BMW Alarm System Dead: Siren Communication Failure

Hey there! I had a similar issue with my 2016 BMW 3 Series last winter. The alarm system completely died, with the same symptoms you're describing. After the first diagnostic, they found the siren module's wiring harness was corroded and had a few loose connections. It turned out to be more serious than expected because water had gotten into the connection housing and damaged multiple pins. The mechanic had to replace the entire siren module and rewire the connections. The job took about 4 hours because they needed to remove some parts to access the module properly. Not trying to worry you, but don't ignore it, a faulty alarm system can drain your battery or cause other electrical issues down the line. Make sure to find a mechanic who's familiar with BMW electrical systems. In my case, fixing it prevented potential issues with the car's central locking system too. Hope this helps with your situation.

Thanks for sharing your experience! This sounds exactly like what I'm dealing with. Really glad to hear you got it sorted out. Did you remember roughly how much the repair ended up costing you? Also, has everything been working properly since the fix, or have you noticed any other electrical quirks?

Hey again! Glad to give you a positive update about your alarm system issue. Just wanted to let you know that since I got my BMW fixed, everything has been working perfectly, no more problems at all! The repair wasn't nearly as expensive as I initially feared. In my case, it turned out to be just a faulty cable connection to the siren module, which cost me 95€ to fix. Much better than having to replace the entire module like I thought might be needed! The mechanic found the issue pretty quickly, seems these connections can get loose or corroded over time. Since the repair, my alarm system has been working like new. The beeps are back when locking/unlocking, and I haven't noticed any other electrical issues. It's such a relief not having to worry about potential battery drain or other problems anymore. My advice would be to definitely get it checked out. These BMW electrical gremlins are usually pretty straightforward fixes when you find the right mechanic who knows what they're doing. Let me know how it goes with yours!

Thanks so much for the detailed follow-up! I actually just got back from a different mechanic today, and you were spot on. They found a corroded wire connection that was causing all the trouble. The repair was pretty quick and cost me less than I expected, around half of what I'd budgeted for. Funny enough, while they were fixing it, they showed me how the water had gotten in through a tiny crack in the housing. The mechanic sealed it up properly this time, so hopefully that'll prevent any future issues. The alarm's working perfectly now, those familiar beeps when locking and unlocking are such a relief to hear again! Really appreciate your help in pointing me in the right direction. It saved me from possibly spending way more at the dealership. Glad we both got our BMW gremlins sorted out without too much hassle!