Thanks again, Maybe. Yes, I've tried all of this and much more. Because I've now replaced both the shoulder belt-force limiter and the ACSM itself, and added a passenger seat mat emulator (bypass), taking that potential issue out of consideration, there's nothing more I can do. Replace the tensioner (the seatbelt receptacle)? Even more unlikely. There's really nothing more that I can replace or change. And because I've replaced all of this, I figure it simply needs some kind of hard reset by the dealer$hip. Maybe with a deeper dive into the codes, they can pinpoint the problem.

I'm not really whining when I post these updates, I just figure that someone in the future will have the same issue and may want to understand the attempts at repair that didn't work.

 

Given that you've already replaced the majority of seemingly relevant ACSM components, the only other thing that I can suggest is to check all wires on the passenger-side ACSM components and sensors for excessive voltage drops on both the power and ground sides of the circuits.

 

I have checked all wires and plugs for damage, but voltage/drops is beyond my capabilities.

What the seller of the bypass noted in the installation instructions is that other module(s) in the car may need re-coding, the JBE (passenger side footwell fuse box) for instance, as it/they may hold error codes in memory. And if this is the case, then it's likely that my original replacement of the limiter (seatbelt spool) would have been the fix - just not completely re-coded everywhere in the module system. Something else to try tomorrow...

 

Do you have a Foxwell BMW scan tool? If so, it should be able to code those items.

 

Voltage drop tests aren't very difficult, especially if you have a LoadPro that connects to your multimeter. But there are safety considerations for how these tests must be performed to prevent accidental airbag and seatbelt pre-tensioner deployment.

German wire color codes:

If you decide to do the electrical troubleshooting, you may find these circuit diagrams helpful:

 

Another thought is to investigate the capabilities of your Foxwell scan tool to read live data from your airbag system module. Live data could potentially identify the fault(s) in your airbag circuits.

 

Related to your spot on points above^...

AI query
Mini Cooper r56 - Given that the seat belt force limiter is mechanical rather than electrical, what abnormality does the airbag control module detect to register a fault code for the seat belt force limiter?

AI answer
The R56 Mini Cooper's seat belt force limiter is indeed a mechanical component integrated within the seat belt retractor assembly. The airbag control module (ACSM/MRS) detects a fault not by monitoring the mechanical function itself, but by monitoring the electrical circuit continuity and resistance of the associated seat belt pretensioner system.

Here is a breakdown of how the system works and what abnormality is detected...

System Components
Mechanical Force Limiter: A torsion bar inside the retractor that twists at a specific load level during a severe crash, allowing controlled belt payout to reduce chest injuries. This part has no electrical connection.

Electrical Pretensioner: A pyrotechnic (small explosive charge) device, typically located in the seat belt buckle or retractor, that is triggered by the control module in a crash to quickly remove slack from the belt.

Airbag Control Module (ACSM/MRS): The central computer that continuously monitors all safety restraint system electrical circuits, including the pretensioners.

Abnormality Detection
The airbag control module runs a constant diagnostic check on the electrical circuits for all pyrotechnic devices (airbags and pretensioners). The specific abnormality it detects for a "seat belt force limiter" or "pretensioner" fault code is an improper electrical resistance in the wiring harness or the component itself.

The fault is typically one of two conditions...
Resistance too High / Open Circuit: This indicates a damaged wire, a loose or corroded connector, or a completely failed igniter in the pretensioner itself. This is the most common cause of a fault code.

Resistance too Low / Short Circuit: This could indicate a short within the wiring or the component.

The control module uses a specific range of resistance as the "normal" operating condition. If the measured resistance falls outside of this predefined range at any point, the module registers a fault code, illuminates the airbag warning light on the dashboard, and often disables the entire SRS system until the fault is resolved and codes cleared with a diagnostic tool.

In summary, while the force limitation itself is mechanical, the system's ability to monitor its readiness relies on the electrical circuit of the associated pretensioner, and a fault code is triggered by an electrical anomaly (incorrect resistance) in that circuit.

 

Thanks for all of this, Maybe. It pretty much sums up what I have deduced (without any formal Mini SRS knowledge). Yes, live data is a choice with the Foxwell, but it doesn't tell me much. However, with the Foxwell looking at the ACSM itself, I can see what's "fitted" and what's not - the passenger limiter shows as "fitted", at least at the time of doing that test (and I'm not driving). I should also be able to turn OFF the switch for passenger airbag bypass; in other words, the passenger airbag system is turned off and I don't know how to get the Foxwell to turn it back on; I can check the box for it to see if it's off or on, but that screen won't let me toggle it. By the way, there's not much sales/support for the Foxwell NT510 Elite. Maybe an experienced auto tech could translate the info, and discern what to click on to read/change some of these things, as the info presented on the Foxwell screen is very confusing, and the company is no help.

