GF91.30-P-5217GZ Switch Heated Seats on, Off, Over

GF91.30-P-5217GZ Switch heated seats on, off, over
- with CODE (873) Heated left and right front seats
- with CODE (401) Front deluxe seats, incl. seat heating and seat ventilation
- with CODE (872) Electrically heated left and right rear seats
- 164 up to Model year 8

Component Identifiaction:

Function requirements
- No undervoltage or overvoltage
- Circuit 15R "ON"
- Terminal 15 "ON"

Switching off the heated seats during the starting procedure
During the starting procedure, the power supply to the heated cushions is switched off. The timer control continues to run if the heated seats are switched off during the starting procedure.

Switching off after circuit 15R "OFF"
After switching off the ignition, the heated seats are also switched off. However, the timer control continues to run for another 5 min as long as circuit 15C is "ON". If the ignition is switched on again, then the heated seats are switched on again in the stage active in accordance with the timer control.

Switching off the heated seats (cancel conditions)
If one of the following criteria occurs, the heated seats are switched off.

The criteria are listed in the order of decreasing priority; i.e. if the heated seats are switched off due to a criterion with a low priority and then another switch-off criterion with a higher priority occurs, this is treated as described for the criterion with the higher priority.

Switching off in the event of a hardware defect
If an actuation of the heated cushions is detected without any current switch request pending or function condition fulfilled, then the supply for the respective seating is switched off by canceling the load actuation. The timer control is switched off by the front SAM control unit and, on vehicles with code 872, by the HS [SIH], seat ventilation and steering wheel heater control unit.

Hardware temperature monitoring
If, when the heated seats are switched on, a temperature which is too high to guarantee reliable operation is detected on the printed circuit board of the front SAM control unit or for vehicles with code 872, of the HS [SIH], seat ventilation and steering wheel heater control unit, then the respective heated cushions are switched off. The front SAM control unit and, for vehicles with code 872, the HS [SIH], seat ventilation and steering wheel heater control unit, continue to run through the timer function.

Switching off in the event of undervoltage
The undervoltage cutout for all control units and consumers is monitored globally by the battery control unit (N82). If the front SAM control unit and, for vehicles with code 872, the HS [SIH], seat ventilation and steering wheel heater control unit, receives the emergency mode message of the battery control unit, the heated seats (load only) are switched off. The same applies when the undervoltage cutout threshold is reached.

If an undervoltage is recognized, the corresponding LEDs in the switches flash on and off at a frequency of 1.5 Hz and a brightness of 50 %. The timer control continues to run if the heated seats are switched off due to undervoltage.

If the control units detect an impermissible actuation of the heat mats, a fault is stored in the fault memory.

Switching off in the event of overvoltage
When the overvoltage threshold of 15.5 V is exceeded, the heated seats (load only) are switched off. The timer control continues to run if the heated seats are switched off due to overvoltage. Switching on again is only possible when a permissible voltage of 15 V is applied.

Exceeding the switch-off threshold temperature
If the interior temperature - or the outside temperature if there is no interior temperature - is higher than the defined switch-off threshold, then specific stages or the complete heated seats function cannot be switched on.

Switching over with switch
By actuating the switch for the heated seats repeatedly, the heated seats can be manually switched over.

The front SAM control unit and the HS [SIH], seat ventilation and steering wheel heater control unit reduce the power output for the respective heated cushions in the seat accordingly.

Automatic switching over and switching off of the heated seats
A timer control for the heated seats is located in the front SAM control unit and in the HS [SIH], seat ventilation and steering wheel heater control unit :
- Switching on of stage 3 for t = 5 min
- Switchover to stage 2 for t = 10 min
- Switchover to stage 1 for t = 20 min
- Heated seats shutoff

If on vehicles with code 401, the seat ventilation is active, the heated seats are switched to stage 1.

The heating periods can be programmed using STAR DIAGNOSIS.

Switching off using switches (front seats)
The heated seats can be switched off by actuating the switches in the upper control panel.

Actuation of the switches is read in by the upper control panel control unit and forwarded via the interior CAN to the front SAM control unit. This then switches off the selected seat cushions in the front seats. At the same time the function LEDs in the upper control panel are switched off.

Switching off using the switches of the over 2nd seat row (for vehicles with code 872)
The heated seats of the 2nd seat row can be switched off by actuating the switches in the RCP [HBF] control unit.
Actuation of the switches is read in by the RCP [HBF] control unit and forwarded via the interior CAN to the HS [SIH], seat ventilation and steering wheel heater control unit. This then switches off the selected seat cushions in the 2nd seat row. At the same time the function LEDs in the RCP [HBF] control unit are switched off.