Seat Climate Control Automatic Shutoff, Basic Function - GF91.30-P-1001A
Model all (CAR)
with code 401 (Climatised front seats)
Model all (CAR)
with code 402 (Rear seat climate control)
Model all (CAR)
with code 872 (Left and right rear seat heating)
Model all (CAR)
with code 873 (Left and right driver's seat heating)
Model all (CAR)
with code 886 (Seat heater for 3rd seat row)
Model all (CAR)
with code 902 (Front comfort seat heating)
Model all (CAR)
with code 902 (Seat heater Plus for driver and front passenger)
Model all (CAR)
with code 903 (Rear comfort seat heating)
Overview:
This document contains information on:
- General
- Shut-off in the event of a hardware defect
- Shutoff in the event of a crash
- Shutoff in the event of an error (short circuit, overload or open circuit (line break))
- Switching off by means of energy management
- Shutoff after circuit 15R OFF
- Shutoff when the engine starts
- Shut-off in the event of "Timeout error"
- Shutoff at end of diagnosis
- Shutoff due to overtemperature of printed circuit boards in respective control unit (only seat heating)
- Shutoff due to heater mat overtemperature (only seat heating Plus)
General
The automatic seat climate control shutoff function switches off the seat heating and seat ventilation under certain conditions. This serves primarily to protect the component parts and the on-board electrical system.
Shut-off in the event of a hardware defect
If the respective control unit reports actuation of the seat climate control to the signal acquisition and actuation module although no request has been issued via a switch, the seat climate control switches off. To do this, the signal acquisition and actuation module switches off power supply to the seat climate control.
Shutoff in the event of a crash
If a crash is detected, the seat climate control switches off.
Shutoff in the event of an error (short circuit, overload or open circuit (line break))
The respective control unit detects a possible short circuit, overload or a line break in the respective heater pad/seat ventilation motor and then switches off the power supply. Diagnosis of the fault sources that have been listed is carried out individually for each heater pad/each seat ventilation motor using the diagnostic tester.
Switching off by means of energy management
In order to prevent the battery from discharging in all phases of the driving cycle, the energy management function continuously evaluates the state of charge. Depending on the situation, the energy management function also switches off the seat climate control. If the seat climate control is switched off, the LEDs in the respective switch remain on initially. If the on-board electrical system returns to the specified voltage again within a period of 3 min., the seat climate control function is also restarted automatically. If the shutoff lasts longer than 3 min, the LEDs also switch off. If the shutoff continues and a new switch-on request for the function is made, the LEDs light up for 1.5 s and then go out.
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 climate control is also switched on again.
Shutoff when the engine starts
When the engine is started (cold start), the seat climate control switches off for 20 s. In the event of a warm start, the seat climate control switches off for 3 to 5 s. The timer control continues to run, and the LEDs in the respective seat heater switch remain switched on. During the starting procedure, there is no assessment of undervoltage.
Shut-off in the event of "Timeout error"
The seat climate control switches off when one of the following conditions occurs:
- The signal acquisition and actuation module's request for actuation of the seat climate control is discontinued.
- The electronic ignition lock control unit detects a "timeout period".
Shutoff at end of diagnosis
The seat climate control switches off after diagnosis has finished.
Shutoff due to overtemperature of printed circuit boards in respective control unit (only seat heating)
- At a printed circuit board temperature of more than 70°C, heating level 3 is no longer available.
- At a printed circuit board temperature of more than 80°C, heating levels 2 and 3 are no longer available.
- At a printed circuit board temperature of more than 90°C, the seat heating is no longer available.
If no circuit board temperature value is present, the respective control unit evaluates the vehicle interior temperature value as a substitute. When a printed circuit board temperature of more than 90°C is reached, the respective control unit stores a fault message in the fault memory. Manual reactivation requires the printed circuit board temperature to drop to T = 2°C below the corresponding temperature threshold.
Shutoff due to heater mat overtemperature (only seat heating Plus)
Temperature sensors in the seat mats measure the temperature in the seat surfaces. If there is a risk of overheating, the corresponding heat mat is switched off.