VW Sharan Door Lock System Failure Causes Alarm Issues

I had a similar issue with my VW Touran from 2018, and having some experience with electrical car problems, I can share what worked in my case. The symptoms were nearly identical, the automatic locks stopped working completely and the car alarm would out of nowhere activate. After initial troubleshooting, it turned out the wiring harness connecting to the driver side door was damaged, causing inconsistent contact signals to the central locking system. The workshop found that the cable insulation had worn through where the wiring harness flexes between the door and body. This created intermittent electrical shorts affecting all vehicle doors and the central locking system. The repair involved replacing part of the wiring harness and checking all door contact points. Total cost was 95€ including diagnostic time. Since the fix, all automatic locks work perfectly and no more false car alarm triggers. To help diagnose your specific case, could you share: Does the key fob battery show good voltage? Are there any other electrical issues, like window controls or mirror adjustments? Can you hear the central locking pump working when attempting to lock/unlock? Did the problem start suddenly or develop gradually? This information would help determine if you're dealing with a similar wiring issue or potentially something else.

Thanks for sharing your experience. Just had my 129433km service done last month and this issue started right after. The key fob battery is new and all other electrical components work fine, including windows and mirrors. Cannot hear the central locking pump at all when pressing the key fob. The problem appeared suddenly after parking overnight. I checked the door switch connections as suggested and noticed some corrosion around the contact points. The wiring harness also looks slightly worn where it connects to the driver door, which might explain the car sensor issues. Will have the workshop inspect these areas specifically. Has anyone tried cleaning the contact points as a temporary fix before replacing the entire wiring harness?

Thanks for the update on your VW Sharan issue. After reading about the corrosion you found, it reminds me even more of my Touran situation. While cleaning contact points can work as a temporary solution, in my experience it only delayed the inevitable wiring harness replacement. I actually tried cleaning the corroded contacts with electrical contact cleaner, which worked for about a week before the door latch problems returned and the car alarm started acting up again. The timing of your issue, right after service, is interesting. The door latches and contact signals can sometimes be disrupted if the door panels were removed during service work. The worn wiring harness you spotted is likely the main culprit though, especially since you cant hear the central locking pump. Given your mileage and the visible wear, I strongly recommend going straight for the proper repair rather than temporary fixes. The wiring harness replacement solved all my electrical issues permanently, and the car sensor systems have worked flawlessly since. Just make sure your workshop thoroughly tests all door contact signals after the repair. In my case, they had to readjust one door latch sensor after the initial fix to get everything working correctly.

Thank you everyone for the detailed insights. After checking everything mentioned, I took my Sharan to the workshop today. They confirmed the electrical issue was indeed caused by a damaged wiring harness, exactly where I spotted the wear. The repair cost was 180€, a bit more than expected since they had to replace the entire driver side door latch assembly along with the wiring. The corrosion had spread into the contact signal unit. They also found and fixed a loose connection in the automatic locks mechanism which was causing the unusual car alarm triggers. The central locking pump now makes a clear sound, all doors lock and unlock perfectly, and no more false alarms. Definitely worth fixing properly rather than attempting temporary solutions with the contact points. For anyone facing similar issues, get the wiring harness checked early, especially if you notice any wear near the door hinges. Waiting too long can lead to more extensive electrical issues affecting multiple systems. Would anyone recommend preventive measures to avoid future wiring harness wear?