The battery supplies electricity to the TCM even when the ignition switch is off. This power allows the TCM to store data such as DTC history and freeze frame data.If serial data communication is lost between any of the LIN devices on the LIN bus network, the master control module will set a no communication code against the non-communicating LIN device. The Diagnostic Trouble Code (DTC) sets when a supervised periodic message that includes the transmitter device availability has not been received.