UART Operation

The UART Data Line lets different controllers in the vehicle to communicate or talk using serial data. The UART Data Line allows the Instrument Cluster, scan tool (when connected), Sensing Diagnostic Module (SDM), Powertrain Control Module (PCM), and the Electronic Brake Control Module (EBCM) to communicate over a single wire. During normal operation the Instrument Cluster polls (talks to) each of the modules on the UART Data Line (SDM, Electronic Brake Control Module (EBCM), and Powertrain Control Module (PCM)). As each module is polled, it is in turn prompted to send a return message containing sensor and diagnostic related data. The Instrument Cluster collects and divides up all of the serial data on the UART Data Line and sends it to the appropriate module when it polls that module. The Instrument Cluster is called the master of the UART Line, where the others are slaves. The Instrument Cluster receives most indicator and gage information in this fashion. Breaks in the UART Data Line are diagnosed in Data Link Connector, in Electrical Diagnosis.