Isuzu N-Series. Manual - part 799

 Engine Control System (4JH1)    6E-247

Legend

1. Accelerator Pedal Position (APP) Sensor
2. Nut

 

Installation Procedure

1. Temporary tighten the APP by two nuts.
2. Refit the accelerator pedal bracket to the body.
3. Connect the idle switch and APP connector.
4. Connect the Tech 2 to the vehicle.
5. Connect the negative battery cable.
6. Select “Data Display” with the Tech 2.
7. Check the accelerator pedal position data and

adjust the APP position.

8. Tighten two nuts.

Crankshaft Position (CKP) Sensor
Replacement

Removal Procedure

1. Disconnect the negative battery cable.
2. Disconnect connector from the CKP sensor.
3. Loosen a bolt and remove the CKP sensor from

the clutch housing.

Legend

1. Crankshaft Position (CKP) Sensor
2. Bolt

 

Installation Procedure

1. Install the CKP sensor to the clutch housing.
2. Tighten CKP sensor by a bolt with specified

tightening torque.

Tighten:
Bolts to 8.0 – 12.0 N

⋅m (0.8 – 1.2 kg⋅m / 5.9 – 8.9

lb

⋅ft)

3. Connect a CKP sensor connector to the CKP

sensor.

4. Connect the negative battery cable.

EGR Solenoid Valve Replacement

Removal Procedure

1. Disconenct the negative battery cable.
2. Disconnect a EGR solenoid valve connector from

the EGR solenoid valve.

3. Disconnect two hoses from the EGR solenoid

valve.

4. Loosen two bolts and remove the EGR solenoid

valve from the bracket.

N6A3893E

2

1

1

N6A3894E

1

2

6E-248    Engine Control System (4JH1) 

Legend

1. EGR Solenoid Valve
2. Intake Throttle Solenoid Valve

 

Installation Procedure

1. Tighten the purge solenoid by tow bolts.
2. Connect a connector to the EGR solenoid valve.
3. Connect two hoses to the EGR solenoid valve.
4. Connect the negative battery cable.

Engine Coolant Temperature (ECT) Sensor
Replacement

Removal Procedure

1. Disconnect the negative battery cable.
2. Drain enough engine coolant so that the coolant

level will be below the ECT sensor.

3. Disconnect connector from the ECT sensor.
4. Loosen and remove the ECT sensor from the

thermostat housing.

Notice:
Cool down the engine before above procedures are
carried out.

Legend

1. Engine Coolant Temperature (ECT) Sensor

 

Installation Procedure

1. Apply sealer to threads of screw at the ECT

sensor.

2. Tighten the ECT sensor with specified tightening

torque.

Tighten:
Bolt to 13 N

⋅m (1.3 kg⋅m / 9.6 lb⋅ft)

3. Connect a ECT sensor connector to the ECT

sensor.

4. Fill the engine coolant.
5. Connect the negative battery cable.

Notice:
Verify any DTCs (diagnosis Trouble Code) are not
stored after replacement.
Verify no engine coolant leaking from the sensor
threads after replacement.

Mass Air Flow (MAF) / Intake Air
Temperature (IAT) Sensor Replacement

Removal Procedure

1. Disconnect the negative battery cable.
2. Disconnect a MAF & IAT sensor connector from

the MAF & IAT sensor assembly.

3. Loosen the clips and remove the MAF & IAT

sensor assembly from the intake duct housing.

N6A3895E

2

1

N6A3896E

1

 Engine Control System (4JH1)    6E-249

Legend

1. Mass Air Flow (MAF) and Intake Air Temperature

(IAT) Sensor

2. Clip

 

Installation Procedure

1. Install the MAF & IAT sensor assembly into intake

air duct.

2. Tighten the clips.
3. Connect a MAF & IAT sensor connector to the

MAF & IAT sensor assembly.

