Isuzu NPR Fire truck 4HK1 engine repair manual

Section 1A

Engine control system

Table of Contents

Page

Engine control system.. 1A-4

Precautions 1A-4

Function and working principle. 1A-5

Parts configuration diagram.. 1A-21

Circuit diagram.. 1A-25

How to diagnose the fault 1A-42

Fault diagnosis operation procedures through fault diagnostic meter 1A-48

Functional check overview.. 1A-50

Inquiry. 1A-51

Engine control system check. 1A-53

Fault diagnostic meter data list 1A-55

Fault diagnostic meter data list contents 1A-58

Fault diagnostic meter output 1A-64

Fault diagnostic meter start failure. 1A-65

Fault diagnostic meter communication failure (reference) 1A-67

Communication failure with ECM (reference) 1A-71

Starting system confirmation. 1A-74

Engine MIL illuminating electrical circuit system confirmation. 1A-77

Engine MIL blinking electrical circuit system confirmation. 1A-78

Exhaust gas recirculation (EGR) control system inspection. 1A-80

Warming-up control system inspection. 1A-84

Exhaust brake/ air inlet restriction control system inspection. 1A-87

Diagnostic trouble code (DTC) overview.. 1A-92

DTC P0016 (Flash code 16) 1A-95

DTC P0087 (Flash code 225) 1A-97

DTC P0088 (Flash code 118) 1A-103

DTC P0089 (Flash code 151) 1A-109

DTC P0091, P0092 (Flash code 247) 1A-112

DTC P0093 (Flash code 227) 1A-116

DTC P0107, P0108 (Flash code 32) 1A-122

DTC P0112, P0113 (Flash code 22) 1A-127

DTC P0117, P0118 (Flash code 23) 1A-132

DTC P0122, P0123 (Flash code 43) 1A-137

DTC P0182, P0183 (Flash code 211) 1A-142

DTC P0192, P0193 (Flash code 245) 1A-147

DTC P0201, P0202, P0203, P0204 (Flash code 271,272,273,274)................................................... 1A-157

DTC P0217 (Flash code 542)...................................................................................................... 1A-170

DTC P0219 (Flash code 543)...................................................................................................... 1A-172

DTC P0234 (Flash code 42)........................................................................................................ 1A-175

DTC P0299 (Flash code 65)........................................................................................................ 1A-178

DTC P0335 (Flash code 15)........................................................................................................ 1A-182

DTC P0336 (Flash code 15)........................................................................................................ 1A-187

DTC P0340 (Flash code 14)........................................................................................................ 1A-190

DTC P0341 (Flash code 14)........................................................................................................ 1A-195

DTC P0380 (Flash code 66)........................................................................................................ 1A-198

DTC P0381 (Flash code 67)........................................................................................................ 1A-201

DTC P0404 (Flash code 45)........................................................................................................ 1A-205

DTC P0409 (Flash code 44)........................................................................................................ 1A-208

DTC P0477, P0478 (Flash code 46)............................................................................................. 1A-212

DTC P0500 (Flash code 25)........................................................................................................ 1A-216

DTC P0502, P0503 (Flash code 25)............................................................................................. 1A-218

DTC P0563 (Flash code 35)........................................................................................................ 1A-223

DTC P0601 (Flash code 53)........................................................................................................ 1A-225

DTC P0602 (Flash code 154)...................................................................................................... 1A-226

DTC P0604, P0606, P060B (Flash codes 153, 51, 36).................................................................... 1A-228

DTC P0641 (Flash code 55)........................................................................................................ 1A-230

DTC P0650 (Flash code 77)........................................................................................................ 1A-233

DTC P0651 (Flash code 56)........................................................................................................ 1A-237

DTC P0685, P0687 (Flash code 416)........................................................................................... 1A-241

DTC P0697 (Flash code 57)........................................................................................................ 1A-245

DTC P1093 (Flash code 227)...................................................................................................... 1A-248

DTC P1261, P1262 (Flash code 34)............................................................................................. 1A-253

