic target injection timing is compensated
based on the coolant tem perature. When the
coolant temperatu re is low, the injection timing
angle is advanced.
LNW21AMF001101-X
3. Feedback control
a. Calculation of actual injection timing
When relation between the compression TDC
position and crank angle reference position
signal is correct on the engine side and the
relation between the injection waveform and
cam angle signal is cor rect on the pump side,
actual injection timing θn can be calculated by
calculating the phase di fference θi between the
crank angle refere nce position signal and c am
angle signal.
Engine Control System 1A-19
Idle Speed (P.N Range in A/T Vehicle) [r/min]
M/T A/T
6
5
4
3
θ
Legend
1. Engine
2. Pump
3. Injection waveform
4. Cam angle signal
5. Crank angle reference positi on signal
6. Actual compression TDC
θ
LNW21ASH001701
Engine speed at
no load
1
2
Air conditioner
system ON
Approx. 580 Approx. 650
Approx. 800 Approx. 870
b. Feedback control
Timing control valve duty ratio is cal culated so
that the actual injection timing coincides the
target injection timing.
Idle Speed Control
• Idle speed is controlled by increasing or
decreasing the specified fuel injection amount
value based on the signal from ECM (engine
control module).
Operation
1. Feedback control
When there is a difference between the target
speed calculated by the E CM an d eng ine speed at
the idle speed, the fuel injection amount is
controlled by changing the signal to the
electromagnetic spi ll va lv e and co ntrol s s o th at the
engine speed coincides the idle speed.
2. Warm-up control
Optimum fast idle engine speed is controlled at
idling by the coolant temperature.
3. Estimated control
Immediately after changing over the air
conditioning switch, before the engine speed
changes, the injection amount is changed by a
constant amount to preven t change of idle speed
by the change of load given to the engine.
1A-20 Engine Control System
Component Layout
Fuse Layout
[Fuse Box Label, In Glove Box]
22
19
16
13
10
1
4
7
25
23
26
[Fuse Box, Front Left of Radiator]
24
1
20
21
17
18
27 28
14
15
11
12
2
5
8
6
9
3
LNW21ALF000401-X
Legend
1. Spare fuse
No. Indication on label Capacity Devices connected
1 CONTROLLER 10A Control unit
HAZARD,HORN (12V) 15A
2
Hazard warning flashing lamp, horn
HAZARD,HORN (24V) 10A
3—10A—
AIR CON (12V) 10A Air conditioner
4
HEATER,AIR CON (24V) 15A Heater, air conditioner
5 FUEL, SEAT HEATER (24V) 10A Fuel, seat heater
6 ABS, HAB, RETARDER (24V) 15A ABS, HAB, retarder
Engine Control System 1A-21
No. Indication on label Capacity Devices connected
7 ROOM LAMP 15A Room lamp
8 STOP LAMP 10A Stop lamp
9 POWER WINDOW (24V) 20A Power window
10
11 FOG.CORNER 10A Fog lamp, cornering lamp
12 ELEC.PTO (24V) 10A PTO switch (electric PTO)
13 WIPER,WASHER 15A Wiper, window washer
14 TURN 10A Turn signal lamp
15
16
17 MIRROR 10A Electrically operated mirror
18 CIGAR,AUDIO 10A Cigarette lighter, audio
19
20
21 AIR BAG 10A SRS airbag
TAIL.ILLUMI (12V) 15A
Tail lamp
TAIL.ILUMI (24V) 10A
GENERATOR (12V) 15A Generator
ELEC.PTO (24V) 20A PTO solenoid valve (electric PTO)
MIRROR HEAT (12V) 10A Heated side mirror
ENG.CONT (24V) 15A ECM
METER (12V) 10A
Meter
METER (24V) 15A
ENGINE STOP (12V) 10A Engine stop
HSA (24V) 10A HSA
22 STARTER 10A Starter
