ID: aiam3787

Dear Mr. Suuronen: This is in response to your letter of November 30, 1983, clarifyin your earlier requests for an interpretation of Standard No. 108. You have asked whether replaceable bulb headlamps may be manufactured in sizes identical to the current sizes for sealed beam headlamps, provided that they meet Standard No. 108 in all other respects.; The replaceable bulb headlamp amendment was adopted with the intent o allowing vehicle manufacturers greater flexibility in the front end design in order to improve aerodynamics. The amendment allows an original equipment two-lamp system of no specified dimensions, and replacement lamps for these systems. It was not directed towards replacement lamps for existing headlamp systems. However, because no exterior dimensions for headlamps are specified by the amendment, replaceable bulb headlamps intended for use in a two-lamp system, with exterior dimensions of sealed beam round or rectangular two-headlamp systems, would be permissible assuming that they meet all other requirements of Standard No. 108, including proving one of the two aiming pad locations specified for replaceable bulb headlamps. However, until Standard No. 108 is amended to allow a four-lamp replaceable bulb headlamp system, these lamps are precluded from being manufactured to replace today's sealed beam round and rectangular sealed beam headlamps used in four-lamp systems.; I hope this provides the clarification you seek. Sincerely, Frank Berndt, Chief Counsel

ID: aiam4999

"Dear Mr. Twyford: This responds to your letter of April 21, 1992, t the Federal Highway Administration, which has been forwarded to this agency for reply. You wish to complain 'about some makes of new cars that have two sets of headlights (4) which operate at the same time.' If this agency plans to do nothing about it, you 'plan to take this matter up with Congressmen and U.S. Senators.' You are not alone in your concern about headlamp glare created by new motor vehicles. Other citizens have brought the subject to the attention of Members of Congress. I enclose a copy of a recent letter from the Deputy Administrator of this agency to Senator Cohen of Maine which is representative of our views on this issue. You will see that a number of factors may be responsible for creating a perception of glare. We note that you have already been in touch with the Department of California Highway Patrol, and that California has no periodic motor vehicle inspection. With respect to the specific comments in your letter, the agency does not 'approve' specific headlamp designs. Standard No. 108 sets forth photometric performance requirements to be met on both the upper and lower beam, and does establish maximum limitations at some of the photometric test points. Further, in a four-headlamp system, the upper and lower beams may be provided by all headlamps. Headlamp manufacturers must ensure that their products meet these requirements, and certify that each headlamp complies by placing a 'DOT' mark on the lamp. There is no requirement that a manufacturer obtain permission from this agency before introducing the lamps into the market. We appreciate your concern. Sincerely, Paul Jackson Rice Chief Counsel Enclosure";

ID: aiam2140

Dear Mr. MacEachern: This is in reply to your letter of November 4, 1975, telling us of you wish to market a rectangular sealed beam headlamp unit for motorcycles. In your opinion this might be prohibited by 'federal inaction to update FMVSS-108 SAE J584 April 1964 to the amended SAE J584b December 1971.'; Substitution of J584b would not be a solution to your problem since i does not specify a Type 2A sealed-beam headlamp unit as one of the approved options. There would have to be both a substitution of J584b and a provision in Standard No. 108 itself that either a Type 2 or Type 2A sealed beam headlamp unit may be used. I enclose a copy of a regulation that tells how you may submit a petition for rulemaking for an appropriate amendment to Standard No. 108.; You also enclosed a letter from the California Highway Patrol statin that it was amending its regulations; >>>'to allow the use of motorcycle headlamps which comply with the typ 2 lower beam photometric requirements and the motorcycle upper beam requirements, though we are not sure what position NHTSA would take upon this interpretation'.<<<; Such action by the California Highway Patrol appears precluded b Section 103(d) of the National Traffic and Motor vehicle Safety Act of 1966. The effect of this section is to prohibit California from having a State lighting standard that differs in any way from Standard No. 108. Since the Federal lighting standard does not allow the California amendment, the State regulation appears invalid.; Notwithstanding California's 'approval' of your headlamp, your sale o this rectangular headlamp for motorcycles as either original equipment or as replacement equipment (but only for motorcycles manufactured on or after January 1, 1972) would appear to be a violation of Section 108(a) (1) (A) of the Act, unless and until Standard No. 108 is amended. There is a maximum penalty of $1,000 for each violation, up to $800,000 for any related series of violations.; Yours truly, Richard B. Dyson, Assistant Chief Counsel

ID: 571.108--Supplement beam--Boykin--16-0884

Mr. Marcus Boykin

B-G Innovative Safety Systems, LLC

79 Pasture Road

Lexington, TN 38351

Dear Mr. Boykin:

This responds to your letter asking about the application of Federal Motor Vehicle Safety Standard (FMVSS) No. 108, “Lamps, reflective devices, and associated equipment,” to a lighting system your company has developed.  In your letter and phone conversation with John Piazza of my staff, you describe your product as “an auxiliary vehicle lamp operating system” for use both as original equipment (OE) and as aftermarket equipment.

You state that your product, which adapts to the existing headlight wiring harness, provides a supplemental lower beam from the existing upper beam when the lower beam fails.  We understand that, when the lower beam is not in a failed state, the headlight system, controls, and telltales function normally.  If the lower beam is selected and has failed or does fail, your system provides a supplemental lower beam from the existing upper beam.  You state that the lighting on the converted upper beam is “diffused down to the same output illumination as” the lower beam.  If the upper beam is selected, the upper beam will continue to function normally. 

