Intermittent Air Bag Warning Light on 2016 LC (1 Viewer)

[016LC]

This past summer I have noticed the red air bag warning light remains illuminated after starting the vehicle. Usually, the first start of the day is fine, but subsequent starts, especially in warmer weather, seem to cause it to remain illuminated. But it is intermittent and now that cooler fall weather has arrived, it is less frequent. I have an OBDII reader and installed it today but it did not show faults of any kind, and from reading the accompanying (very brief) "manual" that came with the reader, it is suggested that it only looks at the main CPU and "check engine light". I am suspicious that the fault is heat related.

Is there a more sophisticated "reader" that I could buy that might provide more detailed guidance, or am I stuck having to go to the dealership? I would much prefer to invest in a useful tool than the dealership, and would prefer a tool that is self-contained rather than hooking up to my mobile phone.

The only change I have made that might impact the air bag system was to remove the second row seating, but that was four years ago, and I followed the great post here and wired the appropriate resistors in place where the air bag circuitry is disconnected. No issues in those four years.

Any ideas as to what's going on?

 

[bloc]

This past summer I have noticed the red air bag warning light remains illuminated after starting the vehicle. Usually, the first start of the day is fine, but subsequent starts, especially in warmer weather, seem to cause it to remain illuminated. But it is intermittent and now that cooler fall weather has arrived, it is less frequent. I have an OBDII reader and installed it today but it did not show faults of any kind, and from reading the accompanying (very brief) "manual" that came with the reader, it is suggested that it only looks at the main CPU and "check engine light". I am suspicious that the fault is heat related.

Is there a more sophisticated "reader" that I could buy that might provide more detailed guidance, or am I stuck having to go to the dealership? I would much prefer to invest in a useful tool than the dealership, and would prefer a tool that is self-contained rather than hooking up to my mobile phone.

The only change I have made that might impact the air bag system was to remove the second row seating, but that was four years ago, and I followed the great post here and wired the appropriate resistors in place where the air bag circuitry is disconnected. No issues in those four years.

Any ideas as to what's going on?

There are a bunch of sensors and modules associated with the SRS system and none are commonly problematic.. at least not often posted about on this board.

I know for a fact my Carista module will read SRS codes as I used it to clear them when my rear-seat-removal bypass resistor got loose on a roadtrip. Carista is cheap and the higher level memberships, if needed for advanced modules, can be had on a discount for temporary use. It is one of the few that will program TPMS sensor IDs into the car. Plus being a standard Bluetooth tool it will work with other software like OBDFusion for diagnostics or the trick tablet/smartphone dashboard setup written about elsewhere on this board.

Alternately if someone in your area has working tech stream they can help pull the codes that way.

 

[KLF]

I highly doubt the dealer will service that given the trickery of the resisters in the rear seat harnesses. They will tell you to put the seats back in and come back. Liability...

Have you checked the resisters to make sure they are still properly seated and in good contact? I have mine firmly taped in place.

 

[bronc076]

How is your battery?

I was having an intermittent airbag warning light. I read the codes and the issue appeared to be with the front left impact sensor Or wiring to that sensor. I cleaned the connector on the sensor and no real change. I was going to swap sensors left to right but the right one was hard to get to so I fired the parts cannon and replaced it. That didn't solve the problem. I figured there was an issue with the wiring at the connector and would fix it in the future. We had a trip coming and I put in a new battery as mine would drop below 12v after the vehicle sat for a few days. I've had no airbag light since replacing the battery.

So I still think I have some resistance in that circuit which makes the SRS module flunk that sensor's test but for now I'm not worried about it.

I use OBD fusion to pull codes.

HTH

 

[Sandroad]

I assume your LC has had the airbag sensor recall work done?

https://static.nhtsa.gov/odi/rcl/2018/RCMN-18V887-0611.pdf

 

[016LC]

Thank you for the helpful comments.
Yes, the seat belt recall work was done shortly after I purchased the LC as a CPO in 2017.
Good point about the dealer not wanting to work on the vehicle air bag system with the second row seats removed. Not an unreasonable position for them to take given the legal climate we live in. I will check the resistors, which I soldered into the short wiring harness from VW that had the correct terminals to plug directly into the Toyota harness.
I am still using the original Panasonic battery in the vehicle which is now heading into its 8th Wisconsin winter so it would make sense to replace it for two reasons--to avoid it not starting on the first sub-zero morning, and maybe it will fix the airbag warning light issue. Does anyone know if Toyota parts departments can source a Panasonic battery? I would be willing to pay a premium for one.
If the issue persists, I will obtain the Carista diagnostic bits.
Thanks again for the great help.

 

[bloc]

Does anyone know if Toyota parts departments can source a Panasonic battery? I would be willing to pay a premium for one.

Not that I’ve found.. and I have tried. There would be a great market for someone that could pull this off.