Here's what I have discovered in the past couple of weeks.
1) my year model seatbelts (receptacles) do not have tensioners (the explosive ones that blow in a collision); mine are simple receptacles with a pair of wires to show whether or not the seatbelt is locked in. (Note: I now have the jumper installed to make the ACSM think the seatbelt is always locked in.) This was big news to me, as I've seen the code for tensioner "not present" when the seatbelt spool/limiter was unplugged; the tensioner is not supposed to be present in the first place! So why did this code come up when the limiter came unplugged?
2) when my code/icon comes up, sometimes the code shows "present" for the limiter, and sometimes "not present" (on my Foxwell). I have to assume that this is referring to the limiter and not the code itself; I cannot clear the code when the code reader shows "present" (even though the Foxwell says it's cleared, it's not - the icon is still on the dashboard) But I can clear it immediately if it shows "not present". I can understand that I can't actually clear a code/icon that doesn't exist (when the limiter shows "present"), buuuuuuuuut, why, in that circumstance, is the error code still showing on the Foxwell, even while showing that the limiter is "present"? This reinforces the idea that the issue is an intermittent short.
3) IIRC, there are two wired coming from the very top of the seatbelt spool, and two more below it, then there's a plug with at least four small wires on the spool/limiter bracket (this is the plug that came undone while I was driving...). This plug/harness runs down and is buried into the main wiring harness that runs under the passenger door. No way I can chase those wires at that point. The replacement seatbelt spool is exactly like my OEM and plugs in the same, but the ACSM still can't see it - all the time, I guess.
4) also, adding the bypass/jumper for the seat weight mat did nothing at all for this issue. (For anyone installing this device, the three DIP switches are set as UP, DOWN, DOWN (on, off, off). The seller suggested trying all of them UP/ON to "clear the codes". I tried this, and it threw more codes, understandably; I reset the DIPS, cleared the codes and went on my way. Then the icon popped up again.)

This tree I'm barking up might be simply explained with info from a previous owner: did they replace anything in the SRS? Is my ACSM the original module? Are we sure the seatbelt receptacles aren't supposed to have tensioners in 2013 Coupes? WTF did you do to/with this car?

My (rhetorical) questions:
1) where does the limiter wiring run, and connect to? It's not to the ACSM as far as I can tell.
2) is the limiter circuit tied to my non-existent seatbelt receptacle tensioners?
3) if the issue is a short within the limiter wiring, why does it take almost the exact same amount of time to throw the code virtually every time? In other words, if it's a short, it would be random; why the common 10-minute delay in throwing the code? Is the SRS/ACSM programmed to "look for all SRS components for ten minutes of driving before throwing codes"?
4) what triggered all of this after six months of carefree daily driving? Did the dealership service department tech trigger something (intentionally) while it was in for an oil change...? All of this started mere days after that oil service.
5) why does Mini charge so *&%^$@%%&*^#$^$ much for repair service? Hundredzzzz of dollars per hour is just insane. I know BMW owns Mini, but Minis ain't BMWs - and I've had 11 of 'em (plus three Minis), so I know the difference.

A Mini Service Advisor will likely have these answers and many more. And they're likely going to charge me $700+ to suss out the problem and re-code a module or two.

Does all of this seem confusing? Yes, yes it does. Once it's all solved, I promise I'll do a tl;dr version for future posterity.

 

I wonder if many of your current Airbag issues might be solved by recoding or coding your airbag control module.

My Launch X431 Pro Elite V2.0 scan tool for BMW/MINI offers both recoding and coding of the airbag control module. See images below.

I think it's worth a try if you can find equivalent functions on your Foxwell scan tool. When I'm unable to glean obvious purposes for scan tool data streams, actuation tests, or coding functions, AI has proven very useful to clarify cryptic scan tool features. I hope this helps.

 

Yep, I've re-coded my original ACSM more than a few times, and then re-coded the replacement ACSM I don't know how many times; as well as re-coding my FRM and JBE. Pretty much every time I change one of the parameters in the chain, I re-code. Re-coding the JBE was a suggestion from the seat mat emulator seller, who said that buyers may have to re-code other modules - made sense, as I wasn't sure which/any modules held onto codes in memory. (For those not in the know, the JBE is your passenger-side footwell fuse box; to which, in my case, I had added a couple of fuse taps to operate my dashcam, as if that change might have had an impact on the SRS. I unplugged the taps, re-coded...) Again, nothing I did changed anything. There is also a function on the Foxwell where I can install/replace assorted SRS components and have them registered (or whatever Foxwell calls it). And as with every other attempt at changing any parameters, nothing positive occurred.

It's possible that someone with INPA or any other advanced OBDII-connect scanning software might be able to dig to a deeper level for my issue. Certainly, a Mini dealership or other Mini-specialist repair shop would know more about the SRS, and have the scanning capabilities needed. But there's only one Mini specialty shop here in Portland, and they're about as expensive as the dealership.

 

We have a solution! After all these months of consternation (read above if you dare) I finally gave up and brought it to the Mini dealership, knowing I was going to have to pay through the nose ($225/hour) for them to do their thing. And frankly, they really didn't do much more than I was able to do at home. I figured it was simply an intermittent wire short, but I had no idea what wires to check and where they traveled to - that's what I figured Mini could figure out, because, you know, $225/hour tells me they're capable of sussing this out.

Here's their process: after checking all the components (if you recall, I replaced both the belt-force limiter - that was throwing the code in the first place - and the ACSM, re-coded via my Foxwell Elite) they found nothing out of the ordinary; two hours' labor turned into four, then into six... over a week or so. Ultimately, a two-wire jumper harness was applied, and all is well. The ACSM (none of them) was ever a problem.

 

Glad to hear a fix was found. And thank you for posting the solution.

 

.