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

GF91.29-P-0011FQ Lumbar Support Adjusting Facility, Function
MODEL 218
- with CODE (275) Electrically adjustable front seats memory package
- except CODE (409) Left/right front multicontour seat
- except CODE (432) Active multicontour seat

Function requirements, general
^ No on-board electrical system limp-home mode
^ Voltage supply connected from driver seat control unit (N32/1) or from front passenger seat control unit (N32/2) to the driver seat lumbar support adjustment control unit (N32/23) or to the front passenger seat lumbar support adjustment control unit (N32/24) is connected and OK

The voltage supply from the respective lumbar support adjustment control unit is sent over the driver seat control unit or the front passenger seat control unit. The rear SAM control unit with fuse and relay module (N10/2) switches the voltage supply for the driver seat control unit or the front passenger seat control unit to match the door status, circuit status and the run-on time. The circuit status is received by the rear SAM control unit with fuse and relay module over the interior CAN (CAN B) from the electronic ignition lock control unit (N73).

Lumbar support adjusting facility function description, general
The lumbar support adjustment is described at the driver seat for left-hand drive vehicles by way of an example, but this also applies for the front passenger seat or for right-hand drive vehicles.
In order to provide optimum support for the vertebral column, the backrest on the driver and front passenger seats each contain a lumbar support unit. The lumbar support consists of two air cushions each, an electrical driver seat lumbar support pneumatic pump (M25/4) to generate compressed air and the driver seat lumbar support adjustment 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 driver seat lumbar support adjustment 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 driver seat lumbar support adjustment switch is pressed in the "forward arrow" direction, the backrest contour in the lumbar support area is changed by inflating the currently active upper lumbar support air cushion or lower lumbar support air cushion. 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 driver seat lumbar support adjustment switch is pressed in the "backward arrow" direction, the lumbar support contour is changed by deflating the air cushions. The deflation starts with the upper air cushion, 1 s ahead of the lower air cushion.

Lumbar support contour height adjustment
When the cross-shaped rocker button of the driver seat lumbar support adjustment 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.
- If the cross-shaped rocker button is moved in the "upward arrow" direction the air pressure in the upper air cushion lumbar support increases and it decreases in the lower air cushion lumbar support.
- If the cross-shaped rocker button is moved in the "downward arrow" direction the air pressure in the upper air cushion lumbar support decreases and it increases in the lower air cushion lumbar support.
The compressed air that is provided is distributed by the driver seat lumbar support adjustment 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 driver seat lumbar support adjustment control unit.