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Brett Emison
Brett Emison
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NHTSA’s Toyota Sudden Acceleration Study: Quick Initial Review

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I wrote this morning that the joint NHTSA / NASA Toyota Sudden Acceleration Report was expected today. Reports of the study and a quick glance at its executive summary show that most preliminary reports of the findings were accurate.

While NHTSA and NASA investigators found a number of potential electronic failure modes, they have not yet identified a precise electronic cause for "large throttle" opening unintended acceleration events.

Electronic failure modes identified by NHTSA/NASA include:

  • Failure mode when combined with driver input can cause the throttle to jump 15 degrees in certain conditions and may not generate an error code to document or trace the error.
  • Multiple failure modes that can result in throttle openings of less than 5 degrees resulting in high idle speed, hesitation, and surging.

The NHTSA/NASA findings suggest to support claims that a number of electronic malfunctions can occur without triggering an error code to document the malfunction.

NHTSA and NASA scientists made sure to point out that although a smoking gun proving electronic malfunction caused large throttle opening unintended acceleration was not found using the hardware and testing performed, that does not mean such malfunctions could not occur.

Update: NHTSA/NASA findings via SRS:

"Due to system complexity which will be described and the many possible electronic software and hardware systems interactions it is not realistic to prove that the ETCSi cannot cause UAs. Today’s vehicles are sufficiently complex that no reasonable amount of analysis or testing can prove electronics and software have no errors. Therefore, absence of proof that the ETCSi caused a UA does not vindicate the system."

[Read the Executive Summary]

[More on Toyota]

[More on Sudden Acceleration]

(c) Copyright 2011 Brett A. Emison