2007 ISUZU KB P190 engine coolant

6E-90 Engine Control System (4JH1)
DTC P0115 (Symptom Code 1) (Flash Code 14)
Circuit Description
The engine coolant temperature (ECT) sensor is
installed to the thermostat housing. The ECT sensor is
a variable resistor. The ECT sensor has a signal circuit
and a low reference circuit. The ECT sensor measures
the temperature of the engine coolant. The engine
control module (ECM) supplies 5 volts to the ECT signal
circuit and a ground for the ECT low reference circuit.
W hen the ECT sensor is cold, the sensor resistance is
high. W hen the engine coolant temperature increases,
the sensor resistance decreases. W ith high senso
r
resistance, the ECM detects a high voltage on the ECT
signal circuit. W ith lower sensor resistance, the ECM
detects a lower voltage on the ECT signal circuit. If the
ECM detects an excessively high ECT 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 ECT 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 ECT substitution of fuel
temperature for engine control.

•
The ECM uses an ECT substitution of 60 °C
(120 °F) for injection timing control.
• The ECM uses an ECT substitution of -15 °C (5 °F)
for glow 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.
•
After starting the engine, the ECT should rise
steadily to about 80°C – 85°C (176°F – 185°F)
then stabilize when the thermostat opens.
• Use the Temperature vs. Resistance table to test
the ECT sensor at various temperature levels to
evaluate the possibility of a skewed sensor.
A
skewed sensor could result in poor driveabilit
y
concerns.


DTC P0115 (Symptom Code 1) (Flash Code 14)
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 Engine Coolant Temperature (ECT) parameter with the scan tool.
Is the ECT parameter less than the specified value? -35°C (-31°F)
Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition. 2. Disconnect the ECT sensor harness connector.
3. Connect a DMM between the signal circuit of the ECT sensor harness (pin 1 of E-41 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 ECT 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 89 of C-57 connector) and
the ECT sensor (pin 1 of E-41 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

Engine Control System (4JH1) 6E-91
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
ECT sensor harness (pins 1 and 2 of E-41
connector).
3. Turn ON the ignition, with the engine OFF.
4. Observe the ECT parameter with the scan tool.
Is the ECT parameter more than the specified
value? 135°C (275°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 ECT sensor harness (pin 1 of
E-41 connector) and a known good ground.
3. Turn ON the ignition, with the engine OFF.
4. Observe the ECT parameter with the scan tool.
Is the ECT parameter more than the specified
value? 135°C (275°F)
Go to Step 8 Go to Step 7
7 1. Test the signal circuit between the ECM (pin 89 of C-57 connector) and the ECT sensor (pin 1 of
E-41 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
8 1. Test the low reference circuit between the ECM (pin 93 of C-57 connector) and the ECT sensor
(pin 2 of E-41 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 89 of C-57 connector) and the ECT sensor (pin 1 of
E-41 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 Turn OFF the ignition. Inspect for an intermittent and for poor connections
at the harness connector of the ECT sensor (pins 1
and 2 of E-41 connector).
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 ECT sensor circuits at the
harness connector of the ECM (pins 89 and 93 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 ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement in this section.
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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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-93
DTC P0115 (Symptom Code 2) (Flash Code 14)
Circuit Description
The engine coolant temperature (ECT) sensor is
installed to the thermostat housing. The ECT sensor is
a variable resistor. The ECT sensor has a signal circuit
and a low reference circuit. The ECT sensor measures
the temperature of the engine coolant. The engine
control module (ECM) supplies 5 volts to the ECT signal
circuit and a ground for the ECT low reference circuit.
W hen the ECT sensor is cold, the sensor resistance is
high. W hen the engine coolant temperature increases,
the sensor resistance decreases. W ith high senso
r
resistance, the ECM detects a high voltage on the ECT
signal circuit. W ith lower sensor resistance, the ECM
detects a lower voltage on the ECT signal circuit. If the
ECM detects an excessively low ECT 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 ECT sensor signal
voltage is less than 0.3 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 ECT substitution of fuel
temperature for engine control.

•
The ECM uses an ECT substitution of 60 °C
(120 °F) for injection timing control.
• The ECM uses an ECT substitution -15 °C (5 °F) fo
r
glow 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.
•
After starting the engine, the ECT should rise
steadily to about 80°C – 85°C (176°F – 185°F)
then stabilize when the thermostat opens.
• Use the Temperature vs. Resistance table to test
the ECT sensor at various temperature levels to
evaluate the possibility of a skewed sensor.
A
skewed sensor could result in poor driveabilit
y
concerns.

