We bought a 2006 Hyundai Sonata in July 2005, just after the new model came out. Shortly after, I noticed something strange: About 50 percent of the time, the "airbag disabled" light would come on while I was driving the car with my wife in the passenger seat. My wife is certainly larger than our children, so the light should not have been triggered.
She took the car back for warranty service. The dealer checked out the car and said it couldn't do anything about it. We repeated this a number of times. As an EE working in the automotive industry, I got fed up with this lackadaisical response to a critical safety issue. I downloaded a copy of the FMVSS (Federal Motor Vehicle Safety Standard) that applied to airbags and seats (all 500-plus pages), and I waded through it to find exactly what the requirements for this "safety" feature were.
The intent of the requirement wasn’t stated anywhere in the document. Nor could I find "real" specifications. The only item I found was a test procedure for verifying compliance with the unspecified requirement. It involved a couple of sandbags -- one the weight of the "average" child, the other 150 pounds, which supposedly represented a small adult. The test called for setting the front passenger seat's fore-aft range to its center and setting the seat back angle to midrange. If the "child" sandbag is on the seat, the airbag should indicate it is disabled. If the "adult" one is on the seat, the airbag should be enabled -- and thus no light.
Apparently, the Hyundai engineers designed to the test, setting the seat micro parameters to a very small range determined by the seat position specified in the test. Only then would the airbag be enabled.
It gets better. The National Highway Traffic Safety Administration ordered a full recall campaign from Hyundai. We received the notice and brought the car in. The service manager explained that we would have to leave the car for several days. The dealer needed to remove the passenger seat assembly and ship it to a service depot in California, where the entire seat computer assembly would be replaced. It actually had no way to reflash the micro other than through the OBDII (onboard diagnostic system) port!
Now that the seat has been repaired, the airbag-is-disabled indicator only comes on about 20 percent of the time.
This entry was submitted by Mark Rackin and edited by Rob Spiegel.
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