NHTSA Interpretation File Search
Overview
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.
Wildcard
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).
Not
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
| Interpretations | Date |
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ID: aiam2450OpenMr. K. W. Schang, Director - Vehicle Safety, Programs, American Motors Corporation, 14250 Plymouth Road, Detroit, MI 48232; Mr. K. W. Schang Director - Vehicle Safety Programs American Motors Corporation 14250 Plymouth Road Detroit MI 48232; Dear Mr. Schang:#This responds to American Motors Corporation's (AMC's September 9, 1976, request for confirmation that Standard No. 101, *Control Location, Identification, and Illumination*, permits the addition of a 'fan' symbol to a control that is identified by the word 'fan' in accordance with the requirements of S4.2.1.#The AMC interpretation is incorrect. Section S4.2.1 states in part:#>>>S4.2.1 . . . . A control may, in addition, be identified by a symbol, but only a symbol shown in column 3 or 4 shall be used. However, if the word 'None' appears in column 3, no symbol shall be provided. . . .<<<#Table I, whose columns are referred to in S4.2.1, contains an entry for 'Heating and Air Conditioning System,' and column 3 for that entry contains the word 'None'. This means that no symbol can be used in addition to the word 'fan' on the control for the fan control switch.#The language in the preambles to three proposals to amend Standard No. 101 that you list in your letter does not have the effect of amending the requirements of the standard itself. As you are no doubt aware, a recent proposal would amend Table I to include a symbol for the heating and air conditioning system, but this proposal has not yet been made final. A copy of the proposal is enclosed for your information.#Sincerely, Frank A. Berndt, Acting Chief Counsel; |
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ID: aiam5395OpenMr. Donald P. Green 809 Huasna Road Arroyo Grande, CA 93420; Mr. Donald P. Green 809 Huasna Road Arroyo Grande CA 93420; Dear Mr. Green: This responds to your letter to this agency askin whether there is a State or Federal regulation prohibiting the use of passenger radial tires on recreational 'pull type' trailers. I regret the delay in responding. You explain that you were told by various tire dealers that radial tires should not be used on trailers because the soft sidewalls of radial tires could cause an uncontrollable swaying that could result in a serious accident. You then state that while towing a trailer mounted with four radial tires, you were caught in a crosswind which caused the trailer to jackknife, resulting in a serious accident. To begin, I am sorry to hear about your accident but am thankful that no one was hurt. The tire safety standards and regulations issued by the National Highway Traffic Safety Administration (NHTSA) require tires to be able to safely carry the load on a vehicle and to be labeled with important safety information, such as tire size, construction, and inflation pressure. There is nothing in our standards or regulations that prohibits the use of passenger car radial tires on trailers. In fact, Federal Motor Vehicle Safety Standard No. 120, 'Tire selection and rims for motor vehicles other than passenger cars,' expressly permits the use of passenger car tires on vehicles like trailers, provided that adjustment is made to the tire's load-carrying capacity. NHTSA also issues consumer advisories to alert consumers to certain practices that should be avoided, such as mixing radial and non-radial tires. However, we have never issued a consumer advisory on the use of passenger car radial tires on trailers, and we are not aware of any widespread hazard due to the use of such tires on trailers. Your State could have requirements for the use of tires on trailers. We suggest that you check with the California Highway Patrol for information on that issue. We regret we are unable to be more helpful. Should you have any further questions, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam0197OpenMr. Bernard Belier, U. S. Resident Engineer, U. S. Technical Research Corporation, 801 Second Avenue, New York, NY 10017; Mr. Bernard Belier U. S. Resident Engineer U. S. Technical Research Corporation 801 Second Avenue New York NY 10017; Dear Mr. Belier:#This is in reply to your letter, dated November 11 1969, in which you seek an interpretation as to how Federal Motor Vehicle Safety Standards (FMVSSs) 103 and 104 are applicable to cars equipped with right-hand drive or a central steering wheel.#For motor vehicles equipped with right-hand drive, the windshield areas to be defrosted and wiped by FMVSSs 103 and 104 respectively, are mirror images of those areas required for vehicles equipped with left-hand drive.#More information is required before a reply can be given on vehicles equipped with a central steering wheel. Defrosting and wiping areas requirements would naturally vary depending on the number and location of the front seat passenger seating positions in the vehicle equipped with a central steering wheel.#We trust that we have been of assistance to you.#Sincerely, Robert Brenner, Acting Director; |
