xcalderon

Hi, and thank you Margate330.

I was able to get it scanned using Techstream. The only code that comes up is the B1100. Comes right back after a second or two of resetting it.

Any other ideas would be appreciated.

-X

tomr51

disconnect the battery feel around under the front seats for connectors. unplug and reconnect them.. This fixed my issue 3 yrs ago.

Margate330

+1 tomr51 This is why everything has to be ruled out first before the B1100 it would be great if you find an unhooked plug or squib.

You are movng ahead for progress- Time to Go In Deep. lol
*Note- for anyone messing with the airbags it is no joke. Manual says wait 90 seconds after disconnection battery but I wait a few mins to be safe before messing with connectors and never supposed to probe air bag components with an ohm meter cuz can set them off- at least that what it says.

OK From Techstream Screen here is a path someone can take- did this on my RX330.
Edit- Someone can do this without TIS subscription. We are looking for it to turn white to say it communicated.


Please post results I am hoping something easy for you.

xcalderon

In the past, I disconnected the battery, waited a few minutes, turned the headlights on, even shorted the positive and negative battery cables to ensure there is no residual energy on any of the components, especially the capacitors, of course. Overkill perhaps but you folks are right, SRS is very delicate and dangerous to work on.

What I didn't do is disconnect the SRS sensors under the seats. So I'll try that. The other week the light was off but then when I turned the ignition off and on again came up. The previous owner told me it just came on one day and no accidents nor bumps. So I'll try the disconnecting procedure and keep you posted.
Thanks for the links on the Techstream, willco.

Margate330

My pics aren't great quality cuz I took it from my cell phone but if someone click on the Occupant Detection button shown above it may show unhooked connectors under the seats if I remember right.
I threw a code once on passenger side for an unhooked Squib when I pulled the seat to run stereo wires and forgot to hook it back up an I think Occupant Detection is where I found the code or maybe SRS can't remember now.
Anyway Good Luck!

Nad1370

DTC B1100 is recorded when a malfunction is detected in the center airbag sensor assembly.
Center airbag ecu detects a short to ground or short to B+ on the circuits of the front airbag sensors. (L/R)
No battery disconnect or re-initializing will get rid of this code.
Have you got this diagnosed by a shop?

Either a harness/connector issue or a bad SRS ECU.
I tend to go with the later if no connector was loose/unplugged.
I doubt you'll find any that came un-plugged since all SRS connectors have a dual lock system in them.
I would also check connectors on the front airbag sensors.
Could have some corrosion (green) build-up in there.

xcalderon

HI, I ran Techstream again and communicated with all ECUs actually. The only code, is the B1100.

I'll check all the connections and that is all I could do at this point.

Has not been diagnosed by Lexus so if all the connectors, double-checked with battery off, seem ok, ouch, next step is Lexus dealer unless other ideas come up.

- X

xcalderon

Is your comment "Center airbag ecu detects a short to ground or short to B+ on the circuits of the front airbag sensors. (L/R)" indeed only for the front airbag sensors? Would seat or other sensors also cause it or exclusive to the front?

A NAPA mechanic shop diagnosed it to the previous owner and said the center airbag sensor assembly needed to be replaced. The only code they mentioned was the B1100. They are a NAPA shop, not a Lexus shop so I'm not 100% sure.

I was able to get to the center airbag sensor assembly, with battery off, I rocked and pushed in the yellow connectors. I did not remove them to inspect for corrosion, however, sometimes with a good push and rock if a bad connection comes back but this time did not. Labor to get to see the SRS sensor assembly but seem very tight for me and I didn't know the procedure to actually remove it or just disconnect and inspect as there is not much space. I'm sure is doable but I don't have the instructions to do.

Instructions to get to disconnect/remove the center airbag sensor would be appreciated as well as instructions for the front airbag sensors.

The battery disconnect procedure and drain of all battery charges by waiting and then shorting the battery cables would most likely be the safest way to go. Not using

Somehow I have a feeling maybe a connector/corrosion as I'm n FL westcoast AND at one time I was reading the codes the light did not come up but next time the IG OFF and ON came back on. So at least 1 time did not for sure..

xcalderon

The connectors under the seat are towards the front part underneath the seat, right? I see one white connector and one yellow. Would the white be for the seat features like moving the seat, heat, etc, and the yellow the SRS sensor?

