On recent Harley models the complete electrics and electronics are managed by two or three computers: the ECU for the entire motor management, the ABS module - if so equipped - for the regulation and control of the brakes, and the Body Control Module - in short called BCM -, i.e. the computer that manages the whole communication between switches and buttons, lighting, instruments, and indicators. A brief example: it's no longer the brake light switch that commands the brake light in the rear of the bike. The brake light switch just sends a pulse to the BCM, which then in turn lights the bulb....