A 10-month inquiry by the US Department of Transportation has found there is no evidence that unintended accelerations in Toyota vehicles were caused by electronic flaws.
The Department of Transportation said its investigation with NASA found that electronic flaws weren't to blame for the reports of sudden unintended acceleration that led to massive Toyota recalls.
“The verdict is in. There is no electronic-based cause for unintended high-speed acceleration in Toyotas. Period,” said Ray LaHood, the US transportation secretary.
The agency reached the conclusion after an investigation that said that the mechanical causes were the same ones identified earlier by the National Highway Traffic Safety Administration, sticking accelerator pedals and floor mat interference.
The findings vindicated the car-maker's long-held position and lifted its shares more than 4 per cent in New York trade.
Earlier in the day, the Japanese car giant raised its annual forecasts as cost cuts and sales exceeded its plans, but a heavy reliance on exports is expected to keep it a laggard as long as the yen stays strong.
The world's top car-maker posted a smaller-than-expected fall in third-quarter profits and hiked its sales forecast for the year to 31 March by 70,000 vehicles to 7.48 million, thanks to better-than-expected sales in Asia, Japan and Russia.
It kept its forecasts unchanged in North America, where its sales have lagged since last year in the wake of a series of recalls.
Although Toyota has recalled more than 12 million vehicles around the world for a range of defects since late 2009, the big lingering question was whether there was a problem with the electronic systems in the cars.
That would signal a huge problem, possibly resulting in additional massive recalls, as such systems are in every Toyota vehicle. It would further shatter the once sterling image for quality production Toyota had boasted for decades.
Toyota in Japan welcomed the findings.
"We believe that the results of the US Department of Transportation's investigation confirms the reliability of our electronic throttle control systems," Toyota said Wednesday in a statement.
"We intend to continue to listen to our customers even closer and to offer not only safe vehicles but vehicles that provide peace of mind."
Toyota executives have repeatedly said they have tested the vehicles many times, trying to find possible electronic problems, and have never found any.
Some of the cases could have been caused by mechanical defects — sticking accelerator pedals and gas pedals that can become trapped in floor mats — that have been dealt with in recalls, it said.
Some of the cases may have been caused by driver errors, such as hitting on the gas when they meant to brake, it said.
"We feel that Toyota vehicles are safe to drive," said Transportation Secretary Ray LaHood.
Toyota has promised to beef up quality controls and be quicker in responding to consumer complaints. But analysts say it is likely to take some years before Toyota can hope to fully win back the trust of American buyers.
Toyota paid the U.S. government a record $48.8 million in fines for its handling of three recalls.