911 Carrera 4 Cabriolet (996) F6-3.4L (1999)
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the ignition is switched on
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reverse gear is engaged
System error
System errors are indicated by the sounding of a continuous tone after reverse gear has been engaged. This continuous tone differs from the continuous
tone emitted when an obstacle is detected.
System components
The Park Assistent consists of:
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a control module which is located under the driver's seat together with a cover plate.
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four ultra-sound sensors which are installed in the rear spoiler.
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an audible signal transmitter which is integrated into the instrument cluster.
WARNING: Danger of injury and damage to vehicle when the vehicle is rolling backwards!
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Reverse gear must be engaged and the ignition must be switched on; otherwise the Park Assistent System is deactivated.
WARNING: Danger of injury and damage to vehicle when the system limits are reached! The system does not free the driver from his/her
responsibility to be careful.
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Short obstacles such as a person lying down cannot be detected.
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The reflection capabilities of the system may be impaired by sound-absorbing obstacles such as powdery snow, and by sound- reflecting obstacles
such as glass bottles.
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Very thin obstacles and obstacles with small reflecting surfaces cannot be detected.
Sensor signals
Every sensor emits an ultrasound beam with the following geometric specification.
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Horizontal beam angle = 120 °
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Vertical beam angle = 60 °
The control module measures the distance between the sensor and any obstacle in cyclical intervals. Measurement is based on echo-sounding techniques.
The sensors are actuated briefly at regular intervals and transmit ultrasonic waves. Next, the sensors are switched to receive mode, and receive the
reflecting sound waves. The control module then calculates the distance between the sensor and the obstacle from the running time of the soundwaves.
Fig. 1
