The trailer-mounted ABS malfunction lamp will be required on air-braked trailers for at least six more months under an interim final rule published by the National Highway Traffic Safety Administration.

The ABS malfunction lamp requirement was scheduled to go away March 1 under the original regulation that made antilock brakes and ABS warning lamps mandatory on trailers in 1997. The sunset provision was written into the regulation with the idea that older tractors generally would have been removed from service by 2009 and that the in-cab malfunction lamps of newer tractors would make the trailer-mounted lamp unnecessary.

However, the Commercial Vehicle Safety Alliance petitioned NHTSA to retain the lamp, and the Truck Trailer Manufacturers Association agrees with them. Jeff Sims, TTMA engineering manager says that the lamp serves as a good diagnostic tool for trailer service shops, and it helps speed roadside inspections.

“The in-cab warning lamp indicates that there is a malfunction in the ABS system, but having a malfunction lamp mounted to the outside of the trailer makes it easy to identify the source of the problem,” he says.

NHTSA is responding to the petitions in two ways. The agency has written an interim final rule that keeps the malfunction lamp requirement in place for six months. In addition, NHTSA has published a notice of proposed rulemaking that would extend the sunset date to March 1, 2011. The extension is intended to provide the agency with sufficient time to analyze the Commercial Vehicle Safety Alliance petition calling for making the lamp permanent.

“Trailer manufacturers had asked NHTSA to make the lamp requirement permanent,” Sims says. “But if the requirement eventually does go away, we want to keep location requirement. There will be trailer customers who will continue to want the lamp even if it is not federally mandated. If the lamp becomes optional, we at least would like the location to be uniform.”