Automatic Transmission Fluid Temperature Sensor
The automatic transmission fluid temperature (TFT) sensor assembly is a thermistor, which is mounted in the wiring harness assembly. Low transmission temperature produces high resistance, while high temperature produces low resistance. The PCM/TCM supplies a 5-volt signal to the TFT sensor assembly through an internal resistor. Then the PCM/TCM measures the voltage drop in the circuit. Voltage is high when the transmission is cold and low when the transmission is hot.
The PCM/TCM uses the TFT sensor assembly in order to regulate torque converter clutch apply, as well as shift quality.
DTC P0711, P0712 and P0713 indicate a fault in the TFT sensor assembly circuit. After the vehicle has been started, transmission temperature should rise steadily and stabilize between 90-115°C (194-239°F), depending on load. All 3 DTCs cause the PCM/TCM to use a default value of 140°C (284°F), thus reacting as if the transmission were hot in either case. When DTCs P0711, P0712 or P0713 are set, the PCM/TCM freezes the shift adapts from being updated, and the MIL illuminates. Some driveability symptoms will be noticed, especially when cold.