Technicians from Toyota will join government investigators in Harrison, N.Y., on Wednesday to inspect the car. Toyota plans to examine an internal data recorder that documents the moments before and after a crash.
The company will use equipment to determine how many times the driver hit the brakes and gas. It used the same tools earlier this week to cast doubt on a California driver who claimed his Prius sped to 94 mph before a patrol officer helped him stop it.
In the Harrison case, authorities have said there is no indication of driver error. A housekeeper told police the car sped up on its own as she eased forward down her employer's driveway on March 9 and hit a wall across the street. She was not hurt.
Toyota recalled more than 8 million cars because their gas pedals could become stuck or be snagged by floor mats. In addition, the government is looking into complaints from at least 60 Toyota drivers who say they got their cars fixed and still had problems. Toyota is checking into those complaints as well.
The investigations reflect challenges faced by the company and government. Dealers and experts have had trouble recreating episodes of sudden acceleration, and Toyota says tests have failed to find other problems beyond the sticking gas pedals and floor mats.
Some safety experts have said electronics, not simpler mechanical flaws, could be causing the problems. Toyota has said it has found no evidence of problems with its electronics but is studying the issue.
"It's not the old garden-variety defect investigation, where you have a broken part and the vehicle is disabled. It's an intermittent problem," said Allan J. Kam, a former senior enforcement attorney for the National Highway Traffic Safety Administration who now directs a private consulting firm.
Toyota officials said they did not know how long the New York investigation would take. The company plans to release the results to Harrison police but not to the media because the police are also investigating.
The Prius is not on Toyota's recall list for sticky accelerators. However, the 2005 hybrid had been serviced for the floor mat problem.
On Monday, Toyota held a press conference in San Diego to challenge the story of James Sikes, who claimed his Prius sped out of control on the freeway last week. The company said its own tests had found almost nothing wrong with the car, and said Sikes had apparently pressed the brakes and gas at least 250 times.
Jason Vines, who was Ford Motor Co.'s top public relations executive when the company faced scrutiny over massive Firestone tire recalls on its cars in 2000, said the San Diego case would prompt similar interest in the New York investigation.
"They've gotten themselves into another box because of doing it one time in San Diego and now not doing it (in Harrison)," Vines said. "It's just going to create more confusion."