Isuzu N-Series. Manual - part 772

 Engine Control System (4JH1)    6E-139

7

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 8

—

8

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.

Load the electrical system by turning ON the
headlights, A/C, etc.

6.

Observe the System Voltage parameter with
the Tech 2.

Is the System Voltage parameter more than the
specified value?

10 volts

Go to Step 9

Go to Step 4

9

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-140    Engine Control System (4JH1) 

P0560 (Symptom Code A) (Flash Code 35)

Circuit Description
The fuel injection pump control unit (PCU) monitors the
system voltage on the engine control module (ECM)
main relay load supply voltage terminal to make sure
that the voltage stays within the proper range.  If the
ECM detects an excessively high or low system
voltage, this DTC will set.

Condition for Setting the DTC

• The PCU detects that the battery voltage feed

circuit voltage is less than 4.5 volts or more than
27 volts.

Action Taken When the DTC Sets

• The ECM does not illuminate the malfunction

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

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.

• A charging system problem may set this DTC.
• Jump starting the vehicle or a battery charger may

have set this DTC.

Notice:

• PCU is part of the fuel injection pump assembly.

DTC P0560 (Symptom Code A) (Flash Code 35)
Schematic Reference: Engine Controls Schematics &
Starting and Charging Schematics
Connector End View Reference: Engine Controls
Connector End Views

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.

Is DTC P0560 (Symptom Code 1 or 2) set?

—

Go to Applicable 

DTC

Go to Step 3

3

1.

Start the engine and let idle for 30 seconds.

2.

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

Does the DTC fail this ignition?

—

Go to Step 4

Go to Diagnostic 

Aids

4

1.

Turn OFF the ignition.

2.

Disconnect the fuel injection pump control unit
(PCU) harness connector.

3.

Inspect for an intermittent, for poor
connections and corrosion on the voltage feed
or ground at the harness connector of the
PCU (pins 6 and 7 of E-110 connector).

4.

Repair or clean the connection(s) as
necessary.

Did you find and correct the condition?

—

Go to Step 6

Go to Step 5

5

Important:
The fuel injection pump must be timed to the
engine.

Replace the fuel injection pump.  Refer to Fuel
Injection Pump Replacement in engine mechanical
section.

Did you complete the replacement?

—

Go to Step 6

—

 Engine Control System (4JH1)    6E-141

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 and let idle for 30 seconds.

5.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

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-142    Engine Control System (4JH1) 

P0561 (Symptom Code A) (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 that the ignition voltage circuit is

changed ON to OFF during 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 if the ignition voltage

circuit is OFF even 1 second passes from the
judgement.

• The ECM limits fuel injection quantity if the ignition

voltage circuit is returned ON within 1 second from
the judgement.

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.

• Faulty or sticking ECM main relay may set this

DTC.

Notice:

• Quick repetition ON and OFF of ignition switch

may set this DTC.

Test Description
The numbers below refer to the step number on the
diagnostic table.
2. If DTC P1625 (Symptom Code B) is present, Tech 2
can communicate with the ECM when the ignition
switch is OFF.

DTC P0561 (Symptom Code A) (Flash Code 18)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

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.

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

Is DTC P1625 (Symptom Code B) set?

—

Go to Applicable 

DTC

Go to Step 3

3

1.

Turn OFF the ignition.

2.

Disconnect the ignition switch harness
connector (B-67) to the ignition switch (behind
the steering column).

3.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the ignition switch (pins 2 and 3
of B-67 connector).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 6

Go to Step 4