A3 Mk1
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Immobilizer self-diagnosis - immobilizer III
General information
Function Immobilizer III comprises:
The electronic immobilizer control unit is an integral part of the dash panel insert, i.e. the dash panel insert has to be replaced in the event of a defective control unit. => Electrical System; Repair Group 90 The immobilizer is a system designed to enable/disable the engine control unit (via CAN wire). The transponder code consists of a fixed code and a variable code. This changes whenever the vehicle is started and thus prevents the transponder being copied. Each immobilizer has a different arithmetic rule for the variable code, which remains the same over the entire service life. On vehicle key matching, the immobilizer writes this arithmetic rule into the key transponder and at the same time learns the respective transponder fixed code. The fixed code identifies each individual key, thus enabling a lost key to be disabled. Whenever the ignition is switched on, the immobilizer reader coil reads out the fixed transponder code for the key and then the variable code and checks whether this key is authorised for starting. The fault lamp lights briefly (max. 3 seconds) and then goes out if use is being made of an authorised vehicle key. The fault lamp flashes continuously when the ignition is switched on if an unauthorised vehicle key is used or in the event of a system fault. The electronic immobilizer is provided with comprehensive self-diagnosis. Fault codes are stored in the fault memory of the immobilizer if faults occur in system components. Faults can be determined using the vehicle diagnostic, testing and information system VAS 5051. Immobilizer self-diagnosis can now only be implemented using the vehicle diagnostic, testing and information system VAS 5051 For security reasons, the immobilizer PIN is encoded. The encoded number (PIN = Personal Identification Number) is made up of 7 digits. The PIN can only be used with the vehicle diagnostic, testing and information system VAS 5051 as of basic CD version V02.00. The 7-digit PIN must be obtained by way of the appropriate Regional Sales Centre/importer on the basis of the 14-position immobilizer/engine control unit identification number. The 14-position immobilizer/engine control unit identification number can be read out with the self-diagnosis function. The PIN is only valid for one day, after which a new number has to be requested. The PIN is of no use to the customer or other dealerships. The 4- digit PIN can no longer be requested in countries in which the online and fax call procedure has been switched to the 7-digit PIN. Attention:
Notes on use/matching of vehicle keys The engine will only start if use is made of an authorised key, i.e. of a key matched to the immobilizer. Vehicle key matching involves matching all vehicle keys, i.e. including spare and emergency keys, to the immobilizer. Matching must be performed for all vehicle keys if new or additional keys are required. If, for any reason, e.g. loss of keys en route, it is not possible to perform matching for all vehicle keys, customers are to be informed of the necessity of subsequent matching for all keys. It is particularly important to re-match all the remaining vehicle keys if any have been lost to ensure that the lost key is no longer authorised to start the vehicle. |