We further understand that, with respect to the OE version of your product, you contemplate a dashboard warning to warn the driver that the normal lower beam is not functioning.  In the aftermarket version of your product, once the vehicle’s lower beam has failed and your device is providing a supplemental lower beam, every time the engine is started the headlights will flash three times to warn the driver that the original equipment lower beam is not operating and that your device is providing a supplemental lower beam.  You state that you are seeking “interpretation and approval” of your device.

As we explain below, while NHTSA does not provide approvals of motor vehicles or motor vehicle equipment and does not make compliance determinations outside of an agency compliance proceeding, we are able to provide you with our interpretation of how NHTSA’s statute and regulations would apply to your product as you have described it to us.  We believe that your product would be considered supplemental lighting.  As such, it may be installed as original equipment as long as it does not impair the effectiveness of any required lighting.  If your product is offered as aftermarket equipment, it would not be directly subject to FMVSS No. 108 but would be subject to the Safety Act’s make inoperative prohibition.

Background

The National Highway Traffic Safety Administration (NHTSA) is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act), 49 U.S.C. Chapter 301, to issue Federal motor vehicle safety standards that set performance requirements for new motor vehicles and new items of motor vehicle equipment.  NHTSA does not provide approvals of motor vehicles or motor vehicle equipment and does not make determinations as to whether a product conforms to the relevant FMVSS outside of an agency compliance proceeding.  Instead, the Safety Act requires manufacturers to self-certify that their products conform to all applicable FMVSSs.  Manufacturers must also ensure that their products are free of safety-related defects.

This letter provides you with our interpretation of how the statute and regulations administered by NHTSA would apply to your product as you have described it to us, based on our understanding of the information provided.  This is not an “approval” of your product.

Vehicle lighting sold as OE is regulated under FMVSS No. 108.  (All references in this letter are to subsections of FMVSS No. 108 unless otherwise noted.).  FMVSS No. 108 requires vehicles to be equipped with certain types of lamps (known as “required” lamps), which must meet very specific and detailed performance standards.[1]  All other lamps are considered “supplemental” lamps.[2]  Unlike OE required lamps, OE supplemental lamps are not required to meet any specific performance requirements.  However, they are required to comply with certain generally-applicable provisions of FMVSS No. 108.  One of these provisions is set forth in S6.2.1, which states: “No additional lamp, reflective device, or other motor vehicle equipment is permitted to be installed that impairs the effectiveness of lighting equipment required by this standard.”

Both OE and aftermarket vehicle lighting are subject to the Safety Act’s “make inoperative” prohibition (49 U.S.C. § 30122), which prohibits a manufacturer, distributor, dealer, rental company, or motor vehicle repair business from knowingly making inoperative any part of a device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable FMVSS.  While this “make inoperative” prohibition does not apply to individual vehicle owners, NHTSA encourages vehicle owners not to remove or otherwise tamper with vehicle safety equipment.  Also, any modifications made by a vehicle owner would have to comply with applicable state law. 

Discussion

FMVSS No. 108 requires vehicles to be equipped with one of several permissible headlighting systems.  Headlighting systems are comprised of headlamps and associated hardware.  The purpose of headlighting is primarily to provide forward illumination.[3] 

The threshold issue presented by your request is whether your product is part of the required headlighting system, and thus subject to FMVSS No. 108’s requirements applicable to headlighting systems or, instead, supplemental lighting that is regulated by FMVSS No. 108’s impairment provision.   

In determining whether lighting equipment that provides forward illumination is part of the required headlighting system or, instead, supplemental lighting, NHTSA looks at several factors.  These include: (1) where the lamp directs its light; (2) whether it uses a headlamp replaceable light source to emit a beam that provides significantly more light flux than supplemental cornering lamps or fog lamps; (3) whether the lamp is intended to be used regularly, or is limited to more narrow driving conditions and situations; (4) whether the vehicle’s complete lighting system, not including the lamp in question, would include all of the forward lighting equipment required by FMVSS No. 108;  (5) whether there is a manual on/off switch; and (6) whether the lighting feature is one that activates only upon the failure of an element of the required headlighting system and acts as a temporary backup of that lighting element.[4] 

The last of these factors is most relevant to your product.  Prior agency interpretations have found that a lighting feature that activates an upper beam light source when the lower beam fails or a lower beam headlamp upon the failure of an upper beam headlamp is supplemental lighting.[5]  The system you describe activates a back-up beam only upon the failure of the required lower beam.  Accordingly, we believe it is supplemental lighting. 

Since you contemplate selling your supplemental lighting device as original and/or aftermarket equipment, we will consider the requirements affecting each of these.

Supplemental lighting installed as original equipment

Supplemental lighting installed as OE (i.e. before sale to first purchaser other than for resale) is permitted if the lighting does not impair the effectiveness of any lighting equipment required by FMVSS No. 108 (S6.2.1).  If you are the manufacturer of original lighting equipment required by FMVSS No. 108, but not the manufacturer of the vehicle on which it is installed, the vehicle manufacturer, and not you, has the legal responsibility under the Safety Act to certify that the vehicle complies with FMVSS No. 108 and all other applicable FMVSSs.  Accordingly, the vehicle manufacturer must certify that supplemental lighting installed as OE complies with S6.2.1.  Effectiveness may be impaired if, among other things, the device creates confusion with the signal sent by another lamp, or functionally interferes with it, or modifies its candlepower to either below the minima or above the maxima permitted by the standard.[6] 

Table XIX has specific photometry requirements (maxima and minima) for lower beams.  Activation of an upper beam light source when a lower beam source fails raises considerations of glare.  The lower beam maxima are meant to ensure that other roadway users are not glared.  If your device produces a supplemental beam that exceeds the lower beam photometric maxima, we would consider that to impair the effectiveness of the headlighting system.  Accordingly, your device needs to modify the upper beam to ensure that the lower beam photometric maxima are not exceeded. [7]  Because your device is supplemental lighting, it would not be required to provide sufficient illumination to meet or exceed the photometric minima required for a lower beam headlamp.  However, we note that by reducing the output illumination of the upper beam to that of the lower beam, the reduced upper beam would provide only a limited amount of illumination that may not be sufficient to usefully illuminate the road. 

