[Surly73]

I've been googling to see if I get any hits mentioning this wire and I'm coming up blank. I think I've seen it in other people's trunk shots, but I can't see the end of it in any of those pictures.

I have this "extra" connector with red/blue wire near the battery harness. While an extra connector may not be unheard of, it doesn't look "managed" like the factory would do it so I think either the PO was fooling around with it, or it was accidentally left disconnected from something.

Any ideas:

[CUTigers]

I think someone said its for shipping. To keep the batt charged.

[wobbles1]

Yep During The Pdi It Is Removed. Its For The Battery Save Switch When Car Is In Transport Mode.

[mike3000fl]

Originally Posted by wobbles1

Yep During The Pdi It Is Removed. Its For The Battery Save Switch When Car Is In Transport Mode.

bingo

[Bimmerlover76]

I think it's part of a hidden feature of the comfort access package... There's usually, along with the tow hook and screwdriver, a... female pleasuring device (ahem), that when plugged in allows seat vibration. Thus, providing comfort during access.

I could be wrong.

[Surly73]

Good answers, good answers

I'm positive I read something about coding for "Transport Mode". I think it was in a BT or AE feature list. I'm surprised that they've chosen to have a dedicated wire for that sort of thing.

Thanks for the answers.

[PDX-335i]

Glad I found this post! I just changed my battery on my 09 335i and found the same thing. After I got the new battery installed there was this connector just hanging out. It had nowhere to go and had me wondering what it was.

BTW - This was the original battery with a sticker from 12/08 on it. Unbelievable that an OEM battery could last that long. It didn't die, but is only charging up to 12.3 volts so I figured it was time to change it out. Good grief it's almost 9 years old!

[Chrisdeibel]

Just curious, the light blue connector that runs along the power cable, you can see the connection just above the negative terminal of the battery, from the OP picture. What exactly is this cable for? Just noticed the other day it was unplugged. Any help is much appreciated!

[vilord]

The light blue connector goes to the Intelligent Battery Sensor (IBS), which monitors the state of charge of the battery, measures the discharge rate of things during sleep modes, and is involved in how the car manages to keep our batteries lasting for almost 10 years.

[Chrisdeibel]

Vilord- Isn’t the IBS the big light blue connector that plugs in on top of the battery in the distribution box that BMW locates on top of it? I was referring to the small light blue connector in the picture from the OP.

[vilord]

Have a look at this image.

The big connector is the +12vdc connection for the IBS. The small connector is the data line that runs to the DME.

[vilord]

Hah. Just noticed this has been disconnected in my car since I bought it 5 years ago, including a battery change...

[lowrydr310]

Originally Posted by vilord

Have a look at this image.

The big connector is the +12vdc connection for the IBS. The small connector is the data line that runs to the DME.

I actually stumbled upon this exact thread a week ago when replacing my battery and seeing the same thing disconnected, but felt no need to comment on a thread started almost 7 years ago!

The image itself isn't helpful. It explains what's there but doesn't indicate whether it's supposed to be connected or left alone. After reading around, the consensus is that it's not connected to anything. There's nothing to connect it to in the trunk or anywhere near the battery compartment.

PS - If you remove your rear seat you'll also find another free hanging connector there too. I read that these are used during transport from the factory when the car is sitting on a container ship, though I have no idea how it's connected. It would make sense to have the car enter a complete OFF state with zero battery drain if sitting in a container for a few weeks.

[vilord]

Mine does have a place in the battery bay to attach it to. All the way in the corner

[TheMidnightNarwhal]

Originally Posted by vilord

Have a look at this image.

The big connector is the +12vdc connection for the IBS. The small connector is the data line that runs to the DME.

But the small one doesn't plug into anything I think since my battery is original and is not plugged either.