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NHTSA Interpretation File Search


NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies. 

Understanding NHTSA’s Online Interpretation Files

NHTSA makes its letters of interpretation available to the public on this webpage. 

An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.

  • Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
  • Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
  • The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
  • Some combination of the above, or other, factors.

Searching NHTSA’s Online Interpretation Files

Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.

Single word search

 Example: car
 Result: Any document containing that word.

Multiple word search

 Example: car seat requirements
 Result: Any document containing any of these words.

Connector word search

 Example: car AND seat AND requirements
 Result: Any document containing all of these words.

 Note: Search operators such as AND or OR must be in all capital letters.

Phrase in double quotes

 Example: "headlamp function"
 Result: Any document with that phrase.

Conjunctive search

Example: functionally AND minima
Result: Any document with both of those words.


Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).

Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).


Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”

Complex searches

You can combine search operators to write more targeted searches.

Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”). 

Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”

Search Tool

NHTSA's Interpretation Files Search

Displaying 51 - 60 of 16503
Interpretations Date

ID: 2524y


Mr. Manuel R. Garcia
PSC Box 1865
APO NY 09406

Dear Mr. Garcia:

This is in reply to your letter of April 2, 1990, to Ms. DeMeter of this Office, with respect to importation requirements for motor vehicles. You have recently bought a l974 BMW l602 made "overseas", and would like information on Federal safety (and EPA) requirements the car must conform to before it is shipped, or, alternatively, whether it is permissible to make the necessary repairs after the car arrives in the United States.

Changes in the law affecting importation of cars subject to the Federal motor vehicle safety standards, which were effective January 31, l990, have made the process of importing nonconforming vehicles much more difficult than before. In brief, your car can be imported only if this agency has made a determination that it is capable of conversion to meet the Federal motor vehicle safety standards. If an affirmative determination has been made, you may import the vehicle only if you have a contract with an importer who has registered with this agency to undertake to conform the vehicle to meet Federal requirements. If the conversion work has been performed abroad, the registered importer is nevertheless responsible for submitting verification that the work has been done. At this early date in implementing the law, the agency has made no determinations of vehicle eligibility, and has appointed only a handful of registered importers. I believe that the regulations of the EPA are similar; importation is accomplished through an "independent commercial importer" (ICI). We are forwarding a copy of your letter to that agency for its response.

You haven't indicated when you anticipate importing the BMW. I suggest, as the time approaches, you write our Director, Office of Vehicle Safety Compliance, National Highway Traffic Safety Administration, Washington, D.C. 20590. He can then provide you with the latest list of registered importers, and vehicles for which affirmative importation determinations have been made. If your car is not among them, you may persuade a registered importer to petition the agency on your behalf. However, there is a fee imposed for consideration of petitions (either $1,560 or $2,150, depending on the car). This is payable in advance, and is non-refundable if a petition is denied. Further, a vehicle owner is not eligible to submit such a petition.

You didn't say how "recently" you bought your car. However, if it was before October 31, l988, and you were stationed outside the U.S. at that time and have never before imported a nonconforming vehicle, the law allows you, until October 31, l992, to import the car personally, without a registered importer and without an importation determination, and to have conversion work done by anyone you choose.

You also asked for "the publication that covers the Code of Federal Regulations and the Federal Register." I am not sure what you mean, but I am enclosing our new vehicle importation form, Form HS-7, which all importers of motor vehicles must execute upon arrival of their vehicles. It is, in essence, a concise form of the new importation regulation. I am also enclosing copies of that regulation, and the ones on registered importers, vehicle eligibility determinations, and fees.


Paul Jackson Rice Chief Counsel

Enclosures ref:59l#592#593#594 d:6/26/90


ID: 2525y



Mr. Brad G. Magor 6282 Young Street Halifax, Nova Scotia B3L-1ZB Canada

Dear Mr. Magor:

This is in reply to your letter of May 1, l990, to the Department of Transportation with respect to your intended purchase of a Canadian truck or van which you will eventually import into the United States. You asked for information on the features required to meet the U.S. safety standards, and whether Canadian vehicles generally have these items.

