2007 ISUZU KB P190 Circuit

Engine Control System (4JH1) 6E-167
DTC P0560 (Symptom Code 2) (Flash Code 35)
Circuit Description
The engine control module (ECM) monitors the system
voltage on the ECM main relay load supply voltage
terminal to make sure that the voltage stays within the
proper range. If the ECM detects an excessively lo
w
system voltage, this DTC will set.
Condition for Setting the DTC
• The ECM detects that the battery voltage feed
circuit voltage is less than 7 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 scan tool.
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
• A charging system problem may set this DTC.

DTC P0560 (Symptom Code 2) (Flash Code 35)
Schematic Reference: Engine Controls Schematics &
Starting and Charging Schematics
Connector End View Reference: 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. Start the engine.
4. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Does the DTC fail this ignition? 

Go to Step 3 Go to Diagnostic
Aids
3 1. Start the engine and let idle for 30 seconds. 2. Load the electrical system by turning ON the headlights, A/C, etc.
3. Observe the System Voltage parameter with the scan tool.
Is the System Voltage parameter more than the
specified value? 10 volts
Go to Diagnostic Aids Go to Step 4
4 Test the charging system. Refer to Diagnosis of The Charging System in the Charging System Section.
Did you find a charging system problem? 

Go to Step 5 Go to Step 6
5 Repair the charging system. Refer to Diagnosis of The Charging System in the Charging System
Section.
Did you complete the repair? 

Go to Step 8 
6 1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent, for a poor connection and corrosion on the battery voltage feed at the
harness connector of the ECM (pin 3 of C-56
connector).
4. Repair or clean the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 8 Go to Step 7
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 

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-169
DTC 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 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 scan tool.
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 scan tool. 2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
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 scan tool.
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-6 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
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 and let idle for 30 seconds.
5. Monitor the DTC Information with the scan tool.
Did the DTC fail this ignition? 

Go to Step 2 Go to Step 7

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ISUZU KB P190 2007

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. W hen the ignition switch is OFF, the
ECM main relay is de-energized after a certain length o
f
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

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ISUZU KB P190 2007

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



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ISUZU KB P190 2007

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. W hen the ignition switch is OFF, the
ECM main relay is de-energized after a certain length o
f
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


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ISUZU KB P190 2007

6E-176 Engine Control System (4JH1)
DTC P0645 (Symptom Code 4) (Flash Code 46)
Circuit Description
The engine control module (ECM) controls the ai
r
conditioning (A/C) compressor relay, which supplies
power to the A/C compressor clutch based on A/C
request input to the ECM from the heating, ventilation
and air conditioning (HVAC) controls. The ECM
commands the A/C compressor relay ON at engine run.
If the ECM detects an open circuit or short to ground on
the A/C compressor relay control circuit, this DTC will
set.
Condition for Running the DTC
• The ignition switch is ON.

• The A/C compressor relay is once commanded
ON.
Condition for Setting the DTC
• The ECM detects a low voltage condition on the
A/C compressor relay control circuit for longer than
3 seconds when the relay is commanded OFF.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
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 scan tool.
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
Notice:
• The A/C compressor relay is commanded OFF
when the engine coolant temperature is reached
around 105°C (221°F) and it commanded ON
again below 100°C (212°F).

DTC P0645 (Symptom Code 4) (Flash Code 46)
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. Turn ON the ignition, with the engine OFF.
4. Turn ON the blower motor switch and the A/C compressor switch.
5. Turn OFF the A/C compressor switch.
6. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Does the DTC fail this ignition? 

Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition. 2. Replace the A/C compressor relay with the tail relay or replace with a known good relay.
3. Turn ON the ignition, with the engine OFF.
4. Turn ON the blower motor switch and the A/C compressor switch.
5. Turn OFF the A/C compressor switch.
6. Monitor the DTC Information with the scan tool.
Does the DTC fail this ignition? 

Go to Step 4 Go to Step 14
4 1. Turn OFF the ignition. 2. Inspect the ECM (10A) fuse (EB-4) in the engine room fuse block.
Is the ECM (10A) fuse (EB-4) open? 

