Isuzu KB P190. Manual — part 301

6E-170 Engine Control System (4JH1)

Step Action

Value(s)

Yes

No

7

Observe the DTC Information with the scan tool.
Are there any DTCs that you have not diagnosed?



Go to Diagnostic

Trouble Code (DTC)

List System

OK

Engine Control System (4JH1) 6E-171

DTC 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 scan tool.

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 A) is present, scan
tool 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 scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Monitor the Diagnostic Trouble Code (DTC)

Information with the scan tool.

Is DTC P1625 (Symptom Code B) set?



Go to Applicable

DTC

Go to Step 3

3

1. Turn OFF the ignition.
2. Disconnect the battery voltage feed harness

connector (C-108) from the junction block
(behind the cabin fuse block).

3. Inspect for an intermittent, for a poor connection

and corrosion at the harness connector of the
battery voltage feed (pin 2 of C-108 connector).

4.

Disconnect the ignition switch harness
connectors (B-62 and B-63) from the junction
block (behind the cabin fuse block).

5. Inspect for an intermittent, for poor connections

and corrosion at the harness connector of the
ignition switch (pin 3 of B-62 connector and pin 3
of B-63 connector).

6. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 6

Go to Step 4

6E-172 Engine Control System (4JH1)

Step Action

Value(s)

Yes

No

4

1. Turn OFF the ignition.
2. Disconnect the ignition voltage feed harness

connector (C-107) from the junction block
(behind the cabin fuse block).

3. Inspect for an intermittent, for a poor connection

and corrosion at the harness connector of the
ignition voltage feed (pin 9 of C-107 connector).

4. Disconnect the engine control module (ECM)

harness connector.

5. 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 C-
56 connector).

6. Test for high resistance on ignition voltage feed

circuit.

7. 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 scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Observe the DTC Information with the scan tool.
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 scan tool.
Are there any DTCs that you have not diagnosed?



Go to Diagnostic

Trouble Code (DTC)

List System

OK

Engine Control System (4JH1) 6E-173

DTC 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 scan tool.

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 scan tool.
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 scan tool.

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 scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the DTC Information with the scan tool.
Did the DTC fail this ignition?



Go to Step 3

Go to Step 5

5

Observe the DTC Information with the scan tool.
Are there any DTCs that you have not diagnosed?



Go to Diagnostic

Trouble Code (DTC)

List System

OK