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 Circuit 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 Service

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 5- 8840-0385-0.

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 shipment 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 electrical 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 work at very low voltages 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 usually not sensed by persons. Persons’ sensitivity level is 4,000 V. Persons are electrostatically charged in various ways and the most typical electrification sources are friction and induction. Shown below are examples.

•Electrification by friction occurs when a person slides on the seat in the vehicle.

•Electrification by induction 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 walk 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 harnesses are identified using colored jacket. The wiring harness used for the main circuit in an electrical system is identified with single color while the wiring harness used for the sub-circuit is identified 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

1

2

3

LNW21ASH000101-X

Legend
1.	Red (stripe color)
2.	Green (base color)
3.	Harness size (0.5 mm2)
	Symbol	Color		Symbol	Color
	B	Black		BR	Brown
	W	White		LG	Light green
	R	Red		GR	Gray
	G	Green		P	Pink
	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	ECM	Actuator	Control
Engine Rotating Speed		Engine Driver Unit	Fuel Injection Volume
(Built-in Injection Pump)			Control
			Fuel Injection Timing
Crankshaft Position		Injection Pump	Control
			Idle Rotating Speed
		Spill Control Valve	Control
Accelerator Position
		Timing Control Valve	Starting Control
Coolant Temperature
			Altitude Control
Fuel Temperature		EGR Valve	EGR Control
(Built-in Injection Pump)
	Engine
	Control
	Module		Intake Air Throttle
Intake Air Pressure		Intake Throttle Valve
			Control
		Exhaust Magnetic Valve	Exhaust Brake Control
Vehicle Speed
		Glow Plug	Warm-Up System
			Control
Idle Up Volume
		Glow Lamp	Starting Aid Control
Intake Air Temperature			Self Diagnosis
		CHECK ENGINE Lamp
Atmospheric Pressure		Swirl Change-Over Valve	Intake Air Swirl Control
(Built-in ECU)
			LNW21ALF000301-X

ECM

ECM Description

The ECM is mounted in the glove box. The ECM monitors various data sent from diversified sensors and controls systems in the powertrain. The ECM diagnoses these systems to detect faults with respect to system operations and inform the driver of faulty condition via the CHECK ENGINE Lamp (MIL) and stores DTCs (diagnostic trouble codes). DTC identifies the trouble generation area to aid repairs by service operators.

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, even when connected to the circuit, will not be lit. In a special case, a normal voltmeter does not indicate correct values since the resistance of the instrument is too low. To get accurate readings, you need a digital voltmeter whose input impedance is at least 10 MΩ . The special tool 5-8840- 0366-0 is a proper choice for this measurement. In the ECM, the output circuit is controlled 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 voltages actually applied to circuits are low and even connecting Test Light to individual circuits may fail turn-on. Since the voltmeter normally used in service factories has low input impedance, correct readings may not be obtained. To get accurate readings, a digital voltmeter whose input impedance is 10 MΩ (for example, 5-8840-0366-0) should be used.

Input/output devices of the ECM include analog-to- digital converter, signal buffer, counter, and special driver. By using electronic switches, the ECM controls most system components and turning off a switch closes the ground circuit. These switches are divided into four-switch or seven-switch groups, and the former group is called quad driver module (QDM) and controls 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 EEPROM fails, the complete ECM assembly must be replaced with new one.

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

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
1	2	3	4	5	6	7	8
9	10 11 12 13 14 15 16
			LNW21ASH000301

1A-6 Engine Control System

Electronically Controlled Distributor Injection Pump

	1	2
		4
	5	3
	12
	11
10	6
9
	7
8
		LNW21ALF000101

Legend
1.	Spill control valve	7.	Timer
2.	Pump cam position sensor (engine speed	8.	Timing control valve
	sensor)	9.	Delivery valve holder
3.	Inlet pipe	10.	Compensation ROM
4.	Fuel temperature sensor	11.	Overflow pipe
5.	Accumulator	12.	Overflow valve
6.	Bearing cover

An electronically controlled distributor injection 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.

Fuel Dehumidifying Agent

Sliding parts in the injection pump are lubricated by the fuel (light oil) as in the existing distributor type injection 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 fuel dehumidifying agent or other fuel additives.

Engine Control System 1A-7

Structure and Operation

1.Higher pressure of injection fuel

An inner cam with a cam ring and radial plunger are used to increase the pressure of the injection fuel.

