Aug 25, 2009 12:19 PM

The National Highway Traffic Safety Administration (NHTSA) has issued a final rule that makes permanent an existing requirement that trailers with antilock brake systems (ABS) be equipped with an external malfunction indicator lamp. The rule takes effect August 31.

The indicator lamp requirement, which is included in the federal motor vehicle safety standard that governs air-braked vehicles, was originally scheduled to sunset March 1, 2009, but had previously been extended to September 1, 2009. The agency had established a sunset date for this requirement in light of the increasing numbers of post-2001 tractors that have an in-cab trailer ABS malfunction lamp, making the external trailer lamp redundant.

NHTSA officials said they are making the requirement permanent in light of additional safety purposes served by the external lamp. It not only warns the driver of a malfunctioning trailer ABS, but, unlike the in-cab lamps, also indicates which trailer in a multi-trailer train has a malfunction. The lamp also assists federal and state roadside inspectors and maintenance personnel in identifying a malfunctioning trailer ABS. This rulemaking was issued in response to petitions from the Commercial Vehicle Safety Alliance.