Honda Motor Co.'s U.S. unit advised dealers not to contact customers about a potentially fatal defect because of a parts shortage, one week before shrapnel from an exploding air bag left a woman looking as if she had been killed with a knife, lawyers for her family said.

"Because not all part numbers are available in abundant supply, American Honda asks that dealers do not proactively contact customers at this time," the company's technical division wrote in a Sept. 22 message, according to documents filed with a lawsuit Monday by the family of Hien Tran, 51, who died from her injuries on Oct. 2.

Honda's admonishment was part of a multiyear campaign by the automaker and air bag maker Takata Corp. to delay letting consumers and regulators know of the potential risk of exploding air bags, lawyers for Tran's family alleged in the complaint in Florida state court in Orlando.