Airbag light: Battery Firing Circuit

inkey$

inkey$

Lifer
 Sevenoaks & Suffolk
Just back from an Inspection 2 and investigation to the airbag light I have on my 3.0se. The code it is throwing is as follows:

SBSR: satellite B-pillar right - 98F Resistance, firing circuit, safety battery terminal (E85), or belt tensioner, rear right (E6x), too high

My go-to indy reckons its a fault with the battery positive firing circuit, which is a ball-ache in terms of both cost and effort - £200+ from BMW plus labour in deconstructing the interior to replace.

Anyone know if it can just be coded out from the M54 ECU?
 
Is it not just the right b-pillar module?
Easy to access behind the trim.
Need to replace with a compatible item, so if it is that you need to get it's part number
 
Don’t you just need a new module and use winkfp to code it to the car?

I’ve got a left one only at the moment sadly
 
bigwinn said:
Don’t you just need a new module and use winkfp to code it to the car?

I’ve got a left one only at the moment sadly
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That's why I asked as I have a right one but not sure if they are all compatible.
 
Speaking as a complete electrical/module novice do you think its worth trying to replace the right (drivers side?) b-pillar module first and see if it then clears?
 
inkey$ said:
Speaking as a complete electrical/module novice do you think its worth trying to replace the right (drivers side?) b-pillar module first and see if it then clears?
Click to expand...
I believe you need to then code it to the car as Stuart suggests.
 
this is the RealOEM breakdown for my car. So I’m after the part number for the 04 Airbag Module, right door?
471BB7A0-C3B6-448C-AB5F-0E485B9A697A.jpeg
 
[ref]bigwinn[/ref], clarify for me if you can. What is needed? The actual airbag or the B-pillar module (silver ecu thingy)
I think I have both but would need to check part number compatibility.
 
i would say its not the SBSR but the seat belt tensioner that needs replacing, first check under seat that you haven't moved the seat and caught a wire.
 
Thanks for all the advice so far. It’s weird as when I bought the car there was no light and it was only after owning for a few days (including moving seats etc) that the light appeared. Feels odd that if it was the battery firing circuit that it would happen just after I bought it.

That said, the car had been sat for a while during the last 12 months and hasn't done a lot of miles, and I know the battery terminals can corrode and throw up issues.
 
I would say it’s the module as opposed to the actual bag

Assume you have had a good old go at clearing it with inpa?

And of course looking for the root cause which I assume is water ingress?
 
bigwinn said:
I would say it’s the module as opposed to the actual bag

Assume you have had a good old go at clearing it with inpa?

And of course looking for the root cause which I assume is water ingress?
Click to expand...
Codes cleared and investigated using INPA. Root cause wise, when I bought the car there was a little water in the boot but clear of the battery. I guess it could have had some impact at some point though.

Reading into the BST error, on an E90 forum I read you can code this error out using NCSExpert of Bimmergeek ProTool. Thats on an E90 of course.
 
I know this is an old thread, but this sounds like the same issue I have had on and off for a couple of years. The culprit is the short wire from the battery safety terminal to the plug at the side of the battery. The wire and/or connectors in the short lead seem to corrode and create a high resistance resulting in the code. Sometimes just moving the wire and clearing the code will work for a while. I think INPA can display the resistance of this circuit and tells you the range of resistance allowed. A test is to unplug the wire add a 2.2 ohm resistor to the circuit in place of the BST. This means the BST will not fire but does show if this is the issue before dropping a load of money on the big cable that includes this wire. If you are OK with the BST being disconnected the resistor can be left in place.
The short wire is unavailable from BMW but could be manufactured if the connectors can be sourced. A used part may have the same high resistance so is a bit of a gamble. I initially cut the wire and added the resistor to the remaining wire, but it still showed high resistance when moved around with a meter connected. Also, the connectors on this wire to the battery terminal broke without any force, showing they were probably part of the issue. Bear in mind the plug on this wire has a shorting bar, so when removed it shorts the wires together, making measuring resistance difficult without dismantling the connector. The plug to the battery terminal is also hard to remove but can be done.
Hope this helps, as I have messed around with this for a long time to try and get to the bottom of the problem.
 
AntF said:
I know this is an old thread, but this sounds like the same issue I have had on and off for a couple of years. The culprit is the short wire from the battery safety terminal to the plug at the side of the battery. The wire and/or connectors in the short lead seem to corrode and create a high resistance resulting in the code. Sometimes just moving the wire and clearing the code will work for a while. I think INPA can display the resistance of this circuit and tells you the range of resistance allowed. A test is to unplug the wire add a 2.2 ohm resistor to the circuit in place of the BST. This means the BST will not fire but does show if this is the issue before dropping a load of money on the big cable that includes this wire. If you are OK with the BST being disconnected the resistor can be left in place.
The short wire is unavailable from BMW but could be manufactured if the connectors can be sourced. A used part may have the same high resistance so is a bit of a gamble. I initially cut the wire and added the resistor to the remaining wire, but it still showed high resistance when moved around with a meter connected. Also, the connectors on this wire to the battery terminal broke without any force, showing they were probably part of the issue. Bear in mind the plug on this wire has a shorting bar, so when removed it shorts the wires together, making measuring resistance difficult without dismantling the connector. The plug to the battery terminal is also hard to remove but can be done.
Hope this helps, as I have messed around with this for a long time to try and get to the bottom of the problem.
Click to expand...

So I think this is the issue with my SRS indicator too. I suspect adding a 3.3 ohm resistor across the cable connector will help of this is the problem (with the BST still connected). The 2.2 ohm that should be there from the BST may have gone up due to corrosion. However adding a 3.3ohm in parallel with the resistance that is there will bring it back down again to a value that the Computer’s ADC will think is a nominal value. I’m about to try this on mine and then clear the code. This will not stop the device functioning but will get the code cleared up hopefully. Might have to play with the value of resistor, maybe 2.7 ohm ?
 
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