2007 ISUZU KB P190 ECO mode

6E-64 Engine Control System (4JH1)
DTC
(Symptom Code) Flash
Code MIL
Status DTC Name on
scan tool Condition for
Running the DTC Condition for
Setting the DTC Possible Cause
P1625
(B) 76 OFF ECM Main Relay
Circuit •
The ignition switch
is OFF. •
The ECM detects
that the ECM main
relay is turned ON
for longer than 2
seconds. •
ECM main relay control circuit is
short to ground.
• ECM battery voltage circuit is
short to battery.
• Faulty ECM main relay.
• Faulty ECM.

P1630 (A) 51 ON Injection Pump
Fuel Metering
Control
 •
The ECM detects
that the PCU
monitored fuel
injection solenoid
valve control
current is too high.
•
Faulty fuel injection pump.
• Faulty PCU.

P1630 (B) 51 ON Injection Pump
Fuel Metering
Control
 •
The ECM detects
that the PCU
continuously flow
the control current
to the fuel injection
solenoid valve.
•
Faulty fuel injection pump.
• Faulty PCU.

P1650 (A) 44 ON CAN Device
Offline
 •
The ECM detects
that the PCU
receives from the
CAN controller
reset or Bus Offline.
•
CAN high circuit is open circuit,
high resistance, short to ground,
short to battery or ignition
voltage.
• CAN low circuit is open circuit,
high resistance, short to ground,
short to battery or ignition
voltage.
• Electrical interference.
• Magnetic interference.
• Faulty PCU.
• Faulty ECM.

P1650 (B) 44 ON CAN Device Hang-
up
 •
The ECM detects
internal CAN
controller does not
react.
•
Faulty ECM.


P1651 (A) 45 ON CAN Malfunction
 •
The ECM detects
that the PCU does
not receive the CAN
messages from the
ECM.
•
CAN high circuit is open circuit,
high resistance, short to ground,
short to battery or ignition
voltage.
• CAN low circuit is open circuit,
high resistance, short to ground,
short to battery or ignition
voltage.
• Electrical interference.
• Magnetic interference.
• Faulty PCU.
• Faulty ECM.


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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-65
DTC
(Symptom Code) Flash
Code MIL
Status DTC Name on
scan tool Condition for
Running the DTC Condition for
Setting the DTC Possible Cause
P1651
(B) 45 ON CAN Malfunction
 •
The ECM does not
receive the CAN
messages from the
PCU.
•
CAN high circuit is open circuit,
high resistance, short to ground,
short to battery or ignition
voltage.
• CAN low circuit is open circuit,
high resistance, short to ground,
short to battery or ignition
voltage.
• Electrical interference.
• Magnetic interference.
• Faulty PCU.
• Faulty ECM.

P1690 (4) 77 OFF Malfunction
Indicator Lamp
(MIL) Control
Circuit Low
Voltage •
The ignition switch
is ON. •
The ECM detects a
low voltage
condition on the
MIL control circuit
for longer than 3
seconds when the
MIL is commanded
OFF.
•
Meter (15A) fuse (C-14) open.
• MIL ignition voltage feed circuit
is open circuit or high resistance.
• MIL control circuit is open circuit,
high resistance or short to
ground.
• Poor harness connector
connection.
• MIL bulb burned out.
• Faulty instrument panel cluster
(meter assembly).
• Faulty ECM.

P1690 (8) 77 OFF Malfunction
Indicator Lamp
(MIL) Circuit High
Voltage •
The ignition switch
is ON. •
The ECM detects a
high voltage
condition on the
MIL control circuit
for longer than 1
second when the
MIL is commanded
ON.
•
MIL control circuit is short to
battery or ignition voltage circuit.
• Faulty instrument panel cluster
(meter assembly).
• Faulty ECM.


