Failure phenomenon: a 2009 annual output of FAW – Volkswagen Magotan 2.0TSI automatic sedan, equipped with a keyless entry system. Say users, insert the key button, the vehicle can not be started, the instrument appears ldquo; rdquo key is not found; tips (Fig. 1), as long as the key is inserted into the main vehicle can be normal start, and keyless entry system can not be activated properly in the car, but the remote control function correctly.
FIG 1
Check Analysis: a vehicle diagnostic scan tool, storing anti-theft system fault code 01176 (key signal is not reliable), all other systems normal. The data stream read, data theft all normal, the failure to determine the range of the keyless entry system failure. Analysis of causes of failure to generate the code, because after inserting the sub-key (sub-key without the ID chip, the equivalent of a button), the vehicle antenna can not search for the master key of the vehicle, resulting in anti-theft security lock, the insert when the main key 15 is powered, the system stores the security ldquo; key signal is not reliable rdquo; fault code, reads the data stream is displayed as usual. MAGOTAN FAW – Volkswagen first keyless entry system installed in a vehicle, a keyless entry system, the system control unit J393 is comfortable, the doors and bumpers and other parts of the antenna and other components. Let’s briefly understand the keyless entry system works.
(1) a door opening process: an ID chip in the master key must be in a region near the outer door handle (about 1.5 m). A contact sensor by contacting the door handle, the media change in capacitance, comfort control unit searches the key ID through the boarding door handle and start authorization antenna, verified, amenity system open the door, pull the handle to open the door.
(2) Ignition starter: If starting the engine with the sub-key, the master key must be located within the ID chip cars (that is, when the door is opened, the car began to search for the antenna inside the car key ID) . If the search to the master key ID chip, then start to unlock the car; if the car antenna search is not the correct key ID, the vehicle will not unlock, can not start.
FIG. 2
End LearnMagotan keyless entry system works, we began to check the status of the failure of the vehicle. Although there is no data flow, but we enter the system components can be checked by performing the malfunction diagnostic keyless. Use VAS5052A inquiry into the boot failure, check the working status of the door handle. Comfort can be seen that the system control unit may recognize that the door handle touch sensor (FIG. 2), then the antenna should be the key to the search ID command and unlock the door lock in an unlocked state but has no action, while the lower door normally there should unlock action. Car remote control function properly, the amenity system to the door lock control circuit means no problem, so far only suspect J393 comfort system damage. In order to determine whether J393 real damage, continued use of the vehicle fault diagnostic check antenna R138, R138 can be seen that normal (FIG. 3), thus determining the amenity system control unit J393 does damage.
Figure 3
Check Analysis: J393 is detached, the control means open the housing, that the inside of obvious signs of water (FIG. 4). Replace the J393 and matching online test troubleshooting.
Figure 4
reviewed: When the system works is not fully understood, it is best to find the relevant information to be studied, it will be a multiplier effect . It is noteworthy that, should pay attention to matching online diagnostic plug connections not loose and do not turn the ignition key, otherwise it will cause a careless J393 is locked, resulting in rework.
(Li Xin)