Inspection Procedure 2: BMU power supply system








PROBABLE CAUSES

  • Open circuits of BMU power supply circuit, short circuits to earth or damage; poor contact of connector.
  • The BMU is failed.

DIAGNOSIS PROCEDURE

STEP 1. 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 2 .
Replace the auxiliary battery.

STEP 2. Connector check: C-107 BMU connector

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

STEP 3. 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 4 .

    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 4. 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 6 .
Go to Step 5 .

STEP 5. 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 6. Perform resistance measurement at C-107 BMU connector

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 3 and earth.
OK: Continuity (2 Ω or less)

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

    Check and repair harness between C-107 (terminal No. 3) BMU connector and body earth.

    • Check earthing line for open circuit and damage.

STEP 7. 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 8 .
Repair.

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

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

STEP 9. 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 10 .
Repair.

STEP 10. Check the trouble symptom

Q. Does the trouble symptom persist?
Replace the BMU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).




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