| 摘要 |
The electrical heating device in the door lock of a motor vehicle must be capable of being switched on from outside in order to thaw out the frozen door lock. Mechanical switch contacts permanently installed for this in the door lock or on the motor vehicle have the disadvantage that the heating device is switched on continuously as a result of an improper jamming of the switch contact and consequently the battery of the motor vehicle is drained. Switch contacts, in which a simple jamming is impossible, for example those which are actuated by a permanent magnet, or electronic switching devices have the disadvantage of a high technical outlay. To reduce the risk of an improper switch-on and to avoid a high technical outlay, the car key, by means of which an interrupted electrical feed line to the heating device is bridged, is used for switching on the heating device.
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