The world's largest automaker, which is trying to repair a reputation damaged by recalls of millions of cars worldwide since October, said the federal grand jury issued the subpoena to its U.S. subsidiary in late June.
Toyota said it was the company's second subpoena from a federal grand jury a panel that can determine whether evidence exists to bring criminal charges.
"The company and its subsidiary are sincerely cooperating with authorities on the probe," Toyota said in a statement.
Defective steering relay rods led Toyota to recall 4Runner sports utility vehicles and T100 pickup trucks in the United States in 2005.
Toyota said the grand jury's subpoena did not specify vehicle models and it was not clear that the subpoena was linked to the 2005 recall, which came several years before safety lapses erupted into a global recall crisis late last year.
The automaker has recalled more than 8.5 million vehicles worldwide since October, including 6 million in the U.S. alone, to address the possibility of unintended acceleration and to fix a braking problem in its Prius hybrid.
In February, Toyota was subpoenaed by a U.S. federal grand jury seeking documents related to unintended acceleration in its vehicles and the braking system of its Prius hybrid.
Earlier this year, Michigan's attorney general also asked Toyota to submit information on the recent U.S. recalls, Toyota spokeswoman Ririko Takeuchi said. She declined to elaborate.
Toyota paid afor being and is facing hundreds of state and federal lawsuits. Congress is considering an upgrade to auto safety laws in the aftermath of the Toyota recalls that began in October.
In Tokyo, Toyota shares fell 2.6 percent Tuesday to close at 3,055 yen before the subpoena announcement was made.