For your information, we also point out below several other requirements of which you should be aware in designing and manufacturing your product.  (Note that it is the responsibility of manufacturers, and not NHTSA, to identity all FMVSSs applicable to their products and certify the compliance of their products with the standards.)

• Your product must not interfere with the activation and operation of the upper beam.    
•  It may not impair the effectiveness of the upper beam headlamp indicator required by S9.5.  When your device is providing a supplemental lower beam, it should do so in a way that the upper beam indicator is not activated.  Also, when the driver (or vehicle, if it has a semiautomatic headlamp beam switching device, or automatic headlights) has activated the upper beams, the upper beams must be activated and the upper beam indicator must be activated.  
• S9.4 requires that “the lower and upper beams must not be energized simultaneously except momentarily for temporary signaling purposes or during switching between beams.” 
• The headlamps must be steady burning, except that they may be flashed for signaling purposes.[8]  We would not consider your system’s momentary flashing function as violating this requirement because it is similar to a signaling function and would not be likely to confuse other motorists because it only flashes upon start-up.  
• The device generally should not function in such a way that it would be likely to confuse other motorists (for example, it should not mask the ability of other drivers to perceive the front turn signal).
• If a telltale or control is offered as original equipment, it must comply with any relevant requirements in FMVSS No. 101, “Controls and displays.”

We wish to point out that Table I-a requires that “[t]he wiring harness or connector assembly of each headlighting system must be designed so that only those light sources intended for meeting lower beam photometrics are energized when the beam selector switch is in the lower beam position[.]”  Although it may appear that a device such as yours might not meet this requirement, NHTSA has interpreted the requirement otherwise. 

This issue arises if the lower beam is activated (with the beam selector switch in the lower beam position) and then fails, after which a system (such as yours) activates a modified upper beam as a backup lower beam.  If the backup lower beam utilizes upper beam light sources that are not normally used for meeting lower beam photometrics, the backup lower beam might be viewed as violating this requirement.[9]  However, prior interpretations have concluded that this Table I-a requirement does not apply to a failure condition in which a supplemental beam supplements a failed lower or upper beam, assuming the supplemental light does not otherwise impair the effectiveness of any required lighting.[10]  Applying that line of reasoning, we believe that your system would not create a noncompliance with the Table I-a requirement.

Supplemental lighting offered and installed as aftermarket equipment

Supplemental lighting offered as aftermarket equipment (accessory lighting) is not directly subject to FMVSS No. 108, which applies only to original equipment and lighting equipment manufactured to replace original lighting equipment required by FMVSS No. 108.  Section 30122 of the Safety Act, however, prohibits a manufacturer, distributor, dealer, rental company, or motor vehicle repair business from knowingly making inoperative, in whole or in part original required lighting equipment.  In applying the make inoperative prohibition to accessory lighting we typically ask whether the accessory lighting would impair the effectiveness of any required lighting.  Generally, if an item of accessory lighting would not be permitted as original equipment, commercial entities will not be permitted to install the lighting as an aftermarket accessory for a vehicle in use.  Thus, the make inoperative analysis is generally the same as the impairment analysis we applied above in the context of supplemental lighting installed as original equipment.  We observe that, due to varying headlamp designs throughout the vehicle fleet, there may be potential compatibility issues with the product you describe and certain vehicles.  In addition, manufacturers of aftermarket lighting accessories are subject to the Safety Act’s defect notification and remedy requirements discussed above.    

We also note that manufacturers of equipment to which an FMVSS applies must meet the manufacturer identification requirements set out in 49 CFR Part 566.  For these and other requirements, you may consult NHTSA’s New Manufacturers Handbook, available at https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/manufacturer_information_march2014.pdf.

If you have any further questions, please contact John Piazza at (202) 366-2992.

Sincerely,

Jonathan Morrison

Chief Counsel

Dated: 5/17/19

Ref: FMVSS No. 108

[1] The standard’s performance requirements also apply to lamps that are “for replacement of like equipment on vehicles to which this standard applies.”  On a related matter, we note that you state that “drivers with a failed light are out of compliance.”  This is incorrect, as FMVSS No. 108 does not regulate lighting in use.  Therefore, if a headlamp fails in operation, the vehicle is not “out of compliance” with the Federal standard (state laws may apply to in-use performance).

[2] NHTSA also uses the term “auxiliary” lamps.

[3] S4 (“Headlamp means a lighting device providing an upper and/or a lower beam used for providing illumination forward of the vehicle.”) (Formatting in original.)

[4] Letter to [Redacted] (Jan. 21, 2004) ((1)-(5)), available at https://isearch.nhtsa.gov/files/swivelinglamp.3.html (last accessed June 20, 2018); letter to L. W. Camp, Ford Motor Company (July 15, 1998) ((6)), available at https://isearch.nhtsa.gov/files/18080.ztv.html (last accessed June 20, 2018). 

