Guys, I know that it is a 3 yrs old thread, but, I'm having the same problem.
2005 X3, manual transmission.
I got the car 1.5 yrs ago, the battery was so bad that I wouldnt start the car. It was the original battery. I went to Autozone and got the top of the line battery ($160 I think). Anyhow, few weeks ago I got the 4x4, abs, and break warning lights, after some research I decided to replace the actuator gear in the transfer case, surprisingly it was almost in new condition. btw, I got new transfer case and differentials fluids.
Well, yesterday, when I was parking, some lights came on for a sec and then just the 4x4 light was on. I parked the car, turn off the car and removed the key.... no automatic interior lights, radio not working, nothing electric was working. While sitting in the car, I locked it with the remote control, then, unlocked it, put the key in, and the car was on without any lights at all, the computer was reset (mpg, travel distance, clock, all was set to zero).
Is it the battery? It's only 15 months old. I usually drive only 5 miles during weekdays and maybe 20-50 during the weekends.
thanks Bimmers community.
Update:
So, went to Autozone, the battery tested as 40% charged. I was asked to leave it in the store charging for 1 hr and it will be good. 1 hr after, only 70% charged. They told me to leave it charging in the store for 20 more min. Not significant improvement. They replace the battery for a brand new one. Hopefully it will fix the problem.
This is the battery:
http://www.autozone.com/routine-main...9459_928773_0/
Duralast Platinum/Battery
Fits Your Vehicle
Click to view video
This product is a fit for your:
2005 BMW Truck X3 AWD 3.0L EFI DOHC 6cyl
Part Number: H8-AGM
Warranty: 3 YR
Live chat by BoldChat
Price: $171.99
Core:
$15.00
Total: $186.99