Isuzu N-Series. Manual - part 655

6E-42 Engine Control System (4HK1)

Reading Diagnostic Trouble Codes (DTCs) with The
Tech 2
The procedure for reading DTC(s) is used a diagnostic
Tech 2. To read DTCs, use the Tech 2 “Read DTC Info
As Stored By ECU”.

Clearing Diagnostic Trouble Codes (DTCs) with The
Tech 2 or without Tech 2
Do not clear DTCs unless directed to do so by the
service information provided for each diagnostic
procedure. To clear DTCs, use with the Tech 2 “Clear
DTC Information”. If there is no Tech 2, clear with
accelerator pedal operation.

Notice:
A history DTC clears after 20 consecutive driving
cycles without a fault.

DTC Clear Method with Accelerator Pedal Operation

1. Turn ON the ignition, with the engine OFF.
2. Use a jumper wire and the DLC terminal “1”

(diagnostic request) is pulled “Low” (grounded) by
jumped to DLC terminal “4”.

3. Depress accelerator pedal within 1 – 3 seconds.
4. Release accelerator pedal within 1 – 3 seconds.
5. Depress accelerator pedal within 1 – 3 seconds.
6. Release accelerator pedal within 1 – 3 seconds.
7. Depress accelerator pedal within 1 – 3 seconds.
8. Release accelerator pedal within 1 – 3 seconds.

Notice:
DO NOT touch the accelerator pedal when it is
released.

Tech 2 Scan Tool

Isuzu recommend using Tech 2. Refer to the Tech 2
Users Guide for proper start up procedures.

Operating Procedure

1. Press Enter at start screen.
2. Select Diagnostic > appropriate vehicle

identification > Engine > 4HK1(Common Rail).

3. The following table shows, which functions are

used the available equipment versions.

N6A6472E

F0: Diagnostic Trouble Codes

F0: Read DTC Info As Stored By ECU

F1: Clear DTC Information

F1: Data Display

F2: Snapshot

F3: Actuator Test

F0: Fuel System

F0: Rail Pressure Control

F1: Injector Balancing

F2: Injection Timing

F3: Pre Injection Stop

F4: Injector Forced Drive

F1: Device Controls

F0: Glow Plug Relay

F1: Exhaust Brake Control

F2: EGR Control

F4: Programming

F0: Injector ID Code

F1: ID Code Registration

F2: Upload ID Code

F3: Download ID Code

N6A6473E

Engine Control System (4HK1) 6E-43

F0: Diagnostic Trouble Codes
The purpose of this mode is to display stored trouble
code in the ECM. When “Clear DTC Information” is
selected, “Clear DTC Information”, warning screen
appears. This screen informs you that by cleaning
DTCs “all stored DTC information in the ECM will be
erased”.

F1: Data Display
The purpose of this mode is to continuously monitor
data parameters. The current actual values of all
important sensors and signals, solenoid commands in
the system are display through this mode.
Refer to the Tech 2 Data List in this section.

F2: Snapshot
“Snapshot” allow you to focus on making the condition
occur, rather than trying to view all of the data in
anticipation of the fault. The snapshot will collect
parameter information around a trigger point that you
select.
Refer to the Tech 2 user instructions for more
information.

F3: Actuator Test
The purpose of this mode is to check for correct
operation of electronic system actuators. Using
actuator test menus can test the state of each actuator
and related sensors. Especially when DTC cannot be
detected, a faulty circuit can be diagnosed by testing.
Even DTC has been detected, the circuit tests using
these menus could help discriminate between a
mechanical trouble and an electrical trouble.

Refer to the Tech 2 Output Controls in this section.

F4: Programming
The purpose of this mode is to program the fuel injector
ID code into the ECM if the fuel injector or ECM is to be
replaced.

Tech 2 Data List

The Tech 2 Data List contains all engine related
parameters that are available on the Tech 2. Use the
Tech 2 Data List only after the following is determined:

• The Diagnostic System Check – Engine Controls

is completed.

• No diagnostic trouble codes (DTCs) are present.
• On-board diagnostics are functioning properly.

Tech 2 values from a properly running engine may be
used for comparison with the engine you are
diagnosing. The Tech 2 Data List represents values
that would be seen on a normal running engine.

Important:
A Tech 2 that displays faulty data should not be used.
The Tech 2 problem should be reported to the
manufacturer. Use of a faulty Tech 2 can result in
misdiagnosis and unnecessary parts replacement.
Only the parameters listed below are referenced in this
service manual for use in diagnosis.