[5] Letter to L. W. Camp, supra (lower beam backing up upper beam); letter to Ian Goldstein, Safe Passage Technologies (July 21, 1998) (upper beam backing up lower beam), available at https://isearch.nhtsa.gov/files/18164.ztv.html.

[6] See, e.g., letter to Byung M. Soh, Target Marketing Systems, Inc. (Sept. 13, 1988), available at https://isearch.nhtsa.gov/gm/88/nht88-3.100.html (last accessed June 20, 2018).

[7] Letter to Ian Goldstein, supra (“Because headlamps are primarily operated on the lower beam, activation of an upper beam light source when a lower beam source fails raises considerations of glare . . . the upper beam in this instance ideally should be activated at a markedly reduced intensity such that it does not impair the effectiveness of required lighting devices [S6.2.1], or, more specifically, that, as a lower beam substitute[] it does not compromise turn signal visibility.”)

[8] Table I-a.

[9] Whether this would occur depends on the design of that particular headlighting system.  For example, this would not be the case if the headlighting system used the same light sources for both the lower and the upper beams.

[10] Letter to L. W. Camp, supra (lower beam supplementing failed upper beam).  See also letter to Ian Goldstein, supra (modified upper beam supplementing failed lower

ID: aiam2437

Dear Mr. Iwase: This is in response to your letter of November 2, 1976, regardin questions on Docket No. 75-8, Notice 5, for a two-lamp rectangular headlamp system. The answers are provided in accordance with the paragraph numbering of your letter.; >>>1) The two-lamp rectangular headlamps must meet the requirements o SAE J579c.<<<; This is an improved performance lamp over the requirements of SAE J579 and, therefore, must meet the requirements of SAE J579c.; >>>2) The maximum permissible candela for the Type 2B headlamp i 75,000 as specified in SAE J579c. The lower limit for other types of headlamps is retained awaiting future rulemaking action.; 3) SAE J580b as specified in the 1976 edition of the SAE Handbook i the correct reference specification for the Type 2B Sealed Beam Headlamp Assembly.; 3-1) Answered above 3-2) Answered above 3-3) Appropriate revisions to subreferenced SAE standards have at thi time not been made for the Type 2B headlamp. In the case of SAE J580b, conducting the tests with a modified deflectometer to fit the Type 2B lamp would be sufficient. It is anticipated that revisions will soon be made to the appropriate subreferenced SAE standards for the Type 2B headlamp.<<<; Your suggested revisions for the referenced and subreferenced SA standards to incorporate the Type 2B headlamp, including a modified design of deflectometer, may be sent directly to:; >>>Society of Automotive Engineers, Detroit Office, Suite 206, 210 West Big Beaver, Troy, Michigan 48084, ATTENTION: Mr. James Tishkowski<<<; We hope this clarifies the questions contained in your letter. If yo have additional questions, please do not hesitate to contact us.; Sincerely, E. T. Driver, Director, Office of Crash Avoidance, Moto Vehicle Programs;

ID: aiam5648

"Dear Ms. Vredenburgh: This is in reply to your letter of September 18 1995, to Kenneth Hardie of this agency, with respect to the Motorcycle Conspicuity Enhancement System (the 'System') described in your letter. You understand 'that this system may only be used during daylight hours and may not affect the headlight', and you ask if there are any other regulations of which you should be aware. We understand that the System is still under development, and that the intent is to offer it both as original and aftermarket equipment. Two Systems will be tested, at a flash rate of 60 to 80 per minute, one at an intensity of 35,000 candlepower, and the other at 50,000 candlepower. One System will have three bulbs, and another, four. Each System will be activated when the headlamp is on. We note that motorcycle headlamps are wired to be activated when the ignition is on because many States require that headlamps be operating at all times. As you know, each motorcycle must be manufactured and certified to conform to all applicable Federal motor vehicle safety standards, including Standard No. 108 Lamps, Reflective Devices, and Associated Equipment. Standard No. 108 prescribes no requirements for supplemental equipment such as the System. However, additional lighting equipment may not be installed by the manufacturer or dealer before sale if the supplemental equipment impairs the effectiveness of lighting equipment required by Standard No. 108 (paragraph S5.1.3). You are therefore correct when you say that the System 'may not affect the headlamp.' One way in which the System could impair the effectiveness of the headlamp is if it continued to operate at a time when the headlamp is required to provide sufficient illumination of the roadway (as you recognize in your comment that 'the system may only be used during daylight hours'). You have not described the method by which the System will be deactivated. We believe that this should not be a manual operation, left to the discretion of the motorcycle operator. In establishing the specifications that allow optional installation of modulating headlamp systems for improving the conspicuity of motorcycles, this agency requires that they be equipped with a sensor that will deactivate the modulation when a certain low ambient light level is reached. Also, the modulation rate is regulated to prevent seizures in susceptible individuals. I enclose a copy of paragraph S5.6 of Standard No. 108 which discusses these light levels. The System must also not impair the effectiveness of the motorcycle's front turn signals. That is to say, it must not mask the signal or detract from its detectability by oncoming drivers. Whether this might occur will depend upon the color and brightness of the System and its proximity to the turn signal lamp. If a motorcycle manufacturer is satisfied that the installation of the System on its product would be permissible under S5.1.3, then it may certify that the motorcycle conforms to all applicable Federal motor vehicle safety standards. NHTSA will not question a determination of non-impairment unless it appears to be clearly erroneous. Satisfaction of Federal new vehicle requirements means that the System is acceptable for sale in the aftermarket under Federal regulations. However, supplementary lighting equipment, whether original or aftermarket, that is not specifically covered by Standard No. 108 remains subject to regulation by the States. We note that many States have vehicle equipment and use regulations regarding auxiliary amber flashing lamps, Many States also prohibit blue as a color for lamps, reserving it for police, fire, and emergency vehicles. We are unable to advise you on the specifics of State laws, and urge you to consult the American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, Va. 22203. If you have any further questions, you may refer them to Taylor Vinson of this Office (202-366-5263). Sincerely, Samuel J. Dubbin Chief Counsel";

