Will airbags work even if the ignition is off?

Dear Car Talk

Dear Car Talk | Aug 01, 1994

Dear Tom and Ray:

Does the ignition key have to be on to make the air bags work? Or will they work even if the ignition is off? I would think the latter is the case so that if one had motor trouble and pulled off to the side of the road, the bags would protect them in case they're hit while sitting in the parked car. But if the bags work with the ignition off, how long will it be before some teenagers decide to go to parking lots and bump cars just to set off the air bags?

TOM: Now that you've suggested it, Vic, probably about 15 minutes.

RAY: About a year ago when we first looked into this question, Ford was the only company whose airbags worked when the ignition was off. That's because the power to the air bag is wired separately from the ignition switch.

TOM: But we've heard that more and more companies are switching over to that kind of arrangement, precisely for the reason you describe; it's possible to be sitting in a parked car, and be hit by somebody else!

RAY: But I wouldn't worry too much about teenagers bumping cars just to set off air bags. An airbag won't deploy unless the sensor detects an impact of about18 mph. And at that speed, a teenager would be risking serious injury to himself, and, more importantly, he would be grounded for life once his parents saw what he did to the family car.

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