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ID: aiam1155OpenMr. J. W. Lane, Manager, Product Promotion, Technical, Publications and Packaging, Mobil Oil Corporation, 150 East 42nd Street, New York, New York 10017; Mr. J. W. Lane Manager Product Promotion Technical Publications and Packaging Mobil Oil Corporation 150 East 42nd Street New York New York 10017; Dear Mr. Lane: This is in reply to your letter of June 1, 1973 and confirms th telephone conversation with Mr. Vinson of my staff on June 14, 1973.; The amendments to Motor Vehicle Safety Standard No. 116 published o May 17, 1973 modified container labeling requirements only for silicone-based brake fluid and hydraulic system mineral oil (paragraph S5.2.2.3) and did not affect the requirements for conventional DOT 3 and DOT 4 fluids (paragraph S5.2.2.2) as your assumed. Therefore you appear to have no problem, and it is not necessary to consider your letter as a petition for reconsideration.; The sample label you enclosed appears to designate the contents a 'Super Heavy Duty Brake Fluid', rather than 'DOT 3 MOTOR VEHICLE BRAKE FLUID' as paragraph S5.2.2.2(e) requires. Otherwise, it is adequate compliance with paragraph S5.2.2.2.; Sincerely, Lawrence R. Schneider, Chief Counsel |
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ID: aiam3168OpenMr. Thomas F. Brown, Mack Trucks, Engineering Division, P.O. Box 1761, Allentown, PA 18105; Mr. Thomas F. Brown Mack Trucks Engineering Division P.O. Box 1761 Allentown PA 18105; Dear Mr. Brown: This responds to your October 17, 1979, letter asking about the prope certification label for an intermediate manufacturer that alters the tires and rims on a chassis thereby affecting the gross axle and vehicle weight ratings. In your letter, you suggest an abbreviated certification label that would list the manufacturer's name and date of manufacture, and would make the statement that the vehicle will conform to certain standards if the incomplete vehicle document is followed. The agency agrees that this is a correct certification.; Intermediate manufacturers are required to attach labels to vehicle that they modify to indicate that some manufacturing operation has occurred on a vehicle between the manufacture of its chassis and its final manufacture. The intermediate manufacturer is permitted to select, from among a number of certification statements, the statement or statements that accurately represent the nature of the work undertaken by that manufacturer. Therefore, it is not necessary for an intermediate manufacturer to use all of the certification statements on its labels.; In the situation that you describe, the intermediate manufacturer wil make a statement on its label identical to one of the statements made by the chassis manufacturer. Although this appears to be redundant, it is necessary to have the intermediate manufacturer's label on the vehicle making the required certification statement so that a final-stage manufacturer can continue to rely upon the certification labels and upon the statements made in the incomplete vehicle document.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4357OpenLyon L. Brinsmade, Esq., Porter & Clements, 3500 Republicbank Center, Houston, TX 77002; Lyon L. Brinsmade Esq. Porter & Clements 3500 Republicbank Center Houston TX 77002; Dear Mr. Brinsmade: This responds to your request for information regarding Federa regulation of semi-trailer manufacturing. You asked about Federal standards applicable to 'pneumatic aluminum tank type semi-trailers' which your client wishes to manufacture abroad and import into the United States. You were particularly concerned about specifications for aspects of the vehicle which pneumatically load and discharge substances into and out of the tank unit.; I would like to take this opportunity to provide some backgroun information concerning this agency's regulations. You are correct that the National Highway Traffic Safety Administration (NHTSA) administers Federal regulations for the manufacture and sale of new motor vehicles, including semi-trailers. NHTSA is authorized, under the National Traffic and Motor Vehicle Safety Act, to issue safety standards applicable to new motor vehicles and items of motor vehicle equipment. As you are aware, however, NHTSA does not approve motor vehicles or motor vehicle equipment, nor do we endorse any commercial products. Instead, the Vehicle Safety Act establishes a 'self-certification' process under which each manufacturer is responsible for certifying that its products meet all applicable requirements. (A general information sheet describing manufacturers' responsibilities under the Vehicle Safety Act is enclosed.); We note that the term 'manufacturer' is defined by section 102(5) o the Act to mean 'any person engaged in the manufacturing or assembling of motor vehicles or motor vehicle equipment, *including any person importing motor vehicles of motor vehicle equipment for resale*.' (Emphasis added.) Therefore