Movement Sensor (IMS)

Fig 1: Identifying Movement Sensor (IMS)

Courtesy of VOLVO CARS CORPORATION

The movement sensor (IMS) uses ultrasound to detect movement inside the passenger compartment. The Doppler effect principle is used to determine if the received sound wave has a different phase compared to the transmitted sound wave. Any difference in phase is interpreted as movement in the vehicle. If a movement is detected, a trigger signal is sent to the central electronic module (CEM), which triggers the alarm.

The movement sensor (IMS) is located in the headlining in the center of the vehicle. This enables it to cover the greatest about of vehicle space possible.

There are diagnostics for both movement sensors.