There is a great similarity, but not identicality, between the Canadian Motor Vehicle Safety Standards (CMVSS), and the Federal Motor Vehicle Safety Standards (FMVSS). Manufacturers in both countries are required to affix a label to their vehicles certifying compliance with all applicable safety standards. We understand that some Canadian manufacturers may have certified compliance of their vehicles with both the CMVSS and the FMVSS. If dual certification has occurred, it will be evident from reading the certification label on the vehicle (usually located in the driver door post area). If the vehicle bears a certification of compliance that includes the FMVSS, you should encounter no problems in importing, registering, and selling it in the United States.

However, if the vehicle is certified only to the CMVSS, you will encounter some difficulty in importing it, notwithstanding the substantial similarity of the CMVSS and FMVSS. By direction of Congress, a vehicle not originally manufactured to conform to the FMVSS may not be admitted into the U.S. unless two things have occurred. The vehicle must be on a list of vehicles that the Department has approved for conversion to the FMVSS. If this has occurred, then the vehicle can only be imported by a "registered importer" (i.e. converter), or one who has a contract with a registered importer to perform the conversion work. A bond equal to l50% of the entered value of the vehicle must be given to secure performance of the conversion work, which is cancelled upon satisfactory evidence that the work has been performed.

The new directives of Congress were only effective on January 31, l990, and we are still working to implement them. We have tentatively proposed an approved general list of vehicles that would include all Canadian trucks and vans manufactured since January 1, l968, that were certified as meeting the CMVSS, and which are of the same make, model, and model year of any truck or van originally manufactured for importation into and sale in the United States, or originally manufactured in the United States, and that were certified as meeting the FMVSS. For example, a l990 Chevrolet truck manufactured in Canada to the CMVSS with a U.S. manufactured and certified counterpart would be covered by this general list. We have received no objections to treating Canadian vehicles in this fashion. A final determination should be published in the near future. We have also accorded registered importer status to a number of applicants. If you choose to buy a vehicle certified to the CMVSS for importation into the United States, we will be pleased to provide the latest list of registered importers as the time draws near for your departure.

The minor differences in the standards that may effect you are principally those regarding speedometer/odometers and lighting. The former must indicate miles and miles per hour (and may indicate kilometers and kilometers per hour). Vehicles must be equipped with headlamps that meet the FMVSS and not those of the ECE. Thus, once a CMVSS-certified vehicle is imported, we do not anticipate that the conversion work should be lengthy or costly. Once the work has been satisfactorily performed and the converter's label attached, you should encounter no difficulties in registering the vehicle or in selling it.

I hope that this answers your questions.


Paul Jackson Rice Chief Counsel ref:59l d:6/28/90


ID: 2526y


Mr. John W. Garringer
158 E. Center Street
Shavertown, Pennsylvania 18708

Dear Mr. Garringer:

This responds to your letter asking whether Federal law permits the installation of tinted plastic film on the bottom of motor vehicle windshields. The purpose of this film would be to reduce glare for the driver and any front seat passengers. I am pleased to have this opportunity to explain how our laws and regulations apply to such a product.

Our agency is authorized under the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381 et seq.; the Safety Act) to issue safety standards applicable to new motor vehicles and new items of motor vehicle equipment. NHTSA, however, does not approve or certify any vehicles or items of equipment, nor do we endorse any commercial products or processes. Instead, the Safety Act specifies that each manufacturer itself must certify that its products meet all applicable safety standards. The agency periodically tests vehicles and items of equipment for compliance with the standards, and also investigates alleged defects related to motor vehicle safety and alleged violations of other statutory provisions.

Pursuant to this authority, NHTSA has issued Standard No. 205, Glazing Materials (49 CFR 571.205), which sets forth performance requirements for windows and other glazing items installed in motor vehicles. Among the requirements set forth in Standard No. 205 are specifications for minimum levels of light transmittance. A minimum of 70 percent light transmittance is required in glazing areas requisite for driving visibility, which includes all windows in passenger cars. In trucks and buses, the windshield and windows to the immediate right and left of the driver and the rearmost window, if the latter is used for driving visibility, are considered to be requisite for driving visibility, and therefore subject to the 70 percent minimum light transmittance requirement.