your client, as a manufacturer of motor vehicles, is responsible for certifying compliance with all applicable motor vehicle safety standards. The procedure, specified in 49 CFR Part 567, requires also that the manufacturer provide safety information on the certification label, including the vehicle's gross vehicle weight rating and gross axle weight rating.; At this time, the only safety standards applicable to all trailers ar Safety Standard No. 108, *Lamps, reflective devices, and associated equipment*, Standard No. 120, *Tire selection and rims for motor vehicles other than passenger cars*, and Standard No. 115, *Vehicle Identification Number--Basic Requirements*. The content requirements for the identification number are found at Part 565. Your client's trailers also must meet Standard No. 106, *Brake hoses*, Standard No. 116, *Motor vehicle brake fluids*, and applicable requirements of Standard No. 121, *Air brake systems*. These standards are found in 49 CFR Part 571.; You were particularly concerned about Federal standards applicable t the pneumatic tank of the semi-trailer. There are no Federal motor vehicle safety standards for pneumatic tank units. However, even in the absence of an applicable safety standard, the Vehicle Safety Act imposes general responsibilities on manufacturers of motor vehicles and motor vehicle equipment regarding safety defects. Manufacturers of motor vehicles and motor vehicle equipment are responsible generally for ensuring that vehicles and equipment they manufacture are free from safety-related defects and can perform their intended function safely. If your client or the agency determines that a safety- related defect or noncompliance exists, your client is obligated under section 151 *et seq*. of the Act to notify purchasers of its product and remedy the problem without charge. Manufacturers who fail to provide notification of or remedy for a defect or noncompliance may be subject to a civil penalty of up to $1,000 per violation.; In addition to the regulations described above, your client should b aware of two procedural rules which apply to all manufacturers subject to the regulations of this agency. The first is 49 CFR Part 566, *Manufacturer Identification*. This rule requires your client to submit its name, address, and a brief description of the items of equipment it manufacturers to this agency within 30 days after it imports its products into the United States.; The other rule is 49 CFR Part 551, *Procedural Rules*. Subpart D o this regulation requires all manufacturers headquartered outside of the United States to designate a permanent resident of the United States as the manufacturer's agent for service of all process, notices, orders and decisions. This designation should be mailed to the Chief Counsel, National Highway Traffic Safety Administration, 400 Seventh Street, S.W., Washington, DC 20590, and must include the following information:; 1. A certification that the designation is valid in form and binding o the manufacturer under the laws, corporate by-laws, or other requirements governing the making of the designation at the time and place where it is made,; 2. The full legal name, principal place of business and mailing addres of the manufacturer,; 3. Marks, trade names, or other designation of origin of any of th manufacturer's products which do not bear its name,; 4. A statement that the designation shall remain in effect unti withdrawn or replaced by the manufacturer.; 5. A declaration of acceptance duly signed by the agent appointed which may be an individual, a firm or a U.S. corporation, and; 6. The full legal name and address of the designated agent. In addition, the designation must be signed by one with authority t appoint the agent. The signer's name and title should be clearly indicated beneath his or her signature.; You asked whether your client's semi-trailers would be affected b regulations administered by other Federal agencies. If the semi-trailer will be used to transport a material designed by the Secretary of Transportation as a 'hazardous material' (see 49 CFR Part 172), then the transportation of that material is regulated by the Office of Hazardous Materials Transportation of the Research and Special Projects Administration (RSPA). You can contact the director of that office, Mr. Alan Roberts, at 366-0656 for more information on RSPA's regulations. In addition, you might be interested in information about regulations for interstate motor carriers issued by the Federal Highway Administration. Mr. Tom Kozlowski of the Office of Motor Carrier Standards, Federal Highway Administration, can provide you with more information. He may be reached at this address, Room 3403, or by telephone at (202) 366-1790.; I hope this information has been helpful. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam3492OpenThe Blunt Company, 4500 City National Bank Building, Detroit, MI 48226; The Blunt Company 4500 City National Bank Building Detroit MI 48226; Gentlemen: This responds to Mr. Michael E. Murphy's letter of August 20, 1981, t Joan Griffin of my staff, regarding Safety Standard No. 127, *Speedometers and Odometers*. Mr. Murphy asks whether an electronic odometer that can be rendered useless by the simple unplugging operation would be legal under the odometer provision of the standard. When the odometer is unplugged, a 'blank' is registered in the odometer record. Mr. Murphy also asks whether the agency is considering any amendments or additions to the standard that are relevant to electronic odometers.; The National Highway Traffic Safety Administration (NHTSA) does no offer prior approval of compliance of any vehicle or equipment with any safety standard. It is the manufacturer's responsibility under the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381 *et seq*.) to determine whether its vehicle or equipment complies with all applicable safety standards and regulations and to certify its vehicle in accordance with that determination. Under certain circumstances, the agency is willing to give an informal opinion concerning whether a vehicle or item of motor vehicle equipment complies with a particular rule. Such opinions are not binding on NHTSA or on the manufacturer. However, in this case on the basis of the limited information contained in Mr. Murphy's letter, we cannot give even an informal opinion whether Chrysler's electronic odometer complies with Standard No. 127. We would need to see either the odometer itself or detailed pictures of it in order to make such a determination. We would also need to know if the odometer was manufactured in accordance with paragraphs S4.2.5.1, S4.2.5.2, S4.2.5.3, or S4.2.6, which specify four methods of resisting tampering.; I would emphasize that the odometer provisions of Standard No. 127 d not require that odometers be completely tamper proof. Rather, the rule simply requires that odometers resist tampering in one of four specified ways that are designed to leave visible evidence if reversal is attempted. It is possible for an odometer to comply with all the requirements of Standard No. 127 and still be susceptible to some form of tampering. Standard No. 127 was designed to prevent the mileage on odometers from being reduced. It was not designed necessarily to prevent tampering of the sort that would be possible with the Chrysler odometer where the odometer can be disconnected so that mileage is not recorded.; We stress that at this time no requirements for the manufacture an sale of odometers are in effect. The odometer provisions of Standard No. 127 (paragraphs S4.2-S5.2) are scheduled to take effect on September 1, 1982. Only odometers manufactured on or after that date must meet the requirements of the standard.; Further, on April 9, 1981, the NHTSA published a Notice of Intent (4 FR 21203) in which it announced that it would issue an NPRM to rescind Standard No. 127. The agency believes that such action may be warranted because there appear to be no direct safety benefits to be gained from the regulation and because of the potential for significant consumer savings. A notice proposing the rescission of the standard was published October 22, 1981 (46 FR 51788).; Finally, you should be aware that Title IV of the Motor Vehicle an Cost Savings Act (15 U.S.C 1981) states that no person shall disconnect an odometer with the intent to change the number of miles thereon. This provision may impact the use of the odometer to which you refer.; We hope you find this information helpful. Please contact this offic if you have further questions.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1505OpenMr. Earl E. Eckert, 510 S. Avenue, Nevada, IA 50201; Mr. Earl E. Eckert 510 S. Avenue Nevada IA 50201; Dear Mr. Eckert: This is in reply to your letter of May 3, 1974, inquiring as to th applicability of the Federal odometer law to trucks over 16,000 pounds.; The Federal odometer regulation does not require transferors o vehicles with a Gross Vehicle Weight Rating of more than 16,000 pounds to provide an odometer disclosure statement upon transfer of the vehicle. By Gross Vehicle Weight Rating, the regulation is referring to the value specified by the manufacturer as the loaded weight of a single vehicle, which appears on its permanent certification label.; I have enclosed copies of pertinent portions of the Act and th regulation for your information.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3538OpenMr. Eldridge G. Pentheny, Jr., Administration Engineer, Iveco Trucks of North America, Inc., 1730 Walton Road, P. O. Box 1102, Blue Bell, Pennsylvania 19422; Mr. Eldridge G. Pentheny Jr. Administration Engineer Iveco Trucks of North America Inc. 1730 Walton Road P. O. Box 1102 Blue Bell Pennsylvania 19422; Dear Mr. Pentheny: This responds to your letter asking whether your auxiliary heate toggle switch design meets the identification requirements of Standard No. 101-80, *Controls and Displays*.; By way of background information, I would point out that the agenc does not give advance approvals of vehicles or equipment. The National Traffic and Motor Vehicle Safety Act places the responsibility on the manufacturer to determine whether its vehicle or equipment