Airbag replacement supplemental steps?

[GON]

Replacing a deployed airbag on the front driver side of a 2005 Lexus GX 470. I purchased a used replacement airbag from a local salvage yard.

Going through the factory service manual, it states these additional actions/ items need to be performed when replacing an airbag:
- airbag replacement has to take place in seconds (I don't recall the exact number), after disconnecting the battery
- airbag sensors must be replaced after an airbag deployment
- calibration of the airbag system

I took a second look at the FSM. I am having sleep issues, and read the FSM pretty tired. Here are some cut and pastes from the FSM:
- Never use the SRS related parts from another vehicle. When replacing the parts, replace them
with new parts.

- Work must be started after 90 seconds from the time that the ignition switch is turned to the LOCK
position and the negative (−) terminal cable is disconnected from the battery.
(The supplemental restraint system is equipped with a back−up power source. So, if work is
started within 90 seconds after disconnecting the negative (−) terminal cable from the battery,
the SRS may deploy).
When the negative (−) terminal cable is disconnected from the battery, memory of the clock and
audio systems is cancelled. So, before starting work, make a record of the contents recorded
in each memory system. Then, when work is finished, reset the clock and audio systems as before.



Are the above must do actions, or best practices? Any thoughts?

 

[nthach]

AFAIK, the SRS ECU is a one-time deal, once the bags blow there’s hard codes logged.

Else, once the battery has been disconnected for more than 90 seconds, the system is “safe” to work on. It’s the time that the capacitors hold a charge to blow the bags if there’s a power loss.

 

[andyd]

I'm hooked on this thread.Please update as the saga unfolds. TIA

 

[LazyDog]

When working on cars w/ sensitive items, I like to let the vehicle modules go to sleep ~ 10 minutes. After this, I not only disconnect the - but + cable. Step on the brakes 2 to fully discharge the computer, all items like heater, fan, and radio are turn off before starting procedure.

I used 10 minutes because not sure how long a modules will stay awake, any fancy keys are kept far from the car or in an aluminum bag.

 

[GON]

Of note, I have replacement used front airbag sensors. I have no issue replacing them, seems very easy. But I am curious if a airbag sensor goes bad after a airbag deployment.

 

[nthach]

Also, discharge any static electricity on your body too. The inflators for an airbag or a seatbelt pretensioner is basically a nano-scale solid-fuel rocket. The explosive charge is “stable” - but if enough voltage contacts the squib pins, well…

 

[LazyDog]

Of note, I have replacement used front airbag sensors. I have no issue replacing them, seems very easy. But I am curious if a airbag sensor goes bad after a airbag deployment.

Your best bet is to change the sensor too, unless you are able to test it before installing new air bag.

 

[nthach]

Of note, I have replacement used front airbag sensors. I have no issue replacing them, seems very easy. But I am curious if a airbag sensor goes bad after a airbag deployment.

If they are a MEMS device, in theory they should be OK but the OEs want new ones installed. Better safe than sorry. In the old days of mechanical ball or mercury switches, they must be reset.

 

[ecotourist]

With all the recalls of airbags, it would be nice to know where that replacement came from (ideally: year, make, model and VIN). If you knew all that you could check for recalls from time to time - a recall would be a sign it should be replaced again.

 

[atikovi]

I took a second look at the FSM. I am having sleep issues, and read the FSM pretty tired. Here are some cut and pastes from the FSM:
- Never use the SRS related parts from another vehicle. When replacing the parts, replace them
with new parts.

Well, yea. Toyota wants you to buy their new parts.

- Work must be started after 90 seconds from the time that the ignition switch is turned to the LOCK
position and the negative (−) terminal cable is disconnected from the battery.

I rarely disconnect the battery when replacing the airbag unless I'll be doing other work that requires it. Just wait a few minutes after turning off the ignition. The chances of it going off is minuscule.

But I am curious if a airbag sensor goes bad after a airbag deployment.

If the crash was severe enough to cause the bag to deploy, it's assumed the sensor was destroyed in the crash. If it looks undamaged, just leave it alone. After you put everything together and cleared the codes, if the sensor is really bad, it will throw a code, and you can replace it then.

 

[Hall]

With all the recalls of airbags, it would be nice to know where that replacement came from (ideally: year, make, model and VIN). If you knew all that you could check for recalls from time to time - a recall would be a sign it should be replaced again.

Would the dealer replace it for free then ? Well, wait, if the existing vehicle already had the recall done, then they won't.... and the junkyard replacements could be pre-recall.

 

[nthach]

Would the dealer replace it for free then ? Well, wait, if the existing vehicle already had the recall done, then they won't.... and the junkyard replacements could be pre-recall.

That’s precisely the dilemma Honda has - the news reported around 8,000 cars that hasn’t had the Takata airbag recall done. Wouldn’t be surprised if many of those cars were scrapped/junked. And are sitting at a junkyard, never got reported to the DMV as a total loss.

 

[Hall]

I'm sure Honda can cross-reference VINs with state BMVs and get the title status of vehicles though.

 

[RhondaHonda]

@GON We have a local airbag / steering column service here that most body shops use. He’s mobile and very affordable. Call a couple shops in your area to ask who does their airbag stuff and they may have something similar. He knows what control modules can be re-used after deployment and which ones need replacement and can get everything working properly.

 

[dishdude]

@GON We have a local airbag / steering column service here that most body shops use. He’s mobile and very affordable. Call a couple shops in your area to ask who does their airbag stuff and they may have something similar. He knows what control modules can be re-used after deployment and which ones need replacement and can get everything working properly.

There are even places you can send the module to be reset, they'll reprogram it and send the same one back. Not sure if that's a necessary step on this model or not.