Airbag fault light. 65776933985 Sensor, B-pillar left

Z

Z4_Tom

Member
 Basingstoke
Anyone in Hampshire who can help?
I am in search for B-pillar sensor replacement and codding in.

My original sensor is

65776933985​


RealOeam.com shows that i can replace it with any of below part numbers:

65776948087(03/18/2004 — 10/25/2023) , Exchangeable retrospectively
65776928571(11/25/2002 — 07/11/2003) , Exchangeable retrospectively
65776928520(09/02/2002 — 07/01/2002) , Exchangeable retrospectively
65776926784(09/02/2002 — 05/22/2002) , Exchangeable retrospectively
65776926782(09/02/2002 — 04/23/2002) , Exchangeable retrospectively

https://www.realoem.com/bmw/enUS/partsearch?id=BT52-EUR-03-2003-E85-BMW-Z4_30i&mg=&sg=&q=6933985

Fault was present when i bought the car.
Fixed the Occupancy sensor fault with the a adapter with resistor (bought it of ebay)
- this is working now and I can hear the signal going off after reaching certain speed - it is pretending that a passenger is sitting there and when i clip "their" seat belt in the signal is not present any more.

I have read the fault codes:
1758802153182.png


After reading many posts about the Airbag Light ON issue, my understanding was that the SBSL sensor needs replacing and coding.

Have removed the sensor of the car to check for any water damage but nothing indicated it, not even any small signs of oxidization.
But what i have found was that the carpet underneath passenger seat was soaking wet ( but only bottom part of it- the foam that is underneath- i could not feel any damp on the top.

Checked all seals around the door and have not found any water leak. But found a lot of water present in the area where roof motor is originally placed by design (btw this motor has been relocated already).
I have cleaned the drainage whole and now for few weeks of our rainy weather there is no more water accumulation there.

Long story short- I wanted to ask you guys- do you think that water accumulation could be dripping under the carpet and damaging SBSL sensor on its way?

Is that 987B code saying that it has been replaced by previous owner but not coded with VIN?
- I think I have found the answer to above question- The code of not coded correct VIN would be "93AB Incorrect Chassis number"


@enuff_zed- forum posts show like you have a lot of experience in this matter- would you be able to suggest anything?
 
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I am not far from you in the Farnham direction, but sadly I don’t know anything about the airbag modules or coding. The normal path of water ingress to the footwell carpet is due to a failed door membrane, through the bottom of the door. This can affect the floor mounted sensors, for instance the yaw sensor on the driver’s side. However, if your roof motor well has been full of water, it is possible for it to slosh over under braking, and I expect the b pillar sensor is right in its path. I can’t offer you a solution, except to warn you that a waterlogged carpet foam is very difficult to dry out properly - towels first, then kitchen roll or other absorbent material, then a couple of weeks with a dehumidifier in the car in a dry environment. Ideally you will remove the seat and roll the carpet back. Then you still have to trace the problem and fix it. Don’t ask how I know this 😭
 
Seeing those numbers I am 99% sure that module is classed as a rare one

@enuff_zed will confirm

Sorry- it will be hard to find one
 
A long shot but it worked for me. I presume you have disconnected battery. Try reinstating module, reconnect battery and then clear code again. From memory I had to clear codes from two areas on my creator device. Then restart car. No more codes reappeared.
 
Out of curiosity- anyone ever tried to repair the SBSL module instead of replacing it?

Based on my car behavior and codes read, It does not look like the whole module is faulty:

- It can pick up that Occupancy sensor is now working with the resistor adapter plugged in,
- Occupancy signal goes off after the car reaching certain speed,
- Occupancy signal goes away when seat belt is clipped in,


I have opened the module itself to inspect for any water damage and have found that the PBA (Printed Board Assembly) is fully covered with conformal coating to prevent that from happening.
I understand that damage quite often is caused by water getting on the pins of the connector but there was no sign of any oxidization.
Just curious if there is any available schematics of the PBA itself that will help identifying faulty components.
So far what i have found is this:

1759220448253.png
It looks like pins 14 and 15 on the SBSL are connecting the loom from tensioner.
Inside the Satellite it looks like we have NPN transistor straight of the pin 14 and a fuse to pin 15.

Info from different forum:
"From the left b-pillar satellite, the two wires leave on pins 14 and 15.
Pin 14 goes to the X275 connector (yellow one under seat) on pin nine (9) and it is RED (RT). Pin nine outputs to pin 2 on seat belt tensioner.
Pin 15 goes to the X275 connector on pin 10 Blue/Brown (BL/BR). Pin 10 outputs to pin one (1) on the seat belt tensioner."

If there was a water present that created a short across these pins it might be that if we find the value of the fuses and transistors the unit can be repaired.

I am just looking at the possible solution knowing now how difficult it is to find the replacements. I can only imagine how many faulty units users of this forum have.



Over the weekend I will be checking the wiring loom from the tensioner to the Satellite through all connectors for any damage, trapped wires and checking the resistance and continuity.
This should define were the real fault actually is.

Is it correct that properly working tensioner will have resistance of 0.5 to 0.7 Ohm ish?
Some of the posts here have a link to youtube video where it has been said that a working tensioner has a 0.7Ohm resistance across two wires.
Anything different from these values should show us a fault code like Resistance to Low or to High?