Tech 2 Parameter

Units Displayed

Typical Data Value at

Engine Idle

Typical Data Value at 1600

RPM

Operating Conditions: Engine Idling or 1600 RPM / Engine Coolant Temperature is between 75-85

°C (167-185°F) / Accelerator

Pedal is Constant / Neutral / Accessories OFF / Vehicle Located at Sea Level

Ignition Voltage

22.0 – 30.0

Battery Voltage

22.0 – 30.0

Desired Idle Speed

RPM

650

Engine Speed

RPM

600 – 700

1550 – 1650

APP Sensor 1 (Accelerator Pedal Position)

0.3 – 0.7

1.2 – 1.6

APP Sensor 2 (Accelerator Pedal Position)

4.1 – 4.5

3.4 – 3.8

Accelerator Pedal Position (APP) Angle

20 – 26

Differential Fuel Rail Pressure

MPa / psi

-5 – 5 MPa / -725 – 725 psi -5 – 5 MPa / -725 – 725 psi

Fuel Rail Pressure Sensor

1.4 – 1.6

More than 2.0 volts

Rail Pressure Feedback

Shutoff Mode /

Wait Mode /

Feedback Mode

Fuel Rail Pressure (FRP) Regulator Command

35 – 45

30 – 40

FRP Regulator Feedback

900 – 1300

800 – 1200

Coolant Temperature Sensor

0.4 – 0.6

6E-44 Engine Control System (4HK1)

Coolant Temperature

°C / °F

75 – 85

°C / 167 – 185°F

75 – 85

°C / 167 – 185°F

Intake Air Temperature Sensor

1.1 – 2.1

Intake Air Temperature

°C / °F

20 – 40

°C / 68 – 104°F

20 – 40

°C / 68 – 104°F

Fuel Temperature Sensor

2.4 – 2.8

Fuel Temperature

°C / °F

20 – 50

°C / 50 – 122°F

20 – 50

°C / 50 – 122°F

Barometric Pressure Sensor

Nearly 2.3 volts at sea

level

Nearly 2.3 volts at sea

level

Barometric Pressure

KPa / psi

Nearly 100 KPa / 14.5 psi

at sea level

Nearly 100 KPa / 14.5 psi

at sea level

EGR Position Sensor

Less than 1.5 volts

Less than 2.0 volts

EGR Position Variance

-5 – 5%

EGR Solenoid Command

Less than 20%

Less than 30%

Boost Pressure Sensor

Nearly 1.0 volt at sea level

Less than 1.3 volts at sea

level

Boost Pressure

KPa / psi

Nearly 100 KPa / 14.5 psi

at sea level

Less than 115 KPa / 16.7

psi at sea level

ASR System Command APP Angle

100

Vehicle Speed

Km/h / MPH

Cylinder 1 Compensation

/st

-5.0 – 5.0 (Varies)

0.0

Cylinder 2 Compensation

/st

-5.0 – 5.0 (Varies)

0.0

Cylinder 3 Compensation

/st

-5.0 – 5.0 (Varies)

0.0

Cylinder 4 Compensation

/st

-5.0 – 5.0 (Varies)

0.0

Engine Mode

Halt Mode / Wait

Mode / Crank

Mode / Fuel Mode

Fuel Mode

Engine Warm Up Switch

On / Off

Off

Ignition Switch

On / Off

Starter Switch

On / Off

Off

Clutch Pedal Switch

Applied / Release

Released

Park / Neutral Switch

On / Off

Parking Brake Switch

Applied / Released

Applied

Exhaust Brake Switch

On / Off

Off

Exhaust Brake Solenoid Valve Command

On / Off

Off

PTO Switch

On / Off

Off

PTO Remote Throttle Angle

PTO Remote Throttle Sensor

Less than 0.4 volts

Idle Up Sensor

0.3 – 0.6

A/C Clutch Switch (Air Conditioning)

On / Off

Off

ABS Exh. Brake Cut Request

Yes / No

TCM Exh. Brake Cut Request

Yes / No

Refrigerator Switch

On / Off

Off

Glow Relay Command

On / Off

Off

Glow Indicator Lamp Command

On / Off

Off

Tech 2 Parameter

Units Displayed

Typical Data Value at

Engine Idle

Typical Data Value at 1600

RPM

Engine Control System (4HK1) 6E-45

Tech 2 Data Definitions

A list of each message displayed on the Tech 2 will be
explained in Engine Controls. This information will
assist in emission or driveability problems. The displays
can be viewed while the vehicle is being driven. Always
perform the Diagnosis System Check – Engine
Controls first. The Diagnostic System Check will
confirm proper system operation.

