Code No. P1A4C: BMU Control Power Supply Voltage Abnormal








TROUBLE JUDGMENT
Check Condition
  • Every time after the BMU is activated.
Judgement Criterion
  • The BMU control power supply voltage is less than 8 V.
or

  • The BMU control power supply voltage is more than 16 V.

FAIL-SAFE AND BACKUP FUNCTION

  • Not available

PROBABLE CAUSES

  • The auxiliary battery is failed.
  • When starting at the voltage more than 16 V from the outside of the vehicle
  • The installation of the auxiliary battery terminal is failed.
  • Open circuits of BMU control power supply circuit, short circuits to earth or damage; poor contact of connector
  • The BMU is failed.

DIAGNOSIS PROCEDURE

STEP 1. Auxiliary battery condition check

Q. Does the auxiliary battery start at the voltage more than 16 V from the outside of the vehicle recently?
Erase the diagnosis code, check end.
Go to Step 2 .

STEP 2. Auxiliary battery condition check

Q. Is the installation status of the auxiliary battery terminal abnormal?
Repair.
Go to Step 3 .

STEP 3. M.U.T.-III other system diagnosis code.

Q. Is the diagnosis code of EV-ECU system set?
Check EV-ECU system (Refer to ).
Go to Step 4 .

STEP 4. Check auxiliary battery

  • Check auxiliary battery (Refer to GROUP 54A - Auxiliary Battery - On-vehicle Service - Battery Test ).

Q. Is the check result normal?
Go to Step 5 .
Replace the auxiliary battery.

STEP 5. Connector check: C-107 BMU connector

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

STEP 6. Perform voltage measurement at C-107 BMU connector

  • Disconnect connector, and measure at harness side.
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 7 .

    Check intermediate connectors B-310, B-301, B-05 and B-06, and repair if necessary. If intermediate connectors are normal, check and repair harness between C-107 (terminal No. 1) BMU connector and auxiliary battery.

    • Check power supply line for open circuit, short circuit to earth.

STEP 7. Perform voltage measurement at C-107 BMU connector

  • Disconnect connector, and measure at harness side.
  • Electric motor switch: ON
  • Voltage between terminal No. 2 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 9 .
Go to Step 8 .

STEP 8. Connector check: A-08X EV control relay connector

Q. Is the check result normal?

    Check intermediate connector B-27 and repair if necessary. If intermediate connector is normal, check and repair harness between A-08X (terminal No. 1) EV control relay connector and C-107 (terminal No. 2) BMU connector.

    • Check power supply line for open circuit, short circuit to earth.
Repair.

STEP 9. Check harness between C-107 (terminal No. 1) BMU connector and auxiliary battery
note Before checking harness, check intermediate connectors B-310, B-301, B-05 and B-06, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 10 .
Repair.

STEP 10. Connector check: A-08X EV control relay connector

Q. Is the check result normal?
Go to Step 11 .
Repair.

STEP 11. Check harness between A-08X (terminal No. 1) EV control relay connector and C-107 (terminal No. 2) BMU connector


note Before checking harness, check intermediate connector B-27, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 12 .
Repair.

STEP 12. M.U.T.-III diagnosis code.

Q. Is the diagnosis code set?
Replace the BMU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).




Yandex.Metrika
MMC-Manuals.ru