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

MODEL 166 

as of model year 2016 

with CODE 401 (Climatised front seats) 

MODEL 292 

with CODE 401 (Climatised front seats) 

Function requirements, general 

• Circuit 15R ON

The electronic ignition lock control unit transmits the circuit 15 status via the interior CAN to the SAM control unit.

Seat ventilation, general 

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

With comfort opening of the vehicle, first the seat cooling (seat ventilation motor drawing) is switched on. If circuit 15R is not switched on within t = 5 min after this or the vehicle is locked again, the seat ventilation is switched off. Detailed information about the comfort opening function is available in the function description "Theft protection and locking, function" in subfunction "Convenience feature (CF [KFB]), function".

The electric seat ventilation function encompasses the following subfunctions:

• Function sequence for manually switching on/off 
• Function sequence for automatic switch off 

Function sequence for manually switching on/off 

Operation takes place via the left front seat ventilation button and the right front seat ventilation button in the upper control panel control unit.

The upper control panel control unit directly reads in the status of the left front seat ventilation button and right front seat ventilation button and sends this via battery sensor LIN to the SAM control unit. The SAM control unit evaluates the status of the respective seat ventilation button and sends a corresponding request on vehicles with CODE 275 (Memory package) via interior CAN or, on vehicles without code 275 (Memory package), via center console switch LIN to the driver seat control unit or to the front passenger seat control unit.

The driver seat control unit then actuates the following components directly:

• Left front seat cushion seat ventilation motors
• Left front backrest seat ventilation motors

The front passenger seat control unit then actuates the following components directly:

• Right front seat cushion seat ventilation motors
• Right front backrest seat ventilation motors

The driver seat control unit and the front passenger seat control unit continuously check the function of all components of the seat ventilation system involved and send the corresponding status on vehicles with CODE 275 (Memory package) via interior CAN or, on vehicles without CODE 275 (Memory package), via center console switch LIN to the SAM control unit.

In accordance with the frequency with which the respective seat ventilation button is pressed, the SAM control unit sends a request to actuate the LEDs via battery sensor LIN to the upper control panel control unit. The upper control panel control unit actuates the LEDs in the respective seat ventilation button accordingly.

• Press one time: 3 LEDs light up, stage 3 of seat ventilation or seat cooling activated (P = 100%).

  First the seat ventilation motors are activated in the "suction" direction of rotation (seat cooling); after t = 10 min the direction of rotation is reversed to "blowing" (seat ventilation).

• Press two times: 2 LEDs light up, stage 2 of seat ventilation activated (P = 65%).
• Press three times: 1 LED lights up, stage 1 of seat ventilation activated (P = 35%).
• Press four times: All LEDs off, seat ventilation switched off.

Reduction of noise level: 

In order to lower the noise level of the seat ventilation when the vehicle is stationary, it is switched down to level 1 if the vehicle speed drops below v = 6 km/h. When the speed reaches v > 9 km/h, the setting that was originally selected is activated. The instrument cluster transmits the vehicle speed to the SAM control unit via the interior CAN. The noise level reduction does not become active until t = 7 min after the seat ventilation has been switched on with the engine running. The reduction of the noise level is not active with comfort opening.

Function sequence for automatic switch off 

If one of the following criteria occurs, the seat ventilation is switched off automatically:

• Switching off in the event of a hardware defect

  If actuation of the seat ventilation motors is detected without any request pending from the seat ventilation button, the power supply to the seat ventilation is switched off.

• Shutoff in the event of an error (short circuit, overload or open circuit (line break)).

  The driver seat control unit or front passenger seat control unit detects a possible short circuit, overload or line break in the respective seat ventilation motor and deactivates the voltage supply. The fault sources that have been listed can be diagnosed individually for each seat ventilation motor using a diagnostic tester.

• Shutoff when the engine starts.

  When the engine is started (cold start), the seat ventilation is deactivated for t = 20 s. During a hot start, the seat ventilation is deactivated for t = 3 to 5 s. The timer control continues to run, and the LEDs remain switched on. No undervoltage is detected during startup.

• Switching off by means of energy 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.

  If the seat ventilation is switched off, the LEDs in the respective seat ventilation button remain on initially. If the on-board electrical system reaches its on-board electrical system voltage again within the next t = 3 min, the seat ventilation function is automatically activated. If the shutoff lasts longer than t = 3 min, the LEDs in the respective seat ventilation button are also switched off. If shutoff continues and the function is requested again by pressing the respective seat ventilation button, the LEDs light up for t = 1.5 s and then go out.

• Shutoff in the event of voltage loss.

  If one of the two supply lines (circuit 30 or circuit 30g) of the driver seat control unit or front passenger seat control unit fails, the seat ventilation is switched off.

• Shutoff after circuit 15R OFF.

  With circuit 15R OFF and circuit 15C ON, timer control runs on for t = 5 min. If circuit 15R is switched on again, the seat ventilation is also switched on again.

• Shut-off in the event of "Timeout error".

  If the request from the SAM control unit to actuate the seat ventilation is discontinued or a "Timeout period" from the electronic ignition lock control unit is recognized, the seat ventilation is switched off.

• Switching off at the end of diagnosis

After the diagnosis has finished, the seat ventilation switches off.

	Seat ventilation electrical function schematic		PE91.30-P-2053-97NBA
	Overview of system components of comfort heating systems		GF91.30-P-9990GN