Ignition Voltage
This parameter displays the ignition voltage measured
at the ignition feed circuit of the ECM. Voltage is
applied to the ECM when the ignition switch is ON
position.

Battery Voltage
This parameter displays the battery voltage measured
at the ECM main relay switched voltage feed circuit of
the ECM. Voltage is applied to the ECM when the ECM
main relay is energized.

Desired Idle Speed
This parameter displays the idle speed requested by
the ECM. The ECM will change desired idle speed
based on engine coolant temperature (ECT) and Idle
up sensor status.

Engine Speed
This parameter displays the speed of the crankshaft as
calculated by the ECM based on inputs from the
crankshaft position (CKP) sensor or camshaft position
(CMP) sensor. The Tech 2 will display the engine speed
in revolution per minute (RPM).

APP Sensor 1 (Accelerator Pedal Position)
This parameter displays the voltage signal sent to the
ECM from the accelerator pedal position (APP) sensor
1 of the APP sensor assembly. APP sensor 1 is a range
of values indicating a low voltage when the accelerator
pedal is not depressed to a high voltage when the
accelerator pedal is fully depressed.

APP Sensor 2 (Accelerator Pedal Position)
This parameter displays the voltage signal sent to the
ECM from the accelerator pedal position (APP) sensor
2 of the APP sensor assembly. APP sensor 2 is a range
of values indicating a high voltage when the accelerator
pedal is not depressed to a low voltage when the
accelerator pedal is fully depressed.

Accelerator Pedal Position (APP) Angle
This parameter displays the angle of the accelerator
pedal as calculated by the ECM using the signals from
the accelerator pedal position sensors. The APP
indicated angle is a range of values indicating a low
percentage when the accelerator pedal is not
depressed to a high percentage when the accelerator
pedal is fully depressed.

Differential Fuel Rail Pressure
This parameter displays the difference of actual and
desired fuel rail pressure (actual value – desired value)
as calculated by the ECM using the signal from the fuel
rail pressure (FRP) sensor. The negative value is
indicating a lower actual fuel rail pressure. The positive
value is indicating a higher actual fuel rail pressure.

Fuel Rail Pressure Sensor
This parameter displays the voltage signal sent to the
ECM from the fuel rail pressure (FRP) sensor. FRP
sensor is a range of values indicating a low voltage
when the fuel rail pressure is low to a high voltage
when the fuel rail pressure is high.

Rail Pressure Feedback
This parameter displays the state of the fuel rail
pressure feedback to the ECM. Wait Mode indicates
the ignition switch is turned ON position. Feedback
Mode indicates the engine is during crank or run.
Shutoff Mode indicates the ignition switch is turned
OFF position.

Fuel Rail Pressure (FRP) Regulator Command
This parameter displays the fuel rail pressure (FRP)
regulator control duty ratio signal based on inputs to the
ECM from various engine sensors. The Tech 2 will
display a low percentage when the FRP regulator is
controlled to open (fuel supply quantity to the fuel rail is
increased). The Tech 2 will display a high percentage
when the FRP regulator is controlled to close (fuel
supply quantity to the fuel rail is reduced).

FRP Regulator Feedback
This parameter displays the fuel rail pressure (FRP)
regulator control feedback current as calculated by the
ECM. The Tech 2 will display a low current when the
FRP regulator is controlled to open (fuel supply
quantity to the fuel rail is increased). The Tech 2 will
display a high current when the FRP regulator is
controlled to close (fuel supply quantity to the fuel rail is
reduced).

Coolant Temperature Sensor
This parameter displays the voltage signal sent to the
ECM from the engine coolant temperature (ECT)
sensor. Coolant temperature sensor is a range of value
indicating a low voltage when the temperature is high
and a high voltage when the temperature is low.

Coolant Temperature
This parameter displays the temperature of the engine
coolant as calculated by the ECM using the signal from
the engine coolant temperature (ECT) sensor. The
Tech 2 will display a low temperature when the ECT
sensor signal voltage is high, and a high temperature
when the ECT sensor signal voltage is low.

Intake Air Temperature Sensor
This parameter displays the voltage signal sent to the
ECM from the intake air temperature (IAT) sensor. IAT
is a range of value indicating a low voltage when the
temperature is high and a high voltage when the
temperature is low.

Content .. 653 654 655 656 ..