The cam ring is supported on the 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 integrated 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 ring internal surface through the rolling of the roller, pushed out in the shaft center direction with the inner cam and compresses the fuel.

Four plungers operate simultaneously. This enables higher pressure (75 ~ 130 MPa) and high rigidity is obtained since the load becomes relative load in the radial direction.

Plunger diameter is ø7.5mm and the cam lift is 2.5mm.

1

5

2 4

3

LNW21ASH000401

Legend

1.Cam ring

2.Rotor

3.Timer piston

4.Roller

5.Plunger

2.Injection timing control

Injection timing is adjusted by shifting the cam ring phase with the fuel pressure applied to the back of the timer piston. The fuel pressure applied to the timer piston is controlled with the ECM (engine control module) through the timing control valve.

3.Fuel injection amount control

Fuel injection amount is adjusted by opening or closing the fuel high pressure 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 of 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 inherent 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.

1

4

3

2

LNW21ASH000501

Legend

1.Priming pump

2.Plug

3.Sensor

4.Cartridge

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

1

2

3

3

4

LNW21ASF000201

Legend
1.	Diaphragm	3.	Exhaust gas
2.	Valve	4.	Vacuum

Engine Control System 1A-9

Injection Nozzle

1

LNW21ASF000301

Legend

1. Edge filter

A two-step valve opening pressure nozzle is used as the injection nozzle. Spray particle size is 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	1st valve opening	18.0 {185}
	opening	pressure	(Nominal value)
	pressure
		2nd valve	22.0 {225}
	MPa(kg/cm2)
		opening pressure	(Nominal value)
	No. of injection holes - Injection		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 provided with a priming pump to bleed the 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 signal read from the pulse of the sensor installed to the cam ring varies. ECM calculates the time difference between this signal and signal of the crank position sensor and calculates the cam position.

1 2

4 3

5

LNW21ASH000701

Legend

1.Iron core

2.Magnetic flux

3.Permanent magnet

4.Coil

5.Pulser

CKP (Crank Position) Sensor

CKP sensor to detect the crank position is installed to the flywheel housing. The sensor detects the rotating angle of the crankshaft in non-contact condition with the pointer installed to the flywheel and sends pulse signal to ECM. ECM calculates the injection timing at the pump cam position based on this pulse signal.

12

LNW21AMH000101

Legend

1.(–) Pin

2.(+) Pin

Engine Control System 1A-11

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 is constantly applied to the sensor from ECM (engine control module) and the accelerator pedal stepping angle 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.

1
	(V)
	5
(WOT)
	4
Voltage	3
Output	2
2	1
49	(Idle)
	0	10	20	30	40	50 (mm)
			Stroke (on Pedal)
						LNW21AMF000701-X

Legend
1. Accelerator position sensor	2. Accelerator switch operating point

Engine Coolant Temperature Sensor (Coolant Temperature Sensor / ECT)

The engine coolant temperature sensor serves for both the ECM and thermo meter 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.

1A-12 Engine Control System

		A	C
			B
	1
A	C	B
	2
			LNW21ASH000801

Legend

1.Thermistor for ECM

2.Thermistor for thermo meter

[Thermistor Characteristics]

		30
		20
	)	10
	(k	7.0
		5.0
	Value
		3.0
	Resistance
		2.0

1.0

0.7

0.5

0.3

0.2

0.1

-20 0 20 40 60 80 100 120

Engine Coolant Temperature ( C)

LNW21ASH000901-X

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 speedometer driven gear, 25 pulses are generated indicating 60 km/h at 637rpm.

Intake Air Temperature Sensor

Intake air temperature sensor is installed to the intake duct. Thermistor is used for the temperature detector as in the thermo sensor to convert the changes of temperature to changes of resistance values and transmits to ECM.

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 manifold pressure is low (at idling), low voltage signal is sent to ECM and when the pressure is high (at full throttle), high voltage signal is transmitted to ECM.

LNW21ASH001101

Engine Control System 1A-13

MAP (Intake Air Pressure) Sensor

	Output Voltage (V)	[MAP Sensor Characteristics]
6		Absolute
		Pressure
			1	2

		5	4	3
						LNW21AMF000801-X
Legend
1.		Pressure at idling (low pressure)			4.	Output pin
2.		Pressure at rating point (absolute pressure (high			5.	Ground pin
		pressure))			6.	Vacuum hose connected pipe
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.

