Posted in MMC L200

P0183 – Fuel Temperature Sensor Circuit High Input MMC L200 IV

 Posted by  Posted on September 28, 2020

OPERATION

  • A power voltage of 5 V is applied to the fuel temperature sensor output terminal (terminal No. 1) of the air flow sensor connector from the engine-ECU (terminal No. 55).
  • The power voltage is earthed to the engine-ECU (terminal No. 79) from the fuel temperature sensor (terminal No. 2).

    • FUNCTION

  • The fuel temperature sensor converts the intake air temperature into a voltage and inputs the voltage signal to the engine-ECU.
  • In response to the signal, the engine-ECU corrects the fuel injection amount, etc.
  • The fuel temperature sensor is a kind of resistor, which has characteristics to reduce its resistance as the intake air temperature rises. Therefore, the sensor output voltage varies with the fuel temperature, and becomes lower as the fuel temperature rises.

    • TROUBLE JUDGEMENT

  • 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 fuel temperature sensor output voltage is 4.95 V or more for 0.5 second.

    • PROBABLE CAUSES

  • Failed fuel temperature sensor
  • Open circuit or harness damage in fuel temperature sensor circuit or loose connector contact
  • Failed engine-ECU

    • DIAGNOSIS PROCEDURE

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

  • Item 21: Fuel temperature sensor

    • Q. Is the check result normal?

    STEP 2. Connector check: A-46 fuel temperature sensor connector

    Q. Is the check result normal?

    STEP 3. Check fuel temperature sensor itself.

    Q. Is the check result normal?

    STEP 4. Perform voltage measurement at A-46 fuel temperature sensor connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 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-46 (terminal No. 1) fuel temperature sensor connector and C-105 (terminal No. 55) engine-ECU connector.

  • Check output line for open circuit.

    • Q. Is the check result normal?

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

  • Item 21: Fuel temperature sensor

    • Q. Is the check result normal?

    STEP 8. Perform resistance measurement at A-46 fuel temperature sensor connector.

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 2 and earth.

    • Q. Is the check result normal?

    STEP 9. Connector check: C-105 engine-ECU connector

    Q. Is the check result normal?

    STEP 10. Check harness between A-46 (terminal No. 2) fuel temperature sensor connector and C-105 (terminal No. 79) engine-ECU connector.

  • Check earthing line for open circuit and damage.

    • Q. Is the check result normal?

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