ID: NCC-231121-001 Autoliv (Veoneer) Spotlight Interpretation 1

June 27, 2024

Richard Seoane 

VP Operations and Business Development 

Thermal Product Area 

Veoneer 

420 South Fairview Avenue Goleta, CA 93117 

Dear Mr. Seoane: 

This responds to your request dated October 10, 2016, concerning the application of Federal Motor Vehicle Safety Standard (“FMVSS”) No. 108, Lamps, reflective devices, and associated equipment, to a lighting system you describe in your letter. As I explain below, based on your description of the system we agree that it is supplemental lighting, but disagree with your assertion that it would not impair the effectiveness of any of the required lighting equipment. 

In responding to this request, the National Highway Traffic Safety Administration (NHTSA) notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Description of the Marking Light and the Request for Interpretation 

In your letter, you request an interpretation of FMVSS No. 108 as applied to an auxiliary light designed to prevent nighttime crashes (the Marking Light). As you describe it, the Marking Light consists of two auxiliary spotlights operated independently of the headlighting system. The spotlights are mounted symmetrically about the vertical centerline of the vehicle, below the headlamps, and pointed down at a fixed angle. The Marking Light operates independently of the upper and lower beam headlamps to produce a narrow, white-light beam pointed down to highlight the path to an object (such as a pedestrian) in or near the forward roadway so that the driver can see it. The Marking Light is activated and controlled by Autoliv’s Night Vision System, which has an infrared camera that detects pedestrian, bicyclist, and animal hazards up to 100 meters in front of the vehicle. The Night Vision System alerts the driver with in-vehicle 

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Richard Seoane 

visual (e.g., head-up display icon and/or dash icon) and audible signals indicating activation of the Marking Light and directs the Marking Light to illuminate the path over the ground to the hazard to visually alert the driver of the presence and location of the hazard. The system does not engage vehicle steering or brakes. The Marking Light cannot be activated manually by the driver or continuously operated; it is activated only by the night vision system when a hazard is detected to assist the driver in seeing the hazard but does not assist the driver in seeing the roadway. You state that the Marking Light is disabled in the presence of oncoming and preceding traffic so that it does not glare drivers on a wet or shiny roadway. 

You explain your position that the Marking Light is a supplemental lamp, not a required lamp such as a headlamp. You then make a variety of different arguments (and provide data) to support your view that the Marking Light does not impair the effectiveness of any of the required lighting. We summarize these arguments in more detail where relevant in the discussion below. 

Applicable Requirements 

FMVSS No. 108, which is codified at 49 C.F.R. § 571.108, sets requirements for vehicle lighting. The standard requires a variety of types of lighting, depending on vehicle type and size, and specifies requirements for these required lighting elements. The standard also sets requirements (referred to as “if equipped” requirements) for some non-mandatory lighting devices, such as daytime running lamps. 

Lighting devices that FMVSS No. 108 does not require or regulate as “if equipped” lighting devices are considered supplemental (or auxiliary) lighting devices. Supplemental lighting is generally permitted as long as it does not impair the effectiveness of any of the lighting equipment required by the standard. See FMVSS No. 108 S6.2.1 (also referred to as the “impairment” provision). 

FMVSS No. 108 applies only to original equipment and lighting equipment manufactured to replace original lighting equipment required by FMVSS No. 108. The standard does not directly apply to supplemental lighting devices sold in the aftermarket. Instead, supplemental lighting offered as an aftermarket accessory is subject to the “make inoperative” prohibition (49 U.S.C. § 301222), which prohibits certain specified commercial entities (such as dealers or repair shops) from taking a vehicle out of compliance with an FMVSS. In applying the “make inoperative” prohibition to aftermarket accessory lighting, NHTSA typically asks whether the accessory lighting would impair the effectiveness of any required lighting. Generally, if an item of accessory lighting would not be permitted as original equipment, commercial entities will not be permitted to install the lighting as an aftermarket accessory for a vehicle in use. 

While the vehicle manufacturer has the legal responsibility under the National Traffic and Motor Vehicle Safety Act (Safety Act) to certify that the vehicle complies with FMVSS No. 108 and all other applicable FMVSS, as a practical matter, vehicle manufacturers generally insist that equipment manufacturers provide assurance that their products meet federal standards. The judgment of impairment is one made, in the first instance, by the person installing the device. That decision, however, may be questioned by NHTSA if it appears clearly erroneous. 

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Richard Seoane 

Discussion 

The threshold issue presented by your request is whether the Marking Light is part of the required headlighting system and thus subject to the requirements applicable to headlighting systems, or supplemental lighting that is regulated by FMVSS No. 108’s impairment provision. We agree with you that the Marking Light would be considered supplemental lighting. 

