P0100
Volume Air Flow Sensor Circuit:
Connectors: A-21X, B-14, C-58 <M/T>, C-55 <A/T>:
CIRCUIT OPERATION
- The volume air flow sensor power is supplied from the MFI relay (terminal 1), and the ground is provided on the ECM (terminal 49)
- 5-volt power is applied to the volume air flow sensor output terminal (terminal 3) from the ECM (terminal 61)
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 ECM
DTC SET CONDITIONS
Check Conditions
- 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 2 seconds.
Check Conditions
- 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 2 seconds.
Check Conditions
- 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 2 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.
- ECM failed.
- PCM failed.
- Air leak between Volume Air Flow Sensor and Throttle Body.
DIAGNOSIS
Required Special Tools:
MB991502: Scan Tool (MUT-II) MB991709: Test Harness Set
STEP 1. Check the volume air flow sensor in one of the following two ways.
1. If scan tool MB991502 is used, go to Step 2.
2. If an analyzer is used, go to Step 3.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
STEP 2. Using scan tool MB991502, check data list item 12: Volume Air Flow Sensor.
1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB99150210 the data reading mode for item 12, Volume Air Flow Sensor.
4. Warm up the engine to normal operating temperature: 80°C to 96°C (176°F to 205°F).
- The standard value during idling should be 10 Hz or more.
- When the engine is revved, the frequency should increase according to the increase in engine speed.
If the checks above meet the specification, the malfunction is intermittent.
Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope With Intermittent Malfunction.
If the checks above do not meet the specification, go to Step 4.
STEP 3. Using the oscilloscope, check the volume air flow sensor.
1. Disconnect volume air flow sensor connector B-14, and connect the test harness special tool (MB991709) in between. (All terminals should be connected.)
2. Connect the oscilloscope probe to volume air flow sensor side connector terminal 3.
NOTE: When measuring with the ECM connector, connect the oscilloscope probe to terminal 61.
3. Start the engine and run at idle.
4. Inspect the waveform.
- The waveform should show a normal pattern similar to the illustration.
5. Turn the ignition switch to "LOCK" (OFF) position.
If the waveform is shown, this malfunction is intermittent.
Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope With Intermittent Malfunction.
If the waveform does not show a normal pattern, go to Step 4.
STEP 4. Check the power supply line at volume air flow sensor connector B-14.
1. Disconnect connector B-14 and measure at the harness side.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 4 and ground.
- Voltage should be battery positive voltage.
4. Turn the ignition switch to "LOCK" (OFF) position.
If within specifications, go to Step 5.
If not within specifications, repair the harness wire between MFI relay connector A-21X and volume air flow sensor connector B-14. Then go to Step 9.
STEP 5. Check the circuits at volume air flow sensor connector B-14.
1. Disconnect connector B-14 and measure at the harness side.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 3 and ground.
- Voltage should be between 4.8 and 5.2 volts.
4. Turn the ignition switch to "LOCK" (OFF) position.
5. Check for the continuity between terminal 5 and ground.
- Should be less than 2 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 harness connector B-14 at the volume air flow sensor for damage.
If harness connector B-14 is in good condition, replace the volume air flow sensor. Then go to Step 9.
If harness connector B-14 is damaged, repair or replace it.
Refer to Harness Connector Inspection. Then go to Step 9.
STEP 7. Check harness connector C-58 at the ECM
If harness connector C-58
If harness connector C-58
STEP 8. Check the harness wire between volume air flow sensor connector B-14 and ECM connector C-58
If the wire between volume air flow sensor connector B-14 and ECM connector C-58
If the wire between volume air flow sensor connector B-14 and ECM connector C-58
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 diagnostic trouble code P0100 does not reset.