A Bora 1.6L manual car, travel to more than 10,000 km, due to accident caused dashboard damage. The owner asked to replace the dashboard assembly, the replacement is completed, but there has been anti-theft alarm light only uninhibited, only 2s after the start will be stalled failure. However, before the replacement, the vehicle was able to start normally.
    FAW-Volkswagen Bora sedan is the third generation of anti-theft system, which is mainly embedded by the instrument in the anti-theft system control unit, combined instrument in the anti-theft warning lights K117 (located in the instrument cluster meter table), the matching engine control unit , An identification coil D2 on the ignition switch and a matching ignition key with a transponder. Under normal circumstances, open the ignition switch, the electronic anti-theft device on the instrument on the anti-theft alarm light K117 will light for 3s off. If the following fault occurs: Ignition key is incorrect; No ignition / key is present in the ignition key; Ignition key is unauthorized; Engine control unit is unauthorized; identification coil D2 is faulty or data cable is faulty, etc. Turn on ignition switch , The burglar alarm lamp K117 will flash or continue to light up.
    Through the analysis of the vehicle failure, I believe that the vehicle into the anti-theft state, the most important because there is no new instrument in the anti-theft system control unit to match. Access to information, that if the new instrument is VDO company production, matching can not enter the password, and enter the fixed code 13861. I press the method described in the input method of the fixed code, but still can not start. The author of the unit is not authorized special maintenance station, no right to get the public's original information and the corresponding technical support, it can not know their own input is wrong or the information is wrong, so maintenance in trouble.
    I repeatedly think, since the original instrument can start, and the new instrument can not start, which indicates that the old instrument anti-theft system control unit is not damaged. Open the original instrument to find a model for the 93C86 8 feet chip. At this point, I whim, can replace the chip as if the sound anti-theft? So the old and new instrument in the chip after cutting the swap. After the recovery, or can not start. Once again opened, but found that due to temporary negligence, there will be more obvious signs of the upper and lower feet welded. At this point, I think this may come to power, the chip will burn no doubt, but still holding the idea of ​​dead horse when the horse, re-chip welding, the correct welding and assembled, unexpectedly can start The. Due to the use of the original instrument within the chip, the password has not changed, so the number of kilometers or more than 10,000 km. For more than a year, this failure never reappears.
    Through the above troubleshooting process, we can easily see that for the like Passat B5, Audi A6 and other vehicles encountered similar situation, as well as some with anti-theft device sound, we can also analogy, with the same method to solve. At the same time, also make the author deeply appreciate that in the maintenance process, encountered in the external environment is not allowed (such as no password, equipment and technical information and other reasons), we also use the usual accumulation of experience, broaden the thinking Solve the problem. Some seemingly impossible things, but also through a thorough understanding of the principle, bold practice to verify, and sometimes will receive unexpected results.