ISUZU KB P190 2007 Workshop Repair Manual

Engine Control System (4JH1) 6E-107
DTC P0243 (Symptom Code 3) (Flash Code 64)
Circuit Description
The engine control module (ECM) controls the
turbocharger wastegate valve based on the barometric
pressure in order to reduce turbocharger spinning
speeds at high altitude area. The ECM controls the
turbocharger wastegate valve diaphragm by acting the
regulated vacuum pressure via controlling the solenoid
valve. The vacuum pressure sensor monitors the
regulated vacuum pressure to the turbocharge
r
wastegate valve. The ECM calculates desired vacuum
pressure and it compares the calculated desired
vacuum pressure to the actual value to determine the
solenoid valve position. W hen the actual vacuum
pressure is higher than the desired value, the solenoid
valve is closed to decrease the vacuum pressure. An
expected vacuum pressure amount should be detected
while the engine running. If the ECM detects the actual
vacuum pressure amount is higher than desired
vacuum pressure amount, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.
• The barometric pressure (BARO) is between 0
hPa and 3500 hPa.
• The intake air temperature (IAT) is between -50°C
(-58 °F) and 200°C (392°F).
• The engine coolant temperature (ECT) is between
-50°C (-58 °F) and 150°C (302°F)
Condition for Setting the DTC
• The ECM detects that the vacuum pressure is 50
hPa higher than the desired vacuum pressure for
3 seconds. This indicates excessive high vacuum
pressure.
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 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.
• Misrouted vacuum hoses will cause this DTC to
set.
Test Description
The numbers below refer to the step number on the
diagnostic table.
4. A skewed vacuum pressure sensor value (shifted to
a high pressure) can set this DTC. The Vacuum
Pressure on the scan tool should read near doubled
barometric pressure (BARO) with the key ON and
engine OFF.
5. A skewed BARO sensor value (shifted to a lowe
r
pressure) may set this DTC. The BARO on the scan
tool should read near surrounding barometric pressure.

DTC P0243 (Symptom Code 3) (Flash Code 64)
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.
Is DTC P0105 (Symptom Code 1, 2, 7 or 9) or
P0243 (Symptom Code 4 or 8) set? 

Go to Applicable DTC Go to Step 3

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

6E-108 Engine Control System (4JH1)
Step Action Value(s) Yes No
3 1. Turn OFF the ignition.
2. Inspect for the following conditions: • Vacuum hoses are damaged or kinked.
• Misrouted vacuum hoses.
• A turbocharger solenoid valve is damaged.
• A vacuum pump is damaged.
• A vacuum regulating valve is damaged.
• A turbocharger wastegate valve is
damaged.
• Contaminated, skewed or slow vacuum
pressure sensor.
3. Repair or replace as necessary.
Did you find and correct the condition? 

Go to Step 15 Go to Step 4
4 1. Turn ON the ignition, with the engine OFF. 2. Observe the Vacuum Pressure Sensor and Barometric Pressure (BARO) with the scan tool.
Does the scan tool indicate that the difference
between the Vacuum Pressure Sensor and doubled
BARO is less than the specified value? 10 hPa

Go to Step 7 Go to Step 5
5 1. Observe the BARO parameter with the scan tool.2. Compare the BARO value to the range specified in the altitude vs. barometric pressure table.
Refer to Altitude vs. Barometric Pressure.
Is the BARO parameter within the range specified? 

Go to Step 6 Go to Step 14
6 1. Turn OFF the ignition. 2. Disconnect the vacuum pressure sensor harness connector.
3. Inspect for an intermittent and for poor connections at the vacuum pressure sensor
harness connector (pins 1 and 3 of C-124
connector).
4. Disconnect the engine control module (ECM) harness connector.
5. Inspect for an intermittent, for poor connections and corrosion on each vacuum pressure sensor
circuit at the harness connector of the ECM (pins
82 and 85 of C-57 connector).
6. Test for high resistance on each vacuum pressure sensor circuit.
7. Test the vacuum pressure sensor signal circuit short to any other circuits.
8. Repair the connection(s) or circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 15 Go to Step 10
7 1. Turn OFF the ignition. 2. Disconnect the vacuum hose from the turbocharger wastegate valve that is connected
to the vacuum pressure sensor and the
turbocharger solenoid valve.
3. Connect a hand-held vacuum pump (5-8840- 0279-0/J-23738-A) to the turbocharger
wastegate valve. This test is in order to verify an
airtight of the turbocharger wastegate valve
inside.
4. Start the engine and let engine idle.
Does the hand-held vacuum pump indicate any
vacuum pressure? 

