GF91.25-P-5202LE Dynamic Seat Control Unit, Component Description

GF91.25-P-5202LE Dynamic Seat Control Unit, Component Description
- with CODE (432) Left and right dynamic multicontour seat as of Model Year 2009 /YoM 08 [model 216.3]
- with CODE (432) Left and right dynamic multicontour seat as of Model Year 2009 up to 2010 /YoM 08 up to YoM 09 [model 221.1]

Component Identification:

Location
The left and right front dynamic seat 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
- Actuation of massage function
- Actuation of the dynamic lateral support
- 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 the pressure valves for seat backrest and seat cushion as well as shoulder support, lateral support, and upper leg support
- Adjusting the stored pressure values when calling up the memory feature and storing the actual contours
- Actuation of the pneumatic pump for dynamic seat control (M40/1)

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 front dynamic multicontour seat 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 pneumatic pump for dynamic seat control; actuation of the compressed air supply
- the central gateway control unit (N93) as router for signals from:
- the ESP control unit (N47-5); for the dynamic and PRE-SAFE function
- the COMAND control unit (A40/3) for adjustment functions

Evaluation of input factors
The input factors read in are evaluated by the front dynamic seat control unit. Actuation of the air cushions in the seat is performed via a piezo valve integrated into the air cushion, which is then actuated by the front dynamic seat 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 dynamic seat contour insert
- Valves in the air cushion of the massage insert for actuation of the massage function

Interior CAN
The dynamic multicontour seat control unit communicates via the interior CAN with:
- the pneumatic pump for dynamic seat control; for actuation of the 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 dynamic seat 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 left front dynamic seat control unit is equipped with a safety circuit. It switches itself off automatically if an output stage is defective. It is also equipped with high-voltage protection, which only switches the high voltage when all the connectors on the left front dynamic seat control unit are plugged in.

The 6-pin plug connects the front dynamic seat 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 dynamic seat control unit with the piezo sensors and piezo valves in the pressure sensor valves of the backrest.

The 14-pin plug is used to connect the front dynamic seat control unit to the piezo valves for the massage insert.

The 20-pin plug connects the front dynamic seat 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 are no variants for the hardware of the front dynamic seat control unit. The assignment for driver or front passenger seat and the country or left-hand/right-hand drive vehicle assignment is also coded by the software.