Isuzu N-Series. Service manual - part 773

 Engine Control System (4JH1)    6E-143

4

1.

Turn OFF the ignition.

2.

Disconnect the engine control module (ECM)
harness connector.

3.

Inspect for an intermittent, for a poor
connection and corrosion on ignition voltage
feed circuit at the harness connector of the
ECM (pin 39 of B-234 connector).

4.

Test for high resistance on ignition voltage
feed circuit.

5.

Repair the connection(s) or circuit(s) as
necessary.

Did you find and correct the condition?

—

Go to Step 6

Go to Step 5

5

Replace the ignition switch.

Did you complete the replacement?

—

Go to Step 6

—

6

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with the Tech 2.

3.

Turn OFF the ignition for 30 seconds.

4.

Start the engine.

5.

Observe the DTC Information with the Tech 2.

6.

Turn OFF the ignition.

Does the DTC fail this ignition before the ECM
turns OFF?

—

Go to Step 2

Go to Step 7

7

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK

Step

Action

Value(s)

Yes

No

6E-144    Engine Control System (4JH1) 

P0561 (Symptom Code B) (Flash Code 18)

Circuit Description
The engine control module (ECM) main relay is
energized when the ECM receives an ignition voltage
switch ON signal.  When the ignition switch is OFF, the
ECM main relay is de-energized after a certain length
of time passed.  If the ECM detects the ignition voltage
switch signal is changed to OFF during the ECM is
energized, this DTC will set.

Condition for Setting the DTC

• The ECM detects internal ignition voltage feed

circuit is failed after initialization.

Action Taken When the DTC Sets

• The ECM does not illuminate the malfunction

indicator lamp (MIL) when the diagnostic runs and
fails.

• The ECM turns OFF the ECM.

Condition for Clearing the DTC

• A history DTC clears after 40 consecutive driving

cycles without a fault.  Or clear with the Tech 2.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

DTC P0561 (Symptom Code B) (Flash Code 18)

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic 

System Check – 

Engine Controls

2

1.

Install the Tech 2.

2.

Turn OFF the ignition for 30 seconds.

3.

Turn ON the ignition, with the engine OFF.

4.

Monitor the Diagnostic Trouble Code (DTC)
Information with the Tech 2.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Step 4

3

Important:
Replacement ECM must be programmed.

Replace the ECM.  Refer to Engine Control Module
(ECM) Replacement in this section.

Did you complete the replacement?

—

Go to Step 4

—

4

1.

Clear the DTCs with the Tech 2.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 5

5

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK

 Engine Control System (4JH1)    6E-145

P0602

Description
The engine control module (ECM) has the ability to set
a diagnostic trouble code (DTC) if it detects that there is
no vehicle identification (VIN) programmed.

Diagnostic Aids
Notice:

• Production and service ECM does not require

software programming when it is replaced except
calibration software update.  This DTC indicates
that a production or service ECM does not
program VIN.

DTC P0602

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic 

System Check – 

Engine Controls

2

1.

Install the Tech 2.

2.

Turn OFF the ignition for 30 seconds.

3.

Turn ON the ignition, with the engine OFF.

4.

Monitor the Diagnostic Trouble Code (DTC)
Information with the Tech 2.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Step 6

3

Important:
Blank engine control module (ECM) must be
programmed.

Program the ECM.  Refer to Engine Control Module
(ECM) Replacement in this section.

Did you complete the programming?

—

Go to Step 4

—

4

1.

Clear the DTCs with the Tech 2.

2.

Turn OFF the ignition for 30 seconds.

3.

Turn ON the ignition, with the engine OFF.

4.

Monitor the DTC Information with the Tech 2.

Does the DTC fail this ignition?

—

Go to Step 5

Go to Step 7

5

Important:
Replacement ECM must be programmed.

Replace the ECM.  Refer to Engine Control Module
(ECM) Replacement in this section.

Did you complete the replacement?

—

Go to Step 6

—

6

1.

Clear the DTCs with the Tech 2.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 7

7

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK

6E-146    Engine Control System (4JH1) 

P0606 (Symptom Code A, B) (Flash Code 28)

Description
This diagnostic applies to internal microprocessor
integrity conditions within the engine control module
(ECM).

Condition for Running the DTC
Symptom Code B

• The accelerator pedal position is less than 1%.
• The desired fuel injection quantity is 0 mg/strk.

Condition for Setting the DTC
Symptom Code A

• The ECM detects that the internal CPU does not

react.

Symptom Code B

• The ECM detects that the engine speed is higher

than 2000 RPM.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM cuts fuel injection.

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL when the diagnostic

runs and does not fail.

• A history DTC clears after 40 consecutive driving

cycles without a fault.  Or clear with the Tech 2.

DTC P0606 (Symptom Code A, B) (Flash Code 28)

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic 

System Check – 

Engine Controls

2

1.

Install the Tech 2.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Monitor the Diagnostic Trouble Code (DTC)
Information with the Tech 2.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Step 4

3

Important:
Replacement ECM must be programmed.

Replace the ECM.  Refer to Engine Control Module
(ECM) Replacement in this section.

Did you complete the replacement?

—

Go to Step 4

—

4

1.

Clear the DTCs with the Tech 2.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 5

5

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK