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Black Box, Sensors, & Air Bags

THE BLACK BOX EXISTS: Most people don't know that their car may have a little black box that records critical data called the Event Data Recorder (EDR) from accidents & near accidents (much like the data recorder in airplanes only much simpler & smaller). Data like speed at impact, G force of impact, duration of impact & intensity over time of impact, whether the driver was wearing the seat belt & did it work, how long the brakes were applied for before impact, did the wheels lock up, etc. Car manufacturers often don't want you to know about this little black box, possibly because it reveals data that can reflect poorly on the performance of passive restrain systems (airbags) & this could cause potential law suites, or force manufacturers to make their air bag sensors better (extra cost means less profit).

THE GM DEALER: I actually learned about the existence of a black box (it's under the drivers seat) in my wife's 1998 Safari minivan (corporate twin to the Astro minivan) from the local General Motors dealer when we had our car repaired after a low speed crash on December 26/2002. The GM dealer told me that the local university has a accident reconstruction department & had the equipment to read the data in this black box. This black box isn't reusable after an accident & the air bags have deployed, so I asked the dealer to hold onto the black box so the university could examine it's data. My concern was that my wife was considerably bruised from the drivers air bag in an extremely low speed crash that should never have set off the air bag & I wanted to see that it didn't happen again to her, me or others. I was told that the air bag was not supposed to go off in a frontal accident unless the speed was in excess of 15 kilometers per hours (about 10 miles per hour), but in this case it did (clearly a malfunction or lack of accurateness in the single stage sensor). The GM dealer admitted that based on the lack of any significant damage to the minivan other than a slight ding on the front bumper, the air bag should not have gone off. Unfortunately the GM dealer didn't honor my request to keep the black box sensor (it got thrown out by the repair shop). I think he wished that he had never told me about it's existence.

IT SHOULDN'T HAVE HAPPEN: Fortunately I took detailed pictures of the accident scene which the university accident reconstruction department was able to use along with examining the bumper & weight of the other vehicle to determine for sure that my wife's Safari minivan was traveling under 7 kph & in fact was almost stopped at the time of impact, so the air bags should never have gone off. Transport Canada confirmed the findings of the university & registered the incident as yet another GM vehicle with poor quality sensors which allowed both frontal air bags to go off when they shouldn't. Besides seriously bruising my wife's hands & arms, the insurance bill to replace the air bags, sensor & bumper was almost $5000. CDN. (for a vehicle that had a wholesale value of about $10,000 at the time). This was paid for by the insurance company & our insurance rates did not go up from this accident because my wife was not at fault, but ultimately we all pay higher insurance premiums because of faulty air bag sensors (if you're in Ontario, you've probably noticed your car insurance premium has gone up by 30 - 50% in the last 2 years).

MORE DISCOVERIES: I discovered that on newer GM Safari & Astro minivans from 2001 on, GM equipment them with a more accurate 2 stage sensor that was much less likely to deploy the air bag when it shouldn't in a low speed crash, but GM wasn't able or willing to put this new sensor in our 1998 Safari minivan to prevent the same thing from happening again. I also discovered that many European car manufacturers had put the much better 2 stage sensor types in their vehicles some 10 years before GM got around to doing it. The whole experience clearly said to me that GM cares far less about the safety of it's customers, than it does about the profit margin it would lose if it had to pay for a slightly more expensive sensor & didn't have all these needless air bag replacements to prop up the income of it's dealers.

BIG BROTHER :-) We also have a 2000 Astro minivan which is virtually identical to the Safari minivan, so I asked the university accident reconstruction department to plug the black box of the Astro into their equipment. It actually revealed an incident a month or so earlier when I was traveling a bit too fast making a left turn during a snow storm (black ice) & the front tire bounced off the curb, enough to throw my steering wheel out of alignment, but not enough to deploy the air bags. I had recalled jamming on my brakes in plenty of time & pumping the brakes (even though I didn't need to because I have an anti lock braking system) & the little black box reveal exactly what I had remembered happening, how long I had applied the brakes for, the G forces of the bump off the curb & even the fact that I was wearing my seat belt. It even accurately recorded the speed I was going before applying the brakes, but wasn't able to record the speed properly after applying the brakes because I was skidding on black ice & it revealed that the anti-lock brakes were working properly. So be careful, because there's this tattle tale black box in your car, big brother is watching you :-) There have been incidents where drivers were convicted based on the information in the Event Data Recorder box.

CBC MARKETPLACE: On January 13/2004 CBC aired a half hour documentary on it's MarketplaceExternal link show.

By Doug Hembruff.
December 2, 2003

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