Description & Operation
Vehicle body electrical systems are controlled by serial communication bus in which each ECU is linked together by a single communication line. The Body Electronic Area Network (BEAN) has been adopted to maintain communication among the body ECU, Engine Control Module (ECM), meter ECU (combination meter/instrument cluster), Air Conditioning (A/C) ECU, door ECU (driver door power window switch panel), sliding roof ECU (if equipped) and theft warning ECU (if equipped). The A/C ECU , which forms a part of the center cluster panel, consists of A/C ECU and switch panel ECU. These 2 ECUs maintain communication in order to exchange information and vary between manual and automatic A/C systems. See Fig 1.
The body ECU is the main controller of the BEAN. Some electrical system functions and operations are directly connected to body ECU, while other system functions and operations are connected to the remaining BEAN ECUs. Each BEAN ECU converts commands and/or requests into digital signal, and then outputs these digital signals to other ECUs of the BEAN. Body ECU also monitors communication between ECUs to aide in diagnostics.