Reatta V6-231 3.8L VIN C SFI (1990)
Body Control Module: Description and Operation
BCM Module
The Body Computer Module (BCM) is the heart of the computer network. The BCM has an internal microprocessor and uses a single data line to
communicate with all the other components. The BCM also controls the on-board diagnostics of the vehicle. The BCM controls sub-systems through
direct outputs or by data transmitted along the data line. The data line is a common circuit wire that is connected to all the sub-systems. This line allows
communication between the BCM and the sub-systems.
The BCM receives information from various sensors on the vehicle and relays this information to the sub-systems that need to perform their function.
The BCM produces this data by rapidly switching a 5.0 volt circuit on and off, this produces a digital signal. Each sub-system has its own code or
address. When the BCM sends information on the data line it also assigns the address of the sub-system that it wants the information to be sent to. As a
result only the sub-systems that are addressed will read and understand the information on the data line at that particular time. This process of reading
and controlling information is continuous as long as the vehicle is running.
