Posted in MMC L200

P0620 – Alternator Control Circuit Euro5b MMC L200 IV

 Posted by  Posted on September 28, 2020

OPERATION

  • When the ignition switch is turned ON, the current should be supplied from the combination meter (terminal No. 52) to the alternator (terminal No. 3). When the engine starts under those conditions, the alternator should generate currents.
  • The engine-ECU checks the voltage of the battery backup terminal (terminal No. 103) to monitor the electricity generation voltage of the alternator.

    • FUNCTION

  • The engine-ECU compares the battery voltage with the voltage generated from the alternator to check whether the electrical generation is normal.

    • TROUBLE JUDGMENT

  • Ignition switch is “ON” position.
  • The engine speed is 1 500 r/min or more.
  • The battery backup voltage is 13.5 V or more.
  • The G-terminal duty ratio is 10.2 % or more and 89.8 % or less.
  • For 30 seconds, the final target generation voltage subtracted from the battery backup voltage equals 0.8 V or more.
  • For 30 seconds, the battery backup voltage subtracted from the final target generation voltage equals 1.9 V or more.

    • PROBABLE CAUSES

  • Failed battery
  • Failed drive belt
  • Loose connector contact
  • Open/short circuit or harness damage in alternator G-terminal circuit
  • Harness damage in battery backup circuit
  • Failed alternator
  • Failed engine-ECU

    • DIAGNOSIS PROCEDURE

    STEP 1. Checking engine start conditions

  • Check whether the user uses the booster cable to start the engine.

    • Q. Have you ever used the booster cable to start the engine?

    STEP 2. Battery check

    Q. Is the check result normal?

    STEP 3. Drive belt tension check

    Q. Is the check result normal?

    STEP 4. Connector check: C-103 engine-ECU connector

    Q. Is the check result normal?

    STEP 5. Perform voltage measurement at C-103 engine-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 121 and earth.

    • Q. Is the check result normal?

    STEP 6. Connector check: A-122 alternator connector

    Q. Is the check result normal?

    STEP 7. Check harness between C-103 (terminal No. 121) engine-ECU connector and A-122 (terminal No. 1) alternator connector.

  • Check output line for open/short circuit and damage.

    • Q. Is the check result normal?

    STEP 8. Check harness between battery and C-103 (terminal No. 103) engine-ECU connector.

  • Check power supply line for damage.

    • Q. Is the check result normal?

    STEP 9. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

    • Q. Is diagnosis code set?

    STEP 10. Replace the drive belt

  • After replacing the drive belt, reconfirm whether the diagnosis code is set.

    • Q. Is diagnosis code set?

    STEP 11. Replace the alternator

  • After replacing the alternator, reconfirm whether the diagnosis code is set.

    • Q. Is diagnosis code set?

    Author: admin