WASHINGTON 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."
The report, released Tuesday by the National Highway Traffic Safety Administration, said that the mechanical safety defects identified more than a year ago including sticky accelerator pedals and pedals trapped by floor mats "remain the only known causes for these kinds of unsafe, unintended acceleration incidents."
The report followed a 10-month study by the National Aeronautics and Space Administration, which was brought in by NHTSA to review only the electronics.
Transportation Secretary Ray LaHood said: "We enlisted the best and brightest engineers to study Toyota's electronics system, and the verdict is in. There is no electronic-based cause for unintended, high-speed acceleration in Toyotas."
For the study, a team of NASA engineers evaluated the electronic circuitry in Toyota vehicles and analyzed more than 280,000 lines of software code.
"NASA found no evidence that a malfunction in electronics caused large unintended accelerations," said Michael Kirsh, principal engineer at the NASA Engineering and Safety Center.
NASA's study "confirmed that there is a theoretical possibility that two faults could combine under very specific conditions" to affect the electronic control systems to create an unintended acceleration. But the team "did not find any evidence that this had occurred in the real world or that there are failure mechanisms that would combine to make this occurrence likely."
Despite the findings, the NHTSA said it was considering taking new actions to deal with sudden acceleration. They include proposing rules by the end of the year to require brake override systems, standardized keyless ignition systems and accident data recorders in all passenger vehicles.
The agency also proposes to start broad research on the reliability and security of electronic control systems and to research the design and placement of accelerator pedals, as well as how drivers use the pedals.
The NASA study came after three congressional hearings into sudden unintended acceleration in Toyota vehicles. Toyota has issued more than 11 million recall notices in the last 16 months, most to resolve sudden-acceleration issues. In December, Toyota agreed to pay more than $32.4 million in fines for failing to inform U.S. regulators promptly about vehicle defects. That followed a $16.4 million fine levied against the automaker by the Transportation Department in April for delaying the recall of gas pedals that could become stuck.
Toyota also faces more than 100 lawsuits in state and federal courts linked to the sudden-acceleration problems over the last decade. Toyota settled at least one of those cases, agreeing to pay $10 million to the families of four people killed when a Lexus ES accelerated out of control near San Diego in 2009.
The Los Angeles Times found that reports of sudden unintended acceleration in some Toyota vehicles surged after the automaker installed electronic throttles.
In the case of the Lexus ES and Camry sedans, total complaints averaged 26 annually for the 1999-2001 model year. After electronic throttles were installed beginning with the 2002 models, complaints jumped to an average of 132 a year. Toyota vehicles also have been involved in more fatal accidents involving sudden acceleration than all other automakers companies. A Times review in 2009 found that there were at least 19 such deaths in Toyotas since the introduction of 2002 model year vehicles, compared with a total of 11 for other automakers.
Last March, the National Highway Traffic Safety Administration enlisted the help of NASA engineers with expertise in computer-controlled electronic systems and electromagnetic interference after complaints that the agency lacked the expertise to conduct such a review. The Department of Transportation also commissioned a study by the National Academy of Sciences, which is expected to release its report in July.
The two studies were expected to cost a combined $3 million, including the cost to purchase vehicles that had been subject to sudden-acceleration complaints.
Toyota said last year it would install brake overrides in all its future vehicles to deal with sudden, unintended acceleration.
(Puzzanghera reports for the Los Angeles Times.)