Transmission Temperature Sensor/Switch: Description and Operation

TRANSMISSION FLUID TEMPERATURE SENSOR
The transmission fluid temperature sensor, which is fitted in the transmission housing, gives the Transmission Control Module (TCM) information about the current transmission fluid temperature.

The sensor is of the NTC type, i.e. the sensor's built-in resistance has a negative temperature dependence: the resistance is reduced when the temperature rises. This property means that the voltage level varies on TCM input pin 33.

The variations in resistance and voltage are shown in the table below.

The sensor is grounded in ground point G34S, car body ground.

The TCM uses the temperature information to calculate gear shifting points and when to connect the lock-up function.

Oil temp Resistance Voltage, pin 33
°C (Ohms) ±10% (V) ±10%

-10 5000 4.6
0 2000 4.1
+20 900 3.4
+40 400 2.4
+80 125 1.1
+100 75 0.7
+150 27 0.3