The cushion surfaces and backrests are heated with the seat heating system.
The seat heating can be switched on as of terminal 15 by pressing the button. The LED integrated in the switch lights to act as a function indicator.
The seat heating is switched off by pressing the button once again or switching off the ignition.
The seats are heated by means of four heating elements incorporated in the upholstery.
Seat moulding and thigh support
Centre section of backrest
The electronic circuitry integrated in the switch controls and monitors the seat heating function.
The heating temperature can be adjusted by means of a potentiometer within the range from 20 o C to 42 o C. The temperature is measured by a temperature sensor in the seat upholstery and passed on to the electronics integrated in the switch.
The electronic circuitry controls the heating function such that the set temperature is reached in the fastest possible time. The heating capacity is then reduced.
Current supply to the heat conductor of the seat heating electronics is interrupted if the vehicle battery voltage drops below 11.8 volts. The function LED installed in the switch however remains on. Current supply to the heat conductor is resumed when the battery voltage again reaches 11.8 volts.
The seat heating electronics monitors the temperature sensor and the heating elements for faults.
If a break or short occurs at the temperature sensor, the seat heating is switched off in order to prevent overheating.
If a fault is recognized, the function LED installed in the switch flashes for 12 seconds when the fault occurs, or, if the fault is already present, when the seat heating is switched on.
A flash code shows what faults the electronic circuitry has currently detected.
Flash code output is started by following procedure:
Switch off ignition
Press and hold the button for seat heating
Switch on ignition (terminal 15) with button depressed
Release the button and press it again briefly
The following faults can be indicated:
Switch faulty (potentiometer or electronics) or switch overheating due to a short-circuit
Temperature sensor has break or short
All 4 heating elements broken or have a short (probably break or short in wiring harness)