A federal grand jury is looking into the way Toyota handled defective steering rods in some of its vehicles. The automaker revealed yesterday that its US subsidiaries had received subpoenas last month demanding documents about such defects.

The newly-revealed grand jury investigation is just the latest headache for Toyota this year. Since last November, Toyota has recalled about 8.5 million vehicles worldwide to resolve the floor-mat interference and sticking pedal problems that may lead to incidents of unintended acceleration. Some vehicles are subject to both recalls. Complaints to the National Highway Traffic Safety Administration (NHTSA) attribute 93 deaths to sudden acceleration of a Toyota vehicle.

Earlier this year, Toyota agreed to pay a record $16.375 million fine levied by the NHTSA for concealing information related to a January recall of 2.3 million vehicles for sticky accelerator pedals. The company also faces more than 200 lawsuits resulting from the sticky accelerator and floor mat recalls.

According to The New York Times, Toyota had already received two other subpoenas this year, one from a grand jury in February for documents related to sudden acceleration and braking and one from the Michigan attorney general in March for information on recalls.

As we’ve reported previously, the NHTSA is already investigating a 2005 recall which involved defective steering rods. Toyota waited 11 months to issue a US recall, after it had already done so for trucks in Japan. The recall in Japan took place in October 2004; the US recall, involving 977,839 similar vehicles, took place September 2005. In 2004, Toyota told US regulators the problems were limited to vehicles in Japan.

Under US law, carmakers have five days to report safety problems to regulators.

Although it has not yet determined the timing, the NHTSA has reports of three deaths and seven injuries linked to the faulty steering rods on 4Runner SUVs and T100 and Hi Lux compact pickups, which involve 1989 to 1998 models.

It was not clear what defects, models or production years the grand jury was investigating, The Times said.