Theory Of Operation
WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) is the Local Interconnect Network (LIN) master for the Light Rain Sensing Module (LRSM). The LRSM performs an internal self test and sends the information to the BCM.