GF91.30-P-0002LE Electric Seat Ventilation, Function

GF91.30-P-0002LE Electric Seat Ventilation, Function
- with CODE (401) Front comfort seats, including seat heating and seat ventilation
- with CODE (402) Rear comfort seats, including seat heating and seat ventilation

General function requirements
^ C. 15R On

Electric seat ventilation, general
With the seat ventilation integrated in the driver/front passenger seats and in the rear outer seats, it is possible to ventilate the seat cushions and the backrests in three ventilation stages.

The status of circuit 15 is provided by the EIS [EZS] control unit (N73) via the interior CAN.

During comfort opening of the vehicle, the seat ventilation of the driver seat is switched on in stage 3. If circuit 15R is not switched on at this time, the seat ventilation is switched off after t = 5 min.

More detailed information can be found in the function description for the convenience feature (CF [KFB]).

The electric seat ventilation comprises the following subfunctions:
^ Function sequence, switching on, over and off manually
^ Function sequence, automatic shutoff

Function sequence, switching on, over and off manually
The front seat ventilation is switched on and off and the ventilation performance regulated via the seat ventilation switch (S22s11) in the left front seat operation switch group (S22) or via the seat ventilation switch (S23s11) in the right front seat operation switch group (S23).

The rear seat ventilation is switched on and off and the ventilation performance regulated via the seat ventilation switch (S55/1s11) in the left rear seat operation switch group (S55/1) or via the seat ventilation switch (S55/2s11) in the right rear seat operation switch group (S55/2).

The electric seat ventilation is operated as follows:
- Operating the seat ventilation switch once activates stage 3 of the seat ventilation. All three light-emitting diodes in the seat ventilation switch are actuated.
- Operating the seat ventilation switch again switches over to stage 2. Two light-emitting diodes in the seat ventilation switch are actuated.
- Operating the seat ventilation switch again switches over to stage 1. One light-emitting diode is actuated in the seat ventilation switch.
- A further actuation of the seat ventilation switch switches the seat ventilation off.

Each actuation of the front seat ventilation switch is read in by the left front door control unit (N69/1) or right front door control unit (N69/2) via the front door LIN and forwarded to the left front seat control unit (N32/1) or right front seat control unit (N32/2) via the interior CAN.

The left front seat control unit then actuates the left front seat ventilation blower regulator (N29/5), or the right front seat control unit then actuates the right front seat ventilation blower regulator (N29/6).

The left front seat ventilation blower regulator actuates the following motor groups:
- Left front seat cushion ventilation motor group (M18/9)
- Left front seat backrest ventilation motor group (M18/10)

The right front seat ventilation blower regulator actuates the following motor groups:
- Right front seat cushion ventilation motor group (M18/11)
- Right front backrest ventilation motor group (M18/12)

Each actuation of the rear seat ventilation switch is read in by the left rear door control unit (N69/3) or right rear door control unit (N69/4) via the rear door LIN and transmitted to the rear seat control unit (N25/6) via the CAN interior.

The rear seat control unit then actuates the left rear seat ventilation blower regulator (N29/3) or right rear seat ventilation blower regulator (N29/4).

The left rear seat ventilation blower regulator actuates the following motor groups:
- Left rear seat backrest ventilation motor group (M18/7)
- Left rear seat cushion ventilation motor group (M18/8)

The right rear seat ventilation blower regulator actuates the following motor groups:
- Right rear seat backrest ventilation motor group (M18/5)
- Right rear seat cushion ventilation motor group (M18/6)

Switching the seat ventilation on, over or off by operating the respective seat ventilation switch is possible at any given time.

The timer control is performed by the left front seat control unit and the right front seat control unit:
- Ventilation stage 3 is active for t = 5 min.
Then the system automatically switches to ventilation stage 2.

- Ventilation stage 2 is active for t = 10 min.
Then the system automatically switches to ventilation stage 1.

The left or right seat adjustment selection switch (S22s10) (with code (275) Memory package (driver seat, steering column, mirror)) in the left front seat operation switch group can be used to switch over the functions between driver and front passenger seat adjustment. The seat ventilation is also part of the functions that can be switched over. The switchover is active for t = 10 s after pressing the seat adjustment selection switch. This status is indicated by a light-emitting diode.

If an adjustment is made during this time, the switchover remains active for another t = 10 s after the adjustment has been completed. The switchover is also terminated when the seat adjustment selection switch is pressed again.

Function sequence, automatic shutoff
The automatic shutoff comprises the following subfunctions:
^ Switching off as under terminal 15R OFF
^ Switching off in the event of undervoltage
^ Switching off in the event of overvoltage
^ Switching off by on-board electrical system management system.

Shutting off after circuit 15R OFF:
If circuit 15C continues to be ON, the timer control continues running for t = 5 min. If circuit 15R is switched on again, the seat ventilation is also switched on in the previously activated ventilation stage.

Shutoff in the event of undervoltage
In the event of undervoltage, the left front seat control unit or right front seat control unit switches the seat ventilation off. The timer control continues to run, the light-emitting diodes in the seat ventilation switch flash.

There is no automatic reactivation of the seat ventilation after a shutoff. If the undervoltage persists, it will no longer be possible to switch the seat ventilation on. The light-emitting diodes flash for t = 0.5 s if another request is received.

It is not possible to switch the seat ventilation on again until a permissible voltage is present again.

Shutoff in the event of overvoltage
In the event of overvoltage, the left front seat control unit or right front seat control unit switches the seat ventilation off.
The timer control continues to run if the seat ventilation is switched off due to overvoltage. The bits for the light-emitting diodes are also set accordingly.

It is not possible to switch the seat ventilation on again until a permissible voltage is present again.

Switching off by on-board electrical system management system.
In order to prevent the battery from discharging in all driving cycle phases, the state of charge is monitored continuously. Depending on the situation, the seat ventilation is also deactivated if necessary.