Federal safety investigators have announced their second probe in less than a week involving fires starting in the driver's side doors of vehicles.
Last week, the agency said it was looking into the cause of fires in 2007 model year Toyota Camry sedans and RAV-4 sport utility vehicles.
In both cases, the agency said it appeared that the fires started in the power window master switch on the door.
NHTSA said it has received 12 consumer complaints as well as manufacturer field reports about the melting or burning of the switch in Trailblazers. NHTSA is reviewing data for about 309,000 Trailblazers made during the two years at issue.
The agency said several of the complaints involved driver door fires, including some that occurred while a Trailblazer was in operation and others during periods when the vehicle was parked.
In both the Toyota and GM cases, no injuries or accidents have been reported.
The Toyota investigation involves more than 830,000 vehicles. The Camry is regularly the top-selling passenger car in America; that was the case in 2007 and last year.