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Isuzu KB P190. Manual - part 296

6E-150 Engine Control System (4JH1)

Step Action

Value(s)

Yes

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

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

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



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

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

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

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

Replace the EGR solenoid valve. Refer to EGR
Solenoid Valve Replacement in this section.
Did you complete the replacement?



Go to Step 15



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



Engine Control System (4JH1) 6E-151

Step Action

Value(s)

Yes

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

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

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 air
temperature, barometric pressure and fuel injection
quantity. The ECM controls the EGR valve by
controlling the EGR solenoid valve. The mass air flow
(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 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.

• 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

Did you perform the Diagnostic System Check-
Engine Controls?



Go to Step 2

Go to Diagnostic

System Check-

Engine Controls

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

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

Engine Control System (4JH1) 6E-153

Step Action

Value(s)

Yes

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.

• A vacuum hose from the vacuum pump is

damaged or kinked.

• A vacuum pump is damaged.
• Oil in the air tubing causing an incorrect

MAF sensor signal. When 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 10

Go to Step 5

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 6

Go to Step 9

1. Turn OFF the ignition.
2. Disconnect the hand-held vacuum pump from the

vacuum hose.

3. Connect the hand-held vacuum pump to the

vacuum port of EGR valve.

4. Start the engine and let engine idle.
5. Apply vacuum pressure to the EGR valve while

observing the MAF Sensor parameter.

Does the MAF Sensor parameter decrease by at
least 200 mg/strk when the vacuum pressure is
applied?



Go to Diagnostic

Aids

Go to Step 7

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