Theory Of Operation
The transmission system uses three temperature sensors. If any one of the sensors fail, the other two sensors are used for the control and temperature monitoring calculations. This Diagnostic Trouble Code (DTC) will only set when more than one temperature sensors fail.
One of the sensors is located in the sump of the transmission and can be monitored with a scan tool under the Oil Temperature Sensor data parameter. The other two sensors (Chip Sensors) are embedded on the Printed Circuit Board (PCB) in two separate areas of the Transmission Control Module (TCM). The TCM is attached to the valve body and therefore provides the three sensors with a strong temperature correlation. The Chip Sensors can not be monitored with the scan tool.
Normally, the Oil Temperature Sensor that is located in the oil sump is used for the transmission control calculations and the sensors located in the TCM are only used for over-temperature shutdown and temperature sensor rationality monitoring.