This what the BCM does: It mostly involves in conveniences.
The Body Control Module (BCM) supplies vehicle occupants with visual and audible information and controls various vehicle functions, To provide and receive information, the module is interfaced to the vehicle's serial bus communications network, the Chrysler Collision Detection (CCD) bus. This network consists of the powertrain control module (PCM), the Transmission Control Module (TCM), the electro/mechanical instrument cluster (MIC), the Airbag Control Module (ACM), the Compass/mini-trip module and the Controller Antilock brake Module (CAB). The BCM is operational when battery power is supplied to the module. Ignition switch power is needed for ignition switch functions.
The PCM can be a combination of 3 different computers but most it relates to engine management system