Your letter did not provide any information on the light transmittance that would be measured through glazing with your Hood Glare product installed on it. The combination of the glazing material and your tinting film must allow at least 70 percent light transmittance to comply with the requirements of Standard No. 205. No manufacturer or dealer would be permitted to install your tinting film on the glazing materials on new vehicles, unless the manufacturer or dealer certifies that the vehicle continues to comply with the 70 percent minimum light transmittance and other requirements of Standard No. 205.

After a vehicle is first sold to a consumer, modifications to the vehicle are affected by section 108(a)(2)(A) of the Safety Act (15 U.S.C. 1397(a)(2)(A)). That section prohibits any manufacturer, dealer, distributor, or repair business from "rendering inoperative" any device or element of design installed in a vehicle in compliance with any safety standard. This provision of the law means that no manufacturer, dealer, distributor, or repair business could install tinting film if the addition of the tinting film to the glazing would result in a light transmittance of less than 70 percent, or otherwise cause the vehicle to no longer comply with the applicable requirements of Standard 205. Violations of this "render inoperative" prohibition can result in Federal civil penalties to the manufacturer, dealer, distributor, or repair business of up to $1000 for each noncomplying installation.

Section 108(a)(2)(A) of the Safety Act does not affect vehicle owners. Hence, vehicle owners themselves may install tinting film or any other product on the glazing of their vehicle, regardless of whether the installation causes the vehicle to no longer comply with Standard No. 205. Individual States have the authority to regulate the operational use of vehicles by their owners, and, therefore, have the authority to regulate or preclude individual owner modifications to the glazing of their vehicles.

I have enclosed an information sheet that summarizes the relationship between Federal auto safety laws and motor vehicle window tinting. I hope this information is helpful. If you have any further questions or need any additional information about this topic, please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992.


Paul Jackson Rice Chief Counsel


ref:205#VSA d:6/l8/90


ID: 2617y


Delbert N. Pier
Legislation and Compliance Coordinator
Hyundai America Technical Center, Inc.
5075 Venture Drive
Ann Arbor, MI 48108

Dear Mr. Pier:

This responds to your letter requesting an interpretation of Federal Motor Vehicle Safety Standard No. 107, Reflecting Surfaces. (49 CFR 571.107). I apologize for the delay in our response.

You explained that Hyundai is planning to test the surface of a windshield wiper blade rail spring by using several rail springs gathered together because one spring would have a limited amount of area to reflect the light source. You asked the National Highway Traffic Safety Administration (NHTSA) to confirm your view that this method of compliance testing is a satisfactory method of complying with section S4 of Standard No. 107.

By way of background information, NHTSA has no authority to approve, endorse or offer assurances of compliance for any motor vehicle or item of motor vehicle equipment. Instead, the National Traffic and Motor Vehicle Safety Act of 1966 ("Vehicle Safety Act") makes manufacturers of motor vehicles or items of motor vehicle equipment responsible for certifying that each of its products conforms with all applicable safety standards. The following represents our opinion based on the facts provided in your letter.

Each safety standard specifies performance requirements and test procedures used by the agency in its compliance testing to evaluate a vehicle or item of equipment. For instance, section S4 of Standard No. 107 specifies specular gloss requirements for certain vehicle components, including windshield wiper arms and blades. That provision requires that the specular gloss of the specified components must not exceed 40 units when measured by the 20 degree method of ASTM Standard D523-62T.

While the agency would follow ASTM Standard D523-62T for purposes of compliance testing, the Vehicle Safety Act does not require a manufacturer to test its products in the manner specified in a motor vehicle safety standard or even to test the product at all. A manufacturer may choose any means of evaluating its products to determine whether the vehicle or item of equipment complies with the requirements of that standard, provided, however, that the manufacturer exercises due care in ensuring that the vehicle or equipment will comply with Federal requirements when tested by the agency according to the procedures specified in the standard. In other words, the manufacturer must show that its chosen means of evaluating compliance is a reasonable surrogate for the test procedure specified by the standard.