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ISUZU KB P190 2007

6E-66 Engine Control System (4JH1)
DTC P0100 (Symptom Code 7) (Flash Code 65)
Circuit Description
The mass air flow (MAF) sensor is an air flow meter that
measures the amount of air that enters the engine. It is
fitted between the air cleaner and turbocharger. A small
quantity of air that enters the engine indicates
deceleration or idle speed. A large quantity of air that
enters the engine indicates acceleration or a high load
condition. The MAF sensor has the following circuits.
• Ignition voltage circuit
• 5 volts reference circuit
• Low reference circuit
• MAF sensor signal circuit
The engine control module (ECM) provides 5 volts
reference voltage through the reference circuit to the
MAF sensor. The ECM monitors the voltage on the 5
volts reference circuit. If the ECM detects an
excessively high MAF sensor 5 volts reference voltage,
this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.
Condition for Setting the DTC
• The ECM detects that the MAF sensor 5 volts
reference circuit voltage is more than 5.2 volts fo
r
0.5 seconds.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM uses a MAF substitution of 1600 mg/strk
for engine control.
• The ECM uses an EGR solenoid valve control
substitution of 10%.
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 MAF Sensor parameter on the scan tool will
only update with engine running.
Test Description
The number below refers to the step number on the
diagnostic table.
3. If the MAF sensor 5 volts reference circuit between
the ECM and the sensor is normal, the sensor signal
voltage low DTC P0100 (Symptom Code B) will set.

DTC P0100 (Symptom Code 7) (Flash Code 65)
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. 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. Disconnect the mass air flow (MAF) sensor harness connector.
3. Start the engine and let idle for 30 seconds.
4. Monitor the DTC Information with the scan tool.
Does DTC P0100 (Symptom Code B) set, but not
DTC P0100 (Symptom Code 7)? 

Go to Step 5 Go to Step 4

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-67
Step Action Value(s) Yes No
4 1. Test the 5 volts reference circuit between the
engine control module (ECM) (pin 83 of C-57
connector) and the MAF sensor (pin 4 of C-116
connector) for the following conditions: • A short to battery or ignition voltage
• A short to the sensor 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 MAF sensor. Refer to Mass Air Flow Sensor Replacement in this section.
Did you complete the replacement? 

Go to Step 7 
6 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 7 
7 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. Monitor the DTC Information with the scan tool.
Did the DTC fail this ignition? 

Go to Step 3 Go to Step 8
8 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-68 Engine Control System (4JH1)
DTC P0100 (Symptom Code 9) (Flash Code 65)
Circuit Description
The mass air flow (MAF) sensor is an air flow meter that
measures the amount of air that enters the engine. It is
fitted between the air cleaner and turbocharger. A small
quantity of air that enters the engine indicates
deceleration or idle speed. A large quantity of air that
enters the engine indicates acceleration or a high load
condition. The MAF sensor has the following circuits.
• Ignition voltage circuit
• 5 volts reference circuit
• Low reference circuit
• MAF sensor signal circuit
The engine control module (ECM) provides 5 volts
reference voltage through the reference circuit to the
MAF sensor. The ECM monitors the voltage on the 5
volts reference circuit. If the ECM detects an
excessively low MAF sensor 5 volts reference voltage,
this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.
Condition for Setting the DTC
• The ECM detects that the MAF sensor 5 volts
reference circuit voltage is less than 4.6 volts fo
r
0.5 seconds.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
•
The ECM uses a MAF substitution of 1600 mg/strk
for engine control.
• The ECM uses an EGR solenoid valve control
substitution of 10%.
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 MAF Sensor parameter on the scan tool will
only update with engine running.
Test Description
The number below refers to the step number on the
diagnostic table.
3. If the MAF sensor 5 volts reference circuit between
the ECM and the sensor is normal, the sensor signal
voltage low DTC P0100 (Symptom Code B) will set.

DTC P0100 (Symptom Code 9) (Flash Code 65)
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. 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. Disconnect the mass air flow (MAF) sensor harness connector.
3. Start the engine and let idle for 30 seconds.
4. Monitor the DTC Information with the scan tool.
Does DTC P0100 (Symptom Code B) set, but not
DTC P0100 (Symptom Code 9)? 

Go to Step 5 Go to Step 4
4 1. Test the 5 volts reference circuit between the engine control module (ECM) (pin 83 of C-57
connector) and the MAF sensor (pin 4 of C-116
connector) for the following conditions: • A short to ground
• A short to the low reference circuit
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 7 Go to Step 6

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-69
Step Action Value(s) Yes No
5 Replace the MAF sensor. Refer to Mass Air Flow
Sensor Replacement in this section.
Did you complete the replacement? 

Go to Step 7 
6 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 7 
7 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. Monitor the DTC Information with the scan tool.
Did the DTC fail this ignition? 

