BMW 8 Diesel Alarm System Dead, No Response or Sound

Hey there! I had a similar issue with my 2019 BMW 7 Series Diesel last year. I've got some experience working on cars, mainly basic maintenance stuff. My alarm system went completely silent too, super annoying! Took it to my regular workshop and turns out it was just a faulty connection in the wiring to the siren unit. They had to trace the cables and found a loose connection that was causing the communication failure. Fixed it up for 95 Euro, and it's been working perfectly since then. What's the error code you're getting? Also, have you noticed any other electrical issues? Knowing these details would help figure out if you're dealing with the same problem I had. By the way, if your 8 Series is anything like my 7, these issues can sometimes be related to the central locking module too. Let me know more details about your car and I'll try to help further!

Thanks for sharing your experience! My 8 Series has 144399 KM on the clock and just had its service last month. The error code I'm getting is U0327, which seems to point to the alarm module communication. Haven't noticed any other electrical issues so far, everything else works perfectly fine. The central locking still works mechanically, just without any sound feedback. Your wiring issue solution sounds promising, might be worth checking that first before replacing any expensive parts. Did your mechanic have to remove any specific panels to access those connections?

Hey again! Thanks for providing those extra details about your 8 Series. Yeah, that U0327 code sounds really familiar, it's exactly what my car was showing too. For accessing the wiring in my 7 Series, the mechanic had to remove the trunk lining on the right side to get to the connections. It wasn't too complicated, but definitely needed someone who knows what they're doing. The siren unit is mounted in that area, and there's quite a bundle of wires running to it. Since your mileage is similar to what mine was when I had the issue (I was around 138000 KM), and the symptoms are identical, I'm pretty confident you're dealing with the same problem. The fact that everything else is working normally also matches my experience, it was just the alarm system acting up on its own. Just a heads up though, make sure whoever works on it checks the entire wiring path. In my case, they initially thought it was just the connection at the siren end, but they eventually found the actual loose connection a bit further along the wiring harness. Saved me from buying a new siren unit, which would've been way more expensive. Let me know how it goes when you get it checked out. I'm curious if it's the same issue!

Thanks so much for all that detailed info! Really helpful to know exactly where your mechanic found the issue. Going to book mine in next week and will definitely mention checking the entire wiring path, not just the siren end connection. You've probably saved me a bunch of money and hassle by sharing your experience. The symptoms match perfectly, and knowing it was fixable without replacing the whole unit is such a relief. Will definitely update you once I get it sorted. Thanks again for taking the time to help out a fellow BMW owner with this annoying alarm issue!