Brian Ross, an ABC reporter, was among the first to report on "runaway Toyotas" in November 2009. Ever since, frustration among dealers is growing over bad publicity.
22Squared, a marketing agency representing 173 Toyota dealers with showrooms in south-eastern states including Florida, Georgia and South Carolina, notified ABC that it wants to shift ads to rival stations, because of "excessive stories on the Toyota issues".
The boycott comes only days after Toyota paid an estimated $3m for a 30-second ad spot during the much-watched Super Bowl.
Ross was quoted by the New York Times as saying: "We knew that what we were reporting could possibly lead to a loss of advertising dollars, and nobody at ABC batted an eye."