I have found this post from 2023: https://z4-forum.com/threads/passenger-pre-tensioner-air-bag-light-fault-code-987b-sbsl.142642 where @EViS had same error code as mine (987B) and the resistance he had was 2.3Ohms :

"I removed the passenger seat this afternoon and tested the pre-tensioner which read 2.3 ohm. Supposedly between 2 and 3 ohms is within spec..."



On the slightly different subject but relevant to this issue:

@bigwinn @enuff_zed @colb
I have noticed on many posts that you guys use the combination of Inpa, NCS, WinKFP, and Tool32 in one suite. Any chance you can point me to trusted source? I would like to get my own diagnostic tool/software set as so far had to borrow someone elses...
 
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Mike6 said:
A long shot but it worked for me. I presume you have disconnected battery. Try reinstating module, reconnect battery and then clear code again. From memory I had to clear codes from two areas on my creator device. Then restart car. No more codes reappeared.
Click to expand...
I have done all of it except checking in the second area @Mike6 or to be fair someone done it for me using the using MP900BT KIT tablet. I need to get my own set of software and hardware to connect and check it myself. In the process of researching now.
 
bigwinn said:
Seeing those numbers I am 99% sure that module is classed as a rare one

@enuff_zed will confirm

Sorry- it will be hard to find one
Click to expand...
I have noticed that over last week trying to source one... absolute disaster. Check even with few Eastern EU vendors and no luck there as well. Hence I am interested if we have someone on the forum or someone knows someone who was trying to repair any of these sensors.
 
Zedebee said:
I am not far from you in the Farnham direction, but sadly I don’t know anything about the airbag modules or coding. The normal path of water ingress to the footwell carpet is due to a failed door membrane, through the bottom of the door. This can affect the floor mounted sensors, for instance the yaw sensor on the driver’s side. However, if your roof motor well has been full of water, it is possible for it to slosh over under braking, and I expect the b pillar sensor is right in its path. I can’t offer you a solution, except to warn you that a waterlogged carpet foam is very difficult to dry out properly - towels first, then kitchen roll or other absorbent material, then a couple of weeks with a dehumidifier in the car in a dry environment. Ideally you will remove the seat and roll the carpet back. Then you still have to trace the problem and fix it. Don’t ask how I know this 😭
Click to expand...
I think this is exactly what happen but it is just assumption.

To dry the carpet I am almost tempted to remove it completely out of the car and tbh.
 
Z4_Tom said:
I have noticed that over last week trying to source one... absolute disaster. Check even with few Eastern EU vendors and no luck there as well. Hence I am interested if we have someone on the forum or someone knows someone who was trying to repair any of these sensors.
Click to expand...
I’ve contacted at least 5 ‘reputable’ air bag repair operations in the uk

As soon as I send details of the unit it’s a definitive nope- can’t fix under any circumstances
 
Z4_Tom said:
I think this is exactly what happen but it is just assumption.

To dry the carpet I am almost tempted to remove it completely out of the car and tbh.
Click to expand...
Ideally, that’s what you should do, and would give you the opportunity to do lot of things which are enabled by having the carpet out.

However, be warned. Removing the entire carpet is not a trivial undertaking.
 
bigwinn said:
I’ve contacted at least 5 ‘reputable’ air bag repair operations in the uk

As soon as I send details of the unit it’s a definitive nope- can’t fix under any circumstances
Click to expand...
Yup, and I sent a complete set of three modules to the software graduates at Lotus and even they admitted defeat.
 
As I understand it and it has been covered on the forum, you can get cheat devices which turn off the airbag light but of course it doesn't fix the fault. I believe the device has been used to get cars through the MOT, otherwise car is just scrap value.
 
Mike6 said:
As I understand it and it has been covered on the forum, you can get cheat devices which turn off the airbag light but of course it doesn't fix the fault. I believe the device has been used to get cars through the MOT, otherwise car is just scrap value.
Click to expand...
You can put resistors in place of airbags or seat pad emulators, and code out the seatbelt warning bong, but I've yet to find a way to 'hide' a fault with the control modules, apart from the ubiquitous piece of tape; or the one I found where they'd filled the well that the warning light sits in with some kind of expanding foam!!!!
 
@enuff_zed I might be able to source soon a 65776933985on the pictures it looks like have not been abused by water or humidity at all. Would u be able to help programming it in when I get it?
 
Z4_Tom said:
@enuff_zed I might be able to source soon a 65776933985on the pictures it looks like have not been abused by water or humidity at all. Would u be able to help programming it in when I get it?
Click to expand...
Yes I can help with that for you.
I assume you are having to take the sellers word for it that it is a good one?
Worth recording the serial number on the bottom right corner of the label. Then if it turns out to be a dud we can create a video showing it installed and the issue showing on the laptop, which may help with a refund.
Only trouble is I don't have any of those so you could come all the way to me only to find it's a dud and I won't be able to supply another one.
 
Z4_Tom said:
It is worth the risk ;) even for over 3 hours drive one way :)
Click to expand...
OK, let me know when you get it and we can sort something out.
Mind you, being in Basingstoke, have you asked Ross at RBM in Hook if he is able to do them?
 
I was thinking about asking him as I have seen very good opinions of him on this forum. Might pop in to see him tomorrow. Thanks for suggesting it
 
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