GF91.29-P-0008GM Lumbar Adjustment Function

GF91.29-P-0008GM Lumbar Adjustment Function
- as of model year 09/YoM 08 model refinement package except CODE (409) Left/right front multicontour seat [model 164.1]
- as of model year 09/YoM 08 except CODE (409) Left/right front multicontour seat [models 164.8 and 251.1]

Function requirements, general
On vehicles without code (275) Memory package (driver seat, steering column, mirrors) and without code (242) Electrically adjustable front passenger seat with memory
^ Circuit 15R ON or
^ Run-on active
^ No on-board electrical system limp-home mode

On vehicles with code (275) Memory package (driver seat, steering column, mirrors) and with code (242) Electrically adjustable front passenger seat with memory
^ No on-board electrical system limp-home mode

Run-on
The lumbar support adjustment can still be adjusted for t = 180 s after circuit 15R has been switched off. If a change in circuit status (e.g. from 15C "ON" to 15C "OFF") or a change in door status occurs during the run-on time, the run-on time restarts.Even in the event of a change in door status or a change in circuit status after any amount of time, the run-on phase restarts, which means that prior to driving off the lumbar support can also be adjusted for t = 180 s after opening a door, without having to switch circuit 15R on. The rear SAM control unit (N10/8) receives the circuit status from the EIS [EZS] control unit (N73) via the interior CAN (CAN B).

Lumbar adjustment function description, general
The lumbar adjustment is described on the driver seat for left-hand vehicles by way of an example, but this also applies for 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. Each lumbar support unit consists of 2 air cushions, an electric-pneumatic driver lumbar support pump (M25/4) for compressed air production and the driver lumbar support regulator control unit (N32/23) with an integrated control valve block for pneumatic regulation. The adjustment is performed via the driver lumbar support adjustment switch (S109/2), which is connected to the lumbar support regulator 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 partial functions:
^ Inflating the air cushions
^ Deflating the air cushions
^ Height adjustment of the lumbar contour

Inflating the air cushions
As long as the cross-shaped rocker button of the lumbar support adjustment switch is pressed in the "forward arrow" direction, the backrest contour in the lumbar area is changed through inflation of the currently active upper or lower lumbar 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 adjustment switch is pressed in the "backward arrow" direction, the seat cushion length is changed through deflation of the air cushions. The deflation starts with the upper air cushion, 1 s ahead of the lower air cushion.

Height adjustment of the lumbar contour
When the cross-shaped rocker button of the 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 the inflation of the other cushion that is 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 supplied compressed air is distributed by the lumbar support regulator 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 regulated by the lumbar support regulator control unit.