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Discussion Starter #1
I replaced battery on my 2008 BMW 328xi, in the process a connector came off on the + battery terminal. I believe it's the airbags connector. I reconnected it and did a battery reset with scan tool. Airbag light stays on. Could have I damaged connector or is there another way to reset airbag?

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beemlyfe
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There is no terminal on the battery connector that is directly wired to the airbag system. Pull the airbag module codes and start there.
 

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I replaced battery on my 2008 BMW 328xi, in the process a connector came off on the + battery terminal. I believe it's the airbags connector. I reconnected it and did a battery reset with scan tool. Airbag light stays on. Could have I damaged connector or is there another way to reset airbag?
There is no terminal on the battery connector that is directly wired to the airbag system. Pull the airbag module codes and start there.
What kind of scanner do I need to pull air bag codes?
Concept is basically correct, but needs some tweaking. :)

The MRS (Multiple Restraint System) Module controls Air Bag Function, Seat Belt Tensioner Function, Seat Belt Warning Lights, AND a pyrotechnic device in the Positive Battery Cable connector known as the BST or Battery Safety Terminal. Here is the TIS circuit diagram for the MRS Module, showing the BST as G19a Component Code in bottom-right of diagram. Note that there are two wires, Blue & Brown, at that connector:
https://www.newtis.info/tisv2/a/en/...trol-module-multiple-restraint-system/f4crY2W
Here is the "Installation Location" for G19a:
https://www.newtis.info/tisv2/a/en/e90-328i-lim/S9WWsSN

Bentley has a better diagram of that connector, and it is attached below. If that connector is removed from the BST, the Air Bag & Seat Belt warning icons appear on your instrument cluster, as the MRS module senses that the circuit is open, and in the event of a frontal collision, the MRS could NOT "blow the BST" to disconnect battery power to the Jumpstart Terminal, Starter & Alternator under the hood (Power to the DME & JB would still remain intact).

Apparently simply plugging the connector back into the BST is NOT enough to have the warning light(s) go out, and there is a Fault Code saved in MRS module memory which must be cleared to extinguish the warning lamps. As Nachfolger suggests, you need a scan tool or software (such as INPA or ISTA) that can connect to the MRS Module and read/clear codes saved in the MRS. A generic P-code reader will NOT be able to do that.

So what scan tool did you use (or do you have available) to "do a battery reset"? There is NOTHING you can do in the DME Power Module related to battery registration, coding, different Amp-Hour setting, etc. that affects the MRS and any code saved there.

What you need is a reading of any code(s) saved in MRS memory, note what fault is identified by any code, the mileage/km at which the code was saved (presumably the mileage at which you changed battery if in fact the BST connector), CLEAR any codes, and see if warning lamp(s) now off and if they stay off. Some people have reported that connector becoming damaged and tending to fall loose if contacts NOT tweaked or connector taped, with warning light/ code returning.

Please let us know what you find,
George

George
 

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If the airbag sensor is lit, it could be that the sensor in the passenger seat is now not working properly. I had to have the seat sensor replaced in my 2011 under the CPO warranty
 

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Discussion Starter #6
What you are saying I believe you are right on about open circuit. This is the scan tool I have. I do have an INPA software, I need a software to download IN PA in my laptop.
Thanks for the quick response.

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What you are saying I believe you are right on about open circuit. This is the scan tool I have. I do have an INPA software, I need a software to download IN PA in my laptop.
It is quite possible that if you have reconnected the BST Connector, there is no longer a "Fault" or open circuit, but the code has been saved in MRS memory, and the warning light stays lit until that Fault Code is CLEARED.

If you have INPA, you can do each of the three things that may be necessary:
1) Connect to MRS module & read any codes, to determine if, in fact, the BST connector is the Fault Code saved; INPA tells you if Fault is currently present (Fehler momentan vorhanden) or NOT (NICHT), and it will ALSO tell you if that Fault would cause the warning lamp (MIL) to light up (Fehler wurde das Aufleuchten der Warnlampe (MIL) verursachen);
2) Clear the Code (at which point the warning light should go off);
3) Periodically scan ALL modules using Functional Jobs (only takes ~ 2 minutes) to see if any Faults have recurred (warning light on dash will also come on if MRS fault occurs).

If you take the time to download & install INPA, I think you will find it worth the time it takes to become familiar with its functions. If you have more money than time, and don't really want to understand your vehicle & how to diagnose issues, probably NOT. :)

I don't know (1) if the warning light on the instrument cluster should go out when you reconnect the BST Connector, (2) if it should go out after X-number of drive cycles/ restarts after reconnect, or (3) if you have to clear the code to make the light go out. Given the safety-related importance of the warning, it may well be the latter where BMW does NOT want untrained owners doing something to turn the light off that is NOT a proper and lasting "fix."

Please let us know what you find,
George
 

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Discussion Starter #8
Thank you for the information, my and I love BMW she owns the 328xi in question and I have an 2000 528i. We have owned a total of 4 BMW. I'm in proccess of installing and figuring out INPA don't want to take our cars to dealer, they want to much for something I can do on my own. I'll keep you posted on this situation, thank you for the information about this.

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