FMVSS No. 108 requires vehicles to be equipped with one of several permissible headlighting systems.1 Headlighting systems are comprised of headlamps and associated hardware. The purpose of headlamps is primarily to provide forward illumination.2 In determining whether lighting equipment that provides forward illumination is part of the required headlighting system or supplemental lighting, NHTSA looks at several factors. These factors have included, among other things: (1) where the lamp directs its light; (2) whether it uses a headlamp replaceable light source to emit a beam that provides significantly more light flux than supplemental cornering lamps or fog lamps; (3) whether the lamp is intended to be used regularly, or is limited to more narrow driving conditions and situations; or (4) whether there is a manual on/off switch.3 

None of our previous interpretations appear to have addressed a frontal lighting concept precisely like the Marking Light. We agree with you, based on the information you have provided us, that it is supplemental lighting because it is not intended to be used regularly, but is instead a narrow beam that is activated only when there is a hazard forward of the vehicle such as a pedestrian or animal near the roadway. 

Because the Marking Light would be considered supplemental lighting, it is permitted as long as it does not impair the effectiveness of any lighting equipment required by the standard. In its previous interpretation letters, NHTSA has identified a number of different ways that a supplemental lamp could impair the effectiveness of the required lighting.4 

With respect to the Marking Light, there are two types of impairment that are potentially relevant. One is the potential to confuse other drivers arising from the Marking Light’s color, location, or activation pattern.5 The other potentially relevant type of impairment is the potential for glare to other road users due to the intensity of the Marking Light. We address each of these potential types of impairment below. 

1 FMVSS No. 108 Table I-a; S10.
2 FMVSS No. 108 S4 (“Headlamp means a lighting device providing an upper and/or a lower beam used for providing illumination forward of the vehicle.”).
3 See Letter from Jacqueline Glassman, Chief Counsel, to [Redacted] (Jan. 21, 2004). Prior to the 2004 interpretation letter, NHTSA issued several interpretations concerning auxiliary driving beams in which the agency treated those lamps as supplemental lighting without expressly considering the issue. See, e.g., Letter from Erika Z. Jones, Chief Counsel, to P. Soardo, Instituto Elettrotecnico Nazionale (May 22, 1987). If the lamps in question in those earlier interpretations would be considered supplemental lighting under the factors set forth in the 2004 interpretation, they may be consistent with that later interpretation. There is not, however, sufficient information about the lighting systems at issue in those earlier interpretation letters to allow application of the factors from the 2004 interpretation. In any case, the 2004 interpretation has been, to date, NHTSA’s view of the issue.
4 See, e.g., Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019).
5 See id. 

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Richard Seoane 

Color and Location 

The impairment provision prohibits auxiliary lamp colors that are likely to confuse other road users.6 For auxiliary lamps located on the front of the vehicle, colors that could cause confusion include red (which could be confused with a tail lamp), green (which could be confused with a traffic signal), and blue (which could be confused with a law enforcement vehicle).7 

You state that because the Marking Light is white, it cannot be confused with a turn signal and would not conflict with the emergency (hazard) lamps or parking lamps. 

We agree that because the Marking Light is white and mounted below the headlamps, it would not likely be confused with the front turn signal (which is amber8) and would not conflict with the vehicle hazard warning (which consists of all required turn signal lamps flashing simultaneously9) or the parking lamps (which must be white or amber10). I therefore agree that the color and location of the Marking Light would not cause confusion with the vehicle’s signal lamps. 

Activation Pattern 

FMVSS No. 108 requires that all auxiliary lamps be steady burning except for auxiliary lamps that supplement required lamps that flash, such as turn signals.11 This requirement means that the lamp must be steady burning when activated, not that it is prohibited from being activated or deactivated automatically.12 However, the (de)activation of the lamp cannot be so frequent or random that the lamp would distract or confuse other road users. For example, a lamp that activates and deactivates on an extremely short time interval due to sensitivity to slight changes in conditions would not be considered steady-burning.13 NHTSA has also interpreted the steady- 

6 Id.
7 Id.
8 FMVSS No. 108 Table I-a.
9 Id. S6.6.2; S4 (definition of vehicle hazard warning signal flasher).
10 Id. Table I-a.
11 See, e.g., Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019); Letter from Anthony Cooke, Chief Counsel, to Kerry Legg, New Flyer, Inc. (Feb. 21, 2008). Before 2007, FMVSS No. 108 included an explicit requirement that, with certain exceptions (e.g., turn signal lamps), all lamps on a vehicle, including auxiliary lamps, must be steady burning. In 2007, NHTSA implemented an administrative rewrite of FMVSS No. 108 which, among other things, converted the blanket “steady burning” requirement (and its exceptions) into individual activation requirements for each type of required lamp. See 72 FR 68234 (Dec. 4, 2007). Although the reorganized rule no longer includes a blanket “steady burning” requirement, NHTSA stated in the preamble to the reorganized rule that its “rewrite of FMVSS No. 108 is considered administrative in nature because the standard’s existing requirements and obligations are not being increased, decreased, or substantively modified.” Id. Moreover, NHTSA continues to believe that flashing auxiliary lamps would impair the effectiveness of required lamps by distracting or confusing other road users.
12 See Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019).
13 See id. 

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burning requirement to mean that headlamp intensity may modulate, but only if the changes in intensity are not detectable by the human eye.14 

You state that the Marking Light is steady burning in that it does not flash (cycle on and off). You state that the Marking Light is activated when the night vision system identifies a pedestrian, bicyclist, or large animal in or near the forward roadway as a hazard. When the object is no longer deemed a hazard, the night vision system switches off the Marking Light. We also understand that the intensity of the Marking Light does not modulate. 

