2007 ISUZU KB P190 Circuit

6E-146 Engine Control System (4JH1)
DTC P0400 (Symptom Code 3) (Flash Code 32)
Circuit Description
The engine control module (ECM) controls the exhaust
gas recirculation (EGR) flow amount based on the
engine speed, engine coolant temperature, intake ai
r
temperature, barometric pressure and fuel injection
quantity. The ECM controls the EGR valve b
y
controlling the EGR solenoid valve. The mass air flo
w
(MAF) sensor monitors EGR gas flow amount. An
expected MAF amount should be detected while the
engine running. If the ECM detects the actual MAF
amount is lower than desired MAF amount, this DTC
will set. This indicates excessive amount of EGR gas
flow.
Condition for Running the DTC
• The ignition switch is ON.
• The engine is running.
• The barometric pressure (BARO) is between 850
hPa and 1100 hPa.
• The intake air temperature (IAT) is between 15°C
(59°F) and 100°C (212°F).
• The ECT is between 35°C (95°F) and 100°C
(211°F).
Condition for Setting the DTC

• The ECM detects that the MAF amount is 150
mg/strk lower than the desired MAF for 60
seconds. This indicates excessive amount of EGR
flow.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicator
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.
• A sticking or intermittently sticking the EGR valve
will cause this DTC to set.
• Misrouted vacuum hoses will cause this DTC to
set.

DTC P0400 (Symptom Code 3) (Flash Code 32)
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 P0100 (Symptom Code 7, 9, B or C) or
P0400 (Symptom Code 4 or 8) set? 

Go to Applicable DTC Go to Step 3
3 1. Install the scan tool. 2. Turn OFF the ignition for 30 seconds.
3. Start the engine and warm up (allow engine coolant temperature to reach at least 60°C
[140°F]).
4. Perform the EGR Solenoid Valve test with the scan tool.
5. 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 4

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ISUZU KB P190 2007

6E-148 Engine Control System (4JH1)
Step Action Value(s) Yes No
7 1. Turn OFF the ignition.
2. Disconnect the MAF sensor harness connector.
3. Inspect for an intermittent, for poor connections and corrosion at the harness connector of the
MAF sensor (pins 2, 4 and 5 of C-116
connector).
4. Disconnect the engine control module (ECM) harness connector.
5. Inspect for an intermittent, for poor connections and corrosion on each MAF sensor circuit at the
harness connector of the ECM (pins 83 and 88 of
C-57 connector).
6. Test for high resistance on each MAF sensor circuit.
7. Test the MAF sensor signal circuit short to intake air temperature (IAT) sensor signal.
8. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 10 Go to Step 8
8 Replace the EGR valve. Refer to EGR Valve Replacement in engine mechanical section.
Did you complete the replacement? 

Go to Step 10 
9 Replace the EGR solenoid valve. Refer to EGR
Solenoid Valve Replacement in this section.
Did you complete the replacement? 

Go to Step 10 
10 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 warm up (allow engine coolant temperature to reach at least 60°C
[140°F]) while observing the MAF Sensor
parameter with the scan tool.
Does the MAF Sensor parameter follow the Desired
MAF parameter within 50 mg/strk? 

Go to Step 11 Go to Step 2
11 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-149
DTC P0400 (Symptom Code 4) (Flash Code 32)
Circuit Description
The engine control module (ECM) controls the exhaust
gas recirculation (EGR) flow amount based on the
engine speed, engine coolant temperature, intake ai
r
temperature, barometric pressure and fuel injection
quantity. The ECM controls the EGR valve b
y
controlling the EGR solenoid valve. The mass air flo
w
(MAF) sensor monitors EGR gas flow amount. An
expected MAF amount should be detected while the
engine running. If the ECM detects that an open circuit
or short to ground on the EGR 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 EGR solenoid valve control circuit for longe
r
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.
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 P0400 (Symptom Code 4) (Flash Code 32)
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 EGR control solenoid valve harness connector.
3. Connect a test lamp between the voltage feed circuit of the EGR control solenoid valve harness
(pin 1 of C-115 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

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ISUZU KB P190 2007

6E-150 Engine Control System (4JH1)
Step Action Value(s) Yes No
6 1. Connect a test lamp between the control circuit
of the EGR solenoid valve harness (pin 2 of C-
115 connector) and battery voltage.
2. Perform the EGR Solenoid Valve test with the scan tool.
3. Command the EGR Solenoid Valve ON with the scan tool.
Does the test lamp illuminate when commanded ON
with the scan tool? 

