ISUZU KB P190 2007 Workshop Repair Manual

Engine Control System (4JH1) 6E-77
Step Action Value(s) Yes No
13 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 14
14 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-78 Engine Control System (4JH1)
DTC P0105 (Symptom Code 2) (Flash Code 34)
Circuit Description
The vacuum pressure sensor is installed to the
turbocharger wastegate control hose and it detects the
regulated vacuum pressure to the turbocharge
r
wastegate valve. The vacuum pressure sensor is a
transducer that varies voltage according to changes in
the vacuum pressure inside the vacuum hose. The
vacuum pressure sensor has the following circuits.
• 5 volts reference circuit
• Low reference circuit
• Vacuum pressure sensor signal circuit
The engine control module (ECM) supplies 5 volts to
the vacuum pressure sensor on the 5 volts reference
circuit. The ECM also provides a ground on the lo
w
reference circuit. The vacuum pressure sensor provides
a signal to the ECM on the vacuum pressure signal
circuit which is relative to the vacuum pressure changes
in the turbocharger wastegate valve control hose. The
ECM should detect a low signal voltage at a high
vacuum pressure and high signal voltage at a lo
w
vacuum pressure. The ECM monitors the vacuum
pressure sensor signal for voltage outside the normal
range of the vacuum pressure sensor. If the ECM
detects an excessively low vacuum pressure senso
r
signal 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 vacuum pressure
sensor signal voltage is less than 0.5 volts for 3
seconds.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM limits fuel injection quantity.
• The ECM uses a barometric pressure of 615 hPa
for turbocharger wastegate valve control.
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.
Test Description
The number below refers to the step number on the
diagnostic table.
4. If the vacuum pressure sensor signal circuit between
the ECM and the sensor is normal, the sensor signal
voltage high DTC P0105 (Symptom Code 1) will set.

DTC P0105 (Symptom Code 2) (Flash Code 34)
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 vacuum pressure sensor harness connector.
3. Connect a DMM between the 5 volts reference circuit of the vacuum pressure sensor harness
(pin 3 of C-124 connector) and a known good
ground.
4. Turn ON the ignition, with the engine OFF.
Is the DMM voltage more than the specified value? 4.5 volts
Go to Step 4 Go to Step 5

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-79
Step Action Value(s) Yes No
4 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 vacuum pressure sensor harness (pins 1 and
3 of C-124 connector).
3. Turn ON the ignition, with the engine OFF.
4. Monitor the DTC Information with the scan tool.
Does DTC P0105 (Symptom Code 1) set, but not
DTC P0105 (Symptom Code 2)? 

Go to Step 7 Go to Step 6
5 1. Test the 5 volts reference circuit between the engine control module (ECM) (pin 82 of C-57
connector) harness and the vacuum pressure
sensor (pin 3 of C-124 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 11 Go to Step 8
6 1. Test the signal circuit between the ECM (pin 85 of C-57 connector) and the vacuum pressure
sensor (pin 1 of C-124 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 11 Go to Step 8
7 1. Turn OFF the ignition. 2. Inspect for an intermittent and for poor connections at the harness connector of the
vacuum pressure sensor (pins 1 and 3 of C-124
connector).
3. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 11 Go to Step 9
8 1. Turn OFF the ignition. 2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for poor connections on the vacuum pressure sensor
circuits at the harness connector of the ECM
(pins 82 and 85 of C-57 connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 11 Go to Step 10
9 Replace the vacuum pressure sensor. Refer to Vacuum Pressure Sensor Replacement in this
section.
Did you complete the replacement? 

Go to Step 11 
10 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 11 

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ISUZU KB P190 2007

6E-80 Engine Control System (4JH1)
Step Action Value(s) Yes No
11 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 12
12 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-81
DTC P0105 (Symptom Code 7) (Flash Code 34)
Circuit Description
The vacuum pressure sensor is installed to the
turbocharger wastegate control hose and it detects the
regulated vacuum pressure to the turbocharge
r
wastegate valve. The vacuum pressure sensor is a
transducer that varies voltage according to changes in
the vacuum pressure inside the vacuum hose. The
vacuum pressure sensor has the following circuits.
• 5 volts reference circuit
• Low reference circuit
• Vacuum pressure sensor signal circuit
The engine control module (ECM) supplies 5 volts to
the vacuum pressure sensor on the 5 volts reference
circuit. The ECM also provides a ground on the lo
w
reference circuit. If the ECM detects an excessively high
vacuum pressure 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 vacuum pressure
sensor 5 volts reference circuit voltage is more
than 5.2 volts for 2.5 seconds.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM limits fuel injection quantity.
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.

DTC P0105 (Symptom Code 7) (Flash Code 34)
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. Test the 5 volts reference circuit between the engine control module (ECM) (pin 82 of C-57
connector) and the vacuum pressure sensor (pin
3 of C-124 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 5 Go to Step 4
4 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 5 
5 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 6

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ISUZU KB P190 2007

6E-82 Engine Control System (4JH1)
Step Action Value(s) Yes No
6 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-83
DTC P0105 (Symptom Code 9) (Flash Code 34)
Circuit Description
The vacuum pressure sensor is installed to the
turbocharger wastegate control hose and it detects the
regulated vacuum pressure to the turbocharge
r
wastegate valve. The vacuum pressure sensor is a
transducer that varies voltage according to changes in
the vacuum pressure inside the vacuum hose. The
vacuum pressure sensor has the following circuits.
• 5 volts reference circuit
• Low reference circuit
• Vacuum pressure sensor signal circuit
The engine control module (ECM) supplies 5 volts to
the vacuum pressure sensor on the 5 volts reference
circuit. The ECM also provides a ground on the lo
w
reference circuit. If the ECM detects an excessively low
vacuum pressure 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 vacuum pressure
sensor 5 volts reference circuit voltage is less than
4.5 volts for 2.5 seconds.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM limits fuel injection quantity.
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.
Test Description
The number below refers to the step number on the
diagnostic table.
3. If the vacuum pressure sensor 5 volts reference
circuit between the ECM and the sensor is normal, the
sensor signal voltage low DTC P0105 (Symptom Code
2) will set.

