Code No. P1603: Battery Backup Circuit Malfunction




OPERATION



FUNCTION



TROUBLE JUDGMENT


Check Condition
Judgment Criterion

PROBABLE CAUSE



DIAGNOSIS PROCEDURE

STEP 1. Check the battery condition.


Q. Was the battery terminal removed just before reading the diagnosis code?
Go to Step 2 .
Go to Step 3 .

STEP 2. 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 P1603 set?
Go to Step 3 .
Check end.

STEP 3. Perform voltage measurement at C-111 engine-ECU <M/T> connector or engine-A/T-ECU <A/T> 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 C-18, C-32 (R. H. drive vehicles) and C-125, and repair if necessary. If intermediate connector is normal, check and repair harness between battery and C-111 (terminal No. 58) engine-A/T-ECU connector.

    • Check power supply line for open/short circuit.

STEP 4. Connector check: C-111 engine-ECU <M/T> connector or engine-A/T-ECU <A/T> connector

Q. Is the check result normal?

Go to Step 5 .

Repair or replace.

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

  • Reconfirmation of diagnosis code.

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