Airbag AND seat belt light on

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Manufactured from 2004 to 2013

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Gg1
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Airbag AND seat belt light on

Post by Gg1 »

Hi Everyone,

I have a BMW 2004 E87 series 1 120i. Purchased 2nd hand. Both, the seat belt and the airbag lights are persistently ON. I scanned the car with ISTA and carly (carly by the way is not worth the purchase) and I get a seat belt tensioner error code. I have tried everything to fix this and read everything in here but nothing works. Here is what I have done:
1) Obviously I tried to clean the fault with ISTA but the error comes back and the lights do not go off.
2) I measured the resistance of the seat belt tensioner and it is fine. No open circuit.
3) I have bought a 2nd seat belt tensioner. Measured that too. Its resistance seems fine. This was a 2nd hand tensioner. I swapped the existing seat belt tensioner with the one I bought (without removing the seat - just placed it temporarily on the side of the seat and connected it below the seat). No luck again.
4) I then thought it could be a hard code in the SRS module. I removed the SRS module (difficult task) and I posted it to an expert company that cleans the fault. The guy said from that company said he can see some unusual data in the module but because they are binary data he will try to fix it. The module came back. I installed it and ..the lights are still there! The person that reset the module is very helpful. He said he is trying his program in a same module for someone else and he will let me know if what he did worked for the other module. He is also willing to clone the module to another one if needed (but I really do not want to take it out again!)

I am assuming the module is fixed so I am now a bit desperate and thinking all other components in the car, such as:
- clock spring? Could that give seat belt tensioner error and activate the seat belt light? Horn works fine and the radio.
- The radio was changed by one of the previous owners. Could it be that they cut a cable somewhere?
- Fuses? I cannot find a fuse related to airbag for this model. I opened the fuse compartment and I have attached the relevant photos here. As you can in one of these photos there are fuses that are not included in the diagram on the top. Does anyone know what are these fuses for? I checked the 30A one and it looks fine - not burnt. Is there a fuse for airbag and seat belt light (both)?

Thank you everyone. I hope someone in the future finds this messages helpful.
Attachments
mysterious fuses
mysterious fuses
IMG_20210710_112708_compress18.jpg (242.54 KiB) Viewed 394 times
fuse diagram 1
fuse diagram 1
IMG_20210710_110322_compress83.jpg (200.76 KiB) Viewed 394 times
fuse diagram 2
fuse diagram 2
IMG_20210710_110251_compress99.jpg (206.54 KiB) Viewed 394 times
pem10
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Re: Airbag AND seat belt light on

Post by pem10 »

Have you checked the the yellow connectors under the seats? They may have worked loose or someone has bent one of the pins when reconnecting.
Worth a look.
Could also be an occupancy sensor.
Gg1
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Re: Airbag AND seat belt light on

Post by Gg1 »

Thank you but I have checked them and they seem fine. They do not seem loose. Pins are fine too. Measured their resistance with a multimeter and it seems fine. The occupancy sensor would not probably give a seat belt tensioner error but an occupancy sensor error. In addition, I can measure the pins for that too with a multimeter and they seem fine. My thinking is a fuse (if there is one?) or the SRS module was not cleaned properly. They key is that both lights are always ON, not one of them.
50pence
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Re: Airbag AND seat belt light on

Post by 50pence »

Does it report a particular tensioner?

If so swap them left to right and see if the problem moves, if it does it's the tensioner, if it doesn't it's something else.

By the way, those might simply be spare fuses?

