Materials:
* Ohmmeter
* Thermometer
* Container with water
Steps:
1. Disconnect the battery terminal.
This will turn off power to the sensor and make it safe for testing.
2. Find the automatic transmission temperature sensor.
Its location may vary depending on the Toyota model, but it is usually located on the automatic transmission housing or on a tray. The sensor is a small black or gray cylinder with one or two wires.
3. Disconnect the electrical connector from the sensor.
The connector is usually held in place by a latch. Press the latch and pull the connector to disconnect it.
4. Take resistance measurements.
Set the ohmmeter to range from 0 to 200 ohms. Connect the red ohmmeter lead to one terminal of the sensor and the black lead to the other.
5. Immerse the sensor in water.
Place the sensor in a container of water and hold it so that the water covers the top of the sensor.
6. Heat the water.
Gradually heat the water over low heat, stirring constantly.
7. Take resistance measurements as the temperature rises.
Record resistance readings every few degrees, starting at room temperature and ending at 100°C (212°F).
8. Interpretation of results:
*Normal Resistance: As the temperature increases, the resistance of the sensor should decrease.
* Faulty sensor: If the resistance does not decrease or decreases too sharply, the sensor may be faulty.
Typical resistance values for Toyota automatic transmission temperature sensors:
| Temperature (°C) | Resistance (Ohm) |
|—|—|
| 0 | 2000-4000 |
| 20 | 1000-2000 |
| 40 | 500-1000 |
| 60 | 250-500 |
| 80 | 125-250 |
| 100 | 62.5-125 |
Note: Specific values may vary depending on sensor model and vehicle.
If the automatic transmission temperature sensor is faulty, it must be replaced. This will help ensure accurate transmission temperature measurements and prevent overheating and other transmission problems.