Go to Step 3 Go to Step 8
8 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-70 Engine Control System (4JH1)
DTC P0100 (Symptom Code B) (Flash Code 65)
Circuit Description
The mass air flow (MAF) sensor is an air flow meter that
measures the amount of air that enters the engine. It is
fitted between the air cleaner and turbocharger. A small
quantity of air that enters the engine indicates
deceleration or idle speed. A large quantity of air that
enters the engine indicates acceleration or a high load
condition. The MAF sensor has the following circuits.
• Ignition voltage circuit
• 5 volts reference circuit
• Low reference circuit
• MAF sensor signal circuit
The engine control module (ECM) monitors the MAF
sensor signal for voltage outside the normal range o
f
the MAF sensor. If the ECM detects an excessively low
MAF sensor signal voltage, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.
• The engine is running.
Condition for Setting the DTC
• The ECM calculated MAF is lower than -18.6 kg/h
for 5 seconds. This indicates the ECM detects that
the MAF sensor signal voltage is smaller than a
predetermined range during engine run.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM uses a MAF substitution of 1600 mg/strk
for engine control.
• The ECM uses an EGR solenoid valve control
substitution of 10%.
Condition for Clearing the MIL/DTC
• The ECM turns OFF the MIL that 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: • W rong direction of MAF sensor installation will
cause this DTC to set.
• Contaminated or restricted MAF sensor will cause
this DTC to set.
• The MAF Sensor parameter on the scan tool will
only update with engine running.
Test Description
The number below refers to the step number on the
diagnostic table.
7. If the MAF sensor signal circuit between the ECM
and the sensor is short to ground or any low reference
circuits, the sensor 5 volts reference voltage low DTC
P0100 (Symptom Code 9) will set.
8. If the MAF sensor signal circuit between the ECM
and the sensor is normal, the sensor signal voltage high
DTC P0100 (Symptom Code C) will set.

DTC P0100 (Symptom Code B) (Flash Code 65)
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 and let idle for 30 seconds.
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. 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 4 Go to Step 5
4 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 17 

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-71
Step Action Value(s) Yes No
5 1. Turn OFF the ignition.
2. Disconnect the mass air flow (MAF) sensor harness connector.
3. Connect a test lamp between the ignition voltage feed circuit of the MAF sensor harness (pin 2 of
C-116 connector) and a known good ground.
4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? 

Go to Step 6 Go to Step 9
6 1. Keep the ignition ON, with the engine OFF. 2. Connect a DMM between the 5 volts reference circuit of the MAF sensor harness (pin 4 of C-116
connector) and a known good ground.
Is the DMM voltage more than the specified value? 4.5 volts
Go to Step 7 Go to Step 10
7 1. Turn OFF the ignition. 2. Connect a 3-amp fused jumper wire between the 5 volts reference circuit and the signal circuit of
the MAF sensor harness (pins 4 and 5 of C-116
connector).
3. Turn ON the ignition, with the engine OFF. DO NOT start the engine.
4. Monitor the DTC Information with the scan tool.
Does DTC P0100 (Symptom Code 9) set, but not
DTC P0100 (Symptom Code B)? 

Go to Step 11 Go to Step 8
8 1. Keep the 3-amp fused jumper wire with connected.
2. Start the engine and let idle for 30 seconds.
Does DTC P0100 (Symptom Code C) set, but not
DTC P0100 (Symptom Code B)? 

Go to Step 13 Go to Step 12
9 Repair the open circuit or high resistance on the ignition voltage feed circuit between the ECM (10A)
fuse (EB-4) and the MAF sensor (pin 2 of C-116
connector).
Did you complete the repair? 

Go to Step 17 
10 1. Test the 5 volts reference circuit between the
engine control module (ECM) (pin 83 of C-57
connector) and the MAF sensor (pin 4 of C-116
connector) for the following conditions: • An open circuit
• A short to ground
• A short to the low reference circuit
• High resistance
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 17 Go to Step 14
11 1. Test the signal circuit between the ECM (pin 88 of C-57 connector) and the MAF sensor (pin 5 of
C-116 connector) for the following conditions: • A short to ground
• A short to the low reference circuit
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 17 Go to Step 16
12 1. Test the signal circuit between the ECM (pin 88 of C-57 connector) and the MAF sensor (pin 5 of
C-116 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 17 Go to Step 14

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ISUZU KB P190 2007