Transmission Temperature Sensor/Switch: Description and Operation

Automatic Transmission Electrical Components:

PURPOSE
The Transmission Fluid Temperature (TFT) Sensor is used by the control module to control:
- Torque Converter Clutch (TCC) apply and release schedule.
- Hot mode determination.
- Shift quality.

OPERATION
The TFT is a thermistor used to indicate transmission fluid temperature. The control module sends a 5.0 volt signal to the TFT through a resistor in the computer and measures the voltage. High sensor resistance produces high signal input voltage which corresponds to low fluid temperature. Low sensor resistance produces low signal input voltage which corresponds to high fluid temperature. With the TFT varying its resistance, the control module can sense transmission fluid temperature by reading the varying voltage.

LOCATION
The sensor is part of the transmission range fluid pressure switch assembly and is attached to the control valve body within the transmission.