Go to Step 13 Go to Step 8

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Control System (4JH1) 6E-109
Step Action Value(s) Yes No
8 1. Turn OFF the ignition.
2. Disconnect the hand-held vacuum pump from the turbocharger wastegate valve.
3. Reconnect the vacuum hose to the turbocharger wastegate valve.
4. Disconnect the vacuum hose from the turbocharger solenoid valve that is connected to
the vacuum regulating valve “Z” port.
5. Connect a hand-held vacuum pump (5-8840- 0279-0/J-23738-A) to the disconnected vacuum
hose.
6. Start the engine and let engine idle.
Does the hand-held vacuum pump indicate less than
28 cmHg (11 inHg)? 

Go to Step 9 Go to Step 12
9 1. Turn OFF the ignition. 2. Disconnect the hand-held vacuum pump from the vacuum hose.
3. Reconnect the vacuum hose to the turbocharger solenoid valve.
4. Disconnect the vacuum hose from the vacuum pressure sensor that is connected to the
turbocharger solenoid valve and the turbocharger
wastegate valve.
5. Connect a hand-held vacuum pump (5-8840- 0279-0/J-23738-A) to the disconnected vacuum
hose.
6. Disconnect the vacuum pressure sensor harness connector in order to active turbocharger
solenoid valve.
7. Start the engine and let engine idle.
Does the needle of hand-held vacuum pump shake
between 0 and 20 cmHg (8 inHg)? 

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

Go to Step 15 

11 Replace the turbocharger solenoid valve. Refer to
Turbocharger Solenoid Valve Replacement in this
section.
Did you complete the replacement? 

Go to Step 15 

12 Replace the vacuum regulating valve.
Did you compete the replacement? 

Go to Step 15 

13 Replace the turbocharger wastegate valve. Refer to
Turbocharger in Engine Mechanical section.
Did you complete the replacement? 

Go to Step 15 

14 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 15 
15 1. Reconnect all previously disconnected hoses or
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 2 Go to Step 16

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

6E-110 Engine Control System (4JH1)
Step Action Value(s) Yes No
16 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


BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Control System (4JH1) 6E-111
DTC P0243 (Symptom Code 4) (Flash Code 64)
Circuit Description
The engine control module (ECM) controls the
turbocharger wastegate valve based on the barometric
pressure in order to reduce turbocharger spinning
speeds at high altitude area. The ECM controls the
turbocharger wastegate valve diaphragm by acting the
regulated vacuum pressure via controlling the solenoid
valve. The vacuum pressure sensor monitors the
regulated vacuum pressure to the turbocharge
r
wastegate valve. The ECM calculates desired vacuum
pressure and it compares the calculated desired
vacuum pressure to the actual value to determine the
solenoid valve position. W hen the actual vacuum
pressure is higher than the desired value, the solenoid
valve is closed to decrease the vacuum pressure. If the
ECM detects that an open circuit or short to ground on
the turbocharger solenoid valve control circuit, this DTC
will set.
Condition for Running the DTC
• The ignition switch is ON.
Condition for Setting the DTC
• The ECM detects that the low voltage condition on
the turbocharger solenoid valve control circuit fo
r
longer than 3 seconds when the solenoid valve is
commanded OFF.
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 turbocharger solenoid valve
control substitution of 68%.
• 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.

DTC P0243 (Symptom Code 4) (Flash Code 64)
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. 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 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 15 
5 1. Turn OFF the ignition.
2. Disconnect the turbocharger solenoid valve harness connector.
3. Connect a test lamp between the voltage feed circuit of the turbocharger solenoid valve harness
(pin 1 of C-123 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 8

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

6E-112 Engine Control System (4JH1)
Step Action Value(s) Yes No
6 1. Connect a test lamp between the control circuit
of the turbocharger solenoid valve harness (pin 2
of C-123 connector) and battery voltage.
2. Turn ON the ignition, with the engine OFF.
Does the test lamp continuously illuminate? 

