Katy Cameron, 54, an employee since 1985 of New United Motor Manufacturing Inc. in Fremont, Calif., alleges that NUMMI managers routinely altered her quality audit reports to delete references to defects that might harm the automaker’s consumer image.

Cameron’s suit, filed this month in Alameda County, Calif., claims that the deletions ranged from minor production flaws to defects that “could have resulted in physical harm and injury to purchasers” of NUMMI’s vehicles.

Among them: defective seat belts, non-functioning headlights and turn signals, and inadequate brake, steering and transmission fluid, according to the lawsuit.

Victor Vanov, a spokesman for Toyota Motor Engineering & Manufacturing North America Inc. in Erlanger, Ky., said Toyota would not discuss the lawsuit. But he stated that “Quality has never been compromised coming out of that plant.”

NUMMI builds the Toyota Corolla sedan and Tacoma pickup, and the Pontiac Vibe. Since 2001, the Corolla has won the J.D. Power & Associates initial quality survey award for best compact sedan in North America four times.

Cameron’s lawyer is San Francisco attorney Kelly Armstrong, who has represented other NUMMI employees in the past. NUMMI is the only Toyota plant that is represented by the UAW.

The lawsuit claims that Cameron was reporting between nine and 15 defects per vehicle during 2005 and 2007. She alleges that plant managers who are not identified in the suit became concerned that she might send copies of her reports to Toyota officials in Japan and attempted to fire her.