 

[016LC]

To update this thread, I first bought a new battery from the Toyota parts dept--TruStart brand that is apparently provided by Toyota to its dealerships. Competetively priced($159) with other offerings of size 27F batteries, and there are a lot of Toyota dealerships around to handle warranty. It did not resolve the intemittent SRS warning light, but at least I am ready for winter.

So I bought an Innova 5610 OBD reader that offers ABS and SRS capability in addition to Check Engine, without having to buy a subscription, but it was not inexpensive($350). But it is self contained, not requiring a cell phone, and uses three AA batteries. It also has buttons rather than a touch screen which old guys like me seem to prefer. It found one SRS code in History--"B1856 Open in rear side squib LH circuit" . This refers to the LH rear seat side air bag that I removed with the second row of seats some four years ago, substituting a 2.2 om resistor for the "squib". So I examined the resistor(still measures 2.2 ohms at the terminals) and harness, and applied some De-Oxit to both sides of the tiny connector, and reassembled it. I have not had any warning lights since then, approximately three weeks, but it has been cold and the issue seems to occur in warm weather--so I may have to wait for spring to see if it is resolved. I have the same resistor harness on the RH side but no codes from there.

I was actually hoping to find an engine code relating to an incident some three years ago--we had just crossed the Canadian border on an August Sunday afternoon, heading toward Glacier Park, and the cruise control suddenly quit working, and the "ECO" light also quit working. It did not go into "limp home" mode, and had the usual power and the transmission worked normally. So we proceeded to Glacier without cruise, set up the tent and hung around at the CG until dinner time, about two hours, started the LC and everything was fine. And no recurrences since then. I am suspicious that it was caused by the accelerator or throttle position sensor based on my 19 years experience with a '98 100 Series LC--replaced the accelerator position sensor four times in 235,000 miles--it did not like long days on the Interstate at a constant speed, nor did it like sub zero starts in the winter, both of which seemed to cause it to fail and go into the limp home mode.

They are wonderful vehicles, but complex. My '83 Mercedes turbodiesel will run without electricity and can be push or pull started. So long as you don't want to drive at night or use brake lights or turn signals, or have climate control.

 

[016LC]

To close the loop on this issue, the SRS light finally came on "permanently", as opposed to intermittently, and the OBD reader showed a "current", as opposed to historical, B1856 fault. So I reexamined the resistor and harness that I had installed after removing the second row seats. For those unfamiliar with the procedure, a length of yellow wire with a male terminal crimped on each end is purchased from a VW dealer, and a plug housing is purchased from a Toyota dealer. The wire is cut and a 2.2 ohm resistor soldered in series with the terminals. The wire is then folded on itself, a sheath of shrink tubing slid over the U-bend, and the terminals inserted in the plug housing.

What I found upon a more careful rexamination of the plug housing is that one of the tiny terminals was free to move axially in the housing by about 1/8th inch, while the other was held fast. So I suspect that the loose terminal was pushed back when the plug was connected, leading to a bad connection. I was able to slide the offending terminal back and forth, but it would not come out of the housing. So I slid a short length of shrink tubing over the wires where they exit the housing and effectively tied the loose one to the tight one, and when inserting the plug, the wires can be pinched between one's fingers to prevent the axial motion.

This fix was made about a month ago and I have had no further faults. If it does recur, I will buy a new wire and plug housing and try again.

Hope this helps someone.

 

[bloc]

To close the loop on this issue, the SRS light finally came on "permanently", as opposed to intermittently, and the OBD reader showed a "current", as opposed to historical, B1856 fault. So I reexamined the resistor and harness that I had installed after removing the second row seats. For those unfamiliar with the procedure, a length of yellow wire with a male terminal crimped on each end is purchased from a VW dealer, and a plug housing is purchased from a Toyota dealer. The wire is cut and a 2.2 ohm resistor soldered in series with the terminals. The wire is then folded on itself, a sheath of shrink tubing slid over the U-bend, and the terminals inserted in the plug housing.

What I found upon a more careful rexamination of the plug housing is that one of the tiny terminals was free to move axially in the housing by about 1/8th inch, while the other was held fast. So I suspect that the loose terminal was pushed back when the plug was connected, leading to a bad connection. I was able to slide the offending terminal back and forth, but it would not come out of the housing. So I slid a short length of shrink tubing over the wires where they exit the housing and effectively tied the loose one to the tight one, and when inserting the plug, the wires can be pinched between one's fingers to prevent the axial motion.

This fix was made about a month ago and I have had no further faults. If it does recur, I will buy a new wire and plug housing and try again.

Hope this helps someone.

Thanks for following up.

I started using two of these a while back and they have worked great. Plus, not terribly expensive. Round version for my 2013, other year models would need to check fitment.

Airbag Simulator/Emulator for Toyota & Lexus - Brad's Hacks

These dongles emulate the presence of an airbag when plugged into a 4th-generation Toyota Sienna or other Toyota/Lexus/Scion.

bradshacks.com