Replaced Occupant Detection Computer, now DTC B1797 (2 Viewers)

[TxAggieLC]

I recently had the dreaded airbag light pop up on my dash and did some diagnosing as well as having the dealership take a look. Turned out it was a faulty occupant detection computer/ecu (89952-0W020, later replaced by 89952-0W021) which I found online for about $330. Replacement was really easy. Just unbolt the passenger seat, take out a couple screws, unplug old, plug in new, and bolt back up. Well, that part was easy.....

After clearing the old codes (B1795 and B1150), I'm now getting B1797 which is "calibration abnormal". Nothing on mud about this code but other toyota forums indicate that I need to "exchange" the data from the existing, broken (?) ecu onto the new ecu. Techstream looks to have an option to pull that data off and put it on the new one but I'm worried that I am pulling corrupt data which will ruin the new ($$$$) ecu. Toyota dealership has been less than helpful, surprise surprise, so I may need to further troubleshoot this myself.

Any thoughts? Possibly, anyone in the greater Houston area that has a 2006 LC or LX willing to let me copy the data from their passenger seat occupant ecu? I find it odd that Toyota doesnt have this info/data available without having to harvest it from another vehicle of same vintage.

 

[jLB]

I recently had the dreaded airbag light pop up on my dash and did some diagnosing as well as having the dealership take a look. Turned out it was a faulty occupant detection computer/ecu (89952-0W020, later replaced by 89952-0W021) which I found online for about $330. Replacement was really easy. Just unbolt the passenger seat, take out a couple screws, unplug old, plug in new, and bolt back up. Well, that part was easy.....

After clearing the old codes (B1795 and B1150), I'm now getting B1797 which is "calibration abnormal". Nothing on mud about this code but other toyota forums indicate that I need to "exchange" the data from the existing, broken (?) ecu onto the new ecu. Techstream looks to have an option to pull that data off and put it on the new one but I'm worried that I am pulling corrupt data which will ruin the new ($$$$) ecu. Toyota dealership has been less than helpful, surprise surprise, so I may need to further troubleshoot this myself.

Any thoughts? Possibly, anyone in the greater Houston area that has a 2006 LC or LX willing to let me copy the data from their passenger seat occupant ecu? I find it odd that Toyota doesnt have this info/data available without having to harvest it from another vehicle of same vintage.

If I remember correctly, you’re fairly close to me, and I do have an 06 LX or 00 LC to pull data from...

 

[jerryb]

there isn't a re calibration option for the sensor in techstream, and possibly read and clear the center airbag controller ecu?
I bet there's a range of outputs listed in the fsm for values, maybe they are out of spec or a short in the connector.

 

[TxAggieLC]

there isn't a re calibration option for the sensor in techstream, and possibly read and clear the center airbag controller ecu?
I bet there's a range of outputs listed in the fsm for values, maybe they are out of spec or a short in the connector.

Well, thats the weird part. The FSM says I need to do a zero point calibration and when I run that in techstream it tries but ultimately fails. This is the prompt I get.

Not sure what to think about what it says... I do get a DTC but its the "abnormal calibration" error and I erase it just before trying to perform the new calibration. No idea what "write error: NG" means or how to fix that. I think that's where I need to get the new occupant ECU flashed with data from a working ECU.

 

[TxAggieLC]

I'll check the FSM again for pointers but I dont think it addresses the need to "exchange data" with another ECU.

 

[jerryb]

I don't think it does either. I'm at work or I would look. What if the light bulb is burned out. Or the seatbelt female receiver is wonky?

 

[jLB]

This seems curious:

Snap on Scan Tools Damaging Occupant Classification Module on Lexus and Toyota​

as does this:

seat is NOT in the correct position, DTC B1797 is output​

 

[TxAggieLC]

This seems curious:

Snap on Scan Tools Damaging Occupant Classification Module on Lexus and Toyota​

as does this:

seat is NOT in the correct position, DTC B1797 is output​

That discussion about the snap on tool doing damage is really interesting. Interestingly, my mechanic did use a snap on diagnostic tool to try to calibrate the ecu and the airbag light only came on after taking it in for some work to be done. Honestly, I thought it was from them standing on the passenger seat to blow out the sunroof drains which somehow damaged the occupant sensor/computer but looks like using the diagnostic tool could have been it too.

 

[jLB]

(It appeared that we were able to clear the code and perform the ZPC, after doing the Occupant Detection download/upload in Techstream.)