In the event that the agency determines an apparent noncompliance exists with a vehicle or item of equipment tested in the agency's compliance program, the manufacturer must show the basis for its certification that the vehicle or equipment complies. The manufacturer may be subject to civil penalties unless it can establish that it exercised due care in its designing and manufacturing of the product and in its checking (through actual testing, computer simulation or otherwise) to ensure compliance, but nevertheless did not have reason to know that the vehicle or item of equipment did not in fact comply. Of course, notwithstanding the exercise of due care, the manufacturer would still be subject to the recall responsibilities of the Vehicle Safety Act for any noncomplying vehicles or equipment.

With these considerations in mind, you appear, based on the statements in your letter, merely to be testing a group of identical components with identical specular gloss levels at one time rather than separately. If this is the case, it appears that your intended method of testing is consistent with the testing procedures in Standard No. 107.

I hope this information answers your questions. Please contact Mr. Marvin Shaw of my staff at (202) 366-2992, if you have further questions.


Paul Jackson Rice Chief Counsel

/ref:107#VSA d:7/l6/90


ID: 2618y


Susan Birenbaum, Esq.
Acting General Counsel
United States Consumer Product Safety Commission
Washington, DC 20207

Dear Ms. Birenbaum:

This responds to your letter asking whether a product would be considered an item of "motor vehicle equipment," within the meaning of the National Traffic and Motor Vehicle Safety Act (the Safety Act). I apologize for the delay in this response. The product in question is called "kwik kool" and is intended to improve the performance of motor vehicles' air conditioning systems. The packaging and labeling for this product that were enclosed with your letter indicate that "kwik kool" is intended exclusively for use with a motor vehicle and by ordinary users of motor vehicles. We conclude that this product is "motor vehicle equipment."

As you are aware, section 102(4) of the Safety Act, 15 U.S.C. 1391(4), defines, in relevant part, the term "motor vehicle equipment" as:

any system, part, or component of a motor vehicle as originally manufactured or any similar part or component manufactured or sold for replacement or improvement of such system, part, or component or as any accessory, or addition to the motor vehicle . . .

"Kwik kool" is an aerosol component that appears to be manufactured and sold for the improvement of motor vehicle air conditioning systems. As such, it is "motor vehicle equipment" within the meaning of the Safety Act.

You noted in your letter that the Consumer Product Safety Act excludes items of "motor vehicle equipment" from those "consumer products" subject to the authority of the Consumer Product Safety Commission under that Act. This agency, on the other hand, has express statutory authority to investigate allegations that an item of motor vehicle equipment contains a defect related to motor vehicle safety. Pursuant to the request in your letter, we have forwarded the complaint enclosed with your letter to our Office of Defects Investigation.

If you have any questions or would like some additional information about this topic, please feel free to contact Mr. Marvin Shaw of my staff at this address or by telephone at (202) 366-2992.


Paul Jackson Rice Chief Counsel

/ref:VSA d:7/l9/90


ID: 2619y


Mr. Michael O'Donnell
P.O. Box 127
Skaneateles, NY 13152

Dear Mr. O'Donnell:

This is in response to your letter to this office asking whether NHTSA's safety standards apply to vehicles in service on the public roads. Specifically, you were interested in the applicability of NHTSA requirements to a 1977 school bus that was converted to a "recreational vehicle/house coach" that is now only for personal and family use.

The Federal Motor Vehicle Safety Standards (FMVSS) promulgated by this agency apply to the manufacture and sale of new motor vehicles and new items of motor vehicle equipment. The requirement that a motor vehicle or item of motor vehicle equipment comply with all applicable FMVSS applies only until the product is first sold to a consumer. Both before and after a vehicle or item of equipment is first sold to a consumer, any modifications to that product are affected by section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1397(a)(2)(A), which states:

No manufacturer, distributor, dealer or motor vehicle repair business shall knowingly render inoperative, in whole or in part, any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard . . . .

