BMW 3 Series Alarm Dead, Common Siren Issue Fix Needed

Hi there! I've got some experience with BMWs as I dealt with a similar alarm issue on my 2008 BMW 5 Series diesel last year. My car had exactly the same symptoms, no beeps, completely dead alarm system. Took it to my trusted workshop and they found a faulty connection in the alarm wiring harness. Basically, some cables had corroded over time and weren't making proper contact anymore. The fix wasn't too complicated, they replaced the damaged connections and reprogrammed the system. Cost me 95 Euro total. Before heading to a workshop, could you share if you've noticed any other electrical issues? Also, which exact 3 Series model do you have (320d, 330d, etc.)? This would help pinpoint if it's the same underlying issue I had. I have some experience with BMWs but I'd still recommend having a professional take a look, as these systems can be tricky to diagnose properly.

Thanks for sharing your experience! I have a 320d with 74138 KM on the clock. Interestingly, I've noticed the central locking sometimes acts up too, there's a slight delay when using the key fob. Other than that, everything electrical seems to work fine. Had my last service about 2 months ago but they didn't spot any alarm-related issues then. Your corrosion theory makes sense though, might be worth checking those connections. Would you recommend going back to your mechanic? Mine's not too familiar with BMW electrical systems.

Hey again! Yes, that delay with the central locking is exactly what I experienced before the alarm completely stopped working. It's definitely a telltale sign. Based on what you're describing, it sounds very similar to what happened with my 5 Series. My mechanic specializes in BMW electronics, and honestly, it made a huge difference. He knew exactly where to look for those corroded connections, they're often hidden in spots where regular mechanics might not think to check. Given that your car is around the same age as mine was when this happened, I'd bet it's the same issue. Trust me, save yourself the headache and go to someone who really knows BMWs. My regular mechanic initially thought it was the siren unit itself and wanted to replace the whole thing, would've cost way more than necessary. The specialist knew better and fixed the actual problem for much less. If you want, I can DM you my mechanic's details. He's great with these issues and his prices are fair. The whole repair took about 2 hours for my car. Also, get them to check the water drainage around the alarm module while they're at it, sometimes water ingress can cause these problems too. Let me know how it goes!

Thanks so much for all this detailed help! You're absolutely right about finding a BMW specialist, no point risking a more expensive fix with someone who's not familiar with these systems. I'd really appreciate those contact details for your mechanic. The water drainage check is a great suggestion too, hadn't thought about that being a potential cause. It makes total sense though, especially with these older models. I'll definitely get both the wiring and drainage checked out. I feel much better knowing this is likely a fixable issue that won't break the bank. Will book it in next week and let you know how it turns out. Really appreciate you taking the time to share your experience, it's saved me a lot of worry about potentially needing to replace the entire system! Best regards, and thanks again for the helpful advice!