Multicontour seat control unit (MCS), component description - GF91.25-P-5201LE

MODEL 216.3 with CODE (409) Left/right front multicontour seat as of model year 2009 /YoM 08

MODEL 221.0 /1 with CODE (409) Left/right front multicontour seat as of model year 2009 up to 2010 /YoM 08 up to YoM 09

Shown on driver seat, model 221

Fig 1: Locating Front Multicontour Backrest Control Unit

Courtesy of MERCEDES-BENZ USA

Location

The left and right front multicontour backrest control unit is located in the center of the driver seat or front passenger seat backrest frame.

Tasks

Inflation and deflation of the multicontour backrest in accordance with the requests issued by the driver or front passenger
Communication via the interior CAN (CAN B) with the left front seat control unit (N32/1) or right front seat control unit (N32/2)
Adjustment of seat hardness and seat contour
Actuation of pressure valves for backrest, seat cushions, shoulder and lateral supports
Adjusting the stored pressure values when calling up the memory feature and storing the actual contours
Actuation of the multicontour seat pneumatic pump (M40)

These are grouped as follows:

Reading in of sensors and signals
Evaluation of input factors
Actuation of components

Reading in of sensors and signals

These input factors are read in via the following connections:

Direct line
Interior CAN

Direct line

Circuit 30
Tml. 31
Piezo sensor in pressure sensor valve for measurement of air pressure in the individual air cushions of the contour insert in the backrest
Piezo sensor in pressure sensor valve for measurement of air pressure in the individual air cushions of the contour insert in the seat cushion

Interior CAN

The left or right front multicontour backrest control unit communicates via the interior CAN with:

the left front seat control unit; adjustment and storage of seat contours
the right front seat control unit; adjustment and storage of seat contours
the multicontour seat pneumatic pump; actuation of compressed air supply
the central gateway control unit (N93) as router for signals from:

the ESP control unit (N47-5); for the PRE-SAFE function
the COMAND control unit (A40/3) for adjustment functions

Evaluation of input factors

The read in input factors are evaluated by the front multicontour backrest control unit. Actuation of the air cushions in the seat is performed via a piezo valve integrated into the multicontour insert, which is then actuated by the multicontour backrest control unit via direct lines with 220 V DC.

Actuation of components

The actuation of the components takes place via the following connections:

Direct line
Interior CAN

Direct line

The following components are actuated via direct lines:

Piezo valves in pressure sensor valves for actuation of air pressure in the individual air cushions of the multicontour seat contour insert

Interior CAN

The front multicontour backrest control unit communicates via the interior CAN with:

the multicontour seat pneumatic pump for actuation of compressed air supply
the central gateway control unit as router for signals for the COMAND control unit for display functions and feedback signals

Design

The front multicontour backrest control unit contains not only the intelligent circuit but also output stages. These are used to transform voltage from 12 V to 220 V direct current. The multicontour backrest control unit also includes a safety circuit. It switches itself off automatically if an output stage is defective. It is also equipped with a high-tension protection, which only switches on the high voltage when each connector on the front multicontour backrest control unit is plugged in.

The 6-pin plug connects the front multicontour backrest control unit via the left front seat control unit or right front seat control unit with the interior CAN and the power supply.

The 28-pin plug connects the front multicontour backrest control unit with the piezo sensors and piezo valves in the pressure sensor valves of the backrest.

The 20-pin plug connects the front multicontour backrest control unit with the piezo sensors and piezo valves in the pressure sensor valves of the seat cushion.

Function

Short-term control

The short-term control is actuated following each adjustment process (manual adjustment, memory request, initialization) for a certain period of time. It compensates for excess pressure deviations from the specified pressure of each air cushion (cushion areas, connected to a pressure sensor, are jointly in the temporary control phase) within a parameterized time period. Vacuum deviations during this phase are not compensated for. This phase is used to immediately compensate for large pressure jumps when sitting down and leaning back in a comfort-oriented fashion.

Long-term control

After the short-term control, the long-term control becomes active for the active cushions, until it is reset by events with a higher priority. Almost without the customer noticing, the lumbar support is regulated in the specified time frame such that the mean value of the actual pressure adjusts to the specified pressure within the repeatability over a certain period of time.

If an adjustment to the specified pressure cannot be achieved in several consecutive steps, a "gross leak" is detected. The affected cushion area is deactivated completely until the malfunction is no longer present.

Non-active air cushions are deflated in increments to a pressure less than the minimum pressure.

Variants

There is only one variant of multicontour seat control unit hardware available which is included in the package contents of the various software variants:

Software for front multicontour backrest (on model 221 only model year 2009 /YoM 08)
Software for dynamic multicontour seat control unit with dynamic function and with massage function (on model 221 only for vehicles as of model year 2009 /YoM 08)
Rear multicontour backrest (only model 221)

The assignment for driver, front passenger seat and the country or left-hand/right-hand drive vehicle assignment is also coded by the software.

Wiring diagram for left front dynamic seat control unit	Model 221 Control unit N32/15	PE91.25-P-2101-99SAA
	Model 216 Control unit N32/15	PE91.25-P-2101-99CAA
Wiring diagram for left front dynamic seat control unit	Model 221 Control unit N32/16	PE91.25-P-2102-99SAA
	Model 216 Control unit N32/16	PE91.25-P-2102-99CAA