Code No. P1608: Battery Current Sensor System

OPERATION

A power voltage of 5 V is applied to the battery current sensor connector terminal from the engine-ECU connector terminal ECB5 and is earthed to the engine-ECU connector terminal AFSE&ECBE from the battery current sensor connector terminal.
The battery current sensor connector terminal outputs a sensor signal, which is input into the engine-ECU connector terminal ECB.

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.

or

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. Check battery current sensor itself.

Battery current sensor connector check.
Check battery current sensor itself (Refer to GROUP 54A - Battery - On-vehicle Service - Battery Current Sensor Check <2200> ).

Q. Is the check result normal?

	Go to Step 2.

	Repair or replace the connector, or replace the battery current sensor.

STEP 2. Perform voltage measurement at battery current sensor connector.

Disconnect connector and measure at harness side.
Ignition switch: ON
Voltage between terminal engine-ECU ECB5 line and body earth.

OK: 4.9 - 5.1 V

Q. Is the check result normal?

	Go to Step 4.

	Go to Step 3.

STEP 3. Check harness between battery current sensor connector terminal and engine-ECU connector terminal ECB5.

Check power supply line for open/short circuit.

Q. Is the check result normal?

	Go to Step 8.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 4. Perform resistance measurement at battery current sensor connector.

Disconnect connector and measure at harness side.
Resistance between terminal engine-ECU AFSE&ECBE line and body earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

	Go to Step 6.

	Go to Step 5.

STEP 5. Check harness between battery current sensor connector terminal and engine-ECU connector terminal AFSE&ECBE.

Check earthing line for open circuit and damage.

Q. Is the check result normal?

	Go to Step 8.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 6. Check harness between battery current sensor connector terminal and engine-ECU connector terminal ECB5.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 7.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 7. Check harness between battery current sensor connector terminal and engine-ECU connector terminal ECB.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

	Go to Step 8.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 8. 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 ).