DTC P0105 (Symptom Code 9) (Flash Code 34)
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 vacuum pressure sensor harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the DTC Information with the scan tool.
Does DTC P0105 (Symptom Code 2) set, but not
DTC P0105 (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 82 of C-57
connector) and the vacuum pressure sensor (pin
3 of C-124 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

6E-84 Engine Control System (4JH1)
Step Action Value(s) Yes No
5 Replace the vacuum pressure sensor. Refer to
Vacuum Pressure 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

Engine Control System (4JH1) 6E-85
DTC P0110 (Symptom Code 1) (Flash Code 23)
Circuit Description
The intake air temperature (IAT) sensor is fitted
between the air cleaner and turbocharger internal to the
mass air flow (MAF) sensor. The IAT sensor is a
variable resistor. The IAT sensor has a signal circuit
and a low reference circuit. The IAT sensor measures
the temperature of the air entering the engine. The
engine control module (ECM) supplies 5 volts to the IAT
signal circuit and a ground for the IAT low reference
circuit. W hen the IAT sensor is cold, the senso
r
resistance is high. W hen the air temperature increases,
the sensor resistance decreases. W ith high senso
r
resistance, the ECM detects a high voltage on the IAT
signal circuit. W ith lower sensor resistance, the ECM
detects a lower voltage on the IAT signal circuit. If the
ECM detects an excessively high IAT signal 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 IAT sensor signal
voltage is more than 4.7 volts for 3 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 an IAT substitution of 0 °C (32 °F)
for engine control.
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.
• Use the Temperature vs. Resistance table to test
the IAT sensor at various temperature levels to
evaluate the possibility of a skewed sensor.
A
skewed sensor could result in poor driveabilit
y
concerns.
Notice: • The mass air flow (MAF) sensor is heated and as
a result the IAT sensor may indicate a higher than
normal intake temperature if the ignition switch is
being ON.

DTC P0110 (Symptom Code 1) (Flash Code 23)
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 ON the ignition, with the engine OFF.
3. Observe the Intake Air Temperature (IAT) parameter with the scan tool.
Is the IAT parameter less than the specified value? -38°C (-36°F)
Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition. 2. Disconnect the mass air flow/intake air temperature (MAF/IAT) sensor harness
connector.
3. Connect a DMM between the signal circuit of the IAT sensor harness (pin 1 of C-116 connector)
and a known good ground.
4. Turn ON the ignition, with the engine OFF.
Is the DMM voltage more than the specified value? 5.5 volts
Go to Step 4 Go to Step 5
4 Important: The IAT sensor may be damaged if the
sensor signal circuit is shorted to a voltage source.
1. Test the signal circuit between the engine control module (ECM) (pin 84 of C-57 connector) and
the IAT sensor (pin 1 of C-116 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 14 Go to Step 13

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ISUZU KB P190 2007

6E-86 Engine Control System (4JH1)
Step Action Value(s) Yes No
5 1. Turn OFF the ignition.
2. Connect a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the
IAT sensor harness (pins 1 and 3 of C-116
connector).
3. Turn ON the ignition, with the engine OFF.
4. Observe the IAT parameter with the scan tool.
Is the IAT parameter more than the specified value? 110°C (230°F)
Go to Step 9 Go to Step 6
6 1. Turn OFF the ignition. 2. Connect a 3-amp fused jumper wire between the signal circuit of the IAT sensor harness (pin 1 of
C-116 connector) and a known good ground.
3. Turn ON the ignition, with the engine OFF.
4. Observe the IAT parameter with the scan tool.
Is the IAT parameter more than the specified value? 110°C (230°F)
Go to Step 8 Go to Step 7
7 1. Test the signal circuit between the ECM (pin 84 of C-57 connector) and the IAT sensor (pin 1 of
C-116 connector) for an open circuit high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 14 Go to Step 11
8 1. Test the low reference circuit between the ECM (pin 92 of C-57 connector) and the IAT sensor
(pin 3 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 14 Go to Step 11
9 1. Test the signal circuit between the ECM (pin 84 of C-57 connector) and the IAT sensor (pin 1 of
C-116 connector) for a short to any 5 volts
reference circuit.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 14 Go to Step 10
10 1. Turn OFF the ignition. 2. Inspect for an intermittent and for poor connections at the harness connector of the IAT
sensor (pins 1 and 3 of C-116 connector).
3. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 14 Go to Step 12
11 1. Turn OFF the ignition. 2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for poor connections on the IAT sensor circuits at the
harness connector of the ECM (pins 84 and 92 of
C-57 connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 14 Go to Step 13
12 Replace the IAT sensor. Refer to Mass Air Flow Sensor Replacement in this section. (IAT sensor is
internal to MAF sensor)
Did you complete the replacement? 

Go to Step 14 
13 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 14 

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TO MODEL INDEX
ISUZU KB P190 2007