P0489 – EGR Valve Position Sensor Circuit Low Input Euro5b MMC L200 IV



OPERATION

  • A power voltage of 5 V is applied to the EGR valve assembly power terminal (terminal No. 3) from the engine-ECU (terminal No. 71) and earthed to the engine-ECU (terminal No. 81) from the EGR valve assembly (terminal No. 2).
  • The sensor signal is inputted to the engine-ECU (terminal No. 57) from the EGR valve assembly output terminal (terminal No. 1).

  • FUNCTION

  • The EGR valve assembly detects the position of the EGR valve and sends the signal to the engine-ECU.
  • Based on the signal, the engine-ECU performs the feedback control of the EGR valve.

  • 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 EGR valve position sensor output voltage is 0.20 V or less for 0.5 second.

  • PROBABLE CAUSES

  • Failed EGR valve position sensor
  • Open/short circuit or harness damage in EGR valve position sensor circuit or loose connector contact
  • Failed engine-ECU

  • DIAGNOSIS PROCEDURE

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

  • Item 16: EGR valve position sensor
  • Q. Is the check result normal?

    STEP 2. Connector check: A-45 EGR valve assembly connector

    Q. Is the check result normal?

    STEP 3. Perform voltage measurement at A-45 EGR valve assembly connector.

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

    STEP 4. Perform voltage measurement at C-105 engine-ECU connector.

  • Measure engine-ECU terminal voltage.
  • Ignition switch: ON
  • Voltage between terminal No. 71 and earth.
  • Q. Is the check result normal?

    STEP 5. Connector check: C-105 engine-ECU connector

    Q. Is the check result normal?

    STEP 6. Check harness between A-45 (terminal No. 3) EGR valve assembly connector and C-105 (terminal No. 71) engine-ECU connector.

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

    STEP 7. M.U.T.-III data list

  • Item 16: EGR valve position sensor
  • Q. Is the check result normal?

    STEP 8. Connector check: C-105 engine-ECU connector

    Q. Is the check result normal?

  • Check power supply line for open circuit and damage.
  • STEP 9. Perform resistance measurement at A-45 EGR valve assembly connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Resistance between terminal No. 2 and earth.
  • Q. Is the check result normal?

    STEP 10. Connector check: C-105 engine-ECU connector

    Q. Is the check result normal?

    STEP 11. Check harness between A-45 (terminal No. 2) EGR valve assembly connector and C-105 (terminal No. 81) engine-ECU connector.

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

    STEP 12. Perform voltage measurement at A-45 EGR valve assembly connector.

  • Use special tool test harness (MB991658) to connect connector and measure at pick-up harness.
  • Engine: Idling (after warning up)
  • Voltage between terminal No. 1 and earth.
  • Q. Is the check result normal?

    STEP 13. Connector check: C-105 engine-ECU connector

    Q. Is the check result normal?

    STEP 14. Check harness between A-45 (terminal No. 1) EGR valve assembly connector and C-105 (terminal No. 57) engine-ECU connector.

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

    STEP 15. Perform voltage measurement at C-105 engine-ECU connector.

  • Measure engine-ECU terminal voltage.
  • Engine: Idling (after warning up)
  • Voltage between terminal No. 57 and earth.
  • Q. Is the check result normal?

    STEP 16. Connector check: C-105 engine-ECU connector

    Q. Is the check result normal?

  • Check output line for open circuit and damage.
  • STEP 17. Connector check: C-105 engine-ECU connector

    Q. Is the check result normal?

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