Disabling airbags during maintenance

Approximately 9/30/03 06:42, Ron Bean uttered for posterity:

The concept is to deal with the inevitable oopsie due to many of the connectors and wirings being in the same general area that is by any measure, fairly crowded.

A small caution, since a deploying airbag can cause significant injury.

Remember the factory manual that seemed so expensive? Perhaps it isn't.

So, you're saying I should spend ~$100[1] to get the answer to a problem I would normally have solved with a screwdriver I already owned, and a small amount of common sense? Dashboards aren't that complicated, even now.

(Granted, by the time I had the dashboard apart on my previous car, I noticed an easier way to do it. But it was a cheap education.)

I wouldn't complain if I could buy the factory manual one chapter at a time. If they don't want to bother, they could outsource it to someone who knows how to do that kind of thing (it's not complicated).

[1] The actual cost for my car seems to be $70 plus shipping (I don't know how much it weighs)

Approximately 9/30/03 17:26, Ron Bean uttered for posterity:

No, you were asking about setting off the airbag. Those cost more than several factory manuals. And if you happen to be in the deployment path, particularly if closer to the wheel than driving position, so are orthopedic surgeons. Of course the cautions on disablement may also be in the FSM, more for legal than technical reasons.

So, you've saved $30 already. >:-)

Seriously, those things are worth their weight in gold even if just for keeping the service folks honest.

Aw, ferchryssakes. Don't be a damned cheapskate. Buy the damned book!

DS

"Ron Bean" wrote

After having been to training on SIR systems, I'd have to say that it's highly unlikely that you can set off the airbags without really trying very hard to do it. I can only speak to the GM systems, but on these systems, once you have disconnected the air bag, it's almost impossible to set them off because of the grounding straps that are built into the connectors.

To be safe, you should disconnect the air bag connector at the base of the steering column and also remove the SIR fuse. Often, there is a capacitor that is active until you remove the fuse and allow a certain amount of time to elapse.

Ian

$70 is also spelled "one hour of shop labor."

My factory shop manual has kept me from paying for plenty of hours of shop labor. It doesn't cost money, it saves money. I don't know a whole lot about cars, but even I can find plenty of mistakes and omissions in my Haynes manual.

I think the system uses a capacitor there somewhere under the dash or kickpad to store a charge in case your battery is disabled in a crash. No capacitor installed, no air bag deployment.

Is the capacitor always separate from the airbag module? If so, it would seem to be pretty safe.

Unless I'm missing something, it appears that there is technically no way to "disable" the airbag module itself-- you just remove anything that might set it off (such as shorting the connector to prevent static electricity). But the module itself is always "live", in the sense that the detonator will go off if it gets the right signal.

In my car all I have to do to disable the air bags is pull two fuses. Real easy.

So what percentage of the amount you paid for the CAR is that $100 manual?

Pretty small price to pay for correct info, I'd say.

Yeah, I wish they'd just put it all online and I could dowload it as PDF, but until they do...

I find that, while it can be educational, it's seldom worth the effort in terms of saving money. An hour of shop labor that actually fixes the problem may equate to several hours of my messing around and not actually fixing it. The goal is to learn something, and then pay someone to do it right.

I noticed that Helm has a set of Service Bulletins for $25-- that might actually be more informative than the shop manual, considering that I'm likely to have someone else do the work anyway.

Approximately 10/1/03 12:19, Ron Bean uttered for posterity:

Nothing beats the FSM and the service bulletins from the manufacturer that may also be available, or the special diagnostic manuals.

Cheap is cheap and good is good. Pick one, you don't get both.

Ahhh, very good theory. Except for one thing: IS STUPID! IS STUPIDEST THEORY I EVER HEARD!!!

The goal, fer cripes sake, is to learn HOW TO DO IT RIGHT YOURSELF. Geez, cars are simple (even modern ones) compared to 90% of the machinery that mankind makes. Anyone that can "learn something" can fix his own car... CORRECTLY... if he wants to.

And how much does "an hour" of shop labor actually cost you? Time to take the car to the shop, time without the car while they get around to fixing yours, time to fix yours, time for you to get back to the shop to pick up the car, time to take it back if you think something might not quite be right...time (and money) futzing around with rental cars and/or public transportation...

My time is worth more than $0.00/hr, so I factor it in when yacking about "an hour of shop labor". Perhaps your time is worth $0.00/hr, in which case never mind.

Geeze, you're dumb.

DS

"Ron Bean" wrote

The capactor is usually built into the SDM (sensing and diagnostic module). Disconnecting power to the system and waiting a couple of minutes means that in theory it can no longer activate the air bag module.

You are right. GM has provided for this by installing spring activated grounding bars that basically short the two wires coming from the air bag together "when" you disconnect the air bag module connector. We've applied full voltage to the air bags when the grounding bars are in place and you cannot get the air bag to go off.

Ian

Have you ever applied power to a bag without the shorting bar? I've set off a couple (intentional) and they make quite a bang. It's enough to make you treat them with respect. Bob

"Bob" wrote

Yes, we did at the training center, flipped them on their back and watched them shoot way up in the air...heh heh.

Plus, one of our electrical guys in the shop gets his jollies by exploding air bags in the middle of the shop. He's an idiot for doing it, but I suppose someone will have to get hurt, or the bag will rocket sideways into a new Cadillac before the shit will hit the fan.

Ian

I've never done one that way... heard it was dangerous lol.

He does it in the shop? Sheesh..... some guys... Bob

It is easy to disconnect the airbomb.

Disconnect the battery and then get coffee. Allow at least a minute for the backup capacitor to bleed-down.

Find the connector and unplug it.

To put it back in, disconnect the battery, wait a minute, and plug it in.

Whenever you're connecting/disconnecting the airbomb, don't be in it's line of fire even with the battery disconnected. It could blow your head off.