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'Unsure' sensor: Promising safety amid product failures

Posted: 16 Oct 2015     Print Version  Bookmark and Share

Keywords:NHTSA 

Automotive airbags are there for a reason: to keep drivers and passengers safe. Ironically, the said 'safety' systems have been found to be faulty and were reported to cause harm such as airbags deploying for no reason. In fact, millions of vehicles have been recalled this year for this very reason.

The National Highway Traffic Safety Administration (NHTSA) announced a recall of more than two million vehicles to fix defective crash sensors that could cause airbags to deploy for no reason, and when they were repaired, 85 per cent were fine but the problem still continued for the remaining 15 per cent. The initial fix was based on installing devices to protect the airbag sensor module from electrical surges. Manufacturers are now replacing the impact sensors with new units.

One of the largest ongoing recalls for airbag failures involve those with defective inflator parts made by Takata that shoot metal shrapnel into the car's occupants. Worldwide, the numbers are rising nearly every month with more manufacturers and models affected. In September, the NHTSA estimated that 18.6 million vehicles were affected. It seems the numbers and the problems continue to grow.

And it's not only Takata bags in the headlines. Mitsubishi just recalled 13,500 model-year 2014 Mitsubishi Mirage and 2012 Mitsubishi i-MiEV vehicles with airbags that may fail to deploy in a crash. Mitsubishi indicated that electrical problems inside the impact sensor for the airbag system may cause the frontal airbags to have a delay in deployment and the side and curtain airbags can completely fail.

An increase in the electrical resistance inside the impact sensor for the airbag is to blame. The defect causes an abnormal communication that is detected by the electronic control unit, which activates the airbag warning light causing airbags to fail in a crash. Mitsubishi said the airbag impact sensors will be replaced with a countermeasure unit.

No recall is being issued for electric power steering problems in 374,000 2013 Honda Accords. Initially 24 complaints were filed with the NHTSA and 235 directly with Honda. After an investigation was announced, another 33 complaints were filed with the NHTSA, with complaints indicating problems with the torque sensors. The NHTSA said technicians were able to identify the bad component and Honda claims that only a small number of sensors were affected and the problem was fixed by the supplier.

Southeast Toyota distributors are recalling 949 model year 2015 Toyota Prius C vehicles manufactured from April 20 to June 30 of 2015 for a tire pressure monitoring system (TPMS) that may be improperly calibrated. The TPMS may fail to warn the driver that the tire pressure is low. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 138, "Tire Pressure Monitoring Systems."

So, why am I listing these? While most of the numbers are small, there's a bigger picture here to consider. As manufacturers continue to install electronics that enable handing off the driving of the vehicle to the vehicle itself, and out of the hands of the driver, there should be greater concern when sensors fail, not less. I wonder how many autonomous vehicles under test were equipped with such sensors? How will the industry ensure occupant safety within an environment where there will be failures?

- Carolyn Mathas
  EDN





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