23 H/LAMP RH 10A Headlamp, RH
24 H/LAMP LH 10A Headlamp, LH
25
26 POWER WINDOW (12V) 30A Power window
External Fuse Box
No. Indication on label Capacity Devices connecte d
27 MARKER LAMP 10A Marker lamp
28 COND FAN 10A Condenser fan
HEATER (12V) 30A Heater
ENG CONTROLLER (24V) 30A ECM (except for turbocharged vehicles)
1A-22 Engine Control System
Relay Layout
Relay Box No.2
Bracket
Spare Power Circuit
18
16
15
14
13
Relay Box No.1
8
7
6
5
Upper
12
11
10
9
20
19
Cooler Relay
1
4
3
2
No. Legend
12 V: On relay
1
24 V: C harge relay
2 Horn relay
Fuse &
Relay Box
RightFront
17
LNW21ALF006101-X
12 V: ABS, VSV, FICD, EXH brake
3
24 V: Headlamp relay
4Tail relay
12 V: Headlamp relay
5
24 V: 4WD relay
6 Dimmer relay
7 Power window relay
8 Fog lamp relay
No. Legend
9 Cornering lamp relay
10 Air conditioner thermo relay
12 V: C harge relay
11
24 V: Key on relay
12 Heater & air conditioner relay
24 V: PTO cut relay for electric PTO in fire engine (MT)
24 V: PTO solenoid relay for electric PTO (AT)
12 V: Exhaust brake cut relay (MT)
13
24 V: Idle on relay for fire engine (AT)
24 V: Idle stop, wiper relay (with CFS (clutch free system))
24 V: PTO solenoid relay for electric PTO (MT)
24 V: PTO buzzer relay for electric PTO (AT)
12 V: OD off relay (AT)
14
24 V: Idle keep relay for fire engine (AT)
Engine Control System 1A-23
24 V: Idle stop, radio relay (with CFS)
24 V: PTO main relay for electric PTO (MT)
24 V: Garbage relay for garbage collector (AT)
15
24 V: Indicator lamp relay for fire engine (AT)
24 V: Idle stop, engine control module relay (with CFS)
4WD relay
16
24 V: Idle stop, mirror relay (with CFS)
24 V: Full automatic air conditioner, high relay
17
24 V: Automatic air conditioner, high relay
24 V: Shift lock relay for fire engine (AT)
24 V: Shift relay for fire engine (AT)
18
24 V: PTO main relay for electric PTO (MT)
19 24 V: PTO solenoid relay for electric PTO (MT)
20 24 V: PTO cut relay for electric PTO (MT)
1A-24 Engine Control System
Engine Component Layout
1
4
Legend
1. EGR valve
2. Crank position sensor (CKP sensor)
3. Intake throttle body
4. MAP sensor
5. NE sensor
6. SPV
3
11
10
9
8
7. Fuel temperature sensor (FT sensor)
8. Oil pressure SW
9. TCV
10. ROM
11. Coolant temperature sensor
2
5
6
7
LNW21ALF003001
Circuit diagram
ECM wiring diagram (1)
Engine Control System 1A-25
D24
Pump Cam Position Sensor
Crankshaft Position Sensor
Vehicle Speed
Sensor
Cooler
Compressor
Freezer
Compressor
Key SW
1 Accelerator Position Sensor
2 Idle Up Volume
5 PTO Position Sensor
Coolant Temperature
Sensor
Fuel Temperature
Sensor
Intake Air Temperature
Sensor
Main Relay
Neutral SW
Inhibitor SW
Exhaust Brake SW
(A/T)
Clutch SW
(M/T)
Starter Relay
Warm-Up SW
ABS/ASR
ECU
Diagnostic SW
Idle SW
1
2
D13
B6
B5
B12
B11
D7
A17
A20
A2
A3
A21
A19
A6
B2
A16
B8
A9
A10
A5
C3
C4
C11
C10
C1
C12
C15
ECM
D9
D16
D26
A11
D20
A15
D6
D12
A1
B3
B9
A22
D21
D10
D22
A13
D4
D23
B7
D19
A12
B10
Spill Valve
EDU
Timing Control Valve
EGR EVRV
TCM
Swirl Control
Check Engine Lamp
Spill Valve Relay
Glow Lamp
TECH 2
Exhaust Brake VSV1
Glow Relay
Stop Lamp Relay
Exhaust Brake Lamp
Intake VSV
Tachometer
VSV
ECM
: Engine Control Module
EDU
: Engine Driver Unit
EVRV
: Electric Vacuum Regulating Valve
TCM
: Transmission Control Module
VSV
: Vacuum Switching Valve
Intake Air
Pressure Sensor
5
C14