DTC P1404 (Flash code 45)........................................................................................................ 1A-255

DTC P1621 (Flash code 54)........................................................................................................ 1A-257

DTC P2122, P2123 (Flash code 121)........................................................................................... 1A-258

DTC P2127, P2128 (Flash code 122)........................................................................................... 1A-264

DTC P2138 (Flash code 124)...................................................................................................... 1A-270

DTC P2146, P2149 (Flash code 158)........................................................................................... 1A-273

DTC P2228, P2229 (Flash code 71)............................................................................................. 1A-279

DTC P253A (Flash code 28)....................................................................................................... 1A-284

DTC P256A (Flash code 31)....................................................................................................... 1A-287

DTC U0073 (Flash code 84)....................................................................................................... 1A-291

Symptom diagnosis................................................................................................................... 1A-296

Phenomena: Intermittence.......................................................................................................... 1A-297

Symptom: Difficult starting........................................................................................................ 1A-300

Phenomena: Surge, unsteady idling or engine stalling.................................................................... 1A-303

Phenomena: High idling speed.................................................................................................... 1A-306

Symptom: Emergency stop......................................................................................................... 1A-307

Symptom: Emergency change..................................................................................................... 1A-309

Symptom: Under-power, acceleration failure or response lag........................................................... 1A-311

Phenomena: Intermitted operation, acceleration failure................................................................... 1A-314

Symptom: Combustion noise...................................................................................................... 1A-316

Symptom: Fuel economical efficiency low.................................................................................... 1A-317

Phenomena: black smoke from exhaust gas................................................................................... 1A-319

Symptom:  White smoke from exhaust gas.................................................................................. 1A-321

Main sensor parameters.............................................................................................................. 1A-323

Special tools............................................................................................................................. 1A-325

Programme............................................................................................................................... 1A-326

Programming rule...................................................................................................................... 1A-326

Programme............................................................................................................................... 1A-326

Injection pump learning.............................................................................................................. 1A-328

Adjustment............................................................................................................................... 1A-328

Engine control system

Precautions

Use of circuit testing tools

In the case of diagnosis according to the diagnostics program, do not use the test lamp for the power train electrical system diagnosis unless otherwise specified. In case the probe terminal will be used for the diagnostic program, please use the terminal testing adapter kit 5-8840-2835-0.

Market available electrical component

The market available electrical components mean the electrical components purchased from the market to install to the vehicle. Since these components are not taken into account during the vehicle design stage, pay attention to them when using these components.

Caution:

The market available electrical component power and ground must be connected to the circuit unconcerned to the electrical control system circuit.

Though the market available electrical components can be used, these may cause the functional fault of the electrical control system in some cases. It includes the devices not connected to the electrical system, for example, the mobile telephone, radio. Therefore, in the power train diagnosis, first check whether such market available electrical components are installed. If so, remove them from the vehicle. If the fault still exists after the componment removal, follow the general flow for diagnosis.

Damage due to ESD

Since the electronic parts in the electrical control system can work under the extremely low voltage, these are easy to be damaged due to ESD. Some electronic parts will be damaged by the static electricity below 100V that not appreciable to the human. The human appreciable ESD requires 4000V voltage. In many cases, the human will carry the static electricity, in which the friction and induction electrification is the most common.

● When the human moves side to side on the seat, it will generate the frictional electrification.

● When the human wearing the insulated shoes is near the highly electrified object, the electrostatic induction will occur at the moment of human touching the ground. The human will be electrified when the charges of the same polarity meet the charges of opposite polarity. Since the static electricity will cause damage, carefully handle the electronic parts and test them.

Caution:

Observe the following rules to prevent the damage due to ESD:

● Do not touch the ECM terminal contact pins and electronic parts soldered to ECM circuit back plate.

● Do not unpack the parks unless the preparation of part installation is finished.

● Connect the package and vehicle normal ground before taking the parts out of the package.

● If moving side to side on the seat, or sitting from standing posture or operating the part while moving in a certain distance, ensure to touch the normal ground before installing the part.

