Battery keeps draining on 128i n51

[Treymiller32]

Originally Posted by Gray_Panther

Let's gooooo!!

Thanks for coming back to the thread and updating it with a solution!

Was the body control module getting hot as well?
Any programming needed or was it plug and play?

I pulled the bcm off a 09 335i, didn't program it and everything is still working fine. The old bcm wasn't getting hot but was causing modules to not properly shutdown.

[dtla1]

Originally Posted by Treymiller32

Finnaly got it, body control module. Everything is working perfect again. Hope this thread can help out people who come across this problem.

Thanks for providing the update. This is one of the modules near the fuses right?

[Treymiller32]

Originally Posted by dtla1

Thanks for providing the update. This is one of the modules near the fuses right?

Its connected to the fusebox right under the fuses. Can access it by removing the kick panel. 2 Plug ins on the front and 1 on the back.

[turbodriven]

Originally Posted by Treymiller32

I pulled the bcm off a 09 335i, didn't program it and everything is still working fine. The old bcm wasn't getting hot but was causing modules to not properly shutdown.

When you were selecting a replacement module, did you have to select a donor with all the same features? Like comfort access, etc?

And how did you come to the conclusion that it was the body control module? Just random part swapping until you got it right?

I ask, because I've got some of the same issues. I've learned to live with it as I drive it daily and only have to connect to a charger when I leave it sit for more than a day or two (weekends sometimes). But I would really like to solve it. I always thought it might be caused by my non-functioning passenger side comfort access door handle. Or possibly a malfunctioning IBS module on the negative battery terminal. One of these days I'll get around to replacing both of those, but I fear they aren't the actual problem, only a symptom of the problem.

[Treymiller32]

Originally Posted by turbodriven

When you were selecting a replacement module, did you have to select a donor with all the same features? Like comfort access, etc?

And how did you come to the conclusion that it was the body control module? Just random part swapping until you got it right?

I ask, because I've got some of the same issues. I've learned to live with it as I drive it daily and only have to connect to a charger when I leave it sit for more than a day or two (weekends sometimes). But I would really like to solve it. I always thought it might be caused by my non-functioning passenger side comfort access door handle. Or possibly a malfunctioning IBS module on the negative battery terminal. One of these days I'll get around to replacing both of those, but I fear they aren't the actual problem, only a symptom of the problem.

To be honest towards the end it was just shots in the dark. Mine is a 128i with the n51. The one i swapped came off a 335i n54. Similar but at the same time very different. Everything has worked fine so far, Haven't had any battery drain issues, clicking stopped, and my car properly goes into sleep mode now. if your having the same issues as i listed in my original posts i would bet its the bcm. To be safe though i would get one that at-least came off the same model and year car.

[turbodriven]

Originally Posted by Treymiller32

To be honest towards the end it was just shots in the dark. Mine is a 128i with the n51. The one i swapped came off a 335i n54. Similar but at the same time very different. Everything has worked fine so far, Haven't had any battery drain issues, clicking stopped, and my car properly goes into sleep mode now. if your having the same issues as i listed in my original posts i would bet its the bcm. To be safe though i would get one that at-least came off the same model and year car.

On Ebay they come listed for a wide range of E-models. So the compatibility for this particular part is broad I'm sure. It's the options I'm worried most about. Most specifically that my car has comfort access. But maybe it doesn't matter on a BCM.

[Treymiller32]

Originally Posted by turbodriven

On Ebay they come listed for a wide range of E-models. So the compatibility for this particular part is broad I'm sure. It's the options I'm worried most about. Most specifically that my car has comfort access. But maybe it doesn't matter on a BCM.

Not quite sure, In my case it all works fine but could be different for others. Best of luck.

[dtla1]

Originally Posted by turbodriven

On Ebay they come listed for a wide range of E-models. So the compatibility for this particular part is broad I'm sure. It's the options I'm worried most about. Most specifically that my car has comfort access. But maybe it doesn't matter on a BCM.

Real OEM is showing that the specific part number is compatible across various models, so it seems you should be ok. The only unknown, and I'm not sure if OP has seen any side effects, is whether you might need to program it. Didn't find much online about it either.

The only small tidbit I found was that you should disable transportation mode, but I'm assuming that would only apply if you bought a new one, used ones should be good to go?

https://www.realoem.com/bmw/enUS/par...&q=61359364819

[Treymiller32]

Originally Posted by dtla1

Real OEM is showing that the specific part number is compatible across various models, so it seems you should be ok. The only unknown, and I'm not sure if OP has seen any side effects, is whether you might need to program it. Didn't find much online about it either.

The only small tidbit I found was that you should disable transportation mode, but I'm assuming that would only apply if you bought a new one, used ones should be good to go?

https://www.realoem.com/bmw/enUS/par...;q=61359364819

Ive heard from some people its a possibility that it needs to be programmed, couldn't find anything online about it though. Just incase i kept the old one if i were to need it for some reason.

[Dartmouth_135i cabrio]

Hallo all, I have had a battery problem as well. Have not changed the battery yet so not know about registering battery.
I have the hands free door unlocking and somebody mentioned to me that if the key(s) is in close proximity to the car it keeps trying to communicate. If the car is still for a while this might draw down the battery as well. It worked for me. I extended the life of my battery with a battery maintainer. The car has over 100k KMs and still on the original battery. The car is driven all year round.