Toyota Unintended Acceleration: “No Electronics-Based Cause”: Not True & Misleading

09 Feb

Engineering Thinking Extra Is A Short Review Of A Current Hot Topic

According to Reuters today (8 Feb 2011), “A government probe cleared Toyota Motor Corp’s electronics of causing unintended acceleration, a big victory for the world’s top automaker as it seeks to recover from the hit it took over runaway vehicle accidents.”

This news release is misleading. The investigation did not “clear” the electronics. Rather, the investigation could not find any evidence for the electronics being the source of the problem. Failure to find a cause is not the same as proving there was not a cause.

The following statement from the Los Angeles Times is more accurate:

“A NASA report on Toyota’s sudden acceleration found ‘no electronic flaws … capable of producing the large throttle openings required to create dangerous high-speed, unintended acceleration incidents.'”

Note that the NASA engineers used more careful language, indicating that they were not able to identify an electronics cause, not “proving” there was no cause.

Although I certainly respect engineers in general, there are aspects of this case that — at least until I have had a chance to review the NASA report — will not allow this particular engineer to agree that the case is closed.

In particular, although “stepping on the gas instead of the brake” is likely a factor in some cases, those cases are generally when moving from a  coasting mode to a quick stop.  (My aunt died in such an instance, when coming to a stop next to a grocery store wall.) In some reported cases, however, the driver is cruising along on the highway when the car suddenly starts accelerating, without the driver moving their foot. In at least one such case, the acceleration was terminated by switching off cruise control.

Also, as reported earlier, Toyota emails indicated that staff members celebrated their efforts to delay safety regulations and investigations (“ET EXTRA: Protecting Your Life: Toyota Joins The Gallery Of Shame“). This does not lead one to believe that Toyota Engineering was primarily concerned with finding the root cause of the issue. This type of behavior also raises serious doubts, including: were the vehicles studied by NASA representative of the failed vehicles, or did Toyota provide test vehicles wherein Toyota had already identified and corrected a root cause, such as an intermittent cruise control linkage?

If I have the opportunity to review the NASA report I will comment further. If anyone who worked on the report would like to comment, please do.

-Ed Walker


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