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Gg1
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Re: Airbag AND seat belt light on

Post by Gg1 »

Interesting about the spare fuses on the top. I was wondering what they are because they are not in the diagram. So I guess there is no fuse related to both of those lights?
It reports driver's side tensioner. Swapping will not be easy as I have to remove two seats.
However, as I mentioned I bought a 2nd seat belt tensioner and tried it (by placing it on the side of the seat so the cables can reach the connections). That did not solve the problem. I measured the old and the new (2nd hand) tensioner with a multimeter. I attached the multimeter on their pins and they both seem fine. No open circuits. Could it be that the other side of the connection has a problem?, i.e. the female yellow connector below the sear?
Gg1
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Re: Airbag AND seat belt light on

Post by Gg1 »

Any other ideas anyone or at least an answer on whether there could be fuses causing this? My best bet is that the airbag module was not cleaned up properly from the hard codes or that the module is defective.
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Dave1
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Re: Airbag AND seat belt light on

Post by Dave1 »

I haven't looked into this in any detail but a search brought up the the post below.

Read on to the solution, it might be something for you to investigate.

viewtopic.php?f=3&t=47233
Gg1
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Re: Airbag AND seat belt light on

Post by Gg1 »

Thank you Dave. I read this post. It is not the occupancy sensor as the first person of the post says because in my case I get driver's seatbelt tensioner error. I am guessing it is the SRS module as the last person in that post suggests. The thing is I removed it and sent it to a professional company for wiping out any faults but that did not fix the issue. The professional was not though sure that the program he used did the job or that the module is not defective (its capacitor is apparently fine because he measured it). I will wait to hear back from him for a week as he is trying the same program to another module that he received for cleaning and he will let me know if that worked. Otherwise I may try to buy a new SRS module and he said he can clone the data to the new one free of charge.
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Dave1
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Re: Airbag AND seat belt light on

Post by Dave1 »

I hope you get it sorted whatever it is. It's a poor when things like this crop up and are difficult to fix. Sometimes technology makes life easier but very often it's a pain and the issue sits in the back of your mind until it is fixed. I have always felt comforted knowing there is this site to visit over the years for help. Good luck and let us know. :)
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Re: Airbag AND seat belt light on

Post by lvfb »

this is only a hunch but going off of the tom fuckery that my 3 series gave me i am going to assume that all bmws behave like this:

change the seatbelt tensioner to the newer one you bought (fingers crossed that it is a good working unit)

clear all codes using INPA (buy the cable for like 15 bucks on amazon and download the software from bmw geek as the bs thats on the cd most amazon stores gives you is sh*t)

turn the car off

disconnect the battery for 30 min.

re connect the battery

clear all codes again

turn car off wait 10 min

turn car on

maybe add a "drive 5 miles and park car and turn off for 15 min"

I know these sound stupid but i have had really weird results when trying to fix it ["it" being what ever electrical issue im having at the time] the orthodox way listed on other forums and after add in my own "rinse and repeat" it gets fixed.

here are times / things ive done where this crack pot theory worked on my 2011 328i convertible e93 -
PROBLEM: passenger seat occupy sensor ( the car always thought someone was in the seat and made you clip the belt or it would beep annoyingly)
WHAT FORUMS SAID TO DO: replace seat pad or seatbelt and it will fix it
WHAT I ACTUALLY DID AFTER TRYING THEIR SUGGESTION: went to junk yard and ripped out a passenger seat sensor from a non convertible 3 series (e92) that DID NOT have an airbag deployed for the passenger side (it did on the driver side) { paid like 7 dollars because they thought it was just the butt cushion and some Sh*tty foam} / plugged the sensor into the chair where the old sensor was plugged into (i believe it was a yellow connector), tried to clear the code with my Sh*tty autozone/auto part store 20 dollar code clearer with no luck. took to a shop and they cleared code with bmw code clearer tool, code went away until i got home and turned off the car and back on again about 30 ish min later, bought OBD plug to usb and installed INPA on my laptop. cleared code and had same issue again about it coming back on when i turned car back on. decided to try the old mat that was in the car so i replugged it back in, cleared codes, took off battery cables so there was no power to car waited 24 hours plugged back in and original sensor worked fine.