Go to Step 7 Go to Step 9
7 Command the EGR Solenoid Valve OFF with the scan tool.
Does the test lamp continuously illuminate same as
step 6 when commanded OFF with the scan tool
(the test lamp slightly illuminates if the circuit is
normal when commanded OFF)? 

Go to Step 10 Go to Step 11
8 Repair the open circuit or high resistance on the voltage feed circuit between the ECM (10A) fuse
(EB-4) and the EGR solenoid valve (pin 1 of C-115
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 EGR solenoid valve (pin 2 of C-115
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
10 1. Test the control circuit between the ECM (pin 97 of C-57 connector) and the EGR 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
11 1. Turn OFF the ignition. 2. Disconnect the EGR solenoid valve harness connector.
3. Inspect for an intermittent and for poor connections at the harness connector of the EGR
solenoid valve (pins 1 and 2 of C-115 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 EGR solenoid valve control
circuit at the harness connector of the ECM (pin
97 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 EGR solenoid valve. Refer to EGR 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 

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ISUZU KB P190 2007

6E-152 Engine Control System (4JH1)
DTC P0400 (Symptom Code 5) (Flash Code 32)
Circuit Description
The engine control module (ECM) controls the exhaust
gas recirculation (EGR) flow amount based on the
engine speed, engine coolant temperature, intake ai
r
temperature, barometric pressure and fuel injection
quantity. The ECM controls the EGR valve b
y
controlling the EGR solenoid valve. The mass air flo
w
(MAF) sensor monitors EGR gas flow amount. 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 insufficient amount of EGR gas
flow.
Condition for Running the DTC
• The ignition switch is ON.
• The engine is running.
• The barometric pressure (BARO) is between 850
hPa and 1100 hPa.
• The intake air temperature (IAT) is between 15°C
(59°F) and 100°C (212°F).
• The ECT is between 35°C (95°F) and 100°C
(211°F).
Condition for Setting the DTC
• The ECM detects that the MAF amount is 150
mg/strk higher than the desired MAF for 60
seconds. This indicates insufficient amount o
f
EGR flow.
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.
• A sticking or intermittently sticking the EGR valve
will cause this DTC to set.
• Misrouted vacuum hoses will cause this DTC to
set.
•
A vacuum pump problem will cause this DTC to
set.

DTC P0400 (Symptom Code 5) (Flash Code 32)
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 P0100 (Symptom Code 7, 9, B or C) or
P0400 (Symptom Code 4 or 8) set? 

Go to Applicable DTC Go to Step 3
3 1. Install the scan tool. 2. Turn OFF the ignition for 30 seconds.
3. Start the engine and warm up (allow engine coolant temperature to reach at least 60°C
[140°F]).
4. Perform the EGR Solenoid Valve test with the scan tool.
5. 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 4

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ISUZU KB P190 2007

6E-154 Engine Control System (4JH1)
Step Action Value(s) Yes No
7 1. Turn OFF the ignition.
2. Disconnect the MAF sensor harness connector.
3. Inspect for an intermittent, for a poor connection and corrosion at the harness connector of the
MAF sensor (pin 3 of C-116 connector).
4. Disconnect the engine control module (ECM) harness connector.
5. Inspect for an intermittent, for a poor connection and corrosion on each MAF sensor circuit at the
harness connector of the ECM (pin 92 of C-57
connector).
6. Test for high resistance on each MAF sensor circuit.
7. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 10 Go to Step 8
8 Replace the EGR valve. Refer to EGR Valve Replacement in engine mechanical section.
Did you complete the replacement? 

Go to Step 10 
9 Replace the EGR solenoid valve. Refer to EGR
Solenoid Valve Replacement in this section.
Did you complete the replacement? 

