Activation and de-activation of the central locking can take place at any door of the vehicle. To this end every door handle contains a proximity sensor and a locking button. To trigger a function, an authorised key must be within about 1.50 metres of the appropriate door handle. Access to the rear is by operating the soft-touch on the tailgate, and again an authorised key must be within about 1.50 metres of the rear.
The driver's desire to open a door is recognised by a sensor in the door handle as he starts to operate it, and the evaluation electronics activated. A coded enquiry, whose content is the vehicle-specific secret code (challenge), is sent by radio to the key. The key calculates the appropriate reply (response), and sends it back to the vehicle. If the key is identified as being authorised, the central-locking system is activated and the vehicle unlocked. The customer decide on the configuration, that is to say, between unlocking the whole vehicle or a single door alone.
The vehicle can also be unlocked, by radio remote control, by pressing the appropriate button on the key. The remote control function operates in a radius of more than 30 metres around the vehicle.
For the vehicle-locking function too, the driver only needs to have the key with him. When the locking button is pressed, the vehicle electronics search by radio transmission for a key that belongs to the car in the vicinity of the door. If an authorised key is present, the central locking system is activated and the vehicle locked.
The vehicle can also be locked, by radio remote control, or by conventional mechanical key operation. For this purpose there is still a mechanical lock cylinder in the driver's door.
To start the vehicle, an authorised key must also be inside it. The enquiry covers the entire passenger compartment. With operation of the starter button, a coded enquiry, whose content is the vehicle-specific secret code and an enquiry-specific variable code (challenge), is sent by radio to the key. The key calculates the appropriate reply (response), and sends it back to the vehicle. The data security of the coding algorithm is at the same level as that of the most modern immobiliser systems.
If the key is identified as being authorised, the steering is released by the electric steering lock, the ignition is activated and the vehicle starts. Of course, this only happens if all other preconditions are fulfilled, for example, an automatic transmission must be in "P" or "N" and the brake pedal depressed, or with a manual gearbox, the clutch pedal must be depressed. When the stop button is operated, the ignition and motor are switched off.
In the usual way, the vehicle can be started or stopped by inserting and turning the key (or, respectively, the reverse of these actions) in the electronic ignition lock.
The new Audi Vehicle Access System will offer the customer comprehensive convenience functions. It combines convenient access with a simple button-start function and optimum protection against theft without any key operation.
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