A U.S. government investigation showed no link between electronic throttles and unintended acceleration in Toyota Motor Corp vehicles, a victory for the world's top automaker battered by recalls over runaway vehicles.
The encouraging result for Toyota stems from a 10-month probe ordered by Congress following recalls of nearly 8 million of its best-selling models in the United States over defective floor mats and accelerator pedals that hurt its reputation for quality.
Some safety advocates and congressional investigators questioned whether software-driven throttles also played a role in unintended acceleration complaints.
There is no electronic-based cause for unintended high-speed acceleration in Toyotas, U.S. Transportation Secretary Ray LaHood said in a statement.
Toyota's U.S.-traded shares were up 4 percent in afternoon trade on the New York Stock Exchange, shortly after the release of the findings.
Although Toyota has cleared a major hurdle in its ongoing safety saga, regulators said they would consider imposing requirements for all vehicles to have braking systems that automatically counteract any instances of unintended acceleration.
Toyota, which has put electronically controlled throttles in its vehicles since 2002, has consistently said those systems were safe.
The probe by National Highway Traffic Safety Administration and NASA engineers found that the only causes of the unwanted acceleration were the previously identified sticking accelerator pedals and loose floormats that could jam the pedals.
Those problems were the root of massive recalls in 2009 and 2010 that created a safety crisis that rocked Toyota to its foundations.
Regulators are looking into 89 deaths that may be associated with sudden acceleration in Toyota and Lexus vehicles but have so far linked only a handful to the floor mat problem.
Although the investigation turned up no flaws that would prompt another massive recall, Toyota still faces significant risks from scores of civil lawsuits stemming from the recalls.
Those cases in federal and state courts, which may turn on the timing of company disclosures to regulators of already established defects, have an estimated potential liability of up to $10 billion.
(Reporting by John Crawley and David Lawder; Editing by Tim Dobbyn)