Code No. P1603: Battery Backup Circuit Malfunction






FUNCTION



  • The engine-A/T-ECU (terminal No. 58) checks open circuit in the battery backup line.

TROUBLE JUDGMENT


Check Conditions
  • After engine starts.
  • Battery voltage is more than 10 V.
Judgment Criterion
  • Battery backup line voltage is less than 6 V for 2 seconds.

PROBABLE CAUSES



  • Open/short circuit in battery backup line circuit or loose connector contact
  • Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE
note
    *1: L.H. drive vehicles
    *2: R.H. drive vehicles

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

  • Temporarily place the ignition switch in LOCK (OFF) position, and 10 seconds after that, place it in ON position again.

Q. Is the diagnosis code of P1603 set?
Go to Step 2 .
Check end.

STEP 2. Connector check: D-214 engine-A/T-ECU connector

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

STEP 3. Perform voltage measurement at D-214 engine-A/T-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 58 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 4 .

    Check intermediate connector A-03*1 or D-137*2 and repair if necessary. If intermediate connector is normal, check and repair harness between the battery and D-214 (terminal No. 58) engine-A/T-ECU connector.

    • Check power supply line for open/short circuit.

STEP 4. Check harness between the battery and D-214 (terminal No. 58) engine-A/T-ECU connector.
note Before checking harness, check intermediate connector A-03*1 or D-137*2, and repair if necessary.

  • Check power supply line for damage.

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

STEP 5. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

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