Isuzu KB P190. Manual - part 275

6E-66 Engine Control System (4JH1)

DTC P0100 (Symptom Code 7) (Flash Code 65)

Circuit Description
The mass air flow (MAF) sensor is an air flow meter that
measures the amount of air that enters the engine. It is
fitted between the air cleaner and turbocharger. A small
quantity of air that enters the engine indicates
deceleration or idle speed. A large quantity of air that
enters the engine indicates acceleration or a high load
condition. The MAF sensor has the following circuits.

•  Ignition voltage circuit
•  5 volts reference circuit
•  Low reference circuit
•  MAF sensor signal circuit

The engine control module (ECM) provides 5 volts
reference voltage through the reference circuit to the
MAF sensor. The ECM monitors the voltage on the 5
volts reference circuit. If the ECM detects an
excessively high MAF 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 MAF sensor 5 volts

reference circuit voltage is more than 5.2 volts for
0.5 seconds.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM uses a MAF substitution of 1600 mg/strk

for engine control.

• 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.

Notice:

• The MAF Sensor parameter on the scan tool will

only update with engine running.

Test Description
The number below refers to the step number on the
diagnostic table.
3. If the MAF sensor 5 volts reference circuit between
the ECM and the sensor is normal, the sensor signal
voltage low DTC P0100 (Symptom Code B) will set.

DTC P0100 (Symptom Code 7) (Flash Code 65)
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.
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

1. Turn OFF the ignition.
2. Disconnect the mass air flow (MAF) sensor

harness connector.

3. Start the engine and let idle for 30 seconds.
4. Monitor the DTC Information with the scan tool.
Does DTC P0100 (Symptom Code B) set, but not
DTC P0100 (Symptom Code 7)?



Go to Step 5

Go to Step 4

Engine Control System (4JH1) 6E-67

Step Action

Value(s)

Yes

1. Test the 5 volts reference circuit between the

engine control module (ECM) (pin 83 of C-57
connector) and the MAF sensor (pin 4 of C-116
connector) for the following conditions:

• A short to battery or ignition voltage
• A short to the sensor ignition voltage

2. Repair the circuit(s) as necessary.
Did you find and correct the condition?



Go to Step 7

Go to Step 6

Replace the MAF sensor. Refer to Mass Air Flow
Sensor Replacement in this section.
Did you complete the replacement?



Go to Step 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 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

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-68 Engine Control System (4JH1)

DTC P0100 (Symptom Code 9) (Flash Code 65)

•  Ignition voltage circuit
•  5 volts reference circuit
•  Low reference circuit
•  MAF sensor signal circuit

The engine control module (ECM) provides 5 volts
reference voltage through the reference circuit to the
MAF sensor. The ECM monitors the voltage on the 5
volts reference circuit. If the ECM detects an
excessively low MAF 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 MAF sensor 5 volts

reference circuit voltage is less than 4.6 volts for
0.5 seconds.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM uses a MAF substitution of 1600 mg/strk

for engine control.

• 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.

Notice:

• The MAF Sensor parameter on the scan tool will

only update with engine running.

Test Description
The number below refers to the step number on the
diagnostic table.
3. If the MAF sensor 5 volts reference circuit between
the ECM and the sensor is normal, the sensor signal
voltage low DTC P0100 (Symptom Code B) will set.

DTC P0100 (Symptom Code 9) (Flash Code 65)
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.
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

1. Turn OFF the ignition.
2. Disconnect the mass air flow (MAF) sensor

harness connector.

3. Start the engine and let idle for 30 seconds.
4. Monitor the DTC Information with the scan tool.
Does DTC P0100 (Symptom Code B) set, but not
DTC P0100 (Symptom Code 9)?



Go to Step 5

Go to Step 4

1. Test the 5 volts reference circuit between the

engine control module (ECM) (pin 83 of C-57
connector) and the MAF sensor (pin 4 of C-116
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

Engine Control System (4JH1) 6E-69

Step Action

Value(s)

Yes

Replace the MAF sensor. Refer to Mass Air Flow
Sensor Replacement in this section.
Did you complete the replacement?



Go to Step 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 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

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

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