This is GM headquarters in Detroit on Jan. 14, 2014.

This is GM headquarters in Detroit on Jan. 14, 2014. Credit: AFP-Getty Images / Stan Honda

General Motors Co. has avoided a recall of about 2 million large pickups and sport utility vehicles over rusted brake lines after a four-year investigation by U.S. regulators.

The brake-line corrosion in the 1999- to 2003-model trucks is routine wear and tear that mostly occurs in northern states where salt is often used on roads in winter, a National Highway Traffic Safety Administration official said in a media briefing before the Thursday announcement. The investigation covered 10 Cadillac, Chevrolet and GMC models, including the Escalade, Avalanche, Silverado, Suburban, Tahoe and Yukon.

The decision spares GM from another large call-back of its vehicles, after last year's ignition-switch recall of 2.59 million of its small cars that prompted congressional hearings, a $35 million civil penalty and a criminal investigation. Automakers in the United States, led by Detroit-based GM, recalled a record 64 million cars and trucks in 2014.

NHTSA also is offering safety advice for owners of pickups made in 2007 or earlier. The agency said that those who live in states that use a lot of salt on roads during winter should ensure that the underside of the truck is washed often and that the brakes are inspected.

"We may not have identified a defect, but there's still a safety issue and that's why we've put out our advisories," NHTSA Administrator Mark Rosekind told reporters Thursday at the New York auto show. "When you look at the data or what was going on at the time, from our perspective, we made the call it wasn't a defect."

NHTSA has moved to speed up investigations because the brake-line probe took four years, an agency official said. NHTSA is understaffed given the increase in automotive recalls, which has spurred President Barack Obama to seek more money for the agency in his next budget.

"We took our time because if there was something there, we wanted to find it," Rosekind said. "I don't think there's any question that if we could, we'd all want this stuff to go faster."

The automaker said it supports NHTSA's recommendations.

"GM has proactively suggested to consumers that they perform regular undercarriage cleaning and post-winter brake line inspections to check for wear," Alan Adler, a GM spokesman, said in an emailed statement.

Since last year, GM has worked to improve quality and its own internal methods of tracking safety problems. Chief Executive Officer Mary Barra has stepped up efforts to shed the company's reputation for foot-dragging on defective parts.

The corroded GM brake lines generated 3,049 complaints, according to documents released by NHTSA. The agency said 2,702 of those were in states where salt is often used and happened more frequently in states that don't require vehicle inspection.

The GM trucks have steel brake lines that owners contended are so rust-prone they fail without notice, spilling brake fluid. The lost fluid means a sudden, sometimes catastrophic loss of braking power, the owners said in complaints.

NHTSA said that of the 94 fires or crashes and 26 injuries reported regarding the trucks, none was severe or resulted in the deployment of an air bag.

GM successfully made the case that the trucks would still stop even if one brake line fails and that the corrosion was part of routine wear and tear on models that were at least eight years old when the investigation began in January 2011.

GM argued that the trucks were long out of factory warranty and that owner's manuals urge customers to have the brake lines inspected. More than 20 states require brake-line inspections at one- or two-year intervals or when stopped for a violation.

The automaker developed a repair kit that should cost about $500 to install.

NHTSA conducted its own tests and found that GM's trucks took longer to come to a full stop if a brake line failed but still met government safety standards.

The agency said that while more vehicle owners complained about GM's trucks, other brands had similar rates of problems.

Automakers have since moved to nylon-coated brake lines to protect them from corrosion, with Toyota Motor Corp. adopting them first, followed by Ford, Fiat Chrysler Automobiles and then GM.

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