Frequently Asked Questions

Most lights are made from polycarbonate which is the toughest, highest melting plastic generally available. However, it can be attacked (which causes cracking) by some chemicals or cleaners. The answer is to avoid incompatible cleaners and/or to use Diamond Shell protected products.

Yes. The Federal Motor Vehicle Safety Standards clearly state that measuring the performance and color of a lamp assembly is done with the light source energized. There is nothing illegal or non-compliant about red or yellow LEDs behind a clear lens, as long as the effective color of the light when illuminated is red or yellow, per SAE J578C requirements as specified in FMVSS-108.

No, reflectors are a legal requirement. Placed as far apart as practicable, they indicate the trailers presence and width/length to other vehicles on the road.

P2 is the minimum standard for clearance, side marker, and identification lights. All Truck-Lite lights meet this standard, even if they are marked PC, P3, etc. PC lights are to be used as a combination light, meaning the light should be mounted on a 45° bevel at the corner of the vehicle, allowing clearance and marker functions to be combined into one light. A PC light can always be used anywhere a P2 light would have been used, but the reverse is not true.

You should be careful to avoid getting paint on the lights; most paints (excluding water based) are incompatible with polycarbonate lights. They may also cause wires or cable insulation to crack.

Hazing and cracking are almost always caused by incompatible chemicals or cleaners. Although polycarbonate lenses are generally very durable, they can crack due to the combination of stress induced by the molding process combined with accelerated chemical exposure.

No, a proper fix is required for safe and efficient operation. Under-voltage is often caused by poor electrical connections.

Yes, the Model 40 with reflex reflector ring can be used in the following situations:

• On any vehicle under 80” wide
• As an “extra” light on over 80” (reflex is legal)
• On vehicles made in 1991 or earlier, when installed by the vehicles owner (although most states enforce the federal requirement)

The legality of a lamps positioning varies on a case-by-case basis, often requiring a special lab test for each position. However, Truck-Lite products specifically state the proper mounting position(s), so you can be sure that your lamp and its positioning are fully compliant with all regulations.

No. There is nothing illegal or non-compliant about having red or yellow LEDs behind clear lenses. When illuminated, the effective colors of the lights are red or yellow, which are approved colors of SAE J578c requirements. Clear lenses are legally approved for SAE J578c regulations as well. For a specific statement of the requirements, please review the NHTSA regulations charts.

On December 1, 1991, the National Highway Traffic Safety Administration (NHTSA) made effective the final ruling regarding the 12 Square Inch Rule. This ruling requires that the total luminous lens area for a stop and turn light must not be less than 75 centimeters squared (11.625 square inches) when used on vehicles over 80-inches wide. It must be noted that a reflex reflector ring cannot be counted as square inch lens area. When the reflex ring is subtracted from the total 12-inch lens, it leaves less than the 12 square inches required.

Over-torquing will generally cause cracking or distortion. Use the torque specifications provided by the manufacturer. A marker light will generally be in the neighborhood of 8 to 20 inch lbs., but a good rule of thumb is to use the minimum torque necessary to secure the device.

States can regulate anything not covered by FMVSS-108, such as any accessory lamps or lamps that are not mandated by FMVSS-108. Generally, the problem is in these areas; sometimes, however, it can simply be a mistake. In that case, Truck-Lite can often write a letter to clarify the issue.

Mild soap and water is usually enough. Caution is necessary if further cleaning is required, as many common household cleaners are not compatible with polycarbonate.

As you are likely aware, the three marker lamps at the top-rear of the trailer, mounted around the center line of the vehicle, are called "identification lights." Their purpose is to alert following drivers that the vehicle with these lights is a commercial vehicle wider than 80 inches. The regulations for mounting locations are, in Canada: at the top, and maybe lower if the door header is narrower than 25 mm; and in the U.S.: "as high as practicable."

For a period of time in the late 1990s, there was a U.S. interpretation that allowed lower mounting of these lamps, but it has since been clarified to require that all lamps are mounted as high as practicable. One case in which they can be mounted lower is for flatbed trailers that have no high structure; it is allowable to mount them in the rear sill of the trailers. With the development of very small LED identification lights, it becomes much easier to locate the lamps in the upper header of most van trailers and most trailers in general.

One other element of the law is that the mounting of lamps is often at the discretion of the vehicle OEM, who is responsible for compliance certification. This certification will be accepted by the NHTSA unless it is "clearly erroneous."

To comply with the spirit of the law, it is recommended that a trailer is designed so that the rear ID lamps can be mounted at a high level. This would avoid regulatory scrutiny, as well as any accident-related product liability issues. Truck-Lite is aware of issues that some trailer manufacturers have experienced with new trailers being held up at the U.S./Canada border due to the lower mounting of lamps, when, in the view of the inspector, the lamps could have been mounted higher.

Everyone loves a good deal, but it almost goes without saying: cheaper is not always better. This is especially true when it comes to safety products. Many times, the compromises that go into a less costly item are downright dangerous. One common strategy that gray market manufacturers use is to copy the appearance of a more established product. The product might look the part, but it often doesn't function like it. The product is often not labeled with the company name. When this happens, the customer is left with no recourse when they encounter a problem.

Checklist for identifying suspect products:

• Always check to see if the actual parts have the manufacturers name and part number on the product
• Is there a lot code or date code that gives you any traceability?
• Does the product have any industry-standard labelling indicating the function of the lighting device?
• What is the design voltage range of the device?
• Does the supplier have a US address? This is important, as exterior lighting products for vehicles are regulated by the Federal Motor Vehicle Safety Standards. If the supplier does not have a US address, the importer of record is the responsible party for compliance to those federal standards.

Efficient design of the circuit is the key to ensuring that the LED lamp assembly will be robust and last for a long time. One key factor is to ensure that the discrete LEDs are operated below their maximum rating. The Truck-Lite Engineering group has been designing LED circuits since 1990 and Truck-Lite have found many different ways of extending the life of the lamp assemblies.

No. In fact, at Truck-Lite’s R&D lab, the original prototype LED stop/turn/tail light has been blinking since 1998!

As you may know, LED lights are monochromatic. Monochromatic means that red LEDs only produce red light, amber LEDs only produce amber light... but now there are white LEDs. White light is often produced by using a blue LED covered by a ceramic phosphor coating. When the blue wave length light is produced, the phosphor releases photons that fill the spectrum and produces white light. Sometimes Truck-Lite use white LEDs with colored lenses to get red or amber lights but this is not common. To answer the question, you needed to know the above information. The color of the light often indicates the lifespan of the LED Lighting. Red LEDs are known to be the longest lasting products, followed by white LEDs, with amber LED technology deteriorating more quickly. The good news is that LED lighting frequently exceed 50,000 hours of life.

Given its weather resistance and clarity, acrylic has long been the most widely used material for lenses. However, polycarbonate is much less likely to shatter, chip or crack upon impact and can withstand higher exposure to heat. Polycarbonate lenses are given a special coating to improve abrasion, UV and chemical resistance; still, to prolong the life of your lenses, it is recommended that you only clean them with a mild detergent and soft cotton cloth.

By nature, LED lights are polarity-sensitive. If the voltage is of the wrong polarity, it is said to be reverse-biased. Very little current will flow, and the device will not light up. Truck-Lite has developed LED lights that are not polarity-sensitive. This is normally indicated in the features and benefits of such a product

Truck-Lite offers a variety of warranties, depending on the product.

Lighting that goes beyond the legal requirements of FMVSS 108 is called auxiliary lighting. Auxiliary lighting can be added to the vehicle as long as it does not cause confusion or impair the effectiveness of any of the required lights.