Airbag Light Woes

Hey all, new to the forum and long time jeeper, first time Taco owner. I just recently moved to CO and managed to sell my old XJ prior to the move and put myself in a bit of a bind after the move in being rushed to buy a car (bad idea...). I ended up buying a 2011 Tacoma (Double Cab w/ long bed) with 197k on the clock, overall it seems to be in great shape for it's age but the hidden gremlins started popping up after the deal was done, which seems shady AF to me but I'm in the mess I'm in now, just looking for a way to get it sorted.

Important context: There was an accident reported front drivers side at ~50k miles, no airbag deployment and I closely inspected everything in that corner, no frame damage or anything messed up. Plus my logic was that if it has gone 150k since then with no major service issues, i'm pretty comfortable with it so I noted this, but proceeded.

-Test drove, no lights, no issues, everything worked and felt great.
-Fast forward ~1 week, paperwork clears and I drive it home. BOTH the airbag and TPMS light come on on the way home. WTF...
-I do some searching around on here and find the thread on bypassing the TPMS with the wiring behind the dash. Since the tires are holding fine, I decide to do this, boom one light gone, one to go.

-I took it to the dealer for diag and they said it was B1900 for the drivers seatbelt pretensioner squib short, gonna be $600 to fix ($400 part only). I did some digging around online and saw mixed reviews of the MyAirbag.com fix and decided that with it being airbag, I'll just bite the bullet and get it done right, with OEM parts.

-After they replaced the seatbelt "Yeahhh so we realized the short is also in the center airbag sensor (ECU, whatever you want to call it), that'll be $990 ($910 is the part) to fix it."

This is where I start to take issue, does this chain of events seem plausible? Given the previous accident I know it's prone to issues like this but from the troubleshooting procedure I've seen posted on some threads you basically isolate both ends of the circuit, test individually, and test the wiring itself right? So I'm not 100% buying their "there was no way to know until we put the good part in there" but I'm also aware of my relative ignorance. I'm hoping someone here can tell me if I'm really just screwed and have to pay the $1k or maybe if anyone has had luck with the MyAirbag SRS ECU resets? Currently they have the part and are just waiting on me to call back and set the appt to get it installed.

Any advice is appreciated!

 

I’m not an air bag expert. It’s possible what you’re being told is true. It’s also possible a senior tech or service manager would have known better to inform you, you definitely need this part AND could possibly need this other part. Something I have happen regularly. Sometimes, knowing the second part is also usually bad, I’ll say you need these 2 parts. Then sometimes I can surprise them at the end with a bill lower than the estimate.

 

Yeah I've been talking to a couple friends who have current and previous ties into the dealership. I'm not opposed to replacing parts if they are bad, I just haven't gotten any real confidence or notes of diag that indicate that the part 'diagnosed' as bad is actually bad. Really i'm just looking for more documentation of measurements or procedures from the dealer before i throw another $1k at a hope and a prayer, it feels an awful lot like they are just throwing parts at it with no guarantee that it will be fixed.

maybe just a bad dealership experience on my end, i'm treading cautiously but also not just going to blindly keep throwing money out it without a little bit more info.

Both the pretensioner and the ECU shorting out seems...unlikely?

 

For reference, I uploaded the .pdf i found on another post of the B1900 troubleshooting tree. That post was an 06 i believe, i don't know how different the process would be for an 11 but this is my thought process.

The way I read this, for B1900, is below:

-check connectors for damage/loose
-check the No 2 floor wire for the short by disconnecting both ends (check easy/cheap stuff first, makes sense)
IF OK
Check the airbag sensor
IF OK
Check Outer Pretensioner

This leads me to believe that if this tree was followed, the airbag sensor would have been cleared prior to replacing the tensioner. So the fact that the tensioner was ID'd and replaced and THEN the center sensor was ID'ed as faulty doesn't line up with how I would think this system would be troubleshot. Even if this isn't the exact procedure, based on this methodology I'd imagine the source could be isolated to one or the other and narrowed down more than it was.

Sorry this is turning into more of a prove the dealer wrong type of thread but hopefully someone can pull some insight on the troubleshooting procedure from this in the future and/or help fill in any knowledge gaps or correct assumptions I'm making.

 

Essentially it's the same steps if you follow the flow chart.

I think what I would do is with the key off unplug the seatbelt pretensioner, manipulate the vehicle side harness connector so the shorting bars aren't shorting it out, turn the key on, and see if B1900 goes to history and B1901 sets as current.

Who knows if they did any diagnostic tests or not, unfortunately alot of the time parts get replaced (at the customers expense) based on a code and then if that doesn't fix it they may do some diagnostics or just sent it elsewhere.
I'm not saying this happens at every shop/dealer all the time but it seems to happen much more often than actual diagnostics, IMO it comes down to multiple factors: laziness, techs not getting paid much for diagnostic time, and/or not understanding how to do diagnostics.

 

Thanks for this! I definitely plan to do some of my own diag when I get back into town tomorrow. In the meantime i've been going back and forth with the dealer and managed to get a little more info out of them, but still nothing that proves the pretensioner bad vs the ECU. They sent me a notably abbreviated version of the doc you posted and this was listed in there, not part of the procedure, but just noting that they probed the pretensioner and measured 100 Ohms so, there's your short and we'll replace that before checking anything else. Has anyone probed these before? From what I can read online it seems like a good resistance is 0-5 Ohms but also lots of mixed reviews on DONT APPLY LEADS to the pretensioner for fear of setting it/the airbags off. Either way this doesn't seem to add up to a short in the pretensioner.