The plaintiffs’ lawyers insist that the source code will provide evidence that defects in the electronic throttle-control system caused sudden acceleration in Toyota vehicles. Toyota has maintained there are no problems with the electronics but has agreed to turn over its source code to plaintiffs’ engineers under stringent security.

On March 31, U.S. District Judge James Selna, who is overseeing the case in Santa Ana, Calif., signed an order under seal approving the deal.