P0381 – Glow Plug Open-Short Malfunction MMC L200 IV



OPERATION

  • The electrical current source is supplied from the engine control relay (terminal No.3) to the glow control unit (terminal No.6). Also, it is supplied from the glow control unit (terminal No.7) to the body earth.
  • The request signal of operating the glow plug is input into the glow control unit (terminal No. 1) from the engine-ECU (terminal No.120).
  • The voltage for the glow plug is applied from the battery to the glow control unit (terminal No.10).
  • The voltage is applied from the glow control unit (terminal No.1, 2, 3 and 4) to each glow plug.
  • The diagnosis signal is output from the glow control unit (terminal No.9) to the engine-ECU (terminal No.126).

  • FUNCTION

  • The voltage applied to the glow control unit (terminal No.10) from the battery is applied to each glow plug in the duty ratio according to the signal from the engine ECU.

  • TROUBLE JUDGMENT

  • While the engine is running
  • The electrical continuity duty to the glow plug is 17 – 83 %.
  • The information that the glow is abnormal is received from the glow control unit.

  • PROBABLE CAUSES

  • Failed glow plug
  • Failed glow control unit
  • Open/short circuit or harness damage in glow plug circuit or loose connector contact.
  • Failed engine-ECU

  • DIAGNOSTIC PROCEDURE

    STEP 1. Connector check: A-151 glow control unit connector

    Q. Is the check result normal?

    STEP 2. Connector check: A-153 No. 1 glow plug connector, A-154 No. 2 glow plug connector, A-155 No. 3 glow plug connector and A-156 No. 4 glow plug connector.

    Q. Is the check result normal?

    STEP 3. Check harness between A-151 (terminal No.1) glow control unit connector and A-153 (terminal No.1) No.1 glow plug connector.

  • Check output line for open/short circuit and damage.
  • Q. Is the check result normal?

    STEP 4. Check harness between A-151 (terminal No. 2) glow control unit connector and A-154 (terminal No. 1) No.2 glow plug connector.

  • Check output line for open/short circuit and damage.
  • Q. Is the check result normal?

    STEP 5. Check harness between A-151 (terminal No. 3) glow control unit connector and A-155 (terminal No. 1) No.3 glow plug connector.

  • Check output line for open/short circuit and damage.
  • Q. Is the check result normal?

    STEP 6. Check harness between A-151 (terminal No. 4) glow control unit connector and A-156 (terminal No. 1) No.4 glow plug connector.

  • Check output line for open/short circuit and damage.
  • Q. Is the check result normal?

    STEP 7. Replace the glow control unit.

  • After replacing the glow control unit, reconfirm whether the diagnosis code is set.
  • Q. Is the diagnosis code set?

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