Transmission Temperature Sensor

WARNING: This page is about a different car, the 2003 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.

Transmission temperature sensor monitors transmission fluid temperature and sends an input signal to Powertrain Control Module (PCM). Input signal is used for controlling torque converter clutch operation, overdrive shifts, low temperature shift compensation, wide open throttle shift strategy and governor pressure.

42RE & 46RE Transmissions - PCM prevents torque converter clutch engagement and overdrive operation when fluid temperature is less than 50°F (10°C). If transmission fluid temperature is more than 260°F (126°C), PCM forces a 4-3 downshift and engages torque converter clutch. Engagement is according to the third gear converted clutch engagement schedule. The overdrive OFF lamp in the instrument panel illuminates when the shift back to third occurs. The transmission will not allow fourth gear operation until fluid temperature decreases to approximately 230°F (110°C).

Transmission fluid temperature readings are supplied to the transmission control module by the thermistor. The temperature readings are used to control engagement of the fourth gear, overdrive clutch, the converter clutch, and governor pressure. Normal resistance value for the thermistor at room temperature is about 2000 ohms. The thermistor is part of the governor pressure sensor assembly and is immersed in transmission fluid at all times. For additional information, see appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.

545RFE Transmission - The transmission temperature sensor is a thermistor that is integral to the Transmission Range (TR) sensor. The transmission temperature sensor is used by the TCM to sense the temperature of the fluid in the sump. Since fluid temperature can affect transmission shift quality and convertor lock up, the TCM requires this information to determine which shift schedule to operate in.

A failure in the temperature sensor or circuit will result in calculated temperature being substituted for actual temperature. Calculated temperature is a predicted fluid temperature which is calculated from a combination of battery (ambient) temperature, engine coolant temperature and in-gear run time since start-up. For additional information, see appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.