Isuzu KB P190. Manual — part 276

6E-70 Engine Control System (4JH1)

DTC P0100 (Symptom Code B) (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) monitors the MAF
sensor signal for voltage outside the normal range of
the MAF sensor. If the ECM detects an excessively low
MAF sensor signal voltage, this DTC will set.
Condition for Running the DTC

• The ignition switch is ON.
• The engine is running.

Condition for Setting the DTC

• The ECM calculated MAF is lower than -18.6 kg/h

for 5 seconds. This indicates the ECM detects that
the MAF sensor signal voltage is smaller than a
predetermined range during engine run.

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 that 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:

• Wrong direction of MAF sensor installation will

cause this DTC to set.

• Contaminated or restricted MAF sensor will cause

this DTC to set.

• 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.
7. If the MAF sensor signal circuit between the ECM
and the sensor is short to ground or any low reference
circuits, the sensor 5 volts reference voltage low DTC
P0100 (Symptom Code 9) will set.
8. If the MAF sensor signal circuit between the ECM
and the sensor is normal, the sensor signal voltage high
DTC P0100 (Symptom Code C) will set.

DTC P0100 (Symptom Code B) (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

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.

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 is 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 17



Engine Control System (4JH1) 6E-71

Step Action

Value(s)

Yes

No

5

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

harness connector.

3. Connect a test lamp between the ignition voltage

feed circuit of the MAF sensor harness (pin 2 of
C-116 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 9

6

1. Keep the ignition ON, with the engine OFF.
2. Connect a DMM between the 5 volts reference

circuit of the MAF sensor harness (pin 4 of C-116
connector) and a known good ground.

Is the DMM voltage more than the specified value?

4.5 volts

Go to Step 7

Go to Step 10

7

1. Turn OFF the ignition.
2. Connect a 3-amp fused jumper wire between the

5 volts reference circuit and the signal circuit of
the MAF sensor harness (pins 4 and 5 of C-116
connector).

3. Turn ON the ignition, with the engine OFF. DO

NOT start the engine.

4. Monitor the DTC Information with the scan tool.
Does DTC P0100 (Symptom Code 9) set, but not
DTC P0100 (Symptom Code B)?



Go to Step 11

Go to Step 8

8

1. Keep the 3-amp fused jumper wire with

connected.

2. Start the engine and let idle for 30 seconds.
Does DTC P0100 (Symptom Code C) set, but not
DTC P0100 (Symptom Code B)?



Go to Step 13

Go to Step 12

9

Repair the open circuit or high resistance on the
ignition voltage feed circuit between the ECM (10A)
fuse (EB-4) and the MAF sensor (pin 2 of C-116
connector).
Did you complete the repair?



Go to Step 17



10

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:

• An open circuit
• A short to ground
• A short to the low reference circuit
• High resistance

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



Go to Step 17

Go to Step 14

11

1. Test the signal circuit between the ECM (pin 88

of C-57 connector) and the MAF sensor (pin 5 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 17

Go to Step 16

12

1. Test the signal circuit between the ECM (pin 88

of C-57 connector) and the MAF sensor (pin 5 of
C-116 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 17

Go to Step 14

6E-72 Engine Control System (4JH1)

Step Action

Value(s)

Yes

No

13

1. Turn OFF the ignition.
2. Inspect for an intermittent and for poor

connections at the harness connector of the MAF
sensor (pins 2, 4 and 5 of C-116 connector).

3. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 17

Go to Step 15

14

1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for poor

connections on the MAF sensor circuits at the
harness connector of the ECM (pins 83 and 88 of
C-57 connector).

4. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 17

Go to Step 16

15

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



Go to Step 17



16

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 17



17

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. Accelerate the engine between idle and W.O.T.

(accelerator pedal full travel) many times while
observing the DTC Information with the scan
tool.

Did the DTC fail this ignition?



Go to Step 3

Go to Step 18

18

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

Engine Control System (4JH1) 6E-73

DTC P0100 (Symptom Code C) (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) monitors the MAF
sensor signal for voltage outside the normal range of
the MAF sensor. If the ECM detects an excessively high
MAF sensor signal voltage, this DTC will set.
Condition for Running the DTC

• The ignition switch is ON.
• The engine is running.

Condition for Setting the DTC

• The ECM calculated MAF is higher than 984 kg/h

for 10 seconds. This indicates the ECM detects
that the MAF sensor signal voltage is higher than a
predetermined range during engine run.

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 signal 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 C) (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

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.

Does the DTC fail this ignition?



Go to Step 3

Go to Diagnostic

Aids

3

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 C)?



Go to Step 4

Go to Step 5