Code No. P1603: Battery Backup Circuit Malfunction




OPERATION




FUNCTION




TROUBLE JUDGEMENT


Check Conditions
Judgement Criterion

FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III diagnosis code



  • Temporarily turn off the power supply mode of the electric motor switch, and 10 seconds after that, operate the electric motor switch without depressing the brake pedal and turn ON the power supply mode of electric motor switch.

Q. Is the diagnosis code of P1603 stored?

Go to Step 2.
Check end.

STEP 2. Perform voltage measurement at engine-ECU connector.



  • Disconnect connector, and measure at harness side.
  • Voltage between terminal BACK and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 3.

    Repair or replace the connector, or check and repair harness between the auxiliary battery and engine-ECU connector terminal BACK.

    • Check power supply line for open/short circuit.

STEP 3. Check harness between the auxiliary battery and engine-ECU connector terminal BACK.



  • Check power supply line for damage.

Q. Is the check result normal?

Go to Step 4.
Repair or replace the connector, or repair the damaged harness wire.

STEP 4. M.U.T.-III diagnosis code



  • Reconfirmation of diagnosis code.

Q. Is diagnosis code stored?

Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).