Code No. P0381: Glow Plug Open/Short Malfunction


OPERATION



  • The electrical current source is supplied from the engine control relay (terminal No.2) to the glow control unit (terminal No.5). Also, it is supplied from the glow control unit (terminal No.6) to the body earth.
  • The request signal of operating the glow plug is input into the glow plug relay (terminal No. 9) 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.8).
  • 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.7) to the engine-ECU (terminal No.125).

FUNCTION



  • The voltage applied to the glow control unit (terminal No.8) from the battery is applied to each glow plug in the duty ratio according to the signal from the engine ECU.

TROUBLE JUDGMENT


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

FAIL-SAFE AND BACKUP FUNCTION



  • The EGR control is stopped (fully closed).

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-34X glow control unit connector

Q. Is the check result normal?
Go to Step 2 .
Repair or replace the connector.

STEP 2. Connector check: B-02 No. 1 glow plug connector, B-03 No. 2 glow plug connector, B-04 No. 3 glow plug connector and B-05 No. 4 glow plug connector.

Q. Is the check result normal?
Go to Step 3 .
Repair or replace the connector.

STEP 3. Check harness between A-34X (terminal No.1) glow control unit connector and B-02 (terminal No.1) No.1 glow plug connector.
note Before checking harness, check intermediate connectors A-17 and B-107, and repair if necessary.

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

Q. Is the check result normal?
Go to Step 4 .
Repair the damaged harness wire.

STEP 4. Check harness between A-34X (terminal No. 2) glow control unit connector and B-03 (terminal No. 1) No.2 glow plug connector.
note Before checking harness, check intermediate connectors A-17 and B-107, and repair if necessary.

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

Q. Is the check result normal?
Go to Step 5 .
Repair the damaged harness wire.

STEP 5. Check harness between A-34X (terminal No. 3) glow control unit connector and B-04 (terminal No. 1) No.3 glow plug connector.
note Before checking harness, check intermediate connectors A-17 and B-107, and repair if necessary.

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

Q. Is the check result normal?
Go to Step 6 .
Repair the damaged harness wire.

STEP 6. Check harness between A-34X (terminal No. 4) glow control unit connector and B-05 (terminal No. 1) No.4 glow plug connector.
note Before checking harness, check intermediate connectors A-17 and B-107, and repair if necessary.

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

Q. Is the check result normal?
Go to Step 7 .
Repair the damaged harness wire.

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?
Replace the engine-ECU.
Check is end.