If any of the commercial entities identified in section 108(a)(2)(A) were to make modifications that resulted in a "render inoperative" violation, the violating commercial entity would be liable for a civil penalty of up to $1,000 for each violation. Please note that this "render inoperative" provision does not apply to a vehicle owner. The vehicle owner may modify his or her vehicle without violating any Federal requirements, irrespective of whether the modification affects the vehicle's compliance with a safety standard.

Please note also that the individual States have the authority to regulate the operation and use of motor vehicles within their borders. Additionally, the individual States have the authority to regulate the modifications that may be made to a vehicle by its owner. You may wish to contact the Department of Motor Vehicles for the State of New York to learn if the State has established any requirements applicable to your use or registration of this vehicle in New York.

I hope you have found this information helpful.


Paul Jackson Rice Chief Counsel /ref: VSA d:7/l8/90


ID: 2620y


Mr. Brian Gill
Senior Manager
Certification Department
American Honda Motor Co., Inc.
100 West Alondra Boulevard
P. O. Box 50
Gardena, California 90247-0805

Dear Mr. Gill:

This responds to your request that this agency determine that the new antitheft device proposed to be installed on the MY 1991 Honda Acura NS-X car line, represents a de minimis change in the system that was the basis for the agency's previous granting of a theft exemption for the car line beginning in MY 1991, and that therefore the Acura NS-X vehicles containing the new device would be fully covered by that exemption.

As you are aware, the Acura NS-X car line was granted an exemption, pursuant to 49 CFR Part 543, from antitheft marking because Honda showed that the antitheft device to be used in lieu of marking on the car line was likely to be as effective as parts marking. This exemption was issued on February 5, 1990, and appeared in the Federal Register on February 9, 1990 (55 FR 4746).

The agency granted the exemption from theft marking because the agency found that based on substantial evidence, the agency believed that the antitheft device is "likely to be as effective in reducing and deterring motor vehicle theft as compliance with the parts-marking requirements of the theft prevention standard (49 CFR Part 541)." In the granting of the exemption from theft marking, the agency stated that it believed that the device will provide the types of performance listed in 49 CFR Part 543.6(a)(3): Promoting activation; attracting attention to unauthorized entries; preventing defeat or circumventing of the device by unauthorized persons; preventing operation of the vehicle by unauthorized entrants; and ensuring the reliability and durability of the device.

In your letter, it was stated that beginning from MY 1991, Honda plans improvements in the antitheft device that is standard equipment on the Acura NS-X in two ways: First, the new antitheft system would be armed by using the auto door lock system control to lock either door. Honda states that in the system that was the subject of the exemption from the theft prevention system, it was necessary to use the control on the driver's door in order to arm the system. According to the attachment provided in your letter, this change would make it possible to arm the the theft deterrent system by locking either door even if the other door is left unlocked. Second, the radio would now be included in the alarm system. Thus, the alarm system will be activated if the radio terminal or the coupler is disconnected, or if the radio's wiring is cut.

After reviewing the proposed changes to the componentry and performance of the antitheft device on which the exemption was based, the agency concludes that the changes are de minimis. While the new device has enhanced componentry and provides some aspects of performance not provided by the original device, it also continues to provide the same aspects of performance provided by the original device and relies on essentially the same componentry to provide that performance. Therefore, it is not necessary for Honda to submit a petition to modify the exemption pursuant to 49 CFR Part 543.9(c)(2).

If Honda does not implement the new antitheft device as described in your letter, or delays implementation until after MY 1991, we request that Honda notify the agency of such decisions.

It is my understanding that, in a May 16, 1990, telephone conversation between Brian Tinkler of Honda and Dorothy Nakama of NHTSA's Office of Chief Counsel, Mr. Tinkler confirmed that Honda was not requesting confidential treatment of any information provided in your letter. Therefore, a copy of your letter, and this response, will be placed together in NHTSA's public docket.