TL:DR i personally think the computers love to store cache memory even after clearing codes... NUKE THAT f**ker by clearing codes/ and unplugging battery for a decent amount of time and see if that worked. worked for me
Gg1
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Re: Airbag AND seat belt light on

Post by Gg1 »

Thank you ivfb. I have tried your method no matter how reasonable it may or may not be (I am desperate so any crazy solution I will try it). I didn't do the driving bit that you suggested.

Unfortunately the light is still On :roll: . One guy from YouTube was recommending something similar and it worked for him (his part 1 and 2 videos are here: https://youtu.be/Y6OujLXimGU and https://youtu.be/FBk2inUf7FI.
I semi tried what he suggests but my battery cables are different.. So if I did the same thing as him.. It did Not work.

Additional information: I measured the resistance of both the drivers and passenger pretensioners' pins. For both of them I get 2.2 Ohm. In other words, the pretensionsers are fine!
The error code I am getting is 0093A9 (apparently this belongs to the ignition circuits section of diagnostics). Two things are the candidates of the problem: 1) the srs ecu module (looking into cloning the existing unit to another unit) or 2) the thick female harness/cable that leaves from the pretensioners and goes around the car.. A section of it I believe is going to the srs ecu module.. While some other cables from it go towards the front of the car. I cannot follow that cable because it is buried below carpets. Could that be the issue?
Thanks everyone
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MED
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Re: Airbag AND seat belt light on

Post by MED »

Gg1..
Only yesterday I got the same fault after the car was parked in 30degree heat for a few days and I started it up the following day... SRS airbag and seatbelt light came on and have not gone out yet.

My very basic checks so far:
Horn works, (initially I thought it wasnt as it seems you need the ignition on for it to work and I was trying without, I jumped at the clock spring being faulty but then turned the ignition on and the horn and buttons work)
Steering wheel buttons work.
All connectors under seats look fine and arnt loose.
Cable from battery is plugged all correct.
No corrosion visable on the battery.
New battery installed 6 months ago.
All seat belts clicked in/out.

I have someone coming over with an OBD reader in the next few days to try and at least see what tripped the error, then the investigations will continue.
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Gg1
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Re: Airbag AND seat belt light on

Post by Gg1 »

I feel for you MED. Starting suddenly like that is strange. I suggest you try to own a scanner. It is cheap. I bought from ebay a cable and downloaded a version of rheingold (ISTA from someone that shows how to do that on youtube. I also bought the carly adaptor but I donot recommend it. You have to pay for license for a year to be able to do anything with that and it gives you the same or less options than ISTA (in total you would need ~$200 for Carly).
Knowing the error code would be useful, even though in my case it is not useful.

What a mystery. Let's keep each other posted here.
lvfb
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Re: Airbag AND seat belt light on

Post by lvfb »

ISTA / INPA/ any of the "laptop" coding software is powerful but is a "pain in the mother f**king ass piece of sh*t why isnt it working mother f**ker is gonna get thrown at the wall" hard learning curve. even for those tech savy.

i was watching a review of the "protools" device that is on bimmergeeks site and looks pretty awesome.

if youre not tech savy i think it might actually be worth buying either:
a laptop that already has it installed
or a hard drive that already has it installed.

also as for testing out the seat belt, go to the junk yard and get another one (def be alot cheaper than ebay or anything like that, i got my 500~ dollar ass sensor for my passenger seat for 7 dollars) and try the methods i mentioned above again.

BMWS HAVE THE MOST ANNOYING ELECTRICAL GRIMLINS EVER! but sometimes they go away after the 3rd or 4th time you have followed the steps
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SamM140
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Re: Airbag AND seat belt light on

Post by SamM140 »

Can’t help the OP but I disagree re Carly.

It might not be the cheapest option these days (£120 in the U.K. with the license) but it’s dead easy to use and being less powerful than some of the other options means there’s less option to screw things up too much. It’s tiny and mine lives in the car now. So far, it’s more than paid for itself given that my indy charges £60 for a plug in diagnostic.
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