Dead Infiniti M: Battery Issues or System Error?

Hey there! I had a similar issue with my 2005 Infiniti Q45 last year, and I have some experience working on cars (though I'm no expert). My car showed pretty much the same symptoms weak battery, dim lights, and warning lights. Turned out it was a faulty cable connection to the control unit that was messing with the BUS system. Took it to my trusted workshop, and they diagnosed and fixed it in about 2 hours. Cost me around 260 Euro, but it solved the problem completely. What model year is your M exactly, and are there any specific error messages showing up? Also, have you noticed any other electrical issues before this happened? This info would help me share more relevant details from my experience. Want to make sure you're dealing with the same issue before suggesting anything specific. Let me know!

Thanks for sharing your experience! My M has 53105 KM on it and was just serviced last month. I'm noticing something similar with the BUS system you mentioned. The weird thing is that everything was working fine until yesterday. No error messages before, just suddenly went dead. Haven't noticed any other electrical issues until now. Did your mechanic mention how common this issue is with Infinitis? Really hoping it's just a cable connection like in your case and not something more serious. Honestly, getting a bit worried about the repair costs here.

Hey again! Good to hear back from you. Yeah, I totally get your concern. When it happened to my Q45 (which had around 60K KM at the time), it also came out of nowhere was working perfectly fine one day and completely dead the next. From what my mechanic told me, these cable connection issues are actually pretty common in Infinitis from that era, especially the M and Q series. Something about the way they designed the wiring harness makes it susceptible to loosening over time. The good news is that it's usually not a major repair. In my case, the mechanic explained that the BUS system acts up when there's a poor connection, and it can make the whole car go haywire exactly what you're describing. The sudden nature of your problem sounds exactly like what I experienced. The fact that you just had it serviced last month actually makes sense sometimes moving things around during routine maintenance can cause these connections to act up. I wouldn't stress too much about the repair costs. Unless they find something else wrong, it should be in the same ballpark as what I paid. My mechanic actually showed me the loose connection when he fixed it it was such a small thing causing such a big problem! Let me know what your mechanic says when you get it checked out. I'm curious if it turns out to be the same issue!

Thanks a lot for all the detailed info! This really puts my mind at ease. You're right the timing with the recent service makes total sense now. I've actually just called my mechanic and scheduled an appointment for tomorrow morning. They seemed pretty familiar with the issue when I described it, just like you said. Really appreciate you sharing your experience it's helped me understand what I might be dealing with and gave me a good idea about the potential costs. I'll update the thread once I get it fixed, in case anyone else runs into the same problem with their Infiniti. Thanks again for taking the time to help out! It's great to get advice from someone who's been through the same thing.