Go to Step 9 Go to Step 7
7 1. Keep the test lamp with connected. 2. Turn OFF the ignition.
3. Disconnect the vacuum pressure sensor harness connector in order to energize the turbocharger
solenoid valve.
4. Turn ON the ignition, with the engine OFF.
Does the test lamp blink? 

Go to Step 11 Go to Step 10
8 Repair the open circuit or high resistance on the voltage feed circuit between the ECM (10A) fuse
(EB-4) and the turbocharger solenoid valve (pin 1 of
C-123 connector).
Did you complete the repair? 

Go to Step 15 
9 1. Test the control circuit between the engine
control module (ECM) (pin 97 of C-57 connector)
and the turbocharger solenoid valve (pin 2 of C-
115 connector) for a short to ground.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 15 Go to Step 14
10 1. Test the control circuit between the ECM (pin 96 of C-57 connector) and the turbocharger solenoid
valve (pin 2 of C-123 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 15 Go to Step 12
11 1. Turn OFF the ignition. 2. Disconnect the turbocharger solenoid valve harness connector.
3. Inspect for an intermittent and for poor connections at the harness connector of the
turbocharger solenoid valve (pins 1 and 2 of C-
123 connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 15 Go to Step 13
12 1. Turn OFF the ignition. 2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for a poor connection on the turbocharger solenoid valve
circuit at the harness connector of the ECM (pin
96 of C-57 connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 15 Go to Step 14
13 Replace the turbocharger solenoid valve. Refer to Turbocharger Solenoid Valve Replacement in this
section.
Did you complete the replacement? 

Go to Step 15 
14 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 15 

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Control System (4JH1) 6E-113
Step Action Value(s) Yes No
15 1. Reconnect all previously disconnected fuse or
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 16
16 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


BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

6E-114 Engine Control System (4JH1)
DTC P0243 (Symptom Code 5) (Flash Code 64)
Circuit Description
The engine control module (ECM) controls the
turbocharger wastegate valve based on the barometric
pressure in order to reduce turbocharger spinning
speeds at high altitude area. The ECM controls the
turbocharger wastegate valve diaphragm by acting the
regulated vacuum pressure via controlling the solenoid
valve. The vacuum pressure sensor monitors the
regulated vacuum pressure to the turbocharge
r
wastegate valve. The ECM calculates desired vacuum
pressure and it compares the calculated desired
vacuum pressure to the actual value to determine the
solenoid valve position. W hen the actual vacuum
pressure is higher than the desired value, the solenoid
valve is closed to decrease the vacuum pressure. An
expected vacuum pressure amount should be detected
while the engine running. If the ECM detects the actual
vacuum pressure amount is lower than desired vacuum
pressure amount, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.
• The barometric pressure (BARO) is between 0
hPa and 3500 hPa.
• The intake air temperature (IAT) is between -50°C
(-58 °F) and 200°C (392°F).
• The engine coolant temperature (ECT) is between
-50°C (-58 °F) and 150°C (302°F)
Condition for Setting the DTC
• The ECM detects that the vacuum pressure is 50
hPa lower than the desired vacuum pressure for 3
seconds. This indicates excessive low vacuum
pressure.
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 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.
• Misrouted vacuum hoses may set this DTC.
• A vacuum pump problem will cause this DTC.
Test Description
The numbers below refer to the step number on the
diagnostic table.
4. A skewed vacuum pressure sensor value (shifted to
a low pressure) can set this DTC. The Vacuum
Pressure on the scan tool should read near doubled
barometric pressure (BARO) with the key ON and
engine OFF.
5. A skewed BARO sensor value (shifted to a highe
r
pressure) may set this DTC. The BARO on the scan
tool should read near surrounding barometric pressure.

DTC P0243 (Symptom Code 5) (Flash Code 64)
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.
Is DTC P0105 (Symptom Code 1, 2, 7 or 9) or
P0243 (Symptom Code 4 or 8) set? 

