GF91.29-P-0011GD Lumbar Support Adjusting Facility, Function

GF91.29-P-0011GD Lumbar Support Adjusting Facility, Function
- with CODE (275) Memory package (driver seat, steering column, mirrors)
- with CODE (242) Electrically adjustable front passenger seat with memory

Function requirements, general
^ No on-board electrical system limp-home mode

On-board electrical system limp-home mode is transmitted by the rear SAM control unit with fuse and relay module (N10/2) via the interior compartment CAN. The driver seat control unit (N32/1) and the front passenger seat control unit (N32/2) (with code (242) Electrically adjustable front passenger seat with memory) then switch off the power supply to the lumbar support adjusting facility.

Lumbar support adjusting facility function description, general
The lumbar support adjusting facility is described on the driver seat for left-hand vehicles by way of an example, but this also applies to the passenger seat.

In order to provide optimum support for the vertebral column, the backrests on the driver and front passenger seats each contain a lumbar support unit. Each lumbar support unit consists of 2 air cushions, an electric pneumatic driver seat lumbar support pump (M25/4) for compressed air production and the driver seat lumbar support adjusting facility control unit (N32/23) with integrated control valve block for pneumatic control. The adjustment is performed via the driver seat lumbar support adjusting facility switch (S109/2), which is connected to the lumbar support adjusting facility control unit via a direct electrical line and is located on the exit side of the seat.

The 4-way lumbar support permits the following subfunctions:
^ Inflating the air cushions
^ Deflating the air cushions
^ Lumbar support contour height adjustment

Inflating the air cushions
As long as the cross-shaped rocker button of the lumbar support adjusting facility switch is pressed in the "forward arrow" direction, the backrest contour in the lumbar support area is changed by inflating the currently active upper or lower lumbar support air cushions. The differences in pressure in the individual cushions are retained. On reaching the maximum pressure, the inflation is stopped.

Deflating the air cushions
As long as the cross-shaped rocker button in the lumbar support adjusting facility switch is pressed in the "backward arrow" direction, the lumbar support contour is changed by deflating the air cushions. Deflation starts with the upper air cushion, 1 s before the lower air cushion.

Lumbar support contour height adjustment
When the cross-shaped rocker button of the lumbar support adjusting facility switch is pressed up or down, the lower or upper air cushion is activated and inflated or deflated separately depending on the request. In this case, deflation of one of the cushions starts approx. 2 s before inflation of the other cushion that has been activated.
- When the cross-shaped rocker button is pressed in the "upward arrow" direction, the air pressure increases in the upper air cushion area and drops in the lower air cushion area.
- When the cross-shaped rocker button is pressed in the "downward arrow" direction, the air pressure drops in the upper air cushion area and increases in the lower air cushion area.

The compressed air that is provided is distributed by the lumbar support adjusting facility control unit (with integrated valve block) to the upper and lower air cushions via the pneumatic lines, based on the driver request.

The pressure is also regulated by the lumbar support adjusting facility control unit.