WASHINGTON — Toyo­ta, dogged by millions of recalls and claims that it still has not fixed its safety problems, took its strongest step yet yesterday to silence critics who blame faulty electronics for runaway cars and trucks.

Toyota assembled a group of experts to rebut studies by an Illinois professor who revved Toyota engines simply by short-circuiting the wiring. Toyota's experts say the experiments were done under conditions that would never happen on the road.
The automaker maintained its assertion that simpler mechanical flaws, not electronics, were to blame.
"There isn't a ghost issue out there," Kristen Tabar, an electronics general manager with Toyota's technical center, told a news conference at the company's North American headquarters in Torrance, Calif.
Meeting with reporters, Toyota addressed the work of David W. Gilbert, an automotive technology professor at Southern Illinois University-Carbondale, whose work has been the basis of doubts about Toyota's mechanical fixes.
At least one outside expert said that even if Toyo­ta's criticisms are accurate, the professor's work shows the systems that allow brakes to override stuck gas pedals can be compromised.
Toyota is mounting a public campaign to reassure its drivers about their safety and defending itself against critics who question the fix for 8 million recalled cars and trucks. Regulators have linked 52 deaths to crashes allegedly caused by the accelerator problems.
The company's fix addresses gas pedal parts and floor mats that can cause the accelerator to become stuck in the depressed position. More than 60 Toyota owners who have had their cars repaired have complained the problem has persisted.
Toyota dealers have fixed more than 1 million vehicles. But the government has warned that if the remedy provided by Toyota does not properly address the problem, federal regulators could order the company to come up with another solution.
Gilbert told a congressional hearing Feb. 23 that he re-created sudden acceleration in a Toyota Tundra by short-circuiting the electronics behind the gas pedal — without triggering any trouble codes in the truck's computer.
The trouble codes send the car's computer into a fail-safe mode that allows the brake to override the gas. Gilbert called his findings a "startling discovery."
Yesterday, Chris Gerdes, director of Stanford University's Center for Automotive Research, and a consulting firm, Exponent Inc., rejected the professor's findings.
Toyota's assembled experts said the professor's experiments could not be re-created on the road. For example, they said, Gilbert had shaved away insulation on wiring and connected wires that would not normally touch each other.
"There is no evidence that I've seen to indicate that this situation is happening at all in the real world," Gerdes said. He added that the professor's work "could result in misguided policy and unwarranted fear."