Toyota Motor first learned in 2008 about a defect in power-window switches that yesterday prompted it to recall 7.43 million vehicles worldwide for fire hazards, according to documents filed with U.S. regulators.

Toyota, based in Toyota City, Japan, received a report in September 2008 from the U.S. about "an unusual smell" from the power-window master switch and "thermal damage" to the switch, the company said in a report posted today on the U.S. National Highway Traffic Safety Administration website.

The automaker sent the part to the supplier to investigate and no "root cause" was found. No other problems with the switch were reported until May 2010, when the company said it began sporadically receiving information about an abnormal smell or smoke coming from driver's side doors, according to the report.

"There was really no trend early on and it took considerable time to diagnose what seemed to be an isolated problem and how it was occurring," John Hanson, a U.S.-based spokesman for Toyota, said in an e-mail.

In 2009 and 2010, Toyota, Asia's biggest carmaker, recalled a record number of vehicles worldwide for defects that may cause unintended acceleration. The company in April 2010 agreed to pay a record $16.4 million U.S. fine for failing to promptly report the flaws with vehicle accelerator pedals.

Nine Injuries

"I'm a little disappointed in that Toyota didn't act sooner especially because of the debacle in 2010 and, more importantly, the tragedy in 2010," said Rebecca Lindland, an analyst with IHS Automotive, referring to deaths that occurred due to unintended acceleration. "It's not surprising that they would delay given their pattern of resisting recalls historically."

The U.S. auto-safety regulator opened an investigation into about 830,000 Camry cars and RAV4 crossover sport-utility vehicles in February after receiving six reports of fires that started in the window switch. It's received reports of nine injuries and 161 fires, Lynda Tran, a NHTSA spokeswoman, said.

"NHTSA is aware of the recall announced by Toyota yesterday and is in contact with the manufacturer," Tran said in an e-mail. "The agency's investigation remains open pending its review of Toyota's documents regarding its recall action."

With the increasing number of fire reports coming shortly after congressional hearings and market-share losses in the U.S., Toyota would have likely been loath to recall more vehicles then for another defect, Lindland said.

'Complete Panic'

"The last thing they could really withstand at that point was another recall," she said in an interview. "I would guess the strategy may have been to address the 10 or 11 complaints and avoid doing a recall at all costs."

According to a report posted on NHTSA's website, the driver of a 2007 Camry reported noticing "black smoke throughout the car" that "immediately turned into flames, which caused poor visibility and complete panic" for the driver and three passengers in the car on Dec. 26, 2011. The flames burned the driver's coat and a passenger's hand as he tried to put it out.

"It was a frightening experience for myself and family members as I strongly feel that no one has a clear explanation as to the cause of the fire and fails to ensure my family's safety and well being," the driver wrote in the report.

Toyota's American depositary receipts, each equal to two ordinary shares, rose 57 cents, or 0.8 percent, to $75.07 at 11:51 a.m. in New York trading.

The carmaker didn't provide an estimate on the costs of the recall.

The recall includes about 2.47 million vehicles in the U.S., 1.4 million in China and 1.39 million in Europe, Joichi Tachikawa, a Tokyo-based spokesman, said yesterday.

The recall includes vehicles from model years 2007 to 2009 from models including the Camry, RAV4, Corolla, Tundra, Sequoia and Yaris.

--With assistance from Anna Mukai in Tokyo. Editors: Bernard Kohn, Cesca Antonelli

To contact the reporter on this story: Angela Greiling Keane in Washington at agreilingkea@bloomberg.net

To contact the editor responsible for this story: Bernard Kohn at bkohn2@bloomberg.net