Brief description of components

The following components deliver signals for the active seat back width adjustment:

• Centre console switch cluster 

  2 buttons for active seat back width adjustment are located in the center console switch cluster (SZM): 1 button for the driver's side, 1 button for the front-passenger side. These buttons have 3 positions. This means that 3 different characteristic maps can be selected: "Comfort", "Normal", "Sport".

• Control panel for seat adjustment 

  Each seat has a seat adjustment control panel. The width of the backrest can be adjusted individually using the "OPEN" and "CLOSE" buttons. The control panel is connected via a K-bus to the center console switch cluster (SZM).

• Sensors in the active seat back width adjustment drive 

  The drive incorporates the following sensors:

  • Limit-position switch
  • 2 Hall sensors
  • Temperature sensor

  The temperature sensor protects against overheating.

  The other sensors monitor the drive's position and direction of rotation.

Several control units are involved in the active seat back width adjustment:

• ALBFA and ALBBF: Active driver seat back width (ALBFA) and active front-passenger seat back width (ALBBF) 

  The ALBFA control unit and the ALBBF control unit activate the active seat back width adjustment drives (driver's seat or front-passenger seat). The signals are transmitted to the PT-CAN.

• DSC: Dynamic Stability Control 

  The DSC control unit sends the following signals for seat back width adjustment to the PT-CAN:

  • Vehicle road speed

    The DSC control unit calculates the car's road speed using the signals from the 4 wheel-speed sensors.

  • Longitudinal acceleration

    The DSC control unit calculates the longitudinal acceleration using the signal from the DSC sensor.

  • Lateral acceleration

    The DSC control unit calculates the lateral acceleration using the signal from the DSC sensor.

  • Yaw rate

    The DSC control unit calculates the rotation around the vertical axis using the signal from the DSC sensor.

  • Steering angle

    The steering angle sensor determines the steering angle in the steering column switch cluster (SZL). The SZL sends the signal to the DSC control unit via the F-CAN (chassis CAN).

  • Steering-angle rate

    The steering angle sensor also determines the steering-angle speed in the steering column switch cluster (SZL). The SZL sends the signal to the DSC control unit via the F-CAN (chassis CAN).

• DME or DDE: Digital engine electronics or Digital diesel electronics 

  The engine control unit delivers the "Engine running" signal.

  The seat back width adjustment is only activated when the engine is running.

• SGM or KGM: Safety and gateway module or body gateway module 
  • up to 09/2005

  The SGM is the gateway between the PT-CAN and the K-CAN. The diagnosis wire is connected to the SGM.

  • from 09/2005

  The KGM is the gateway between the PT-CAN and the K-CAN. The diagnosis wire is connected to the KGM.

• SMFA and SMBF: Driver's seat module and front-passenger seat module 

  The seat module controls the seat memory. The seat module sends a CAN message in order to set a specific seat back width (memory for seat back width adjustment).

  Signal path: Seat module -> K-CAN -> Safety and gateway module (SGM) -> PT-CAN -> ALBFA or ALBBF

The following components are controlled:

• Drive for active seat back width adjustment 

  A drive for seat back width adjustment is located in the left - and right-hand seat backrests.

  During cornering, the drive on the outside adjusts the seat back width.

  The backrest side section is moved in the process.

• LEDs in the center console switch cluster 

  3 LEDs are positioned above the button in the SZM. The LEDs are activated depending on which characteristic map is selected (Comfort, Normal, Sport).