P0100

Volume Air Flow Sensor Circuit:

Connectors:

CIRCUIT OPERATION
- The volume air flow sensor power is supplied from the MFI relay (terminal 1), and the ground is provided on the PCM (terminal 57).
- 5-volt power is applied to the volume air flow sensor output terminal (terminal 3) from the PCM (terminal 65). The volume air flow sensor generates a pulse signal when the output terminal and ground are opened/closed (opened/short).

TECHNICAL DESCRIPTION
- while the engine is running, the volume air flow sensor outputs a pulse signal which corresponds to the volume of air flow.
- The PCM checks whether the frequency of this signal output by the volume air flow sensor while the engine is running is at or above the set value.

DTC SET CONDITIONS

Check Area
- Engine speed is higher than 500 r/min.

Judgement Criteria
- Volume air flow sensor output frequency has continued to be 3.3 Hz or lower for two seconds.

Check Area
- Throttle position sensor voltage is 2 volts or lower.
- Engine speed is lower than 2,000 r/min.

Judgement Criteria
- Volume air flow sensor output frequency has continued to be 800 Hz or higher for two seconds.

Check Area
- Throttle position sensor voltage is 1.5 volts or higher.
- Engine speed is higher than 2,000 r/min.

Judgement Criteria
- Volume air flow sensor output frequency has continued to be 60 Hz or lower for two seconds.

TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Volume air flow sensor failed.
- Open or shorted volume air flow sensor circuit, or loose connector.
- PCM failed.

DIAGNOSIS
Required Special Tools
MB991502: Scan Tool (MUT-II)
MB991709: Test Harness




STEP 1. Check the volume air flow sensor in one of the following two ways.
1. For using scan tool MB991502, go to Step 2.
2. For using an analyzer, go to Step 3.

CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.

STEP 2. Using scan tool MB991502, check data list item 12: Volume Air Flow Sensor.
1. Set scan tool MB991502 to the data reading mode for item 12, Volume Air Flow Sensor.
2. Warm up the engine to normal operating temperature: 80° C to 96° C (176° C to 205° F).

- The standard value during idling should be 10 Hz or more.
- When the engine is raced, the frequency should increase according to the increase in engine speed.

If the checks above do not meet the specification, go to Step 4.

If the checks above meet the specification, it can be assumed that this malfunction is intermittent.

Refer to vehicle level Testing and Inspection.




STEP 3. Using the analyzer, check the volume air flow sensor.

1. Disconnect the volume air flow sensor connector A-01, and connect the test harness special tool (MB991709) in between. (All terminals should be connected.)
2. Connect the analyzer special patterns pickup to the volume air flow sensor side connector terminal 3.

NOTE: When measuring with the PCM connector connect the analyzer special patterns pickup to terminal 65.

3. Start the engine and run at idle.




4. Inspect the waveform.
- The waveform should show a normal pattern similar to the illustration.

5. Stop the engine.

If the waveform does not show a normal pattern, go to Step 4.

If a normal waveform is shown, it can be assumed that this malfunction is intermittent.

Refer to vehicle level Testing and Inspection.




STEP 4. Check the power supply line at the volume air flow sensor connector A-01.

1. Disconnect the connector A-01 and measure at the harness side.
2. Turn the ignition switch "ON".

3. Measure the voltage between terminal 4 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).

4. Turn the ignition switch "OFF".

If within specifications, go to Step 5.

If not within specifications, inspect the intermediate connector C-14 and repair or replace if necessary. Refer to vehicle level Testing and Inspection.If the intermediate connector C-14 is in good condition, repair the harness wire between the MFI relay connector C-59 and the volume air flow sensor connector A-01. Then go to Step 9.




STEP 5. Check the circuits at the volume air flow sensor connector A-01.

1. Disconnect connector A-01 and measure at the harness side.
2. Turn the ignition switch "ON".

3. Measure the voltage between terminal 3 and ground.
- Voltage should be between 4.8 and 5.2 volts.

4. Turn the ignition switch "OFF".




5. Check for the continuity between terminal 5 and ground.
- There should be continuity (0 ohms).

If all checks above meet the specifications, go to Step 6.

If any check above does not meet the specifications, go to Step 7.




STEP 6. Check the harness connector A-01 at the volume air flow sensor for damage.

If harness connector A-01 is damaged, repair or replace it. Refer to vehicle level Testing and Inspection.

If harness connector A-01 is in good condition, replace the volume air flow sensor.

Then go to Step 9.







STEP 7. Check the harness wire between the volume air flow sensor connector A-01 and the PCM connector C-90.

NOTE: After checking the intermediate connector C-71 inspect the wire. If the intermediate connector C-71 is damaged, repair or replace it. Refer to vehicle level Testing and Inspection. Then go to Step 9.

If the wire between the volume air flow sensor connector A-01 and the PCM connector C-90 are not damaged, go to Step 8.

If the wire between the volume air flow sensor connector A-01 and the PCM connector C-90 are damaged, repair it. Then go to Step 9.




STEP 8. Check harness connector C-90 at the PCM for damage.

If harness connector C-90 is damaged, repair or replace it. Refer to vehicle level Testing and Inspection.

If harness connector C-90 is in good condition, replace the PCM.

Then go to Step 9.

STEP 9. Test the OBD-II drive cycle.

1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 6 - Other Monitor.

2. Read the diagnostic trouble code, and confirm that a diagnostic trouble code is not being output.