Feedback requested-X3 TCU, Battery matter
 

I have a 2005 X3 as listed in my sig with about 66K on the odo. Obviously i am out of warranty. It has factory NAV, SIRIUS, BT, etc and the other day the SOS light on the headliner started flashing. As a result it eliminated the sound of the radio and BT applications on a Thursday. I believe it was trying to sync a phone call (that is my hunch) even though my wife never pressed the button. I did some searching and i couldn't "reset" i through the volume/CD Eject button combination reset, so i scheduled an appointment with BMW for 7AM Monday.

Since the radio wouldn't work we decided to drive my Evo over the weekend and on Sunday, due to that TINY light flashing, the battery was dead. I jumped it and let it run on Sunday enough to keep a chrage and drove it to BMW on Monday. Turns out the the car had a dead battery and a bad TCU. They did a service authorization to cover the TCU under warranty even though the warranty had expired which is great (as i have to trust they actually did give me the $2,000 part) but i paid for a new battery and labor.

I just wanted to ask if anyone else has had this problem that was that drastic and i couldn't find anyone that had the SOS light flash that the problem turned out to be that catastrophic?

-Jon

I've had one incident this spring where my 2004 kept trying to dial BMW Assist despite the fact I haven't subscribed to them after the first year. No matter what I did with the buttons in the headliner or on the steering wheel, it kept cycling through the same sequence of weird things. It fixed itself within a few hours.

Folks on the forum suggested that some rain water might have seeped into the TCM and caused it to fritz. It was indeed raining that day so that was likely the cause. It never happened again.

There have been many posts on this and other forums about BMW battery issues whereby the battery wasn't the problem, but went flat due to the vehicle having too high a current draw. The vehicle is designed to go into sleep mode, and then it draws very little power. If something stops it going into sleep mode (like a tiny light flashing) then the current draw can flatten the battery in a few days. That sounds like what happened, IMO.

If you got a new TCU under a goodwill policy, then that is great. Your battery is 4-5 years old, and that is about how long a battery lasts. This likely just pushed it over the edge, but it was either due or very close to being due to be replaced in any case.

All of this is speculation, not having been party to the diagnosis, but it fits.

I've seen quite a few of the TCUs go bad and they stay on and are the cause of radio problems and battery drain. So they were able to get the TCU covered as it is a known problem and the cost is ultimately passed on to the manufacturer of the TCU by BMW in certain types of failures.

Thanks for all the replies guys, and it was raining that day...sometimes i think the car is just a little too smart and gets itself into trouble. And the goodwill gesture on the TCU was a nice thing and yeah the baterry is almost 5 years old, so it "should" be time for a replacement.

That is why i really love my Evo since it is mechanical and it is just point and go, but nothing beat driving a bimmer for sport and luxury.

If anyone has anymore comments, post them up.

Thanks,

Jon