Barry Felrice Associate Administrator for Rulemaking / ref:Part 543 d:7/ll/90


ID: 2621y



Mr. Ed McCarron Western Star Trucks Inc. 2076 Enterprise Way Kelowna, British Columbia, Canada V1Y 6H8

Dear Mr. McCarron:

This responds to your letter asking about the application of Safety Standard No. 302, Flammability of Interior Materials, to a particular mattress design, and how the mattress would be tested under the standard. I regret the delay in responding.

Paragraph S4.1 of Standard 302 sets forth a listing of the vehicle occupant compartment components that must be certified as complying with the flammability resistance requirements of paragraph S4.3. Paragraph S4.1 includes a reference to "mattress covers." You ask whether NHTSA would consider six components of your mattress design to be included in the term "mattress cover" and thus subject to Standard 302. (The first five components you ask about, and a portion of the sixth, satisfy the criterion in S4.2 of being within 1/2 inch of the occupant compartment air space.)

As we understand your sketch, the first three components (which you called the "cover," "foam" and "foam backing") encase the mattress core, or filling. As such, if our understanding is correct, these three constitute the mattress ticking, which we consider as the fabric case permanently enclosing the filling of a mattress. NHTSA has said in past interpretations of Standard 302 that the term "mattress cover" includes both a removable covering put over a finished mattress and the mattress ticking. Thus, the first three components would be subject to the standard.

These three components, which you said in a telephone conversation are quilted together, would be tested separately under S4.2.1 of the standard if they do not adhere to other materials at every point of contact. (The fact that these three are quilted, or stitched, indicates to us that they do not so adhere.) If any of these components adhere to other material at every point of contact, then it would be tested as a composite with the other material.

The fourth component in your sketch is the mattress "fill." Paragraph S4.1 of the standard lists mattress covers only. NHTSA has consistently interpreted S4.1 as not including the mattress filling.

The fifth component is a fabric "corner reinforcement" that appears to be approximately two inches in length and stitched on the outside of the mattress cover. NHTSA indicated in interpretative letters of Standard 302 dated December 15, 1972 and May 1, 1972 that a component that is "incorporated into" a component that is listed in S4.1 is subject to the standard. (The agency said in the December 1972 letter that "mattress cover" includes tufting, since tufting is incorporated into mattress covers.) Since the fifth component is sewn to the corner of the mattress and appears to be made part of the mattress cover, we believe that the corner reinforcement is incorporated into the mattress cover. Thus, the fifth component would be subject to the standard. If it does not adhere to another material at every point of contact, it is tested separately under S4.2.1.

The sixth component is the "fill backing" which appears to be an internal divider between the mattress fill and the springs. It appears from your sketch that the fill backing is not part of the mattress ticking, because the backing is inside the mattress and is separate from the mattress ticking. Thus, we conclude the sixth component is excluded from the standard.

I hope this information is helpful.


Paul Jackson Rice Chief Counsel

/ref:302 d:7/ll/90


ID: 2622y


Herr Hanno Westermann
Hella KG Hueck & Co
Postfach 28 40
4780 Lippstadt
W. Germany

Dear Herr Westermann:

This is in reply to your letter to Dr. Burgett of this agency with respect to "multi bulb devices", specifically "how the requirements for one-, two-, or three compartment lamps (lighted sections) as it is documented in FMVSS No. 108, Figure lb have to be interpreted. . . ." You have asked this question because "Hella would like to equip motor vehicles with signalling devices which have --opposite to conventional lamps--a great number of replaceable miniature bulbs instead of e.g. one 32 cp bulb." Your question assumes that Standard No. l08 is to be interpreted in a manner that equates the number of lighted sections with the number of bulbs providing the light. Finally, you have stated that the total area of the lamp is not larger than current one-compartment lamps.

We regret the delay in responding to your letter, but we have recently completed rulemaking, begun in September l988, which is relevant to your question. On May 15, l990, an amendment to Standard No. l08 was published, effective December 1, l990, the effect of which is to restrict Figure 1b to replacement equipment. I enclose a copy of the amendment for your information.

