Under pressure from federal regulators and legislators, General Motors this year has been reviewing past safety problems. That has resulted in 54 recalls affecting about 25.7 million vehicles in the United States. But the automaker has yet to recall almost 1.8 million full-size pickups and sport utility vehicles from the 1999 to 2003 model years for corrosion-related brake failures.
The National Highway Traffic Safety Administration has been investigating the issue since 2010, and the agency has now received about 1,000 complaints from owners, some of whom report narrowly avoiding crashes.
"Hit brakes and a line blew. Almost hit car in front of me," the owner of a 2003 Chevrolet Silverado wrote in a complaint filed in June. "Like all G.M. trucks in snow country my brake lines rusted through along with my rear backing plates. I don't know how many people have to be killed from blown brake lines for them to do anything. I guess a lot since they held off 10 years on their current problem."
G.M. has resisted recalling the pickups and S.U.V.s., telling federal regulators that rusted brake lines are a routine maintenance issue. In addition, the automaker says, the vehicles have dual brake lines, so "the affected vehicle would be capable of stopping."
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In a statement this year about the issue, the company said that rusted brake lines were an industrywide problem.
"Brake line wear on vehicles is a maintenance issue that affects the auto industry, not just General Motors," the company said. "The trucks in question are long out of factory warranty, and owners' manuals urge customers to have their brake lines inspected the same way brake pads need replacement for wear."
General Motors' assertion that rusting brake lines are an industry issue is not supported by complaints filed with Carcomplaints.com, Mike Wickenden, its owner, wrote in an email. He said the website had received 56 complaints about the 1999-2003 Silverado, compared with five for the Dodge Ram, two for the Ford F-Series and none for the Toyota Tundra.
In contrast to G.M., Subaru last week said it was recalling about 660,000 vehicles in the United States, telling investigators it was worried that the brake lines "could perforate after exposure to seven or more winter seasons." The Japanese automaker took action without an investigation by federal regulators.
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General Motors does not comment on other automakers' recalls, Alan Adler, a spokesman for G.M., wrote in an email.
The highway safety agency's investigation into G.M. vehicles was prompted by a defect petition filed in 2010 by an Ohio man after the brakes on his 2003 Chevrolet Silverado 2500 heavy-duty pickup failed because of corroded brake lines.
In January 2011, the agency intensified its investigation to a more serious engineering analysis, saying there were 761 complaints from owners, most of whom were in states that used a lot of road salt during the winter. That included reports of 26 crashes and three injuries, the seriousness of which were not detailed. There were no reports of deaths. There has been no update of those numbers in the investigatory file.
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The agency's engineering analysis investigation has taken far longer than its self-imposed goal of 12 months. The agency has previously been criticized by the inspector general of the Transportation Department for taking too long to conclude such investigations. The agency had no immediate comment.
Last week, Senator Richard Blumenthal, Democrat of Connecticut, and Senator Edward J. Markey, Democrat of Massachusetts, wrote to N.H.T.S.A., saying they wanted information about how the agency handles investigations, including defect petitions of the type filed in the G.M. brake case. The senators said they wanted to make sure such investigations "are responded to in a timely and complete manner."
The models originally under investigation include the 2002-3 Cadillac Escalade, the 1999-2003 Chevrolet Silverado and GMC Sierra pickups, the 1999-2003 Chevrolet Suburban, the 2000-3 Chevrolet Tahoe and GMC Yukon, the 2000 GMC Yukon XL and the 2002-3 Chevrolet Avalanche 1500 and 2500. However, in a 2012 letter to G.M., a federal regulator asked for additional information covering the 2004-6 model years.
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Some owners of much newer G.M. models have also filed complaints, although in far smaller numbers, including one owner of a 2012 GMC Sierra. "At 81,000 miles the rear steel brake line from the frame to the rear end rusted out and burst," the owner complained to regulators early in 2012.
Many owners are also unhappy that G.M. will not help with repair bills, which can exceed $2,000. They included a Silverado owner in Maryland, whose letter to the automaker was included in the agency's investigatory files.
"I declined to take your offer for a voucher toward a new vehicle because I will not be purchasing any further General Motors vehicles since G.M. does not stand behind vehicles when a serious malfunction occurs," the owner wrote the automaker in July 2012. "My children and I could have been fatally injured due to the disintegration of the brake line."
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— By Christopher Jensen, The New York Times