Isuzu 4JA1 Workshop Manual page 412

6E-158 Engine Control System (4JH1)
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.
Step
1 Did you perform the 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?
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
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?
Action
the ignition switch
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
Value(s)


harness

Yes
Go to Diagnostic
System Check-
Go to Step 2 Engine Controls
Go to Applicable
DTC Go to Step 3
Go to Step 6 Go to Step 4
No