Function and working principle

Engine control (common rail) system

System overview and details

The engine control system means the electrical control system to control the engine to the optimal combustion state according to the driving condition. It consists of the following parts:

● Electronically controlled fuel injection system (common rail type)

● EGR

Besides, the engine control system includes the following system control functions.

● Warming-up control system

● Engine rotary output

● Communication and self-diagnosis function

Electronically controlled fuel injection system (common rail type)

The common rail system is provided with the pressure chamber and injector. The pressure chamber is designed to store the pressurized fuel and called the common rail; the injector is provided with the electronic control solenoid valve to inject the pressurized fuel to the combustion chamber. Since the injection control (the injection pressure, injection rate and injection time) is controlled by ECM, the common rail system allows the independent control of the engine speed and load. Even if the engine speed is low, the stable injection pressure can be maintained, which will greatly reduce the specific black smoke upon the diesel engine start and acceleration. Through this control, the exhaust gas will become clean, the exhaust volume will be less and the output will be higher.

Injection volume control

It controls the injector winding according to the signal obtained from the engine speed and accelerator pedal opening and consequently controls the fuel injection volume to achieve the best volume.

Injection pressure control

To allow the high pressure injection even if the engine speed is low, the common rail inside fuel pressure should be controlled. Work out the appropriate pressure in the common rail according to the engine speed and fuel injection volume, discharge the proper amount of fuel through the control injection pump and feed it to the common rail under pressure.

Injection time control

It substitutes the timing function and works out the appropriate fuel injection time according to the engine speed and injection volume and then controls the injector.

Injection rate control

To enhance the cylinder combustion efficiency, inject (pre-injection) a little fuel for ignition. After the ignition, carry out the second time injection (main injection). Control the injection time and injection volume through the injector (the injector coil).

Fuel System

The common rail system consists of 2 fuel pressure systems.

● Low pressure inlet line: between the fuel tank and injection pump

● High pressure line: between the injection pump and injector

The fuel is sucked into injection pump from the fuel tank and boosted in the pump to supply to the common rail. At this point, the signal from ECM controls the suction control valve (the common rail pressure regulator) to control the fuel volume supplied to the common rail.

Fuel system diagram

EGR (Exhaust gas recirculation)

Egr system recycles a part of exhaust gas to the intake manifold and consequently reduces the nitrogen oxides (NOx) emission. Through the EGR system, the driving operability and exhaust gas emission reduction can be achieved. The control current from the EGR controls the solenoid valve to work and consequently control the EGR valve lift. In addition, this system detects the actual valve lift with the EGR position sensor to realize the fine control over the EGR.

EGR will start working when the engine speed, engine coolant temperature, intake temperature and barometric pressure conditions are met. Then it will work out the valve opening according to the engine speed and target fuel injection volume. Basing on the calculated valve opening, it decides the solenoid valve drive load and then drives the valve. The air intake throttle will be shut down during EGR operation to enable the intake manifold inside pressure to reach the target value.

Warming-up control

Warming-up control system

The warming-up control system is designed to ease the engine start at low temperature and reduce the white smoke and noise. With the starter switch active, ECM detects the engine coolant temperature according to the signal from the engine coolant temperature (ECT) sensor to adjust the warming-up time and achieve the appropriate starting conditions for the engine. In addition, the residual heat of warming-up can maintain the idling stable. ECM decides the warming-up time according to the engine coolant temperature to drive the warming-up relay and indicator lamp to work.

Overview of exhaust brake control

The exhaust brake exhaust pipe is provided with valve inside. Closing the valve can increase the exhaust stroke resistance and enhance the engine brake effect. The exhaust brake valve works according to the vacuum pressure. The exhaust brake vacuum pressure is controlled by the open and close of solenoid valve. ECM will enable the solenoid valve if the engine speed is above 575rpm and all the exhaust brake operating conditions are met.

Exhaust brake operating conditions

● Exhaust brake switch on

● Accelerator pedal not depressed

● Not detecting accelerator pedal position (APP) sensor abnormal, exhaust brake circuit abnormal, clutch switch abnormal, APP sensor switch abnormal, A/D switch abnormal etc.

