4.1.2 Substrate Temperature Sensor
The TCM is situated within the transmission on the valve body. As the TCM controls a number of high power solenoids and is surrounded by transmission fluid it can get very hot. If the temperature of the hardware rises above a pre-determined level the TCM will be shut down. Prior to the TCM shutting down the TCM will log a fault code, and during shutdown the transmission will enter mechanical limp-home mode. A temperature dependent resistor mounted on the processor performs monitoring of the substrate temperature.