David McNew / Getty Images, file Toyota is to recall over 7 million vehicles over faulty window switches.

UPDATED 9:43 a.m. EDT: Toyota Motor Co., still in recovery mode after a series of problems that plagued its global operations over the last three years, announced Wednesday it is recalling 2.5 million vehicles sold in the United States due to a potential risk of fire.

The recall involves 7.43 million vehicles worldwide sold under the Toyota and Scion brands. This is the largest safety-related service action the maker has announced since it began a series of recalls related to the risk of unintended acceleration in late 2009. That and other safety issues led Toyota to recall 14 million vehicles in 2009 and 2010.

It's the biggest single recall since Ford Motor Co pulled back 7.9 million vehicles in 1996.

Many of the vehicles involved in the new Toyota recall also were called back one or more times due to unintended acceleration issues.

The latest recall is the result of a problem with a potentially defective power window switch on the driver’s side of the affected vehicles which, the maker says, “may experience a 'notchy' or sticky feel during operation. If commercially available lubricants are applied to the switch in an attempt to address the 'notchy' or sticky feel, melting of the switch assembly or smoke could occur and lead to a fire under some circumstances.”

Toyota already announced recalls for several models involving similar window switches and in February, the National Highway Traffic Safety Administration announced it would open an investigation into the issue. But at the time it focused on just 830,000 Camry and RAV-4 models sold during the 2007 model year.

The massive size of the new recall underscores the risks manufacturers like Toyota face when they share basic components on a wide range of vehicles hoping to improve manufacturing economies of scale.

In the U.S., the vehicles involved in the latest recall include:

2007 – 2009 Camry sedans, approx. 938,100 vehicles;

2007 – 2009 Camry Hybrids, approx. 116,800 vehicles;

2007 – 2009 RAV4 crossovers, approx. 336,400 vehicles;

2007 – 2009 Tundra pickups, approx. 337,100 vehicles;

2007 – 2008 Yaris subcompacts, approx. 110,300 vehicles;

2008 Highlander SUVs, approx. 135,400 vehicles;

2008 Highlander Hybrids, approx. 23,200 vehicles;

2008 – 2009 Scion xD models, approx. 34,400 vehicles;

2008 – 2009 Scion xA models, approx. 77,500 vehicles;

2008- 2009 Sequoia SUVs, approx. 38,500 vehicles;

2009 Corolla compacts, approx. 270,900 vehicles; and

2009 Matrix crossovers; approx. 53,800 vehicles.

To check whether your call is involved, you can go to Toyota's recall web page. The maker estimates the inspection and repair process will take little more than an hour and involves the disassembly of the master switch and, if necessary, the application of a special fluorine grease.

NHTSA has received more than 200 reports of problems involving the defective switch including fires, though there are no known crashes or injuries. At least 39 similar problems were reported in Japan, where 460,000 Toyota vehicles were recalled.

Another 1.39 million vehicles are subject to the new recall in Europe, while the massive safety campaign also covers Australia, China and other parts of Asia and the Mideast.

In the U.S. market, the Toyota announcement is the largest recall of the year and could revive concerns about quality control at a manufacturer normally at the top of the charts. Such concerns plagued the maker during much of 2009 and 2010 and officials including President Akio Toyoda were hauled before Congress to explain the massive recalls related to the unintended acceleration issue.

Toyoda has repeatedly promised, since that scandal began, to ramp up the maker’s quality control process, and it is important to note that all the vehicles impacted by the latest recall were produced during or before the 2009 model year. Nonetheless, the new service action will again put an unwanted spotlight on the maker.

Toyota had more vehicles involved in recalls than any other maker in the U.S. in 2010 and came just short of achieving that dubious distinction again in 2011. A large recall late in the year, however, put Honda at the top of the list. Indeed, Honda recalled 1.7 million vehicles as part of three separate service actions last week – while NHTSA launched an investigation into potential problems involving another 600,000 vehicles.

While there have been scores of recalls announced this year involving every brand from Chevrolet to Ferrari, with today’s announcement, it appears that both Toyota and Honda are again in an unwanted race to lead the recall list again for 2012.

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