 

[TxAggieLC]

Update: huuuuge shoutout and thank you to @jLB!! Downloaded the detection computer data from his LX and it uploaded directly onto the new computer in my LC. Then cleared the DTCs and ran the ZPC, now all is back to normal.

Still not sure what the culprit was for the old computer biting the dust (could easily just be old age I guess) but at least we have a solution for others. Thanks again J!!!

 

[lexusrider]

Hi, I have 2007 Lexus IS 350 and I'm in the same exact spot.
First I got the code B1795 then I bought another detection computer ECU 89952-0W060 plugged it in cleared the DTCs, all codes gone but abnormal calibration showed up B1797, then I started the zero calibration but got the wire error.
Then went back to the service manuals and it said that you have to copy the memory from old ECU to the new one.
(Not thinking much ) I did that.
Then guess what the code B1795 showed up again. (back to original issue)
Now I'm thinking that it might be just the software corrupted issue. I'm wondering if there is someone close by and I should do the same trick. download from someones (working) IS350 IS250 and download it to mine.
unless there is a way to do this via techstream and send it over the internet

 

[TxAggieLC]

Hi, I have 2007 Lexus IS 350 and I'm in the same exact spot.
First I got the code B1795 then I bought another detection computer ECU 89952-0W060 plugged it in cleared the DTCs, all codes gone but abnormal calibration showed up B1797, then I started the zero calibration but got the wire error.
Then went back to the service manuals and it said that you have to copy the memory from old ECU to the new one.
(Not thinking much ) I did that.
Then guess what the code B1795 showed up again. (back to original issue)
Now I'm thinking that it might be just the software corrupted issue. I'm wondering if there is someone close by and I should do the same trick. download from someones (working) IS350 IS250 and download it to mine.
unless there is a way to do this via techstream and send it over the internet

Man, I really hope you didnt toast the new occupant ecu by trying to copy over the software from the old one. Those things arent cheap....

I'd say try to find someone nearby who had a similar vintage IS250 with the same ECU and copy over from them. It was actually a really easy process, assuming you're familiar with techstream which it sounds like you are. @jLB and I thought about the idea of downloading the software and sending it over the internet but couldnt find a way. I just dont think techstream is setup for that kind of functionality.

 

[lexusrider]

Thx for the reply, I know I didn't fry it, it still measures the weights (at least the "filtered pressure sensor output" and "pressure sensor output" at zero), also noticed something interesting, if I run the zero calibration (it most likely will fail since I have existing DTC) but then it allows me to clear B1795 and leaves B1797 "calibration abnormal". At this point I see both pressure sensor outputs behave normally.
I'm about to give up, I replaced this ECU, tested another gel mat, tested for any shorts in the wire harness between this ECU and the main SRS one. I'm running out of options to try out here. Unless I omitted something.
BTW here is the current live data output (measured with no one on the seat)

Maybe someone will notice something I didn't
also when I manage to temporarily clear B1795 (still having B1797) this is what I see

 

[TxAggieLC]

I'd hedge my bets that it just comes down to the need to copy over data from a fully functioning ecu. Your story sounds just like mine (same DTCs and tests) and it came down to having someone lend a hand (well lend a land cruiser to be precise).

 

[jLB]

it came down to having someone lend a hand (well lend a land cruiser to be precise).

Technically, it was one of those "pretentious", "bug eyed", "Grey Poupon carrying", step siblings.

 

[TxAggieLC]

Hahaha!! All land cruiser on the inside (where it counts).

 

[godzilla10]

I got the same problem and trying to find a donor or can you subscribe to techstream for 2 days and download the files? please help

 

[jspurl3]

Hi guys sorry to bring up this old thread, but I’m in the same boat. I have an 07 LC with B1150 and B1797. Happy to replace the unit but is there anyone willing transfer the data from there’s?

I’m in Baton Rouge LA but happy to travel!!

 

[jLB]

Hi guys sorry to bring up this old thread, but I’m in the same boat. I have an 07 LC with B1150 and B1797. Happy to replace the unit but is there anyone willing transfer the data from there’s?

I’m in Baton Rouge LA but happy to travel!!

PM sent.

 

[Wenbob]

PM sent.

Hello jLB, do u mind also share me the data . I have a 06 lc100 with same B1797 code. Currently failed to perform zero point calibriation from Techstream.