1

2

LNW21ASH001201

Legend

1.EDU

2.Left side cover

Connecting Diagram
Battery	High Voltage	D SPV+
A	Generating
	Circuit
ECM	Control
B
ECM	Circuit	E
C			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.

	B	1
		7
		2
		3
	B	5
		4
		6
		8
		LNW21AMF000901

Legend
1.	SPV drive signal	5.	Valve
2.	EDU	6.	High pressure fuel passage
3.	ECM	7.	SPV
4.	High pressure fuel	8.	B-B section

Engine Control System 1A-15

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 side. The timer piston is moved by the balance with the timer spring. By sliding the cam ring connected movably with the timer piston in the rotating direction, the injection timing is controlled.

1

6

5

2

3

4

7

LNW21ASF000401

Legend
1.	Cam ring	5.	High pressure chamber
2.	Low pressure chamber	6.	Timer piston
3.	Timer spring	7.	From ECM
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 resistance) type is installed to the accelerator pedal. Reference voltage is constantly applied to the sensor from the ECM (engine control module) to detect the accelerator pedal stepping angle from changes of voltage. An idle position switch (accelerator 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 speed drive of SPV which controls fuel injection amount.

The fuel injection amount is controlled 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

electronically controlled with ECM (engine control module).

1A-16 Engine Control System

			4
	A		5	10
		B	3	6
17
				9
			2
			7	8
		B	1
			19
				11
	A		13
			18
16	15
			12
			14
				LNW21ALF003101

Legend
1.	Timer piston	11.	Crankshaft position signal
2.	Plunger	12.	Engine
3.	Cam ring	13.	High pressure fuel passage
4.	Pump cam position signal (engine speed signal)	14.	Injection timing control signal
5.	Spill control valve	15.	Timing control valve
6.	Spill control valve drive signal	16.	Timer piston
7.	Engine driver unit	17.	Pump cam position sensor (engine speed
8.	Engine control module		sensor)
9.	Accelerator pedal opening signal	18.	A-A section
10.	Accelerator position signal	19.	B-B section

Fuel Injection Amount Control

The electromagnetic spill valve is opened by the signal from ECM (engine control module), pressure in the fuel forced feed unit (rotor unit) is decreased and injection is completed. Injection amount is controlled at this timing.

Engine Control System 1A-17

Operation

ECM calculates the basic injection amount optimum 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.

At the time of start, the optimum fuel injection amount is determined by the starter signal and coolant temperature. (Injection amount increases more when the coolant temperature is lower.)

Accelerator Position	Engine Speed Sensor	Intake Air Pressure
Sensor		Sensor
		Increase When Higher
		Intake Air Temperature
	Basic Max. Injection	Sensor
		Varying Depending on
	Amount
		Conditions
		Fuel Temperature Sensor
	Compen-	Increases When Lower
	sation	Coolant Temperature
		Sensor
		Increases When Lower
Basic Injection Amount	Max. Injection Amount
		Fuel Temperature Sensor
Select Lower Injection		Compensates to Increasing
Amount Side
		Side When Higher
Compen-
sation
		Compensation ROM
Injection Amount		Compensation Value
		of Each Pump
Determine
EDU		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 compensation by signals of sensors to the basic maximum injection amount (amount which can be theoretically injected) determined based 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 designated 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 optimum target injection timing 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 speed, the injection timing angle advances.)

Crank angle feedback system is employed to calculate the actual injection timing and feed back the result at the target injection timing.

	Accelerator Position	Speed Sensor	Crank Position Sensor
	Sensor
	Basic Target Injection	Actual Injection Timing
	Timing		Intake Air Pressure
			Sensor
			Angle Advances
	Compen-		When Lower
			Coolant Temperature
	sation
			Sensor
			Angle Advances
			When Lower
	Target Injection Timing	Compen-
		sation
	Comparison with Target		Compensation ROM
	Injection Timing and		Compensation Value
	Actual Injection Timing		of Each Pump
	Calculation of Duty Ratio
	Timing Control Valve
			LNW21AMF001101-X

1.Basic target injection timing

Determined based on the accelerator opening and engine speed.

2.Injection timing compensation

a.Intake air pressure compensation

Basic target injection timing is compensated by the intake air pressure. When the atmospheric 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 temperature. When the coolant temperature is low, the injection timing angle is advanced.

