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

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

General function requirements
^ Circuit 15R ON

The electronic ignition lock control unit (N73) sends the circuit 15 status to the interior CAN (CAN B).

Electric seat ventilation, general
The seat cushions and backrests of the front seats can be ventilated in three stages using the seat ventilation.

During comfort opening of the vehicle, the seat ventilation 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.

During comfort closing the seat ventilation is immediately deactivated.

It is possible to determine whether the driver seat alone or also the passenger seat is to be ventilated with variant coding.

Detailed information on comfort opening is available in the "Convenience feature (CF [KFB])" function description.

The electric seat ventilation function comprises the following subfunctions:
^ Manual on/off function sequence
^ Automatic switch off function sequence

Manual on/off function sequence
The seat ventilation is switched on and off with the left seat ventilation button (N72/1s13) and right front seat ventilation button (N72/1s14) in the upper control panel control unit (N72/1) and the ventilation output is regulated.

Each actuation of the seat ventilation button is transmitted by the upper control panel control unit to the front SAM control unit with fuse and relay module (N10/1) via he instrument panel LIN (LIN 1). It transmits the request to the rear SAM control unit with fuse and relay module (N10/2) via the interior CAN. The rear SAM control unit then actuates the left front seat ventilation blower regulator (N29/5) or right front seat ventilation blower regulator (N29/6).

The left front seat ventilation blower regulator actuates the following components:
- Left front seat cushion seat ventilation motors (M18/9)
- Right front seat cushion seat ventilation motors (M18/10)

The right front seat ventilation blower regulator actuates the following components:
- Right front seat cushion seat ventilation motors M18/11
- Right front backrest seat ventilation motors M18/12

The seat ventilation depends on the ventilation stage selected with the seat ventilation button and the ventilation stage activated is indicated by LEDs in the corresponding seat ventilation button:
Press once: Ventilation stage 3 (three LEDs illuminated)
Press two times: Ventilation stage 2 (two LEDs illuminated)
Press three times: Ventilation stage 1 (one LED illuminated)
Press four times: Seat ventilation switched off (no LED illuminated)

Automatic switch off function sequence
- Shutoff 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.

- Switching off in event of overvoltage or undervoltage
If the rear SAM control unit switches the seat ventilation motors off, the LED in the corresponding seat ventilation button initially remains on. If the on-board electrical system reaches its normal voltage within the next t = 3 min., the seat ventilation function is automatically reactivated.

However, if the shutoff lasts longer than t = 3 min., the LED in the seat ventilation button is also switched off.

It the shutoff procedure continues and the function is requested again for the corresponding seat ventilation button, the LED comes on for t = 1.5 s and then goes out.

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

- Shutoff during startup of engine
The seat ventilation motors are switched off while the engine is started up. The LEDs in the function indicator are still illuminated. Undervoltage is not recognized while starting and no faults are stored.