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 873 (Seat heaters for driver and front passenger) 

MODEL ALL (CAR) with CODE 902 (Seat heater Plus for driver and front passenger) 

Overview: 

This document contains information on:

• General
• Shutoff in the event of a hardware defect, function
• Shutoff in the event of a crash, function
• Shutoff in the event of a fault (short circuit, overload or open circuit (line break)), function
• Shutoff by energy management, function
• Shutoff after circuit 15R OFF, function
• Shutoff during engine start, function
• Shutoff in the event of a "Timeout error", function
• Shutoff at end of diagnosis, function
• Shutoff in the event of overtemperature of the printed circuit boards in the respective control unit (seat heating only), function
• Shutoff due to heat mat overtemperature (only seat heating Plus), function

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.

Shutoff in the event of a hardware defect, function 

If the respective control unit reports actuation of the seat climate control to the central control unit (SAM), although no request from a switch has been made, the seat climate control switches itself off. The central control unit (SAM) switches off the power supply of the seat climate control to do so.

Shutoff in the event of a crash, function 

If a crash is detected, the seat climate control switches off.

Shutoff in the event of a fault (short circuit, overload or open circuit (line break)), function 

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.

Shutoff by energy management, function 

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 is 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, function 

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 during engine start, function 

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.

Shutoff in the event of a "Timeout error", function 

The seat climate control switches off when one of the following conditions occurs:

• The request from the central control unit (SAM) control unit to actuate the seat climate control is withdrawn.
• The electronic ignition lock control unit detects a "timeout period".

Shutoff at end of diagnosis, function 

The seat climate control switches off after diagnosis has finished.

Shutoff in the event of overtemperature of the printed circuit boards in the respective control unit (seat heating only), function 

• 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 heat mat overtemperature (only seat heating Plus), function 

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.