Functional Description - Body Control Module
During an engine cranking event, when the BCM receives a crank signal from the Powertrain Control Module (PCM), the BCM energizes the BCM controlled starter relay with an internal high side driver control.
The BCM is the gateway for all bus communications needing to be gated from one bus network to a different bus network. This grants the modules on different busses the ability to interact with each other. If the Local Interface Network (LIN) or CAN bus communications go down, the BCM will set the appropriate DTCs and display SNA values.