● Clutch pedal not depressed

● System voltage above 24V

● Vehicle speed exceeding specified range

ECM

Overview of ECM

ECM monitors the information from every sensor all the time to control the power train. ECM performs system diagnostic function to detect the system operation problem, remind the driver through the engine MIL and record DTC at the same time. DTC identifies the trouble zone to help the maintenance man.

ECM functions

ECM exports 5V voltage to power various sensors and switches. However, since the power is supplied by the ECM resistance, the test lamp connected to the circuit will not be on even if the resistance is very high. In some case, the common voltmeter cannot display the correct reading since its resistance is too low. To display the correct reading, ensure to use the digital multimeter of 10MΩ input impedance at least (5-8840-2691-0). ECM controls the ground circuit or power circuit through the transistor or other unit and consequently controls the output circuit.

ECM and composition parts

ECM can achieve the high steerability and fuel efficiency while maintaining the specified waste gas exhaust. ECM monitors the engine and vehicle performance through the crankshaft position (CKP) sensor and vehicle speed sensor (VSS) etc.

ECM voltage description

ECM applies the standard voltage to each switch and sensor. This is because the ECM resistance is very high while the voltage applied to the circuit is low. The test lamp will not illuminate even if connected in the circuit. Since the input impedance of voltmeter generally used by the maintenance man is very low, sometimes the voltmeter cannot display the correct reading. In such a case, use digital multimeter of 10MΩ input impedance (5- 8840 -2691-0) to get the correct voltage reading.

The ECM input/output unit is equipped with analog-digital converter, signal damping, counter and special actuator. ECM can control most composition parts through the electronic switch.

EEPROM

EEPROM is permanent storage chip soldered to the ECM back plate. To control the power train, ECM transmits the necessary program and calibration message to EEPROM.

Different from ROM, EEPROM cannot be replaced. If EEPROM is detected abnormal, replace the ECM directly.

Considerations for ECM repair

ECM can withstand the general current relevant to vehicle driving. Do not allow the circuit overload. During the open circuit and short circuit test, do not connect the ECM circuit to the ground wire or apply the voltage unless otherwise specified. For such circuit tests, ensure to use the digital multimeter (5-8840-2691-0).

The injection pump is the core part of common rail electronic fuel injection system. The injection pump is installed to the engine front. The common rail pressure regulator and fuel temperature (FT) sensor are the composition parts of the injection pump.

The fuel is fed to the injection pump from the fuel tank through the inside supply pump (rotor type). The supply pump feeds the fuel into 2 plunger compartments in the injection pump. The fuel fed to the plunger compartment is regulated by the common rail pressure regulator. The common rail pressure regulator is only controlled by the ECM supply current. The fuel flow will reach the maximum if no current is fed to the solenoid valve. Contrarily, the fuel will stop flowing when the solenoid valve current reaches the maximum. As the engine rotates, the two plungers build high pressure in the common rail. It controls the common rail pressure regulator according to the ECM signal and consequently controls the fuel volume and pressure to the common rail. In this way, the optimal operating state can be realized to enhance the fuel economical efficiency and reduce the NOx emission.

Key

1. Fuel temperature (FT) sensor

Suction control valve (common rail pressure regulator)

ECM controls the load factor of common rail pressure regulator (the power-on time of common rail pressure regulator) to regulate the fuel volume fed to the high pressure plunger. To achieve the desired rail pressure, feed the proper amount of fuel to reduce the drive load of the injection pump. When the current is fed to the common rail pressure regulator, the variable electromotive force corresponding to the load factor will be generated to vary the fuel line opening and consequently adjust the fuel volume. When the common rail pressure regulator is switched off, the retracting spring will retract, the fuel line will completely open and the fuel will flow to the plunger (the maximum intake and maximum discharge). With the common rail pressure regulator open, the fuel line will close (normally open) under the function of the retracting spring. Through the open and close of common rail pressure regulator, the fuel corresponding to the working load rate will be supplied and then discharged from the plunger.

