Lumbar support, rear seats

The pneumatic lumbar support can be used to adjust the contour of the backrest on an individual basis.

Brief description of components

Seat module, driver's side rear / passenger's side rear

The seat modules are fitted at the seat.

The seat modules are linked across the K CAN SYSTEM data bus to the control units of the body area.

Rear centre console switch centre (BZMF)

The rear centre console switch centre control unit is

• the interface from the K CAN SYSTEM data bus to the control units of the body area and
  
• the interface to the seat switches.
  

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

Operating switch rear driver's side / passenger's side rear

Depending on the equipment, various switch blocks are fitted.

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

Lumbar support

A lumbar support consists of the following components fitted in each backrest:

• 2 inflatable cushions
  
• 4 solenoid valves
  
• 1 air pump
  

Main functions

Lumbar support adjustment

The lumbar support adjustment is achieved by the varying inflation of 2 cushions in the backrest. The 2 cushions are inflated or deflated via 2 solenoid valves in each cushion. The air pressure required to inflate the 2 cushions is supplied by the air pump.

The air pump and solenoid valves are activated by the relevant seat module in such a way that the required contour is set up with the desired hardness.

The desired lumbar support setting can be chosen via the operating switch.

• The adjustment request is transferred from the switch block across a ribbon cable to the rear centre console switch centre (BZMF).
  
• The rear centre console switch centre (BZMF) makes the message available to the Car Access System (CAS) across the K CAN SYSTEM data bus.
  
• The Car Access System (CAS) is the ”gateway control unit” and it forwards the message across the K CAN PERIPHERALS data bus to the corresponding seat module.
  
• The seat module activates the corresponding solenoid valve via its output stages and, if applicable, the air pump.