Theory Of Operation
WARNING: This page is about a different car, the 2019 RAM 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The purpose of the diagnostic is to check the transmission sump oil temperature sensor for rationality failures by performing three separate checks. These checks include stuck in range, maximum gradient, and three sensor compare. This fluid temperature sensor (thermistor), which correlates resistance to temperature, measures the temperature of the fluid coming from transmission valve body. Temperature values are calculated by the TCM based on the sensor's voltage output for shift map determination, Torque Converter Clutch (TCC) operation, and torque converter fluid temperature sensor rationality checks.
- Condition One, Stuck In Range: If the absolute value of the change in transmission sump oil temperature is less than or equal to a calibrated threshold for a calibrated amount of time when compared to the actual increase of engine coolant temperature, a DTC will be set.
- Condition Two, Maximum Gradient: If the absolute value of the change in transmission sump oil temperature is greater than or equal to a calibrated threshold for a calibrated amount of time, a DTC will be set.
- Condition Three, Three Sensor Compare: If the transmission sump oil temperature is less than or equal to a calibrated threshold while the torque converter fluid temperature and engine coolant temperature are greater than or equal to its calibrated threshold for a calibrated amount of time, a DTC will be set.