Fuel temperature (FT) sensor

FT sensor is installed to the injection pump and the thermistor changes the resistance along with the temperature variation. The resistance will be low if the fuel temperature is high and high if the fuel temperature is low. ECM applies 5V voltage to FT sensor through the load resistor and works out the fuel temperature according to the voltage variation to control the injection pump. The voltage will be low if the resistance is low (the temperature is high) and high if the resistance is high (the temperature is low).

Common rail

Key

1. Pressure limiting valve

Due to the common rail type electrical control fuel injection system, the common rail is provided between the injection pump and injector to store the high pressure fuel. The pressure sensor and pressure limiting valve are installed on the common rail. The pressure sensor detects the fuel pressure in the common rail and transmits the signal to ECM. Basing on this signal, ECM controls the fuel pressure in the common rail with the injection pump common rail pressure regulator. If the common rail inside fuel pressure is too high, the pressure limiting valve will open to release the pressure.

Common rail pressure sensor

The common rail pressure sensor is installed to the common rail to detect the fuel pressure in the rail and convert the pressure into voltage signal. The higher the pressure, the higher the voltage; the lower the pressure, the lower the voltage. ECM works out the actual common rail pressure (the fuel pressure) according to the voltage signal from the sensor to control the fuel injection.

Pressure limiting valve

Key

1. Valve

2. Valve body

3. Valve guide

4. Spring

5. Housing

6. Fuel inlet

In the case of abnormal high pressure, the pressure limiting valve will open to release the pressure. The valve will open when the common rail inside pressure exceeds 220MPa and close when the pressure is below 50MPa. The fuel discharged from the pressure limiting valve will flow to the fuel tank.

Injector

Key

1. Wiring bolt

2. Return to the pipeline installation department

3. O-ring

4. Injection pipe installation part

5. Identification marking

Compared to the earlier injection nozzle, the electrical control injector controlled by ECM is provided with command piston and solenoid valve. This information is recorded in the ID code (24 English numbers) to display the injector characteristics. This system controls the injection volume to achieve the optimal effect with the injector flow information (ID code). When a new injector is installed to the vehicle, ensure to enter ID code in ECM.

To enhance the injection volume accuracy, use the 2D bar code or ID code on the injector. With the code, the decentralized control injection volume can be achieved on each pressure zone to enhance the combustion rate, reduce the exhaust and provide the stable output .

● Without injection

If ECM does not power the solenoid valve through the two-way valve (TWV), it will close the outlet throttling orifice with the piston force. At this point, the fuel pressure applied to the nozzle front end will be balance with the fuel pressure applied to control room through the inlet. In this pressure balance state, the sum of pressure applied to command piston and nozzle piston gravity will be higher than the pressure applied to the nozzle front end. Therefore, the nozzle will be pushed down to close the injection hole.

● Injection

If ECM powers the solenoid valve, TWV will be pulled to open the outlet throttling orifice and the fuel will flow to the oil return port. At this point, the nozzle and command piston are lifted together with the pressure applied to the nozzle front end. Then the nozzle injection hole will open to inject the fuel.

● Injection end

When the ECM stops powering the solenoid valve, TWV will fall and the outlet opening part will close. At this point, the fuel cannot flow to the return port from the control room and the fuel pressure inside will rise quickly. Then the nozzle will be depressed by the command piston to close the injection port and then the fuel injection will stop.

Engine coolant temperature (ECT) sensor

ECT sensor is installed near the thermostat shell and the thermistor changes the resistance along with the temperature variation. The resistance will be lower if the engine coolant temperature is high and high if the engine coolant temperature is low. ECM applies 5V voltage to ECT sensor through the load resistor and works out the engine coolant temperature according to the voltage variation to control the fuel injection. The voltage will be low if the resistance is low (the temperature is high) and high if the resistance is high (the temperature is low).

