Code No. P0515: Battery Temperature Sensor System

OPERATION

A power voltage of 5 V is applied to the battery temperature sensor output terminal (terminal No. 2) from the engine-ECU (terminal No. 98).
The power voltage is earthed to the engine-ECU (terminal No. 101) from the battery temperature sensor (terminal No. 3).

FUNCTION

The battery temperature sensor converts the battery temperature into a voltage and inputs the signal to the engine-ECU.
In response to the signal, the engine-ECU controls charging and discharging.
The battery temperature sensor is a kind of resistor, which has characteristics to reduce its resistance as the battery temperature rises. Therefore, the sensor output voltage varies with the battery temperature, and becomes lower as the battery temperature rises.

TROUBLE JUDGMENT

Check Condition

2 seconds later after the ignition switch has been in ON position or just after the engine has started up.

Judgment Criterion

Battery temperature sensor output voltage is more than 4.6 V (corresponding to a battery temperature of below -50°C or less) for 2 seconds.

Battery temperature sensor output voltage is less than 0.2 V (corresponding to a battery temperature of 90°C or more) for 2 seconds.

PROBABLE CAUSES

Failed battery temperature sensor
Open/short circuit or harness damage in battery temperature 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 temperature sensor itself.

Check battery temperature 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-77 battery current sensor connector.

Disconnect connector and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 2 and earth.

OK: 4.5 - 4.9 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. 2) battery current sensor connector and B-09 (terminal No. 98) engine-ECU connector.

Check output 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. 2) battery current sensor connector and B-09 (terminal No. 98) engine-ECU connector.

Check output line for damage.

Q. Is the check result normal?

	Go to Step 6 .

	Repair the damaged harness wire.