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Home >> Mercedes Benz >> 2009 >> E350 Base >> Repair and Diagnosis >> Restraints >> Seat Belts >> Seats, Restraint Systems -- Basic Knowledge -- E350 (211.256) >> Basic Knowledge >> Manual inflation/deflation of air cushion on dynamic seat, function - GF91.25-P-2011T

Manual inflation/deflation of air cushion on dynamic seat, function - GF91.25-P-2011T

MODEL 211.0/2/6 with CODE (433) Left dynamic seat, incl. multicontour seat with CODE (434) Right dynamic seat, incl. multicontour seat 

Shown on left front seat 

Fig 1: Identifying Air Cushion On Dynamic Seat Manual Inflation/Deflation Components
G07286234Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Function (described on left front seat) 

By manual actuation of switches:

the corresponding adjustment request is forwarded to the left front dynamic seat control unit (N32/19), which then actuates the valves in the air cushions accordingly. The air required to inflate the air cushions is generated by the pneumatic pump for dynamic seat control (M40/1).

IMPORTANT If the left front seat cushion fore/aft switch (S109s5), left front side bolsters adjustment (S109s2) or the left front lumbar support adjustment switch (S109s3) is pressed for longer than 2 min, then the request from each switch is ignored and an error is stored. This also applies to the right-hand seat switch.

Actuation of left front seat cushion fore/aft switch (S109s5) towards "+" 

As long as the rocker switch is pressed towards "+", the seat cushion length will change with a simultaneous inflation of the air cushion seat cushion (4) (until a max. pressure of roughly 300 mbar is reached).

Actuation of left front seat cushion fore/aft switch (S109s5) towards "-" 

As long as the rocker switch is pressed towards "-", the seat cushion length changes by deflating the air cushion seat cushion (4). In doing so the pneumatic valve is opened after the minimum residual pressure is reached for no longer than t = 1 min (upon actuation).

Actuation of left front lumbar support adjustment switch (S109s3) towards "+" 

As long as the cross-shaped rocker button is pressed towards "+", the backrest contour in the lumbar area is changed through inflation of the currently active air cushion upper or lower lumbar (2 or 3). Inflation is stopped upon reaching the maximum pressure of roughly 200 mbar per air cushion.

Actuation of left front lumbar support adjustment switch (S109s3) towards "-" 

As long as the cross-shaped rocker button is pressed towards "-", the backrest contour in the lumbar area is changed through deflation of the currently active air cushion upper or lower lumbar (2 or 3). In doing so the pneumatic valves are opened after the minimum residual pressure is reached for no longer than t = 1 min (upon actuation).

Actuation of left front lumbar support adjustment switch (S109s3) towards  "AIR FLOW UP "

As long as the cross-shaped rocker button is pressed towards "AIR FLOW UP ", the backrest contour in the lumbar area changes sequentially through deflation up to a supply pressure p = more than 50 mbar of the air cushion lower lumbar (3), then inflation up to p = 100 mbar (dwell time t = 0.5 s) and finally deflation up to p = more than 50 mbar of the air cushion upper lumbar (2), then inflation up to p = 100 mbar of the air cushion lower lumbar (3). In each case only the air cushion upper or lower lumbar (2 or 3) is actuated. Entry into this so-called wave cycle ensues depending on which air cushion lumbar is active at any given time.

Actuation of left front lumbar support adjustment switch (S109s3) towards  "AIR FLOW DOWN "

As long as the cross-shaped rocker button is pressed towards "AIR FLOW DOWN ", the backrest contour in the lumbar area is sequentially changed by deflation up to a supply pressure p > 50 mbar of the air cushion upper lumbar (2), then inflation up to p = 100 mbar (dwell time t = 0.5 s) and then finally deflation up to p > 50 mbar of the air cushion lower lumbar (3), and then inflation up to p = 100 mbar of the air cushion upper lumbar (2). In each case only the air cushion upper or lower lumbar (2 or 3) is actuated. Entry into this so-called wave cycle ensues depending on which air cushion lumbar is active at any given time.

Leakage detection for air cushion upper and lower lumbar, and seat cushion 

If in the air cushion upper (2) and lower lumbar (3), and seat cushion (4), the specified pressure value is not reached after 10 successive pressure increases, then such a status is deemed to be a gross leak and the appropriate air cushion is deactivated. In addition to this an error is stored, which can then be read out using STAR DIAGNOSIS.

Actuation of left front side cushion adjustment switch (S109s2) towards "+" 

The air cushion lateral supports (1) can be inflated to maximum pressure when the switch is pressed towards "+". Inflation is stopped once the maximum pressure of roughly 450 mbar is reached.

Actuation of left front side cushion adjustment switch (S109s2) towards "-" 

Pressing the switch towards "-" causes the air cushions to be deflated to a minimum pressure. In doing so the pneumatic valve is opened after the minimum residual pressure p = 15 mbar is reached for no longer than t = 1 min (upon actuation).

IMPORTANT If the left front side cushion adjustment switch (S109s2) is pressed for longer than 2 min, the switch signal is ignored and an error is stored. This applies equally to the right-hand seat.

Leakage detection for air cushion lateral support (1) 

If the leakage value is > 10 mbar/min, a gross leak is detected and the lateral support function is deactivated.

Actuation of several switches 

If several switches are pressed simultaneously, only the adjustment with the highest priority is performed.

Priority 1: Lumbar

Priority 2: Seat cushion

Priority 3: Lateral support

Priority 4: Pulsation or dynamic lumbar

IMPORTANT All functions are interrupted if there is an overvoltage or an undervoltage. In the event of excess temperature in a valve, the relevant function is then deactivated.

Background functions 

In a group of cushions the cushions are arranged as overlapping and thus their function during the wave cycle is coupled. As for each group of cushions only one air cushion is active, the adjacent cushions are not deemed to be active (empty).

To ensure that this is the case, the following background information is required:

Memory position storage of dynamic seat function GF91.25-P-2014T 
Dynamic seat control unit, location/task GF91.25-P-2105T 
Dynamic seat switch, location/task GF91.25-P-2110T 
Pneumatic pump for dynamic seat control, location/task GF91.25-P-2115T