[CTFRuNnEr]

I have been doing some research on an issue with my 2007 328xi where after about 12+ hours sitting the battery is either dead or it is so drained it just clicks. I have replaced the battery and the issue still happens, I have Bavarian Technic so I have been using that to monitor voltages etc and voltages seem fine between 12.9 volts and 13.8 volts. I do see a code about the IBS so I am leaning towards that. The other odd thing is my start button light never goes out any more 4 hours later without my fob even though I do not have comfort access it still is on so something is keeping it from sleeping it seems. Is the IBS the only cause of it not sleeping or could something else keep it from sleeping? I am just looking for ideas to check out like maybe some way to verify the IBS is bad or something.

Thanks

[ctuna]

Quite a few things can stop the car from sleeping.
doors and sensors.

I think you can pull the plug to the IBS (at the battery )and the car runs
on default values. Are you sure you hooked it back up to the battery in
a powered connection on the battery distribution block.
Not all the slots are powered.

electical e90 pdf
http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU

http://www.bimmerfest.com/forums/sho...15&postcount=6

[CTFRuNnEr]

Well in disconnecting the IBS the car now sleeps and it is no longer deep discharging car has sat for a few days and still starts right up. Guess its a failed IBS as before it was pretty much dead after 12 hours. Thank you for your useful info.

[ctuna]

Thanks for posting that it worked.
I have also been told this is useful technique when
trying to start a dead car.
If you get a new IBS tell us if this fixes it .