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 correct on the pump side, actual injection timing θ n can be calculated by calculating the phase difference θ i between the crank angle reference position signal and cam angle signal.

Engine Control System 1A-19

6

θ

1

5 θ

4

2

3

LNW21ASH001701

Legend

1.Engine

2.Pump

3.Injection waveform

4.Cam angle signal

5.Crank angle reference position signal

6.Actual compression TDC

b.Feedback control

Timing control valve duty ratio is calculated 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 ECM and engine speed at the idle speed, the fuel injection amount is controlled by changing the signal to the electromagnetic spill valve and controls so that 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 prevent change of idle speed by the change of load given to the engine.

Idle Speed (P.N Range in A/T Vehicle) [r/min]

		M/T	A/T
	Engine speed at	Approx. 580	Approx. 650
	no load
	Air conditioner	Approx. 800	Approx. 870
	system ON

1A-20 Engine Control System

Component Layout

Fuse Layout

[Fuse Box Label, In Glove Box]

	22	19	16	13	10	7	4	1
25	23	20	17	14	11	8	5	2
26	24	21	18	15	12	9	6	3

1

[Fuse Box, Front Left of Radiator]

27 28

LNW21ALF000401-X

Legend

1. Spare fuse

	No.	Indication on label	Capacity	Devices connected
	1	CONTROLLER	10A	Control unit
	2	HAZARD,HORN (12V)	15A	Hazard warning flashing lamp, horn
		HAZARD,HORN (24V)	10A
	3	—	10A	—
	4	AIR CON (12V)	10A	Air conditioner
		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	TAIL.ILLUMI (12V)	15A	Tail lamp
		TAIL.ILUMI (24V)	10A
	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	GENERATOR (12V)	15A	Generator
		ELEC.PTO (24V)	20A	PTO solenoid valve (electric PTO)
	16	MIRROR HEAT (12V)	10A	Heated side mirror
		ENG.CONT (24V)	15A	ECM
	17	MIRROR	10A	Electrically operated mirror
	18	CIGAR,AUDIO	10A	Cigarette lighter, audio
	19	METER (12V)	10A	Meter
		METER (24V)	15A
	20	ENGINE STOP (12V)	10A	Engine stop
		HSA (24V)	10A	HSA
	21	AIR BAG	10A	SRS airbag
	22	STARTER	10A	Starter
	23	H/LAMP RH	10A	Headlamp, RH
	24	H/LAMP LH	10A	Headlamp, LH
	25	HEATER (12V)	30A	Heater
		ENG CONTROLLER (24V)	30A	ECM (except for turbocharged vehicles)
	26	POWER WINDOW (12V)	30A	Power window
	External Fuse Box
	No.	Indication on label	Capacity	Devices connected
	27	MARKER LAMP	10A	Marker lamp
	28	COND FAN	10A	Condenser fan

1A-22 Engine Control System

Relay Layout

		Relay Box No.1
	13
	16 15 14
	18
Relay Box No.2
					12
Bracket					11
Spare Power Circuit			6	7	8 9 10
		5
		Upper
	Fuse &	Front			Right
	Relay Box
19 20
Cooler Relay	4
	3
2
1		17
					LNW21ALF006101-X

	No.		Legend
	1	12	V: On relay
		24	V: Charge relay
	2	Horn relay
	3	12	V: ABS, VSV, FICD, EXH brake
		24	V: Headlamp relay
	4	Tail relay
	5	12	V: Headlamp relay
		24	V: 4WD relay
	6	Dimmer relay
	7	Power window relay
	8	Fog lamp relay

Engine Control System 1A-23

	No.		Legend
	9	Cornering lamp relay
	10	Air conditioner thermo relay
	11	12	V: Charge relay
		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)
	13
		12	V: Exhaust brake cut relay (MT)
		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)
	14
		12	V: OD off relay (AT)
		24	V: Idle keep relay for fire engine (AT)
		24	V: Idle stop, radio relay (with CFS)
		24	V: PTO main relay for electric PTO (MT)
	15	24	V: Garbage relay for garbage collector (AT)
		24	V: Indicator lamp relay for fire engine (AT)
		24	V: Idle stop, engine control module relay (with CFS)
	16	4WD relay
		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)
	18	24	V: Shift relay for fire engine (AT)
		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