Your question relates to "signalling devices" for new motor vehicles, and Figure 1b shows that, specifically, you refer to turn signal lamps. Beginning December l, l990, Standard No. 108 will specify two different standards for turn signal lamps. If the lamp is intended for use on multipurpose passenger vehicles, trucks, buses, and trailers whose overall width is 80 inches or more, it must be designed to conform to SAE Standard J1395 APR85 Turn Signal Lamps for Use on Motor Vehicles 2032 mm or More in Overall Width. SAE J1395 also provides that these lamps may be used on vehicles less than this width, except for passenger cars. If a motor vehicle is not equipped with a turn signal lamp designed to conform to SAE J1395, it must be equipped with a turn signal lamp designed to conform to SAE Standard J588 NOV84 Turn Signal Lamps for Use on Motor Vehicles Less Than 2032 mm in Overall Width. In the May l990 amendments, section S3 of Standard No. 108 was amended to add a definition for "Multiple Compartment Lamp". Such a lamp is "a device which gives its indication by two or more separately lighted areas which are joined by one or more common parts, such as a housing or lens." The multiple bulb device that you described appears to meet this definition.

SAE J1395 establishes luminous intensity minima and maxima photometric requirements without reference to either compartments or lighted sections, and all that is required is for the lamp to comply at the individual test points specified. New section S5.1.1.31 clarifies that measurements of a multiple compartment turn signal lamp on vehicles to which SAE J1395 applies are to made for the entire lamp and not for the individual compartments.

However, SAE J588 NOV84 continues to specify different minimum photometric requirements for one, two, and three "lighted sections". Because the SAE does not prescribe photometric requirements for more than three lighted sections, we have concluded that any device that contains more than three lighted sections need only comply with the requirements prescribed for three lighted sections.

I hope that this is responsive to your request.


Paul Jackson Rice Chief Counsel ref:l08 d:8/22/90


ID: 2623y


Mr. Jack Rademacher
Chief Engineer
Polar Tank Trailer, Inc.
12810 County Road 17
Holdingford, MN 56340

Dear Mr. Rademacher:

This is in reply to your letter of May 8, l990, to Stephen P. Wood of this Office, asking for reconsideration of a recent interpretation of Standard No. l08.

We assume you mean our letter of January 9, 1990, to Howard Kossover of Oklahoma City. That interpretation stated that if rear lamps on a semi-trailer were mounted 27 inches forward of the rear edge of the vehicle, they were not mounted "on the rear", the location specified by Standard No. l08. We also observed that compliance with the 45-degree visibility requirements in that location appeared questionable. You say that it has long been the practice of the Truck Trailer Manufacturers Association (TTMA) and its members that "if the 45 degree visibility requirement of these lights were met 'on the rear' of the trailer both inboard and outboard, the manufacturer met the intent of the standard." You inform us that the liquid bulk transport industry is especially affected by this interpretation because of reasons of practicality unique to tank transports. On these vehicles, you state that the rear lamps have been "mounted as far as 36 inches forward from the rear of the bumper", but that, in this location, they "still maintain the 45 degree visibility requirements." You therefore ask for reconsideration of the interpretation if the 45 degree visibility requirements are met.

The lamps in your letter (and Mr. Kossover's) are stop, turn signal, and taillamps. Only the taillamps are presence lamps. The stop lamps and turn signal lamps operate independently of the headlamps. That is to say, they are intended for use at all times and not just at night or under other conditions of reduced visibility. They indicate actions taken by the vehicle operator to signal his operational intentions to other drivers and pedestrians. Problems with depth perception of following drivers could result if the lamps are not mounted "on the rear" as the standard requires. We are willing to interpret "on the rear" as meaning the trailing edge of the rear fender, which may not extend as far rearward as the bulk tank container, provided the visibility requirements are met, but we conclude that a mounting location for stop and turn signal lamps that is 36 inches forward from the rear of the bumper is not "on the rear" as the standard requires.


Paul Jackson Rice Chief Counsel

ref:l08 d:8/22/90


Request an Interpretation

You may email your request to or send your request in hard copy to:

The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590

If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.

Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.