We agree that, based on the facts represented to us in your letter, the Marking Light is steady burning and would therefore not violate the impairment provision in this respect. This conclusion assumes that the Marking Light does not activate and deactivate frequently (which could confuse or distract other road users) or change intensity while activated in a way that is detectable to the human eye. 

Brightness (Photometric Intensity) 

Supplemental lighting can also impair the effectiveness of the required lighting if it is so intense that it glares other road users15 or, relatedly, masks any of the required signal lighting.16 As a point of reference, we note that FMVSS No. 108 specifies two upper beam (or high beam) maxima, at H-V and 4D-V.17 The magnitude of the specified maxima depends on the type of upper beam system; for the purposes of this letter, we will compare the Marking Light to the highest specified maxima at each test point, which are 75,000 candela (cd) at H-V and 12,000 cd 

14 See, e.g., Letter from Stephen Wood, Acting Chief Counsel, to Kiminori Hyodo, Koito Manufacturing Co., Ltd. (Nov. 5, 2005); Letter from John Womack, Acting Chief Counsel, NHTSA, to Joe De Sousa (Mar. 10, 1994) (stating, in the context of a modulating motorcycle headlamp, that “there is no failure to conform if the modulating light from the lamp is perceived to be a steady beam”).
15 See, e.g., Letter from John Womack, Acting Chief Counsel, to Yoshiaki Matsui, Stanley Elec. Co., Ltd. (Sept. 20, 1995) (fog lamp supplementing lower beam) (“Finally, as a cautionary note, we believe that Stanley should evaluate the glare potential of the headlamp when the fog lamp and lower beam are operating simultaneously, as it is important to safety that oncoming drivers not be distracted or discomforted in the operation of their vehicles.”). Cf. Letter from Jacqueline Glassman, Chief Counsel, to Rusty Riggin, Willow Development (Aug. 2, 2002) (explaining that a supplemental rear cornering lamp could violate the impairment provision if it was so intense that it “create[d] distracting glare”).
16 See, e.g., Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019) (“NHTSA has in the past stated that auxiliary lamps that were so bright as to ‘mask’ adjacent required turning signal lamps would be prohibited due to impairment.”); Letter From Samuel Dubbin, Chief Counsel, to Richard Russell (Dec. 22, 1995) (“[W]e would regard the vehicle manufacturer’s certification as negated if the brightness and location of the auxiliary lamps were such as to affect an oncoming driver’s ability to perceive the front turn signals.”).
17 FMVSS 108 Table XVIII. The photometry requirements specified in Table XVIII consist of test points at which the intensity of the light is measured. The requirements at each test point consist of minima and/or maxima. The test points are defined with respect to an angular coordinate system relative to the headlamp. Thus, H-V identifies a test point zero degrees up and zero degrees down relative to the headlamp, and 4D-V identifies a test point 4 degrees down relative to the headlamp. See also Letter from Erika Jones, Chief Counsel, to Byung Soh, Target Marketing Systems (Sept. 13, 1988) (“Effectiveness may be impaired if the device creates a noncompliance in the existing lighting equipment or modifies its candlepower to either below the minima or above the maxima permitted by the standard.”); Letter from Erika Jones, Chief Counsel, to George Ziolo (Sept. 12, 1988) (vehicle equipped with two upper beam headlamp systems would violate the impairment provision because it would exceed the upper beam maxima at H-V and 4D-V). 

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at 4D-V. We consider the upper beam maxima as proper comparators because the Marking Light, like the upper beam, is designed to activate when no other cars are nearby.18 Just as upper beam headlamps are subject to maximum intensity limits, even though they are designed to turn off in the presence of oncoming traffic, the same concerns apply to forward-facing auxiliary lighting. 

You argue in your letter that the Marking Light will not glare other road users or mask any of the required signal lighting. You state that the Marking Light is disabled in the presence of oncoming traffic, so that its downward angle does not glare other drivers on a wet or shiny roadway. You also state that because the Marking Light is low to the ground and produces very little light above the horizontal plane of the headlamps, it cannot glare another driver or pedestrians. You state that because of these features, the Marking Light does not impair an oncoming driver’s ability to perceive the front turn signals. In a meeting with our office, you also indicated that the spotlamps on each side of the vehicle are generally not additive (combined). 

You also provided data on the intensity of the Marking Light (an iso-candela plot) based on on-vehicle measurements at a test laboratory. The photometric testing indicates that the Marking Light’s maximum intensity is 113,440 cd (at approximately four degrees down). You noted that the test setup resulted in higher estimated light intensities than what would be more accurately estimated by a goniometric component test conducted in a properly designed component lamp goniometry facility with appropriate stray light control. 

We believe that the Marking Light would violate the impairment provision because it would exceed—dramatically—the maximum permissible brightness of upper beams at 4D-V. This extreme intensity is a concern even if the Marking Light beam is aimed at a downward angle and the system is designed so that the light is disabled in the presence of oncoming and preceding vehicles, because it could still glare other motorists if the vision system does not correctly detect an oncoming or preceding vehicle and prevent the Marking Light from activating. This glare could happen, for example, if the vehicle crests the top of a hill when another vehicle is approaching, the vehicle encounters another vehicle at an intersection without detecting the other vehicle approaching from the side, or if the Marking Light reflects off wet pavement. 

We recognize that the photometric test setup led to overestimates of the Marking Light’s intensity. Nevertheless, the Marking Light is so intense that a more accurate estimate would likely still greatly exceed the upper beam maximum. We also note that the Marking Light’s intensity dramatically exceeds not only the upper beam maximum at 4D-V (12,000 cd), but also the maximum allowed for any individual upper beam headlamp (75,000 cd at H-V). This intensity presents a risk that other road users could be subject to significant glare. 

