DOT's LaHood wants to know what Toyota knew, when it knew it, and how it knew it.

The National Highway Traffic Safety Administration has just announced that it is using its statutory authority to obtain documents from Toyota to determine if the automaker conducted three of its recent recalls in a timely manner.

Federal law requires all auto manufacturers to notify NHTSA within five days of determining that a safety defect exists and promptly conduct a recall.

“Safety recalls are very serious matters and automakers are required to quickly report defects,” said U.S. Transportation Secretary Ray LaHood.

Press reports earlier today coming out of Japan claim that Toyota is preparing to shut plants in the U.S. once again next month due to a continuing slump in sales. Toyota in the U.S. did not respond to requests from TheDetroitBureau.com for clarification.

The safety agency is under attack by critics for its lack of action and/or slow response to a growing number of Toyota complaints. More than 30 deaths are now attributed to accidents involving Toyota products, which were subsequently recalled. And complaints to NHTSA’s Auto Safety Hotline are growing rapidly as adverse publicity continues.

No end appears in sight for the world’s largest automaker. The Japanese company faces hearings in front of at least two Congressional and one Senate panel.

The U.S. auto safety agency is now requiring Toyota to provide documents showing when and how it learned of the defects affecting approximately 6 million vehicles in the U.S.

The probe will explore how the Toyota learned of these defects, such as through consumer complaints or factory testing. Investigators are also looking into whether Toyota discovered the problems during pre-production or post-production of the affected vehicles.

Officials are also checking whether Toyota has covered all affected models in its recent recalls to ensure Toyota did not miss any problems. NHTSA will obtain information on production data, incidents, complaints and warranty complaints, copies of tests, dates of meetings, timelines, and supplier information.

The three recalls in question involve millions of Toyota and Lexus vehicles. Two of the recalls are about the entrapment of gas pedals by floor mats.

The first recall was announced on September 26, 2007, and was followed by a subsequent one on October 6, 2009. The October recall was then expanded on January 29, 2010, to include additional vehicles.

The third recall, involving sticking gas pedals, was announced on January 21, 2010.

“Our top priority is safety and we expect that all manufacturers address automotive safety issues quickly and in a forthright manner,” said David Strickland, Administrator for the National Highway Traffic Safety Administration.

NHTSA has the authority to seek civil penalties for a variety of violations by manufacturers, equipment suppliers, registered importers and vehicle customizers. If agency officials determine that an auto manufacturer violated its statutory obligations, the manufacturer could be liable for a maximum of $16.4 million in civil penalties.

The size of the penalty is trivial, of course, compared with the negative  effects of being caught breaking U.S. law.