P0102 – Air flow Sensor Circuit Low Input MMC L200 IV



OPERATION

  • Power is supplied by the engine control relay (terminal No. 3) to the air flow sensor (terminal No. 5), and the air flow sensor (terminal No. 4) is earthed through the engine-ECU (terminal No. 155).
  • The air flow sensor (terminal No. 3) outputs a sensor signal, which is input into the engine-ECU (terminal No. 140).

  • FUNCTION

  • The air flow sensor outputs pulse signal that varies in accordance with the intake air volume.
  • In response to the signal, the engine-ECU controls EGR control, etc.

  • TROUBLE JUDGMENT

  • Battery positive voltage is 8 – 16 V
  • 2 seconds later after the ignition switch has been in “ON” position or the engine has started up.
  • The air flow sensor output voltage is 0.50 V or less.

  • PROBABLE CAUSES

  • Failed air flow sensor
  • Open/short circuit or harness damage in air flow sensor circuit or loose connector contact
  • Failed engine-ECU

  • DIAGNOSIS PROCEDURE

    STEP 1. M.U.T.-III data list

  • Item 114: Air flow sensor
  • Q. Is the check result normal?

    STEP 2. Connector check: A-135 air flow sensor connector

    Q. Is the check result normal?

    STEP 3. Perform voltage measurement at A-135 air flow sensor connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 5 and earth.
  • Q. Is the check result normal?

    STEP 4. Connector check: A-20X engine control relay connector

    Q. Is the check result normal?

  • Check power supply for open/short circuit.
  • STEP 5. Perform resistance measurement at A-135 air flow sensor connector.

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 4 and earth.
  • Q. Is the check result normal?

    STEP 6. Connector check: C-103 engine-ECU connector

    Q. Is the check result normal?

    STEP 7. Check harness between A-135 (terminal No. 4) air flow sensor connector and C-103 (terminal No. 155) engine-ECU connector.

  • Check earthing line for damage.
  • Q. Is the check result normal?

    STEP 8. M.U.T.-III data list

  • Item 114: Air flow sensor
  • Q. Is the check result normal?

    STEP 9. Perform voltage measurement at A-135 air flow sensor connector.

  • Disconnect connector, and measure at harness side.
  • Voltage between terminal No. 3 and earth.
  • Q. Is the check result normal?

    STEP 10. Connector check: C-103 engine-ECU connector

    Q. Is the check result normal?

    STEP 11. Check harness between A-135 (terminal No. 3) air flow sensor connector and C-103 (terminal No. 140) engine-ECU connector.

  • Check output line for short circuit.
  • Q. Is the check result normal?

    STEP 12. Perform voltage measurement at C-103 engine-ECU connector.

  • Measure engine-ECU terminal voltage.
  • Disconnect A-135 air flow sensor connector.
  • Ignition switch: ON
  • Voltage between terminal No. 140 and earth.
  • Q. Is the check result normal?

    STEP 13. Connector check: C-103 engine-ECU connector

    Q. Is the check result normal?

  • Check output line for open circuit.
  • STEP 14. Connector check: C-103 engine-ECU connector

    Q. Is the check result normal?

    Author: admin