Battery Backed-Up Sounder (BBUS)

The BBUS uses an integral sounder to produce an audio warning when the alarm is triggered. An inclination sensor is incorporated into the BBUS, to monitor vehicle attitude, see Inclination Sensor.

Operation of the BBUS is controlled by the central junction box (CJB) via exchange signals on the local interconnect network (LIN). Under normal operation the BBUS is powered by a permanent battery power supply from the central junction box (CJB). However, if the power feed is disrupted an integral rechargeable battery powers the BBUS.

On receipt of the arming signals, the BBUS sounder and the inclination sensor respond with a status signal. If there is no response to the arming signals within 12 seconds, the central junction box (CJB) assumes there is a fault and sends a disarm signal to the sounder or the inclination sensor, as appropriate. The central junction box (CJB) also stores a related fault code.

If the alarm is subsequently triggered, with the BBUS sounder disarmed, the central junction box (CJB) uses the passive anti-theft horn or vehicle horn to sound the audio warning.