Z3's Electrical Nightmare: FlexRay Bus Mystery Unfolds

Hi there! I had nearly identical issues with my 2004 BMW Z4 last year. The symptoms started pretty similar, unusual electrical failures, systems going haywire, and warning lights everywhere. Initially thought it was something major with the FlexRay system too. Turned out it was just a corroded main ground cable connection near the battery tray. The cable had some moisture damage and wasn't making proper contact. The mechanics found it during diagnostics, they cleaned the connection points, replaced the damaged section of the cable, and added some protective coating to prevent future corrosion. It wasn't a serious repair at all, despite how scary the symptoms seemed. The whole car went back to normal after fixing that one connection. No electrical gremlins since then. You might want to have a shop check your ground connections first before diving into more complex diagnostics. These older BMW models can be sensitive to ground issues. Hope this helps.

Thanks so much for sharing your experience! That's really helpful, and it's actually reassuring to hear it might just be a ground cable issue rather than something more serious. My symptoms sound exactly like what you described. Quick question, do you remember roughly how much you ended up paying for the repair? Also, has everything been running smoothly since then, or have you noticed any other electrical quirks pop up?

Hey again! Yep, happy to report everything's been running perfectly since I got it fixed! Actually, I just had it sorted last week, the mechanic confirmed it was indeed the FlexRay bus fault, just like we suspected. They found a damaged cable connection that was causing all those crazy electrical symptoms. The repair was surprisingly affordable, only paid 95 € for the fix, which included fixing the faulty cable connection and testing everything. Much cheaper than I initially feared when all those warning lights were going nuts! Since the repair, my Z4's been running like a dream, no more unusual system failures, all electronics working properly, and those annoying warning lights are gone for good. It's such a relief when these things turn out to be simpler than expected. By the way, if you do get it checked out, make sure they thoroughly test all the connections. These BMWs can be pretty sensitive when it comes to electrical stuff, but once you get it sorted, they're solid. Let me know how it goes with yours!

Thanks for the follow-up! Just got back from the mechanic today and wanted to share what happened. You were spot on about getting those connections checked! Took it to a specialist who actually found two issues, a corroded ground cable and a loose connection in the main wiring harness. The whole diagnostic and repair process took about three hours, but man, what a difference! All those crazy electrical problems are completely gone. Radio's working, no more unusual warning lights, everything's back to normal. Total bill came to 180 bucks, a bit more than yours but still way less than I was expecting. They even threw in a protective coating on the connections to prevent future issues. Really appreciate your advice about this. Would've probably spent way more time and money worrying about complex computer issues if you hadn't shared your experience. The car's running perfectly now, feels like I've got a new Z3! Thanks again for helping me dodge what could've been a much bigger headache!