Electric Seat Ventilation, Function - GF91.30-P-0002GWM
Model 463 (except 463.342)
as of model year 2019
with code PA9 (Seat Comfort package Plus)
Show on model 463
Function requirements, general
- Circuit 15R ON or circuit 15 ON:
The electronic ignition lock control unit sends the status of circuit 15 via the interior CAN to the rear SAM control unit.
Seat ventilation, general
The seat cushions and backrests can be ventilated in three stages using the seat ventilation. The rear SAM control unit is the master control unit for the seat ventilation function.
The electric seat ventilation function encompasses the following subfunctions:
- Function sequence for switching seat ventilation on/off
- Seat ventilation function sequence
- Function sequence, automatic shutoff
Function sequence for switching seat ventilation on/off
The seat ventilation is switched on and off and the ventilation output regulated (output state of seat ventilation deactivated, all LEDs off) using the seat ventilation switch in the respective switch group, seat climate control and front central locking system:
- Press once: 3 LEDs light up, stage 3 of seat ventilation or seat cooling activated (100 % heat output)
First, the seat ventilation motors are actuated in the "suction" direction of rotation (seat cooling), and after 10 minutes the direction of rotation is reversed to "blowing" (seat ventilation).
- Press twice: 2 LEDs light up, stage 2 of seat ventilation activated (65 % heat output)
- Press three times: 1 LED lights up, stage 1 of seat ventilation activated (35 % heat output)
- Pressing four times: All LEDs off seat ventilation switched off
Function note
The seat ventilation is automatically switched off (timed). The timer control is realized by the rear SAM control unit.
- Seat ventilation stage 3 is active for 8 minutes. Then it switches automatically to stage 2.
- Seat ventilation stage 2 is active for 10 minutes. Then it switches automatically to stage 1
- Seat ventilation stage 1 active for 20 min. Then seat ventilation is automatically switched off.
The timer control of the three levels can be adjusted via the diagnostic tester in the rear SAM control unit.
Seat ventilation function sequence
Function sequence for driver seat ventilation
The left front door control unit reads in the status of the left front seat ventilation switch via left front door LIN and sends a corresponding request to the rear SAM control unit via interior CAN. The rear SAM control unit evaluates this and sends the request to switch on the seat ventilation over the interior CAN to the driver seat control unit.
The driver seat control unit then actuates the following motor groups directly:
- Left front seat cushion seat ventilation motors
- Left front backrest seat ventilation motors
The respective driver seat control unit continuously checks the function of all components involved in the seat ventilation and sends the relevant status over the interior CAN to the rear SAM control unit.
Corresponding to the actuation frequency of the left front seat ventilation switch, the rear SAM control unit sends the status of the seat ventilation over the interior CAN, left front door control unit and left front door LIN to the seat climate control switch group and the left front central locking system, which actuates the LEDs in the left front seat ventilation switch accordingly.
Function sequence for front passenger seat ventilation
The right front door control unit reads in the status of the right front seat ventilation switch via right front door LIN and sends a corresponding request to the rear SAM control unit via interior CAN. The rear SAM control unit evaluates this and sends the request to switch on the seat ventilation over the interior CAN to the front passenger seat control unit.
The front passenger seat control unit then actuates the following motor groups directly:
- Right front seat cushion seat ventilation motors
- Right front backrest seat ventilation motors
The respective front passenger seat control unit continuously checks the function of all components involved in the seat ventilation and sends the relevant status over the interior CAN to the rear SAM control unit.
Corresponding to the actuation frequency of the right front seat ventilation switch, the rear SAM control unit sends the status of the seat ventilation via interior CAN, right front door control unit and right front door LIN to the seat climate control switch group and the right front central locking system, which actuates the LEDs in the right front seat ventilation switch accordingly.
Reduction of noise level
In order to reduce the noise level of the seat ventilation when the vehicle is stationary, it is shifted down to level 1 if the vehicle speed drops below 6 km/h. As of 9 km/h, the originally selected stage is activated. The instrument cluster sends the vehicle speed via user interface CAN, electronic ignition lock control unit and interior CAN to the rear SAM control unit. The noise level reduction does not become active until 7 minutes after the respective seat ventilation has been switched on for the first time with the engine running.
Function sequence, automatic shutoff
The seat ventilation is switched off automatically if one of the following events occurs:
- Shut-off in the event of a hardware defect
If the respective control unit reports an active actuation of the seat ventilation motors to the rear SAM control unit although a request has not been sent by a seat ventilation switch, the power supply of the seat ventilation motors is switched off by an integrated protection relay by the rear SAM control unit.
- Shutoff in the event of a fault (short circuit overload or line break)
The respective control unit detects a short circuit, an overload or a line break in the respective seat ventilation motor and therefore switches off the power 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 switched off for 20 s. With a hot start, the seat ventilation is switched off for 3 to 5 s. The timer control continues to run, and the LEDs in the respective seat ventilation switch remain switched on. No undervoltage assessment takes place 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 switched off if necessary.
If the seat ventilation is switched off, the LEDs in the respective seat ventilation switch remain on initially. If the on-board electrical system reaches its specified voltage again within the next 3 min, the seat ventilation function is automatically reactivated. If the shutoff lasts longer than 3 min, the LEDs in the respective seat ventilation switch are also switched off. If shutoff continues and the function is requested again by pressing the respective seat ventilation switch, the LEDs light up for 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 respective control unit fails, the seat ventilation is switched off.
- Shutoff after circuit 15R OFF
For circuit 15R OFF and circuit 15C ON, the timer control runs on for another 5 minutes. 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 of the rear SAM control unit for actuating the seat ventilation is discontinued or a "Timeout period" from the electronic ignition lock control unit is recognized, the seat ventilation is switched off.
- Shutoff at end of diagnosis
The seat ventilation is switched off after diagnosis is finished.
| Seat ventilation electrical function schematic | PE91.30-P-2053-97ZGB | ||
| Overview of system components of comfort heating systems | GF91.30-P-9990GW |