Mass Movement Sensor Module (MMS)

Fig 1: Locating Mass Movement Sensor Module (MMS)

Courtesy of VOLVO CARS CORPORATION

The mass movement sensor module (MMS) is located in the roof under its own panels.

The two sensors in the XC90 are located along the front edge of the roof and in the roof above the cargo compartment.

The mass movement sensor module (MMS) is used to detect movement in the passenger compartment when the alarm is activated.

When the alarm is activated, the upper electronic module (UEM) carries out a check of the sensors.

The sensors communicate serially with the upper electronic module (UEM). If two sensors are installed, these are connected in parallel to the upper electronic module (UEM).

When the sensors are activated, they transmit microwaves into the vehicle. The microwaves bounce back from the interior of the vehicle and the sensors react to variations in the rebounding waves. A system that uses microwaves is more stable than a system that uses ultrasound sensors and reduces the number of false alarms. For example, microwaves are not affected by the changing temperature of different layers of air inside a vehicle parked in the sun. The cause of the alarm can be read off and verified via VIDA (Volvo scan tool).

The mass movement sensor module (MMS) is powered and grounded via the upper electronic module (UEM).