Power Seat Control Module: Description and Operation

GF91.25-P-5210FL Dynamic Multicontour Seat Control Unit, Component Description
- with CODE (432) Left and right dynamic multicontour seat

Component Identification:

Location
The left front dynamic multicontour seat control unit (N32/19) or right front dynamic multicontour seat control unit (N32/22) is located in the center of the backrest frame of the driver or passenger seat.

Tasks
- Inflating or deflecting multicontour backrest according to requirements read in by the driver dynamic multicontour seat button group (S109) or passenger dynamic multicontour seat button group (S108)
- Control of massage function via left front seat massage function actuator motor (M94) or right front seat massage function actuator motor (M95), actuated by the massage function button (S108s1) (driver) or the massage function button (S109s1) (passenger)
- Control of dynamic lateral support, actuated by the dynamic button (S108s6) (driver) or dynamic button (S109s6) (passenger)
- Reading in voltage-coded driver dynamic multicontour seat button group or passenger dynamic multicontour seat button group
- Communication via interior CAN (CAN B) with driver seat control unit (N32/1) or passenger seat control unit (N32/2)
- Adjusting stored pressure values when calling memory function and storing actual contours (with code (275) Electrically adjustable front seats with memory package)
- Shutoff of the respective function if the pressure valve responsible has overheated

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 30g
- Tml. 31

The following sensors are read in via direct lines:
- Driver dynamic multicontour seat button group (S109) or
- Passenger dynamic multicontour seat button group (S108)
- Limit switch in left front seat massage function actuator motor (M94) or
- Limit switch in right front seat massage function actuator motor (M95)

Interior CAN
The dynamic multicontour seat control unit communicates via interior CAN with:
- Driver seat control unit (N32/1); adjustment storage of driver seat seat contours (with code (275) Electrically adjustable front seats with memory package)
- Passenger seat control unit (N32/2); adjustment and storage of passenger seat seat contours (with code (275) Electrically adjustable front seats with memory package)
- Dynamic multicontour seat pneumatic pump (M40/1); control of compressed air supply
- Front SAM control unit with fuse and relay module (N10/1) as router for signals from electronic stability program control unit (N30/4) (Vehicles without code (233) DISTRONIC PLUS) or electronic stability program control unit Premium (N30/7) (vehicles with code (233) DISTRONIC PLUS) for dynamic presafe function

Evaluation of input factors
The input factors read in are evaluated by the dynamic multicontour seat control unit. The air cushions in the seat contour insert are actuated by the piezo valves integrated into the dynamic multicontour seat control unit.

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:
- LED status in driver dynamic multicontour seat button group (S108) or passenger dynamic multicontour seat button group (S109) for display of corresponding two-stage pulse or dynamic program.
- Windings in left front seat massage function actuator motor (M94) or right front seat massage function actuator motor (M95)
- Main valve in left front seat massage function actuator motor (M94) or right front seat massage function actuator motor (M95)

The air cushions in the seat contour insert are actuated by the piezo valves integrated into the dynamic multicontour seat control unit. The air cushions in the massage insert are actuated via the seat massage function actuator motor controlled by the dynamic multicontour seat control unit.

Interior CAN
The dynamic multicontour seat control unit communicates via the interior CAN with:
- Dynamic multicontour seat pneumatic pump; control of compressed air supply

Design
The left front and right front dynamic multicontour seat control units contain not only the intelligent circuit but also piezo sensors. These sensors are used to measure and monitor the pressure. The air pressures in the cushions are adjusted by the piezo valves integrated into the dynamic multicontour seat control unit. The dynamic multicontour seat control unit is connected to the driver dynamic multicontour seat button group or passenger dynamic multicontour seat button group on the seat and to the windings on the seat massage function actuator motor via the 1 pin connector.

The dynamic multicontour seat control unit is connected to the interior CAN and the power supply via the driver seat control unit or passenger seat control unit (with code (275) Electrically adjustable front seats with memory package) using a 7-pin connector. Without code (275) Electrically adjustable front seats with memory package, the connection runs over the multipoint connector on the seat. It is also connected via the coupling to the limit switches and the main valve on the seat massage function actuator motor.

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 (lumbar) are deflated in increments to a pressure less than the minimum pressure.

Variants
Variants for the hardware of the dynamic multicontour seat control unit are not available. 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.