Margate330

Already great posts above. Only like to add the Napa tech is following the "recommended" procedure seen below and prob the most cost effective path moving forward IMHO. According to the manual if no other airbag or related codes present(which you just proved by running a deep scan- ignore codes not related to this) or corroded or bad or unhooked connections(some of which are in hard to get places but Techstream should've picked up unhooked connections), etc. If a new assembly works you are good, if it doesn't you will prob have your work cut out for you in a big way so hoping a replacement assembly works for you and life is good- again just IMHO.
PS- I would try some of the easy things to check like posted above for corroded connectors on front sensors and plugs under seats, etc since i know the Techstream will detect unhooked components but it's the ones making bad connections/corroded that could be a nightmare to track down if applicable. Everyone do at our own risk and just my opinion only.




And it's buried DEEP in a place nobody would find it if you weren't looking for it. lol

xcalderon

Great post and thank so much for the info.

It makes sense that Techstream would catch unhooked connections (actually the ECU should throw it and Techstream should catch). Seems to me like the corroded connections should also be reported by the ECU (most likely but who knows). From what I have now I would know how to get and replace the Airbag Sensor Assy Center but don't have enough pages and charts to check all the corroded connectors and where they are located. The info and help you have kindly shared are absolutely awesome; can't thank you enough.

I've seen some used Airbag Sensor Assy Center for sale on e-Bay from salvaged cars and they claim they are good. Exact part number as mine. Assuming they are good, would the step 28 on the center assembly 2.pdf document instructions, namely: "Occupant Classification ECU Initialization" be the step where to register the VIN and this vehicle with the new ECU? I don't think so as Techstream says to use this function after replacing the seat. If so, for $60 or so may be worth trying a salvage ECU before going to Lexus. NAPA was a $1K verbal quote so I would say Lexus would be at least that. What do you think?

The instructions do not say to initialize the new Airbag Sensor Assy Center with new VIN or so. I just read such comments on the Sensor Resetting services on the Web but maybe if just the exact part number does not need to have it initialized, just replaced. ???

BTW, thanks so much for the steps for disassembly and to get to the Airbag Sensor Assy Center. Previously I did the front console parts and was able to see the SRS ECU and push connectors but I didn't remove the Console Box Assy thus was not able to get clear access to it and now I see why.

I don't understand why steps 2 and 3 to remove the front seat ASSY. What is this ASSY? The actual seats? Would that be needed to remove the Console Box Assy perhaps?

You rock!

Margate330

Just to clarify I should've mentioned it is critical that the SRS Airbag selection turns from yellow to white(when you click or double click on it showing it is communicating- if it stays yellow this is where the problem prob is and need to hunt this problem down first because can't scan components with Techstream if the specific ECU they are wired to isn't communicating.

If it stays yellow and won't turn white it could be bad assembly or wiring problem on the center assembly itself.
>> Like this.


This is my car showing the 3 systems turned white shoing they are communicating.

xcalderon

Yes, they turn white. Actually, after doing a Health Check they all turn white. Thanks for the double-check.

Margate330

+1 Awesome
Can see why the next step is to replace the assembly at this point like NAPA says because chasing down "what-if's" can be costly and time consuming at $150.00 per hour.
The good news is that previous owner was prob/hopefully honest and not hiding a recent collision covered up by broken/shorted parts in unseen places.

The Occupant Detection ECU is hidden under the front seat and from what I remember it weighs the passengers and works into the calculations of air bag deployment thru the Airbag Center Assembly Ecu.
I'll see if I can find procedure to initialize thru Techstream and hopefully someone knows more ideas check or has info on this.

PS- I still would check for corroded connections on front sensors(battery unplugged) and other stuff as others mentioned since easy to do.

xcalderon

Yes, if you could find out if the Airbag Sensor Assy Center needs to be initialized or not would be great. If I could use another one with the exact part number then maybe worth trying. The procedure you sent shows is only a swap. The Occupant Classification ECU initialization on line item 28 of the procedure is I because the seats were removed and they were disconnected. Thank you again.

Xavier.

PS- On the corroded connectors, would you be so kind as to send me the corresponding diagrams as for locations, etc? Please?