Go to Applicable DTC Go to Step 3

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Control System (4JH1) 6E-115
Step Action Value(s) Yes No
3 1. Turn OFF the ignition.
2. Inspect for the following conditions: • Vacuum hoses are damaged or kinked.
• Misrouted vacuum hoses.
• A turbocharger solenoid valve is damaged.
• A vacuum pump is damaged.
• A vacuum regulating valve is damaged.
• A turbocharger wastegate valve is
damaged.
• Contaminated, skewed or slow vacuum
pressure sensor.
3. Repair or replace as necessary.
Did you find and correct the condition? 

Go to Step 15 Go to Step 4
4 1. Turn ON the ignition, with the engine OFF. 2. Observe the Vacuum Pressure Sensor and Barometric Pressure (BARO) with the scan tool.
Does the scan tool indicate that the difference
between the Vacuum Pressure Sensor and doubled
BARO is less than the specified value? 10 hPa

Go to Step 7 Go to Step 5
5 1. Observe the BARO parameter with the scan tool.2. Compare the BARO value to the range specified in the altitude vs. barometric pressure table.
Refer to Altitude vs. Barometric Pressure.
Is the BARO parameter within the range specified? 

Go to Step 6 Go to Step 14
6 1. Turn OFF the ignition. 2. Disconnect the vacuum pressure sensor harness connector.
3. Inspect for an intermittent and for a poor connection at the vacuum pressure sensor
harness connector (pin 2 of C-124 connector).
4. Disconnect the engine control module (ECM) harness connector.
5. Inspect for an intermittent, for a poor connection and corrosion on vacuum pressure sensor circuit
at the harness connector of the ECM (pin 93 of
C-57 connector).
6. Test for high resistance on vacuum pressure sensor low reference circuit.
7. Repair the connection(s) or circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 15 Go to Step 10
7 1. Turn OFF the ignition. 2. Disconnect the vacuum hose from the turbocharger wastegate valve that is connected
to the vacuum pressure sensor and the
turbocharger solenoid valve.
3. Start the engine and accelerate the engine as necessary.
Is there boost pressure leak from the turbocharger
wastegate valve port? 

Go to Step 13 Go to Step 8

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

6E-116 Engine Control System (4JH1)
Step Action Value(s) Yes No
8 1. Turn OFF the ignition.
2. Reconnect the vacuum hose to the turbocharger wastegate valve.
3. Disconnect the vacuum hose from the turbocharger solenoid valve that is connected to
the vacuum regulating valve “Z” port.
4. Connect a hand-held vacuum pump (5-8840- 0279-0/J-23738-A) to the disconnected vacuum
hose.
5. Start the engine and let engine idle.
Does the hand-held vacuum pump indicate more
than 23 cmHg (9 inHg)? 

Go to Step 9 Go to Step 12
9 1. Turn OFF the ignition. 2. Disconnect the hand-held vacuum pump from the vacuum hose.
3. Reconnect the vacuum hose to the turbocharger solenoid valve.
4. Disconnect the vacuum hose from the vacuum pressure sensor that is connected to the
turbocharger solenoid valve and the turbocharger
wastegate valve.
5. Connect a hand-held vacuum pump (5-8840- 0279-0/J-23738-A) to the disconnected vacuum
hose.
6. Disconnect the vacuum pressure sensor harness connector in order to active turbocharger
solenoid valve.
7 Start the engine and let engine idle.
Does the needle of hand-held vacuum pump shake
between 0 and 20 cmHg (8 inHg)? 

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

Go to Step 15 
11 Replace the turbocharger solenoid valve. Refer to
Turbocharger Solenoid Valve Replacement in this
section.
Did you complete the replacement? 

Go to Step 15 
12 Replace the vacuum regulating valve.
Did you compete the replacement? 

Go to Step 15 
13 Replace the turbocharger wastegate valve. Refer to
Turbocharger in Engine Mechanical section.
Did you complete the replacement? 

Go to Step 15 
14 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 15 
15 1. Reconnect all previously disconnected hoses or
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 2 Go to Step 16

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007