Body Control Module (BCM)

The Body Control Module (BCM) monitors several inputs in order to arm and disarm the CTD system. The BCM controls the alarm function outputs. When the BCM detects an unauthorized entry (any door opened), the BCM applies ground to the horn, the park lamp and the headlamp relays. The BCM will send messages to the security indicator in the instrument cluster through the Class 2 serial data link. The BCM had the following 8 basic modes for operating the CTD system. The more detailed descriptions are below.
^ Off state
^ Idle state
^ Disarmed state
^ Ready-to-arm state
^ Arm initiated state
^ Arm delay state
^ Armed state
^ Alarm state

The BCM has the following 6 discrete inputs in order to monitor the CTD system:
^ Ignition 1
^ Driver door mini-wedge (door jamb) switch
^ Passenger door mini-wedge (door jamb) switch
^ Door lock relay
^ Door key switch
^ Passenger door unlock relay

The BCM applies ground once per second for approximately 2 minutes, or until a valid input to disarm the system is received by the BCM.