3	2

5

11

6

9

10

8	7

LNW21ALF003001

Legend
1.	EGR valve	7.	Fuel temperature sensor (FT sensor)
2.	Crank position sensor (CKP sensor)	8.	Oil pressure SW
3.	Intake throttle body	9.	TCV
4.	MAP sensor	10.	ROM
5.	NE sensor	11.	Coolant temperature sensor
6.	SPV

Engine Control System 1A-25

Circuit diagram

ECM wiring diagram (1)

			D24
		Main Relay
			D13		D9
					D16
			B6		D26
	Pump Cam Position Sensor		B5		A11	Spill Valve
					D20
						EDU
					A15
	Crankshaft Position Sensor		B12		D6
			B11		D12	Timing Control Valve
	Vehicle Speed		D7
	Sensor
	Cooler					EGR EVRV
	Compressor				A1
	Freezer
	Compressor	Neutral SW	A17
			A20
			A2		B3
		Inhibitor SW	A3			TCM
					B9
		Exhaust Brake SW	A21
		(A/T)	A19			Swirl Control
			A6		A22	VSV
	Key SW	Clutch SW			D21	Check Engine Lamp
		(M/T)
					D10
		Starter Relay			D22	Spill Valve Relay
						Glow Lamp
		Warm-Up SW	B2		A13
						TECH 2
			A16
		ABS/ASR
			B8	ECM		Exhaust Brake VSV1
		ECU			D4
		Diagnostic SW	A9		D23	Glow Relay
		Idle SW
			A10
						Stop Lamp Relay
			A5
					B7
					D19	Exhaust Brake Lamp
1	Accelerator Position Sensor				A12	Intake VSV
2	Idle Up Volume		C3		B10	Tachometer
5	PTO Position Sensor
			C4
			C11			ECM	: Engine Control Module
		1
			C10			EDU	: Engine Driver Unit
	Coolant Temperature	2
	Sensor		C1
						EVRV: Electric Vacuum Regulating Valve
	Fuel Temperature
	Sensor		C12			TCM	: Transmission Control Module
	Intake Air Temperature					VSV	: Vacuum Switching Valve
	Sensor		C15
		5	C14
	Intake Air		C9
	Pressure Sensor		C6		D3
						Pump
			C5		D17
						ROM	LNW21AXF000301-X

1A-26 Engine Control System

ECM Wiring Diagram (2)

1.25 B/L
		CKP			NE
	ROM	Sensor		Sensor
0.5	0.5	0.5	0.5 0.5		0.5
G/B	G/R	W	R	G	L
D17D3		B5B11		B6B12		D13
		(+) ()		(+) ()
Engine Control Module (ECM)
Compensation ROM and NE Sensor are built in the Injection Pump
						LNW21ALF000701-X

Engine Control System 1A-27

ECM Wiring Diagram (3)

			AP (Accelerator Position) Sensor
2					1
			Idle Up Volume
		PTO Accelerator Sensor
	0.5	0.5	0.5	0.5	0.5
	Y/B	R/B	Y/G	G/O	Y/R
Engine Control Module	C6	C14	C10	C11	C3
(ECM)	(Sensor	Signal	Signal	Signal	(Sensor
	Ground)				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 or short occurs on the share power supply 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 are displayed, the power supply wire 1 or ground wire 2 must be checked.

	DTC	Sensor actuator (detection item)
	24	Accelerator position	Connector not
		sensor	connected,
			harness open wiring,
	31	idle up volume
			or
			short, failure of
			main unit

1A-28 Engine Control System

ECM wiring diagram (4)

			3	2			1
ECM						Sensor
						Ground
C-1		C-12		C-15	C-9	C-5	C-4
					0.5	0.5	0.5
					Y/G	W/	L/W
						GRN
0.3	0.5	0.3	0.5	0.3	0.5
BLU/	W/	R/G	W/	R/Y	W/
RED GRN			GRN	GRN
SIG	GND	SIG	GND	SIG	GND
Engine Coolant		Fuel Temperature		Intake Air		Intake Air
Temperature		Sensor		Temperature		Pressure Sensor
Sensor				Sensor
							LNW21ALF000601-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 or short occurs on the share power supply 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 sensor, intake air temperature sensor and intake air pressure sensor. In the event of the open wiring in the wire 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.

•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	Connector not
			connected,
	23	Intake air temperature
		sensor	open wiring or
			short of harness,
	41	Fuel temperature sensor
			failure of
			main unit
	32	Intake air pressure
		sensor