DTC P0115 (Symptom Code 2) (Flash Code 14)
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 Engine Coolant Temperature (ECT) parameter with the scan tool.
Is the ECT parameter more than the specified value? 135°C (275°F)
Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition. 2. Disconnect the ECT sensor harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Observe the Coolant Temperature parameter with the scan tool.
Is the ECT parameter less than the specified value? -35°C (-31°F)
Go to Step 5 Go to Step 4
4 1. Test the signal circuit between the engine control module (ECM) (pin 89 of C-57 connector) and
the ECT sensor (pin 1 of E-41 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 8 Go to Step 6

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ISUZU KB P190 2007

6E-94 Engine Control System (4JH1)
Step Action Value(s) Yes No
5 Replace the ECT sensor. Refer to Engine Coolant
Temperature Sensor Replacement in this section.
Did you complete the replacement? 

Go to Step 8 
6 1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect connections on the ECT sensor circuits at the harness connector of the ECM (pins 89
and 93 of C-57 connector) for corrosion.
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 
8 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 2 Go to Step 9
9 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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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

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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

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ISUZU KB P190 2007

6E-118 Engine Control System (4JH1)
DTC P0243 (Symptom Code 6) (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.
The mass air flow (MAF) sensor monitors boost
pressure by monitoring the amount of mass air flow. An
expected MAF amount should be detected while the
engine running. If the ECM detects the actual MAF
amount is higher than desired MAF amount, this DTC
will set. This indicates excessive high boost pressure
and turbocharger wastegate valve most likely did not
active.
Condition for Running the DTC
• The ignition switch is ON.
• The engine coolant temperature (ECT) is between
-50°C (-58 °F) and 150°C (302°F).
• The EGR solenoid valve control is OFF.
• The MAF sensor DTC P0100 is not set.
• The vacuum pressure sensor DTC P0105 is not
set.
• The intake air temperature (IAT) sensor DTC
P0110 is not set.
Condition for Setting the DTC
• The ECM detects that the MAF amount is 56
mg/strk higher than the desired MAF for 3
seconds. This indicates an excessive high boost
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.
• Check the wastegate for a sticking or stuck
condition. Refer to W astegate Operation in the
Engine Mechanical section.
• Use the scan tool to verify the integrity of the MAF
sensor signal. Compare the sensor values unde
r
all load conditions for an excessively high value.
Use the scan tool data list values for nominal
sensor readings.
• The fuel with which gasoline was mixed may set
this DTC.
• A sticking or intermittently sticking the EGR valve
may set this DTC.
• Misrouted vacuum hoses may set this DTC.

DTC P0243 (Symptom Code 6) (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), P0243
(Symptom Code 3, 4, 5 or 8) or P0400 (Symptom
Code 3, 4, 5 or 8) set? 

Go to Applicable DTC Go to Step 3

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Engine Control System (4JH1) 6E-119
Step Action Value(s) Yes No
3 1. Inspect the following for possible causes of high
boost pressure. • W astegate valve for a stuck closed
condition. Refer to the Turbocharger in
Engine Mechanical section for diagnosis.
• Restricted intake or collapsed hose.
2. Repair the condition as necessary.
Did you find and correction the condition? 

Go to Step 11 Go to Step 4
4 1. Turn OFF the ignition for 30 seconds. 2. Start the engine and warm up (allow engine coolant temperature to reach at least 60°C
[140°F]).
3. Perform the EGR Solenoid Valve test with the scan tool.
4. Command the EGR Solenoid Valve ON and OFF with the scan tool while observing the Mass Air
Flow (MAF) Sensor parameter.
Does the MAF Sensor parameter decrease by at
least 200 mg/strk within 2 seconds when the EGR
Solenoid Valve is commanded ON? 

Go to Diagnostic Aids Go to Step 5
5 1. Turn OFF the ignition. 2. Inspect for the following conditions: • An EGR valve control vacuum hose is
damaged or kinked.
• EGR solenoid valve vacuum hoses are
damaged or kinked.
• EGR solenoid valve ventilation is damaged.
• An EGR valve is stuck close.
• Restricted or collapsed EGR passage
between the exhaust manifold and EGR
valve.
• Oil in the air tubing causing an incorrect
MAF sensor signal. W hen there is
adhesion of oil, inside of the tubing,
intercooler and turbocharger needs to be
wipe off.
• Contaminated or skewed MAF sensor.
3. Repair or replace as necessary.
Did you find and correct the condition? 

Go to Step 11 Go to Step 6
6 1. Turn OFF the ignition. 2. Disconnect the EGR valve control vacuum hose from the EGR valve.
3. Connect a hand-held vacuum pump (5-8840- 0279-0/J-23738-A) to the disconnected vacuum
hose.
4. Start the engine and let engine idle.
5. Perform the EGR Solenoid Valve test with the scan tool.
6. Command the EGR Solenoid Valve ON and OFF with the scan tool.
Does the hand-held vacuum pump indicate more
than 50 cmHg (20 inHg) when commanding the ON
and less than 10 cmHg (4 inHg) when commanding
OFF? 

Go to Step 7 Go to Step 10

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