Smoking Toyota Window Switch First Reported in 2008

Toyota Motor Corp. knew it might have a problem with its power-window switch four years ago, according to documents it filed with the U.S. National Highway Traffic Safety Administration.

This week the company launched a recall of more than 7.4 million vehicles to repair the improperly lubricated switch, which could overheat and smoke or cause a fire.

Toyota says the faulty component was supplied by Japan's Tokai Rika Co. from plants in China, Japan, Thailand and the U.S.

The carmaker tells the NHTSA it received an isolated field report of a problem with one switch in 2008. But Toyota recorded no further complaints until early 2010, when it stepped up its own investigation.

The NHTSA launched its own probe in February into reports it received of 161 fires and nine injuries blamed on the switches.