The steering wheel heater is ready for operation as of terminal 15. It is switched on by pressing the key once on the multifunction steering wheel. The steering wheel heater is switched off again by pressing the key a second time.
The steering wheel temperature is measured by a temperature sensor which is located on the heating element. The electronic control ensures the steering wheel heats up as fast as possible to the specified temperature of 36 °C. The heating capacity of the steering wheel is reduced just before reaching this temperature.
Once the set temperature has been reached, the steering wheel temperature is controlled by a pulse width modulated signal. When the steering wheel temperature is greater than the setpoint, the heating element is operated at 10% of its heating cycle. The steering wheel heater remains switched on and the control is still active.
The heating element and the switch-on monitor are switched off in the event of a break or short in the temperature sensor.
The steering wheel heating system is monitored. The monitoring functions checks whether the steering wheel heats up within the defined temperature limits. The steering wheel heater and function indicator are switched off if there is no temperature increase within this period of time.
The steering wheel heating element is switched off in the event of undervoltage or overvoltage.
The heating element is switched off if the supply voltage at the switch drops below 11.6 V for 5 sec. The switch-on monitor in the switch remains active. The status of the steering wheel heating system is retained.The steering wheel heater is switched on again when the supply voltage increases to above 12.4 V for 5 sec.
The heating element is switched off if the supply voltage at the switch increases to above 16.5 V for 5 sec. The switch-on monitor in the switch remains active. The status of the steering wheel heating system is retained. The steering wheel heater is switched on again when the supply voltage drops below 15.5 V for 5 sec.