Camshaft position (CMP) sensor

Key

1. Camshaft gear

2. Rotation direction

The camshaft position (CMP) sensor is installed to the cylinder head rear section. The cam section of the camshaft generates the CMP signal when passing through the sensor. ECM determines the cylinder conditions and crankshaft angle according to the CMP signal and CKP sensor input CKP signal to control the fuel injection and calculate the engine speed. Though these controls base on CKP signal in general, they will work according to the CMP signal in the case of CKP sensor abnormal.

Crankshaft position (CKP) sensor

Key

The CKP sensor is installed to the flywheel housing. When the flywheel hole passes through the sensor, it will generate CKP signal. ECM determines the cylinder conditions and camshaft angle according to the CKP signal and CMP sensor input CMP signal to control the fuel injection and calculate the engine speed. Though these controls base on CKP signal in general, they will work according to the CMP signal in the case of CKP sensor abnormal.

Accelerator pedal position (APP) sensor 1

APP sensor is installed to the accelerator pedal control bracket. This sensor consists 2 sensors in one shell. ECM determines the acceleration and deceleration target value with the APP sensor. APP sensor is pin hole 1C type sensor. The signal voltage changes along with the accelerator pedal angle variation proportionably. APP sensor 1 signal voltage is low at in the early stage and increases as the pedal depressed. APP sensor 2 signal voltage is high at in the early stage and decreases as the pedal depressed.

Vehicle speed sensor

The vehicle speed sensor (VSS) is installed to the transmission. The vehicle speed sensor is equipped with HALL effect circuit. The magnet and output shaft generate the magnetic field when rotating together and then generate the pulse signal through the interaction with the magnetic field.

Atmospheric pressure sensor

The barometric pressure sensor is installed to the dashboard and changes the signal voltage along with the pressure. ECM detects the low signal voltage when the pressure is low in the high elevation area; contrarily, it detects the high signal voltage when the pressure is high. With these voltage signals, ECM can regulate the fuel injection volume and injection time to correct the elevation.

Intake air temperature (IAT) sensor

Intake air temperature (IAT) sensor

IAT sensor is installed to the guide tube between the air filter and turbocharger. When the IAT sensor temperature is low, the sensor resistance will be high. When the air temperature increases, the sensor resistance will be lower. When the sensor resistance is high, ECM will detect the high voltage on the signal circuit. When the sensor resistance is low, ECM will detect the low voltage on the signal circuit.

EGR valve

EGR valve is installed to the intake manifold. ECM controls the opening of EGR valve according to the engine operating state. According to the duty ratio signal from ECM, it controls the magnetic coil in EGR valve. Through the position sensor, it can detect the EGR valve opening. The position sensor is provided with 3 sensors in EGR valve to detect 3 locations respectively. Position sensors 1, 2, 3 are pin hole 1C type. The position sensor exports the valve open/close state in form of signal, which is in proportion with the variation of EGR valve opening.

Intake pressure sensor

The intake air pressure sensor is installed to the air inlet duct to detect the intake air pressure and convert the pressure into voltage signal. ECM detects high voltage when the pressure is high. It detects low voltage when the pressure is low. ECM works out the intake air pressure according to the voltage signal from the sensor to control the fuel injection and turbocharger.

Engine malfunction warning lamp

The engine malfunction warning lamp is installed inside the instrument to remind the driver of the engine or related system abnormal. When ECM detects abnormal through the self-diagnosis function, the engine malfunction warning lamp will be on. Short the data link connector (DLC) terminals to make the engine malfunction warning lamp blink. Then the DTC detecting state can be confirmed.

Data Link Connector (DLC)

DLC is installed to the lower left of the driver and it is the communication connector for the fault diagnostic meter and each control unit. It is provided with the diagnosis switch function. Through the short-circuit of DLC, it can enable the diagnosis switch.

Parts configuration diagram

Engine composition parts layout

(1/2)

(2/2)

Key

1. Crankshaft position (CKP) sensor

Engine composition parts layout 1

Key

1. ECM

Engine composition parts layout 3

Circuit diagram

Circuit diagram sketch (1/2)

(2/2)

Terminal arrangement