SRS Air Bag Light Flickering On Solved

I thought I would pass along a repair I just did on my 1996 Toyota Tacoma Xtracab 4WD V6 5-Speed truck. My SRS Air Bag light had begun to flicker on and sometimes would not go off after starting the truck. I checked the truck's battery with a load tester and confirmed it was in good condition. So I removed the lower instrument console cover to gain access to the SRS Air Bag Sensor Control Module. After disconnecting the battery, I removed the yellow connector from the Air Bag Control Module and shot some Deoxit D5 contact cleaner spray on the module's and plug's contracts and reconnected it. I then removed the bolts holding the module, sandpapered the bolts and chassis contacting surfaces and then reinstalled them to make sure the module was getting a good ground. I have now been driving the truck for a week and the SRS Air Bag light comes on at start up but then goes off and stays off.

 

I hope you have solved this problem. Sounds like a good remedy.

While I never really investigated mine fully like you, same problem has come and gone several times over the last few years on my 95.5 model, 2.7, auto. Sometimes it comes on with truck just sitting, no key in the ignition. At first I thought it was temp related, because it seemed to happen most often during +90 degree days. Then it happened during Fall days.

It's been over 6 months though this time with no light, and I did nothing to prevent it. Not sure if that's good or bad sign. This Winter I may just get motivated and use your method to see if it stays away once and for all.

 

I have been plagued with this issue off and on for the past year on my '98 Tacoma xtra-cab SR5 2.7 auto. It only comes on when the truck is shut off. It takes it about 15-30 seconds to slowly fade on. It's weird but it seemed to start happening after really heavy rains (I don't have a garage). The first time I noticed it, I came out to start the truck and the battery was dead. I charged it overnight and when I went to get in the truck I noticed that the airbag light was on. I started the truck and the light came on for the usual test and then went off. Then when I shut the truck off, it will take about 15-30 seconds to slowly come on. At the time, i didn't have time to mess with it so I disconnected my battery and left it for a week or so, and the next time I got in it the light never came back on. It was good for a couple months and then did it again. It rained hard, came out to a dead battery... rinse, repeat. It will be good for a few months and then happen again out of the blue.
My truck was in a front-end accident almost 10 years ago and the insurance company wanted to total it but I fixed it and kept driving it. The airbags never deployed then so I doubt they would work anyways. But it is annoying. I am one step away from a battery disconnect switch to at least protect the battery from draining. I guess I can try your fix and see if that helps before I do something drastic. :-D
I thought I was the only one dealing with this though.

 

Thanks for posting this. I'm now having that exact same issue (minus flickering) - it's never done that, but it stays on solid.

 

I am now wondering if the SRS Air Bag Sensor Control Module may have some fault. This control module is no longer available new from the dealer. I know the circuit board inside the module has electrolytic capacitors that typically go bad over time. Has anyone ever taken apart the SRS Air Bag Sensor Control Module, replaced the electrolytic capacitors, and then confirmed it fixed the SRS Air Bag Light flickering problem?

 

Following up... I followed the steps described by the OP @cbhunt and it seems to have solved my airbag light flickering problem completely. Thank you!

 

Seems like that's the kind of process that's really easy to screw up and FUBAR the circuit board entirely.

Probably less effort to just go to a pink n' pull or junkyard and get another one.

 

I wonder if it’s a problem related to the capacitor plauge. Fascinating how it affected almost all of us at one point or another wether we know it or not.

https://en.m.wikipedia.org/wiki/Capacitor_plague

Normally I would agree to use a junkyard replacement but it would likely be a temporary solution if its also susceptible to the capacitor issues. In this case I wouldn’t worry too much about replacing them, not too hard to do. edit: replacing them verrry very carefully.

 

This. And if someone doesn’t feel comfortable swapping them there are online services to have it done.

Not every city has an electronics repair place with a decent turnaround.

 

Depends on who you are, and what you do for a living/hobby. I find measuring aquifer-system compaction using borehole extensomters to be relatively straightforward, but that's what I do for a living, lol. While I am very careful when I do it, it's more than that.

Reading that article, it seems like if your capacitors have survived this long, that's not likely to be the issue since it seems to be something that failed relatively quickly. Most of the failures happened by 2005, up to about 6 years after manufacture. We're going on 17+ years now. Seems like if your components were susceptible to it, it would have happened by now. Plus, if you look at the damage in some of the pics in that article, I wouldn't be surprised if the failure also damaged other parts of the circuitry.

And not that Toyota couldn't have gotten it's circuit boards elsewhere, but it also seemed more centered on personal computer equipment (Dell, Apple, etc...). Certainly something that would have warranted a recall. I know there was that Takata inflator recall, but I don't recall one about the ECU, though I certainly didn't do an exhaustive search for it.

 

I suspect faulty airbag modules are caused by capacitors going bad (which is cheap and easy to repair if you know how to solder). I am waiting to get my hands on faulty modules to confirm. Most of the time in old electronics, it is the capacitors.

It is easy to identify a bad capacitor, they are either bulging or leaking. You just need to desolder it from the circuit board and solder a new one with the same uf specs back on (while paying attention to the polarity). Though when the capacitor has leaked all over the place you will need to clean it up first.

The faulty ones were mostly cheap no-name capacitors and maybe even knock offs of well established reputable brands. If manufacturers weren't as focused on cost cuttings, they would not have used this cheap bottom-of-the-line junk

Anyway, yes capacitors do go bad over time but not as quick and massively as these did. For example, I had to replace the capacitors in my original xbox not so long ago, they lasted 20 years. Not bad!

Nope, the takata airbags weren't related to electronics but to the airbag's propellant incorrect mixture, causing it to burn too fast and cause the airbag to explode

 

I will be very interested to hear your report @onakat about trying your hand at replacing the electrolytic capacitors in a faulty SRS Airbag Control Module to see if it operates properly again. I am not an electronics repair technician but have replaced electrolytic capacitors in a faulty LCD TV power supply board and on a subwoofer amplifier board that brought both devices back to life. As mentioned, faulty electrolytic capacitors are a common problem with consumer electronics equipment and may be the problem with faulty Toyota SRS Airbag Control Module. I did a search on airbag control module service vendors who might perform such repairs. I could find plenty of companies that offer resetting the airbag module after a deployment but none that advertised repair/replacement of faulty circuit board components. If someone on the forum tries this, a photo DIY of such a repair would be great to read.

I do have a follow-up to my repair process described in my post above. Some time after my repair, I started again to have some intermittent flickering of my SRS airbag light. While doing a major service on the engine, I decided to replace the battery in my truck with a new Interstate Group 35 AGM battery. The new battery appears to have stopped my SRS airbag warning light issues. The light now comes on at start up, goes out after a few seconds, and remains off while operating the truck. The SRS airbag control module is very sensitive to supply voltage. So an old, weak battery will cause the module to do strange things. So consider checking/replacing your battery if you are having problems diagnosing the cause of an SRS airbag warning light.

 

I have to get my hands on faulty modules first! When I do, I will open them up to see what's wrong and post the results!