Code No. P1608: Battery Current Sensor System


OPERATION



  • A power voltage of 5 V is applied to the battery current sensor (terminal No. 1) from the engine-ECU (terminal No. 148) and is earthed to the engine-ECU (terminal No. 155) from the battery current sensor (terminal No. 3).
  • The battery current sensor (terminal No. 4) outputs a sensor signal, which is input into the engine-ECU (terminal No. 138).

FUNCTION



  • The battery current sensor detects a battery current and inputs a signal into the engine-ECU.
  • In response to the signal, the engine-ECU controls charging and discharging.

TROUBLE JUDGMENT


Check Condition
  • Battery positive voltage is 8 - 16 V.
  • 2 seconds later after the ignition switch has been in "ON" position or the engine has started up.
Judgment Criterion
  • The battery current sensor output voltage is less than 0.2 V.


  • The battery current sensor output voltage is more than 4.7 V.

FAIL-SAFE AND BACKUP FUNCTION



  • The AS&G control is prohibited.

PROBABLE CAUSES



  • Failed battery current sensor
  • Open/short circuit or harness damage in battery current sensor circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: A-41 battery current sensor connector

Q. Is the check result normal?
Go to Step 2.
Repair or replace the connector.

STEP 2. Check battery current sensor itself.

  • Check battery current sensor itself (Refer to GROUP 54A - Battery - Inspection - Battery Current Sensor Check ).

Q. Is the check result normal?
Go to Step 3.
Replace the battery current sensor.

STEP 3. Perform voltage measurement at A-41 battery current sensor connector.

  • Disconnect connector and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: 4.9 - 5.1 V

Q. Is the check result normal?
Go to Step 6.
Go to Step 4.

STEP 4. Connector check: B-10 engine-ECU connector

Q. Is the check result normal?
Go to Step 5.
Repair or replace the connector.

STEP 5. Check harness between A-41 (terminal No. 1) battery current sensor connector and B-10 (terminal No. 148) engine-ECU connector.

  • Check power supply line for open/short circuit.

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

STEP 6. Perform resistance measurement at A-41 battery current sensor 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 9.
Go to Step 7.

STEP 7. Connector check: B-10 engine-ECU connector

Q. Is the check result normal?
Go to Step 8.
Repair or replace the connector.

STEP 8. Check harness between A-41 (terminal No. 3) battery current sensor connector and B-10 (terminal No. 155) engine-ECU connector.

  • Check earthing line for open circuit and damage.

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

STEP 9. Connector check: B-10 engine-ECU connector

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

STEP 10. Check harness between A-41 (terminal No. 1) battery current sensor connector and B-10 (terminal No. 148) engine-ECU connector.

  • Check power supply line for damage.

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

STEP 11. Check harness between A-41 (terminal No. 4) battery current sensor connector and B-10 (terminal No. 138) engine-ECU connector.

  • Check output line for open/short circuit and damage.

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

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

  • Reconfirmation of diagnosis code.

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