Code No.15: A/T fluid temperature sensor system

OPERATION

The A/T fluid temperature sensor converts the automatic fluid temperature to voltage, and send the information to the engine-A/T-ECU.
The A/T fluid temperature rises, the resistance decreases. Thus, the sensor output voltage depends on the automatic fluid temperature. As the A/T fluid temperature rises, the output voltage will decrease.

DIAGNOSIS CODE SET CONDITIONS

If the A/T fluid temperature sensor output voltage is 4.5 volts or more after driving for 10 minutes or more, there is an open circuit in the A/T fluid temperature sensor and diagnosis code 15 is set.

PROBABLE CAUSES

Malfunction of the A/T fluid temperature sensor
Damaged harness wires and connectors
Malfunction of the engine-A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

Item 15: A/T fluid temperature sensor (Refer to Data List Table

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

	Go to Step 2.

STEP 2. Measure the resistance at A/T control solenoid valve assembly connector B-109.

Disconnect the connector, and measure the resistance between terminal 1 and 2 at the sensor side.
OK:

16.7 - 20.5 kΩ (at 0°C)

7.3 - 8.9 kΩ (at 20°C)

3.4 - 4.2 kΩ (at 40°C)

1.9 - 2.2 kΩ (at 60°C)

1.0 - 1.2 kΩ (at 80°C)

0.57 - 0.69 kΩ (at 100°C)

Q. Is the check result normal?

Go to Step 3.

Replace the A/T fluid temperature sensor.

STEP 3. Connector check: B-109 A/T control solenoid valve assembly

Check for the contact with terminals.

Q. Is the check result normal?

Go to Step 4.

Repair the defective connector.

STEP 4. Measure the resistance at A/T control solenoid valve assembly connector B-109.

Disconnect the connector, and measure the resistance between terminal 2 and earth at the wiring harness side.
OK: 2 Ω or less

Q. Is the check result normal?

Go to Step 9.

Go to Step 5.

STEP 5. Measure the voltage at engine-A/T-ECU connector C-113.

(1)Connect A/T control solenoid valve assembly connector B-109.

(2)Turn the ignition switch to the ON position.

(3)Measure the voltage between engine-A/T-ECU connector C-113 terminal No.96 and earth.
OK: 0.5 V or less

Q. Is the check result normal?

Go to Step 8.

Go to Step 6.

STEP 6. Connector check: C-113 engine-A/T-ECU connector

Check for the contact with terminals.

Q. Is the check result normal?

Go to Step 7.

Repair the defective connector.

STEP 7. M.U.T.-III data list

Item 15: A/T fluid temperature sensor (Refer to Data List Table

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

	Replace the engine-A/T-ECU.

STEP 8. Connector check: C-113 engine-A/T-ECU connector

Check for the contact with terminals.

Q. Is the check result normal?

Go to Step 14.

Repair the defective connector.

STEP 9. Measure the voltage at A/T control solenoid valve assembly connector B-109.

(1)Disconnect the connector, and measure the voltage between terminal 1 and earth at the wiring harness side.
(2)Turn the ignition switch to the ON position.
OK: 4.5 - 4.9 V

Q. Is the check result normal?

Go to Step 7.

Go to Step 10.

STEP 10. Measure the voltage at engine-A/T-ECU connector C-113.

(1)Connect A/T control solenoid valve assembly connector B-109.

(2)Turn the ignition switch to the ON position.

(3)Measure the voltage between engine-A/T-ECU connector C-113 terminal No.119 and earth.
OK:

3.8 - 4.0 V (at 20°C)

3.2 - 3.4 V (at 40°C)

1.7 - 1.9 V (at 80°C)

Q. Is the check result normal?

Go to Step 12.

Go to Step 11.

STEP 11. Connector check: C-113 engine-A/T-ECU connector

Check for the contact with terminals.

Q. Is the check result normal?

Go to Step 7.

Repair the defective connector.

STEP 12. Connector check: C-113 engine-A/T-ECU connector

Check for the contact with terminals.

Q. Is the check result normal?

Go to Step 13.

Repair the defective connector.

STEP 13. Check the harness between A/T control solenoid valve assembly connector B-109 terminal No.1 and engine-A/T-ECU connector C-113 terminal No.119.

Check the output line for short-circuited or open circuit.

Q. Is the check result normal?

Go to Step 7.

Repair the wiring harness.

STEP 14. Check the harness between A/T control solenoid valve assembly connector B-109 terminal No.2 and engine-A/T-ECU connector C-113 terminal No.96.

Check the earth line for open circuit.

Q. Is the check result normal?

Go to Step 7.

Repair the wiring harness.