Conclusion 

I conclude that the Marking Light would be prohibited by the impairment provision in FMVSS No. 108 with respect to the Marking Light’s intensity at 4D-V.
18 FMVSS No. 108 S4 (upper beam defined as “beam intended primarily for distance illumination and for use when not meeting or closely following other vehicles”). 

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Richard Seoane 

If you have any further questions, please contact John Piazza of my staff at (202) 366-2992. 

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 6/27/24
Ref: Standard No. 108

ID: aiam4257

Dear Mr. Chikada: This is in reply to your letter of November 21, 1986, with reference t the distance between a front turn signal lamp and a lower beam headlamp.; In brief, SAE Standard J588e, incorporated by reference in Standard No 108 requires a minimum separation distance of 4 inches between the optical axis (filament center) of the front turn signal lamp to the inside diameter of the retaining ring of the lower beam headlamp. You have pointed out that a replaceable bulb headlamp does not have a retaining ring, and you have presented two possible substitutes as a measuring point. The first (your Item A) is the outer edge of the headlamp, and the second (your Item B) is the end of the effective area of the reflector. You believe that Item B is the more appropriate.; We concur with your interpretation. Of the two options, the distance t the edge of the effective area of the reflector is the one most similar to the inside diameter of the retaining ring of the lower beam headlamp. The basis for this interpretation is the assumption that the headlamp lens between the outer edge of the headlamp and the edge of the effective area of the reflector is not used for production of the lamp's beam, has no significant luminance, and therefore will not mask the turn signal.; Sincerely, Erika Z. Jones, Chief Counsel

ID: aiam2932

Dear Mr. Gerth:#This is in response to your letter of November 27 1978, requesting an interpretation of Federal Motor Vehicle Safety Standard No. 101-80, *Controls and Displays*. Specifically, you asked whether it is permissible to use symbols for the parking lamp functions of the headlamp switch, in addition to the headlamp symbols required in Table I of the Standard.#The answer to your question is yes. Section 5 of the standard states that each passenger car 'with any control listed in S5.1 or in column 1 of Table 1, ... shall meet the requirements of this standard for the location, identification, and illumination of such control or display.' Since no symbols or other designations are required under the standard for parking lamps where their control is not combined with that for headlamps or for 'lamps-off' positions on controls, it is up to the manufacturer whether to label these additional functions and whether to use words or symbols. Footnote 2 of Table 1 of the standard does provide that a manufacturer must use the single headlamp symbol to designate several functions when clearance, identification, parking and/or side marker lamps are all controlled with the headlamp switch. This footnote was not intended to preclude additional symbols for these other functions, however. In fact, S5.2.1 provides that 'additional words or symbols may be used at the manufacturer's discretion for the purpose of clarity.'#Regarding your drawings, clearance lamps are listed in paragraph S5.1 and in column 1 of Table 1 of the standard. Therefore, they must be identified by the symbols shown in column 3 of Table 1 or by the words 'Clearance Lamps' or 'Cl Lps'. The 'parking right and left' symbol shown on the drawing submitted with your letter would not satisfy the requirements for clearance-lamp designations. However, the symbol labeled 'Clearance Lamps' that appears on the drawings which Mr. Gebhard M. Hespeler and Mr. Craig Jones submitted on December 20, 1978, would conform with the requirements. I have enclosed a copy of that drawing.#If you have any further questions, please do not hesitate to write.#Sincerely, Joseph J. Levin, Jr., Chief Counsel;

ID: aiam2931

Dear Mr. Gerth:#This is in response to your letter of November 27 1978, requesting an interpretation of Federal Motor Vehicle Safety Standard No. 101-80, *Controls and Displays*. Specifically, you asked whether it is permissible to use symbols for the parking lamp functions of the headlamp switch, in addition to the headlamp symbols required in Table I of the Standard.#The answer to your question is yes. Section 5 of the standard states that each passenger car 'with any control listed in S5.1 or in column 1 of Table 1, ... shall meet the requirements of this standard for the location, identification, and illumination of such control or display.' Since no symbols or other designations are required under the standard for parking lamps where their control is not combined with that for headlamps or for 'lamps-off' positions on controls, it is up to the manufacturer whether to label these additional functions and whether to use words or symbols. Footnote 2 of Table 1 of the standard does provide that a manufacturer must use the single headlamp symbol to designate several functions when clearance, identification, parking and/or side marker lamps are all controlled with the headlamp switch. This footnote was not intended to preclude additional symbols for these other functions, however. In fact, S5.2.1 provides that 'additional words or symbols may be used at the manufacturer's discretion for the purpose of clarity.'#Regarding your drawings, clearance lamps are listed in paragraph S5.1 and in column 1 of Table 1 of the standard. Therefore, they must be identified by the symbols shown in column 3 of Table 1 or by the words 'Clearance Lamps' or 'Cl Lps'. The 'parking right and left' symbol shown on the drawing submitted with your letter would not satisfy the requirements for clearance-lamp designations. However, the symbol labeled 'Clearance Lamps' that appears on the drawings which Mr. Gebhard M. Hespeler and Mr. Craig Jones submitted on December 20, 1978, would conform with the requirements. I have enclosed a copy of that drawing.#If you have any further questions, please do not hesitate to write.#Sincerely, Joseph J. Levin, Jr., Chief Counsel;