June 15 (Reuters) - U.S. safety regulators have intensified a probe into possible driver-side door fires in some 2006 and 2007 model-year Chevrolet Trailblazer sport utility vehicles.
The National Highway Traffic Safety Administration said its investigation was raised to an engineering analysis from a preliminary investigation after General Motors Co, which owns the Chevy brand, sent the agency data showing 167 reports and 698 warranty claims relating to the issue.
The investigation was initially opened into more than 309,000 vehicles in February, but the upgraded probe covers 341,786 vehicles, a GM spokesman said.
An engineering analysis is the next step in a process that could lead to a recall, although sometimes NHTSA closes such probes without requiring any action.
GM continues to cooperate with NHTSA, and no injuries or accidents related to the issues have been reported, the spokesman said. GM is investigating the issue itself, including studying the other vehicles from those model years built on the same platform: the GMC Envoy, Buick Rainier, Saab 9-7x and Isuzu Ascender.
GM no longer builds any of the potentially affected vehicles.
NHTSA said it has received 83 complaints, including 66 alleging the door module had melted or burned, with the other 17 referring to erratic or inoperative window switches. Twenty-eight of the reports NHTSA received have led to driver door fires, some of which allege the vehicle was unattended or not in operation.