When it comes to lighting, there's another factor added to the equation: compliance with federal safety standards.

Major truck and trailer lighting manufacturers say there's a flood of products – mostly LED lamps and mostly from offshore – that don't meet Federal Motor Vehicle Safety Standard 108. Some are counterfeit. Others are will-fit replacements.

"Some of the Asian manufacturers think all they have to do is stick a number of LEDs in a product and make it the same size and shape as some of the U.S. products and hit the marketplace with it, not realizing the U.S. has regulations that they have to abide by," says Tim Murphy, vice president of engineering for Peterson Manufacturing.

"I think customers get pretty intrigued by the price points," says Dominick Grote, vice president of sales and marketing for Grote Industries. "It's not visible right out of the box whether a part's legal or not, so we're definitely running into it."

Non-compliant lighting is a safety issue, because it isn't as bright as it should be. Some of these non-compliant lamps meet less than half of the required light output that's necessary to meet DOT requirements. These products also tend to be of inferior quality, meaning they don't last as long as they should.

"A lot of these products don't have the features in them that are going to allow them to live the life of the vehicle," says Brad Van Riper, vice president of research and development at Truck-Lite.

Through a trade group called the Transportation Safety Equipment Institute, major lighting manufacturers buy samples of various lamps and test them for compliance. "We're finding grossly noncompliant products in the marketplace," says Van Riper. That information is sent to the National Highway Traffic Safety Administration, which is responsible for enforcing the lighting standard.

The rise in non-compliant lamps has coincided with the increasing popularity of LED lighting. Unscrupulous companies are using low-quality LEDs, says Van Riper. "Many times a supplier will qualify the compliance using good LEDs, then go into production without the proper care to ensure that the rest of the production meets the requirements. Some of that could be honest mistakes, but I think it's pretty clear that you can buy much lower-cost LEDs if you don't want to produce parts you don't have to take responsibility for."

Non-compliant lighting is even showing up on original equipment, Murphy says. "OEMs can get caught, too, because they look at the cost of a product from offshore," Murphy says. "If they get a certificate [of compliance] from the source, it may not be valid, but they may put the part on the vehicle and not realize they're not meeting the law."

Lighting makers applaud the recent addition of two enforcement engineers to NHTSA's staff who will be taking aim at noncompliant lighting. In addition, many experts in the industry support a rewrite of FMVSS-108, which is in the works.

The rule has been on the books for more than 30 years, amended in a piecemeal fashion, with more interpretations on record than any other federal vehicle safety standard, according to TSEI. The rewrite will make the standard easier to understand and easier to enforce.