F30 Batterysafety terminal wiring?

[sunnyblueskies]

Hi guys.
Probably a complete stupid question, but I can't find an answer, or maybe looked in the wrong places.

2014 328d xdrive

On the battery, positive post, is the Battery safety terminal. Beside the main, larger, wires connecting to the clamp and to the battery post, there are 3 thinner wires. 2 of those go to the ignitor of the pyrotechnic device but what is the other single wire?
I've added the picture to describe it better. It's just a single wire with a plain jane wire connection on the battery post clamp.
From there it goes, just like the other 2 wires into the wiring harness.

Reason I ask is, it had slipped off, now it's back on there. But what is it actually for?

[328 Power 04]

That connector was a red wire, right?
That connection is B73*5B, which is a +12V wire between the Gas Generator, Battery Safety Terminal and the Intelligent Battery Sensor (IBS, controls charging functions). That wire is what the IBS uses to measure the voltage from the battery directly. If the wire is disconnected, the alternator will only charge at 13.8-13.9V fixed rate and will not change charging patterns. You will also have a code registered.

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[sunnyblueskies]

Absolutely perfect. Thanks so much. That explains a lot of things. Yes there were codes stored, but without knowing what one little wire is/does a error can't be 'attached' to it. Right?

Where is that diagram from? I couldn't find anything detail of the BST positive terminal.
You made my day.

[328 Power 04]

I just used BMW's own TIS system for these. Wiring diagrams, function descriptions, and some good picture diagrams.

I would think the error was for an IBS disconnection or something. The little sensor also gets powered by that wire. It seems to have just +12V, ground, and LIN bus communication.

[sunnyblueskies]

Yes the error was for the IBS, it actually stated that it is missing. The wire coming from the positive post was actually disconnected at the positive post. It's just a regular flat automotive wire connection. But the insulations on both wires plugged into the IBS socket had cracked as well. Who knows, might have shortened out there too.
Unfortunately they cracked right at the plug end, so I can't just put some tape or anything around. Tried to dismantle the little socket to cut the wires a bit shorter and reconnect........ of course one of the little pins decides to break before I even worked on getting the wire off. Argggg.
Now I'm waiting for a new repair wire with a socket for it.
Fun fun fun.