Movement Sensor (IMS)
The movement sensor (IMS) is in the interior light in the ceiling. The movement sensor (IMS) is used to detect movement inside the passenger compartment when the alarm is activated.
When the alarm is activated, the central electronic module (CEM) checks the sensor.
The sensor communicates serially with the central electronic module (CEM).
When the sensor is activated it sends out ultrasound into the passenger compartment. The sound waves are reflected back to the sensor by the vehicle interior and if the sensor detects change in reflections or movements in the passenger compartment then the alarm is triggered. The sensor is also sensitive to air turbulence and therefore all windows and roof hatch, if appropriate, must be closed so that the sensor shall function optimally without the risk of false alarms.