Isuzu 4JA1 Workshop Manual page 307

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%.
Step
1 Did you perform the 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?
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 7)?
Action
Engine Control System (4JH1) 6E-53
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
Value(s) Yes

Go to Step 2

Go to Step 3

Go to Step 5
No
Go to Diagnostic
System Check-
Engine Controls
Go to Diagnostic
Aids
Go to Step 4