Isuzu N-Series. Manual - part 754

 

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Isuzu N-Series. Manual - part 754

 

 

 Engine Control System (4JH1)    6E-67

10

1.

Test the signal circuit between the ECM (pin
88 of B-233 connector) and the MAF sensor
(pin 5 of J-182 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

11

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 J-182
connector).

3.

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 poor
connections on the MAF sensor circuits at the
harness connector of the ECM (pins 83 and
88 of B-233 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 MAF sensor.  Refer to Mass Air Flow
Sensor 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

—

15

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with the Tech 2.

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 Tech 2.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 16

16

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK

Step

Action

Value(s)

Yes

No

6E-68    Engine Control System (4JH1) 

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 806 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 Tech 2.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Notice:

• The MAF Sensor parameter on the Tech 2 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 Tech 2.

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 Tech 2.

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 Tech 2.

Does DTC P0100 (Symptom Code B) set, but not
DTC P0100 (Symptom Code C)?

—

Go to Step 4

Go to Step 5

 Engine Control System (4JH1)    6E-69

4

1.

Turn OFF the ignition.

2.

Connect a test lamp between the low
reference circuit of the MAF sensor harness
(pin 3 of J-182 connector) and a battery
voltage.

Does the test lamp illuminate?

—

Go to Step 7

Go to Step 6

5

Important:
The MAF 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 88 of B-233
connector) and the MAF sensor (pin 5 of J-
182 connector) for the following conditions: 

• A short to battery or ignition voltage
• A short to 5 volts reference

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 10

6

1.

Test the low reference circuit between the
ECM (pin 92 of B-233 connector) and the MAF
sensor (pin 3 of J-182 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 11

Go to Step 8

7

1.

Turn OFF the ignition.

2.

Inspect for an intermittent and for a poor
connection at the harness connector of the
MAF sensor (pin 3 of J-182 connector).

3.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 9

8

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector.

3.

Inspect for an intermittent and for a poor
connection on the MAF sensor circuit at the
harness connector of the ECM (pin 92 of B-
233 connector).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 10

9

Replace the MAF sensor.  Refer to Mass Air Flow
Sensor Replacement in this section.

Did you complete the replacement?

—

Go to Step 11

—

10

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 11

—

Step

Action

Value(s)

Yes

No

6E-70    Engine Control System (4JH1) 

11

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with the Tech 2.

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 Tech 2.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 12

12

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic 

Trouble Code (DTC) 

List

System OK

Step

Action

Value(s)

Yes

No

 

 

 

 

 

 

 

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