4. Connect the negative battery cable.

Vehicle Speed Sensor (VSS) Replacement

Removal Procedure

1. Disconnect the negative battery cable.
2. Disconnect the vehicle speed sensor connector.
3. Loosen and remove the vehicle speed sensor.

Legend

1. Vehicle Speed Sensor (VSS)

 

Installation Procedure

1. Tighten the vehicle speed sensor to the specified

tightening torque.

Tighten:
Hexagonal part of the sensor: 25 N

⋅m (2.5 kg⋅m /

18 lb

⋅ft)

Caution:
Tightening must be made at the hexagonal part of the
sensor.  To tighten the connector itself would cause
damage.

2. Connect the vehicle speed sensor connector to the

vehicle speed sensor.

3. Connect the negative battery cable.

N6A3897E

2

1

N6A3905E

1

6E-250    Engine Control System (4JH1) 

Description and Operation

Engine Control Module (ECM) Description

The engine control module (ECM) is designed to
withstand normal current draws associated with vehicle
operation.  Avoid overloading any circuit.  When testing
for opens and shorts, do not ground or apply voltage to
any of the ECM circuits unless instructed to do so.  In
some cases, these circuits should only be tested using
a digital multimeter (DMM).  The ECM should remain
connected to the ECM harness.
The ECM is located behind the radio via mounting
bracket.  The ECM mainly controls the following.

• The fuel system control
• The exhaust gas recirculation (EGR) system

control

• The preheating (glow) system control
• A/C compressor control
• Exhaust brake control
• On-board diagnostics for engine control

The ECM constantly observes the information from
various sensors.  The ECM controls the systems that
affect vehicle performance.  The ECM performs the
diagnostic function of the system.  The ECM can
recognize operational problems, alert the driver
through the malfunction indicator lamp (MIL), and store
diagnostic trouble codes (DTCs).  DTCs identify the
system faults to aid the technician in making repairs.

ECM Voltage Description
The ECM supplies a buffered voltage to various
switches and sensors.  The ECM can do this because
resistance in the ECM is so high in value that a test
lamp may not illuminate when connected to the circuit.
An ordinary shop voltmeter may not give an accurate
reading because the voltmeter input impedance is too
low.  Use a 10-megaohm input impedance DMM, to
ensure accurate voltage readings.  The input and/or
output devices in the ECM include analog-to-digital
converters, signal buffers, counters, and special
drivers.  The ECM controls most components with
electronic switches which complete a ground circuit
when turned ON.

Aftermarket Electrical and Vacuum Equipment
Aftermarket or add-on electrical and vacuum
equipment is defined as any equipment which connects
to the vehicle’s electrical or vacuum systems that is
installed on a vehicle after the vehicle leaves the
factory.  No allowances have been made in the vehicle
design for this type of equipment.  No add-on vacuum
equipment should be added to this vehicle.  Add-on
electrical equipment must only be connected to the
vehicle’s electrical system at the battery power and
ground.  Add-on electrical equipment, even when
installed to these guidelines, may still cause the
powertrain system to malfunction.  This may also
include equipment not connected to the vehicle
electrical system such as portable telephones and
audios.  Therefore, the first step in diagnosing any
powertrain fault is to eliminate all aftermarket electrical
equipment from the vehicle.  After this is done, if the
fault still exists, the fault may be diagnosed in the
normal manner.

Electrostatic Discharge Damage
Electronic components used in the ECM are often
designed to carry very low voltage.  Electronic
components are susceptible to damage caused by
electrostatic discharge.  By comparison, as much as
4,000 volts may be needed for a person to feel even
the zap of a static discharge.  There are several ways
for a person to become statically charged.  The most
common methods of charging are by friction and
induction.

• An example of charging by friction is a person

sliding across a vehicle seat.

Important:
To prevent possible electrostatic discharge damage,
follow these guidelines:

• Do not touch the ECM connector pins or soldered

components on the ECM circuit board.

• Do not open the replacement part package until

the part is ready to be installed.

N6A3830E