Multicontour Seat (MCS), Function - GF91.25-P-0001GR

MODEL 166 up to model year 2016 with CODE 399 (Multicontour front seats with massage function)

Function requirements, general

No overvoltage or undervoltage
Circuit 15R ON or circuit 15 ON

The electronic ignition lock control unit transmits the status of circuit 15 over interior CAN to the multicontour seat control units.

Function description of multicontour seat, general

The contour and surface hardness of the backrest and the seat cushion of the driver and front passenger seat can be changed individually. This is done by air cushions that can be inflated independently of each other. In order to prevent back tension during long journeys, the multicontour seat is also equipped with a massage function.

PRE-SAFE®:

In critical situations, the seat contour of the driver or front passenger seat is automatically changed to achieve a favorable seat position and securing of the occupant. Detailed information on this can be found in the "PRE-SAFE® function" function description.

MODEL 166 up to model year 2016

with CODE 275 (Memory package (driver seat, steering column, mirrors))

with CODE 399 (Multicontour front seats with massage function) MODEL 166

up to model year 2016

with CODE 399 (Multicontour front seats with massage function)

with CODE P64 (Memory package)

Using the memory function, the current seat settings can be stored and called up again along with other settings. Detailed information about this can be found in the subfunction "Electrical seat adjustment (ESA), function".

The multicontour seat function comprises the following subfunctions:

Function sequence, manual adjustment of the air cushions
Function sequence for the massage function

Function sequence, manual adjustment of the air cushions

The contours and surface hardness of the backrest and seat cushion on the multicontour seat can be individually adjusted by inflating and deflating the air cushions.

The air cushions are located in the following areas:

In the seat side bolsters of the backrest on the left and right
In the seat side bolsters of the seat cushion on the left and right
In the upper lumbar area
In the lower lumbar support area

Inflation and deflation are controlled via a menu in the COMAND controller unit. Operation takes place via the Audio/COMAND control panel and is displayed on the Audio/COMAND display.

After pressing the right free programming button on the Audio/COMAND control panel, the "Seats" submenu is called up on the Audio/COMAND display. "Driver seat" or "Front passenger seat" can be selected using the Audio/COMAND controller and then the "Multicontour seat" setting selected.

The Audio/COMAND control panel sends the control signals over the telematics CAN to the COMAND controller unit. The COMAND controller unit then activates the Audio/COMAND display over telematics CAN and transmits the information for display of the "Seats" submenu over the LVDS line. The COMAND controller unit evaluates the control signals of the Audio/COMAND control panel for adjustment and sends these via interior CAN to the respective multicontour seat control unit.

The inflation and deflation of the air cushions is controlled by the respective multicontour seat control unit by actuating integrated piezo valves. The pressure values are recorded by integrated pressure sensors and stored by the relevant multicontour seat control unit.

The air supply, required for inflating the air cushions, is supplied by the multicontour seat pneumatic pump. The respective multicontour seat control unit transmits the switch-on request via interior CAN to the multicontour seat pneumatic pump.

Short-term and long-term control

The short-term control compensates for overpressure deviations in the air cushions. It activates following every adjustment and only remains active for a short, parameterizable period of time. This function is used among others to compensate for sitting down or leaning back immediately and in a comfort-oriented fashion. After the short-term control, the long-term control becomes active. Here, the pressure supply is regulated such that the specified pressure is always achieved. This is done almost without the driver or front passenger noticing.

The manual adjustment is aborted under the following conditions

Overvoltage or undervoltage
Inflation or deflation timeout
Leak in one or more air cushions

Function sequence for the massage function

The massage function is a comfort function and helps the driver or front passenger to relax, particularly during longer trips. As long as the massage function is active, the contour of the seven-row massage insert is sequentially altered by building up, maintaining and deflating the pressure.

The air supply, required for inflating the air cushions, is supplied by the multicontour seat pneumatic pump. The intensity of the massage function can be adjusted in two stages. The pulsation takes place in pressure jumps in the upward or downward direction. The dwell time can be set with the diagnostic tester.

The function sequence for the multicontour seat massage function is structured as follows:

Function sequence for starting and stopping
Function sequence for massage

Function sequence for starting and stopping

After pressing the right free programming button on the Audio/COMAND control panel, the "Seats" submenu is activated on the Audio/COMAND display. "Driver seat" or "Front passenger seat" can be selected using the Audio/COMAND controller and then one of the following massage programs can be selected in the "Massage" menu:

"0: Off"
"1: Slow and gentle"
"2: Slow and strong"
"3: Fast and gentle"
"4: Fast and strong"

The COMAND controller unit evaluates the control signals of the Audio/COMAND control panel for adjustment and sends these via interior CAN to the respective multicontour seat control unit.

Function sequence for massage

After activating the massage program, the respective multicontour seat control unit actuates the corresponding massage function control unit via the seat LIN. The massage function control unit moves a slide valve in a cylinder with seven air outlets. By moving the slide valve, the air outlets to the air cushions for the massage insert are opened or closed. Starting with the lower air cushion, the contour in row 1 of the massage insert changes sequentially by inflating, holding and deflating the pressure. After a defined waiting time, the cycle for row 2 is started according to the same pattern. If the waiting time has elapsed during inflation of layer 7 of the massage insert, the cycle continues with layer 1 of the massage insert. The respective massage function control unit can move the slide valve in a total of 23 slider positions and hold it there.

The individual positions are compared to a reference position (limit switch). Parallel to the control cycle, the individual steps are also counted and therefore monitored by the respective massage function control unit. The pressure difference between a deflated massage cushion and an inflated one is approx. p = 100 mbar. Alternate deflation and inflation of the air cushions in the massage insert creates a wavy or rolling massage function, depending on the massage program. Depending on the settings, the massage function is terminated automatically after t = 15 - 25 min.

With the following adjustment, a massage cycle is interrupted and the main valve closed by the respective massage function control unit. The massage function is continued after the end of the interruption conditions when the next cycle starts:

Manual adjustment of multicontour seat
Memory adjustment request (with CODE 275 (Memory package (driver seat, steering column, mirror)) or CODE P64 (Memory package))

Abort conditions:

Overvoltage or undervoltage
Overloading of the multicontour seat pneumatic pump
PRE-SAFE® adjustment request

	Electrical function schematic for multicontour seat		PE91.25-P-2051-97NAA
	Overview of system components, electric seats		GF91.29-P-9992GR