Transmission Temperature Sensor/Switch, A/T
TRANSMISSION TEMPERATURE SENSORTransmission fluid temperature readings are supplied to the Powertrain Control Module by the Transmission Temperature Sensor. The temperature sensor is located in the governor pressure sensor connector. The temperature readings are used to control engagement of the overdrive clutch, the converter clutch, and governor pressure. Normal resistance value for the thermistor at room temperature is approximately 1000 ohms.
The Powertrain Control Module (PCM) prevents engagement of the converter clutch and overdrive clutch, when fluid temperature is below approximately 30 °F.
If fluid temperature exceeds 260 °F, the Powertrain Control Module will cause a 4-3 downshift and engage the converter clutch. Engagement is according to the third gear converter clutch engagement schedule.
The overdrive OFF lamp in the instrument panel, also illuminates when the shift back to third occurs. The transmission will not allow fourth gear operation until fluid temperature decreases to approximately 230 °F.