C9
C6
C5 D17
D3
Pump
ROM
LNW21AXF000301-X
1A-26 Engine Control System
ECM Wiring Diagram (2)
1.25 B/L
CKP
ROM
0.5
0.5
G/B
G/R
Engine Control Module (ECM)
Compensation ROM and NE Sensor are built in the Injection Pump
Sensor
0.5
W
B5
(+)
0.5
R
B11
()
Sensor
0.5
G
B6
(+)
NE
B12
()
0.5
L
D13D3D17
LNW21ALF000701-X
ECM Wiring Diagram (3)
Engine Control System 1A-27
AP (Accelerator Position) Sensor
2 1
Engine Control Module
(ECM)
0.5
Y/B
C6
(Sensor
Ground)
PTO Accelerator Sensor
0.5
R/B
C14
Signal
Idle Up Volume
0.5
Y/G
C10
Signal
0.5
G/O
C11
Signal
0.5
Y/R
C3
(Sensor
Power)
LNW21ALF000501-X
Characteristics of Circuit
• Multiple DTC is generated when several troubles
(failures) occur. When multiple sensors or switches
share a ground, or an open wiring o r short occurs
on the share power sup ply or ground, DTCs with
respect to related sensors or switches are
displayed.
If several DTCs are displayed, it is necessary to
inspect the shared power supply or ground for
open wiring or short.
The harness 1 shown above figure is the power
common to the AP sensor and idle up volume, and
the harness 2 is a common ground. In the event of
open wiring in wire 1 or 2, DTC 24 and 31 are
displayed at the same time. Like this, the case
where two or more DTC’s are displayed is the
multiple DTC.
• If multiple DTC24 and 31 a re di splayed , the power
supply wire 1 or ground wire 2 must be checked.
DTC Sensor actuator (detection item)
24 Accelerator position
sensor
31 idle up volume
Connector not
connected,
harness open wiring,
or
short, failure of
main unit
1A-28 Engine Control System
ECM wiring diagram (4)
32 1
ECM
C-1 C-12 C-15 C-9 C-5
0.5
Y/G
0.3
0.5
BLU/
RED
W/
GRN
SIG
Engine Coolant
Temperature
Sensor
GND
0.3
0.5
R/G
W/
GRN
SIG
GND
Fuel Temperature
Sensor
0.3
0.5
R/Y
W/
GRN
SIG
Intake Air
Temperature
Sensor
GND
Sensor
Ground
0.5
W/
GRN
Intake Air
Pressure Sensor
C-4
0.5
L/W
Characteristics of Circuit
• Multiple DTC is generated when several troubles
(failures) occur. When multiple sensors or switches
share a ground, or an open wiring o r short occurs
on the share power sup ply or ground, DTCs with
respect to related sensors or switches are
displayed.
If several DTCs are displayed, it is necessary to
inspect the shared power supply or ground for
open wiring or short.
The harness 1 in above figure is a common ground
for the engine coolant temperature sensor, fuel
temperature senso r, intake air temperature sensor
and intake air pressure sen sor. In the event of the
open wiring in the wi re 1, DTC 21, 23, 41 and 32
are displayed at the same time. In the event of the
open wiring in the wire 2, DTC 21 , 23, and 41 are
displayed at the time. Like this, the case where two
or more DTC’s are displayed is the multiple DTC.
LNW21ALF000601-X
• If multiple DTC21, 23, 41, and 32 are displayed,
the ground wire 1 must be checked.
• If multiple DTC21, 23, and 41 are displayed, the
ground wire 2 must be checked.
• If multiple DTC21 and 23 are displayed, the ground
wire 3 must be checked.
DTC Sensor actuator (detection item)
21 Engine coolant
temperature sensor
23 Intake air temperature
sensor
Connector not
connected,
open wiring or
short of harness,
41 Fuel temperature sensor
32 Intake air pressure
failure of
main unit
sensor
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