Go to Step 5 Go to Step 6
5 Replace the ECM (10A) fuse (EB-4). If the fuse continues to open, repair the short to ground on one
of the circuits that is fed by the ECM (10A) fuse (EB-
4) or replace the shorted attached component fed by
the ECM (10A) fuse (EB-4).
Did you complete the repair? 

Go to Step 16 

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-177
Step Action Value(s) Yes No
6 1. Turn OFF the ignition.
2. Remove the A/C compressor relay.
3. Connect a test lamp between the voltage feed circuit of the A/C compressor relay coil side (pin
3 of X-14 connector) and a known good ground.
4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? 

Go to Step 7 Go to Step 9
7 1. Turn OFF the ignition. 2. Connect a test lamp between the A/C compressor relay control circuit (pin 5 of X-14
connector) and battery voltage.
3. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? 

Go to Step 10 Go to Step 8
8 1. Keep the test lamp with connected. 2. Start the engine.
3. Turn ON the blower motor switch and the A/C compressor switch.
Does the test lamp illuminate when the A/C
Compressor Relay parameter is ON? 

Go to Step 12 Go to Step 11
9 Repair the open circuit or high resistance on the voltage feed circuit between the ECM (10A) fuse
(EB-4) and the A/C compressor relay (pin 3 of X-14
connector).
Did you complete the repair? 

Go to Step 16 
10 1. Test the control circuit of the A/C compressor
relay between the ECM (pin 41 of C-56
connector) and the A/C compressor relay (pin 5
of X-14 connector) for a short to ground.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 16 Go to Step 15
11 1. Test the control circuit of the A/C compressor relay between the engine control module (ECM)
(pin 41 of C-56 connector) and A/C compressor
relay (pin 5 of X-14 connector) for an open circuit
or high resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 16 Go to Step 13
12 1. Turn OFF the ignition. 2. Inspect for an intermittent and for poor connections on the A/C compressor relay
terminal (pins 3 and 5 of X-14 connector).
3. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 16 Go to Step 14
13 1. Turn OFF the ignition. 2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for a poor connection on the A/C compressor relay control
circuit at the harness connector of the ECM (pin
41 of C-56 connector).
4. Repair the connection (s) as necessary.
Did you find and correct the condition? 

Go to Step 16 Go to Step 15
14 Replace the A/C compressor relay. Did you complete the replacement? 

Go to Step 16 

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-179
DTC P0645 (Symptom Code 8) (Flash Code 46)
Circuit Description
The engine control module (ECM) controls the ai
r
conditioning (A/C) compressor relay, which supplies
power to the A/C compressor clutch based on A/C
request input to the ECM from the heating, ventilation
and air conditioning (HVAC) controls. The ECM
commands the A/C compressor relay ON at engine run.
If the ECM detects a short to battery or ignition voltage
on the A/C compressor relay control circuit, this DTC
will set.
Condition for Running the DTC
• The ignition switch is ON.

• The A/C compressor relay is once commanded
ON.
Condition for Setting the DTC • The ECM detects a high voltage condition on the
A/C compressor relay control circuit for longer than
3 seconds when the relay is commanded ON.
Action Taken When the DTC Sets • The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
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 scan tool.
Diagnostic Aids • If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
Notice: • The A/C compressor relay is commanded OFF
when the engine coolant temperature is reached
around 105°C (221°F) and it commanded ON
again below 100°C (212°F).

DTC P0645 (Symptom Code 8) (Flash Code 46)
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. Start the engine.
4. Turn ON the blower motor switch and the A/C compressor switch.
5. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool when the A/C
Relay Command parameter is ON.
Does the DTC fail this ignition? 

Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition. 2. Replace the A/C compressor relay with the tail relay or replace with a known good relay.
3. Start the engine.
4. Turn ON the blower motor switch and the A/C compressor switch.
5. Monitor the DTC Information with the scan tool when the A/C Relay Command parameter is ON.
Does the DTC fail this ignition? 

Go to Step 4 Go to Step 5
4 1. Test the control circuit of the A/C compressor relay between the ECM (pin 41 of C-56
connector) and the A/C compressor relay (pin 5
of X-14 connector) for a short to battery or
ignition voltage.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 7 Go to Step 6
5 Replace the A/C compressor relay. Did you complete the replacement? 

Go to Step 7 

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TO MODEL INDEX
ISUZU KB P190 2007