Go to Step 10 
10 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 warm up (allow engine coolant temperature to reach at least 60°C
[140°F]) while observing the MAF Sensor
parameter with the scan tool.
Does the MAF Sensor parameter follow the Desired
MAF parameter within 50 mg/strk? 

Go to Step 11 Go to Step 2
11 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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TO MODEL INDEX
ISUZU KB P190 2007

Engine Control System (4JH1) 6E-155
DTC P0400 (Symptom Code 8) (Flash Code 32)
Circuit Description
The engine control module (ECM) controls the exhaust
gas recirculation (EGR) flow amount based on the
engine speed, engine coolant temperature, intake ai
r
temperature, barometric pressure and fuel injection
quantity. The ECM controls the EGR valve by
controlling the EGR solenoid valve. The mass air flo
w
(MAF) sensor monitors EGR gas flow amount. An
expected MAF amount should be detected while the
engine running. If the ECM detects that detects a short
to battery or ignition voltage on the EGR 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 high voltage condition
on the EGR solenoid valve control circuit for longe
r
than 3 seconds when the solenoid valve is
commanded ON.
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 control circuit of the EGR solenoid valve
between the ECM and the solenoid valve is normal, the
control circuit voltage low DTC P0400 (Symptom Code
4) will set.

DTC P0400 (Symptom Code 8) (Flash Code 32)
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 warm up (allow engine coolant temperature to reach at least 60°C
[140°F]).
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 EGR control solenoid valve harness connector.
3. Start the engine.
4. Monitor the DTC Information with the scan tool.
Does the DTC P0400 (Symptom Code 4) set, but not
DTC P0400 (Symptom Code 8)? 

Go to Step 5 Go to Step 4
4 1. Test the control circuit between the engine control module (ECM) (pin 97 of C-57 connector)
and the EGR solenoid valve (pin 2 of C-115
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 EGR solenoid valve. Refer to EGR Solenoid Valve Replacement in this section.
Did you complete the replacement? 

Go to Step 7 

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-157
DTC P0500 (Symptom Code 1, A) (Flash Code 24)
Circuit Description
The vehicle speed sensor (VSS) is used by the engine
control module (ECM) and speedometer, which
generates a speed signal from the transmission output
shaft. The VSS has the following circuits.
• Ignition voltage feed circuit
• VSS signal circuit
• VSS low reference circuit
The VSS uses a hall effect element. It interacts with the
magnetic field created by the rotating magnet and
outputs square wave pulse signal. The 12 volts
operating supply from the Meter fuse (except 2W D with
A/T) or Back Up fuse (2W D with A/T). The ECM
calculates the vehicle speed by the VSS. If the vehicle
is 2W D with automatic transmission, VSS signals are
sent from the transmission control module (TCM). If the
ECM detects VSS signals are generated with high
frequencies, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.
Condition for Setting the DTC
• The ECM detects that the vehicle speed is highe
r
than 200 km/h (125 MPH) for 5 seconds.
(Symptom Code 1)

•
The ECM detects that the vehicle speed senso
r
signal frequency is too high for 0.6 seconds.
(Symptom Code A)
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 vehicle speed substitution of 5
km/h (3 MPH) 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
• Electrical or magnetic interference may affect
intermittent condition.
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.

DTC P0500 (Symptom Code 1, A) (Flash Code 24)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Chart for 2WD with A/T
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. Inspect all of the circuits going to the automatic transmission (A/T) vehicle speed sensor (VSS)
for the following: • Routed too closely to fuel injection solenoid
wiring or components
• Routed too closely to after-market add-on
electrical equipment
• Routed too closely to solenoids, relays, and
motors
2. If you find incorrect routing, correct the harness routing.
Did you find and correct the condition? 

Go to Step 7 Go to Step 3
3 1. Turn OFF the ignition. 2. Disconnect the A/T VSS harness connector.
3. Inspect for an intermittent and for poor connections at the harness connector of the A/T
VSS (pins 1, 2 and 3 of E-30 connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 7 Go to Step 4

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ISUZU KB P190 2007