Active Seat

The active seat serves to relax the back muscles and spinal column.

Brief description of components

Seat module driver's side/passenger side

Depending on equipment, the seats are equipped with different seat modules. In general, there are 2 different module sizes:

• Module with 10-chamber plug connection
  
• Module with 8-chamber plug connection
  

If the seat is equipped with the special equipment lumbar support adjustment or Active Seat, the module is fitted with a 10-chamber plug connection.

The seat module is secured directly to the corresponding seat.

The seat modules are networked with the vehicle via the CAN BUS.

Centre console switch centre

The control unit centre console switch centre has the following functions:

• CAN BUS interface to the vehicle electrical system
  
• Interface to the seat switches
  
• Interface to the controller
  

The control unit centre console switch centre is fitted in the front centre armrest.

Operating switch driver seat/passenger seat

Depending on the equipment, various switch blocks are fitted.

The switch blocks are connected by means of ribbon cables to the centre console switch centre (BZM).

Active Seat

Each seat contains:

• 2 fluid bubbles
  
• 1 hydraulic pump
  
• 1 solenoid valve
  
• 2 underpressure switches
  

Fluid bubbles

The fluid bubbles are filled with a water-glysantine mixture. They are connected to the pump unit by means of plastic hoses.

Hydraulic pump

Pump with alternating direction of rotation for filling and emptying the fluid bubbles

Solenoid valve

The solenoid valve opens and closes the inlet to the fluid bubbles.

Underpressure switches

Each fluid bubble contains an underpressure switch.

Both switches are arranged in line in the circuit as openers.

Main functions

Activation of active seat

The active seat is activated by pressing the corresponding switch.

• The adjustment command is transferred from the switch block to the BZM across a ribbon cable.
  
• The BZM sends the message across the K-CAN SYSTEM to the Car Access System (CAS).
  
• The CAS as ”gateway control unit” passes the message on to the corresponding seat module via the K-CAN PERIPHERALS.
  
• The seat module activates the hydraulic pump and the solenoid valve directly via its output stages.
  

Function sequence, active seat

The system is filled with a defined quantity of fluid.

• The hydraulic pump pumps the fluid alternately into the left and right fluid bubble. In the end positions and middle position, the procedure is interrupted briefly.
  
• The solenoid valve opens and closes the inlet to the fluid bubbles. The solenoid valve is closed when the system is switched off and in the pauses between the adjustments.
  
• The underpressure switches detect the end positions. In addition, the seat module senses the middle position (by dividing the time between the switch operations in two).
  
• The middle position is learned by the seat module.
  

At high vehicle transversal acceleration, the procedure of the active seat is interrupted. The transversal acceleration signal is provided by the yaw rate sensor via the bus system.

Safety function

Consumer shutdown

In the case of signal ”Control peak reduction priority” from the power module, the power of the seat heating is reduced or it is switched off.

The function indicator (LEDs) remains switched on when the active seat is switched off for a brief period.