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. 99) and is earthed to the engine-ECU (terminal No. 101) 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. 100).

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

Ignition switch is "ON" position.

Judgment Criterion

The battery current sensor output voltage is less than 0.2 V for 2 seconds.

or

The battery current sensor output voltage is more than 4.8 V for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION

Prohibits charge and discharge control.

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-77 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 <Low CO₂ specification, FFV> ).

Q. Is the check result normal?

	Go to Step 3 .

	Replace the battery current sensor.

STEP 3. Perform voltage measurement at A-77 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 7 .

	Go to Step 4 .

STEP 4. Connector check: B-09 engine-ECU connector

Q. Is the check result normal?

	Go to Step 5 .

	Repair or replace the connector.

STEP 5. Check harness between A-77 (terminal No. 1) battery current sensor connector and B-09 (terminal No. 99) engine-ECU connector.

Check power supply line for open/short circuit.

Q. Is the check result normal?

	Go to Step 6 .

	Repair the damaged harness wire.

STEP 6. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Q. Is 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 ).

STEP 7. Perform resistance measurement at A-77 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 10 .

	Go to Step 8 .

STEP 8. Connector check: B-09 engine-ECU connector

Q. Is the check result normal?

	Go to Step 9 .

	Repair or replace the connector.

STEP 9. Check harness between A-77 (terminal No. 3) battery current sensor connector and B-09 (terminal No. 101) engine-ECU connector.

Check earthing line for open circuit and damage.

Q. Is the check result normal?

	Go to Step 6 .

	Repair the damaged harness wire.

STEP 10. Connector check: B-09 engine-ECU connector

Q. Is the check result normal?

	Go to Step 11 .

	Repair or replace the connector.

STEP 11. Check harness between A-77 (terminal No. 1) battery current sensor connector and B-09 (terminal No. 99) engine-ECU connector.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 12 .

	Repair the damaged harness wire.

STEP 12. Check harness between A-77 (terminal No. 4) battery current sensor connector and B-09 (terminal No. 100) engine-ECU connector.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

	Go to Step 6 .

	Repair the damaged harness wire.