Principle Of Operation

To activate this feature, the ignition must be in the KL R or KL 15 and press the switch which is located in the Center Console Switch Center (driver and/or passenger front seat).

The switch provides a ground to the control module and an LED in the switch will illuminate. If there is a fault in the system the LED will not illuminate.

Fig 1: Identifying Center Console Switches

Courtesy of BMW OF NORTH AMERICA, INC.

The control module, fluid bladders (2 and 3) and pump (1) is contained in each seat. The pump contains a Hall sensor to monitor the number motor revolutions and two pressure sensors to monitor each bladder for vacuum (indicating empty).

The fluid bladders (2 per seat) contain water glysantin mixture and are connected to the fluid pump. The fluid bladders are equal in volume at rest (15 mm. high) and will raise from 0 up 30 mm. when filled alternately from left to right.

Fig 2: Identifying Control Module, Fluid Bladders And Pump

Courtesy of BMW OF NORTH AMERICA, INC.

The control modules (one per seat) are connected to the P-Bus. The driver's side control module contains an acceleration sensor that monitors transverse acceleration of the vehicle.

Active Seat operation is temporarily interrupted during high acceleration.