comply with applicable requirements. A manufacturer then certifies that its vehicles or equipment comply with all applicable standards. The following interpretation only represent the agency's opinion based on the information provided in your letter.; On the top of the switch is the fan symbol specified by Table 1 of th standard and an arrow pointed upward. When the top of the switch is depressed, the heater fan is activated to recirculate cab air without heating it. On the bottom of the switch is a flame symbol and an arrow pointing downward. When the bottom of the switch is depressed, the heater, including the heater fan, is activated. As explained below, use of the flame symbol for the heater does not meet the identification requirements of Standard No. 101-80.; Section S5.2.2 states: >>>Identification shall be provided for each function of ...*any heating and air conditioning system control, and for the extreme positions of any such control that regulates a function over a quantitative range. *If this identification is not specified in Tables 1 or 2, it shall be in word form unless color coding is used.* If color coding is used to identify the extreme positions of a temperature control, the hot extreme shall be identified by the color red and the cold extreme by the color blue. [Emphasis added.]; Since the auxiliary heater toggle switch is a heating system control each of its functions must be identified. The switch controls two functions, recirculating air by use of the fan and heating air.; Except for the identification of a heating and/or air conditioning fan neither Tables 1 or 2 specify identification for the functions of a heating system. Therefore, except for a heating and/or air conditioning fan, the functions of a heating system must be identified by words or color coding. I will separately discuss the identification required for the two functions of the auxiliary heater toggle switch.; Depressing the top of the switch activates the fan in order t recirculate air without heating it. This function may be characterized either as recirculation of air or as an on-off switch for the fan. Under the latter characterization, the fan symbol should be used since Table 1 specifies that symbol for a heating and/or air conditioning fan. Thus, the identification on the top of the toggle switch meets the requirements of Standard No. 101-80.; Depressing the bottom of the toggle switch activates both the fan an the heater in order to circulate and heat air. Since neither Table 1 nor Table 2 specify identification for the heating function, it must be in word form. (As explained below, color coding is not appropriate in this instance.) Use of the fan symbol in addition to words identifying the heating function is not necessary, even though the fan operates as part of the heating function, since there is no separate control for the fan. Since the bottom of the toggle switch does not identify the heating function by using words, it does not comply with the requirements of Standard No. 101-80.; In a telephone conversation with Edward Glancy of this office, yo indicated that you desire to use the flame symbol for purposes of international harmonization, noting that is the symbol specified by the ISO for heat. While Standard No. 101-80 specifies a number of other ISO symbols, it does not specify that symbol. Section S5.2.1(a) of the standard does permit the use of additional words or symbols for the purpose of clarity, so long as the words or symbols specified by the standard are used. Thus, you may use the ISO flame symbol if you also identify the bottom of the toggle switch by using words. Since you indicated that you are already producing the vehicles in question, we suggest that you consider simply adding a label with the words 'AUX. HEAT' (or other identifying words) adjacent to the bottom of the toggle switch.; In the above-mentioned telephone conversation, you asked whethe coloring the bottom of the toggle switch red would be considered color coding as that phrase is used in S5.2.2. The answer is no, since the use of any one color by itself does not constitute color coding. We interpret section S5.2.2 (quoted above) to require that color coding must be readily understandable. Although there may be other appropriate uses of color coding, the standard's example of using red and blue to identify the extreme positions of a temperature control is the only one that comes to mind. The use of red for the hot extreme is readily understood only when used in conjunction with blue for the cold extreme.; As you may know, it is the policy of this agency to both promot international harmonization and avoid unnecessary design restrictions. If you wish to produce vehicles using ISO symbols not specified by Standard No. 101-80, you may wish to consider filing a petition for rulemaking on that issue.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4707OpenMr. T. Chikada Manager, Automotive Lighting Engineering Control Dept. Stanley Electric Co., Ltd. 2-9-13, Nakameguro, Meguro-ku Tokyo 153, Japan; Mr. T. Chikada Manager Automotive Lighting Engineering Control Dept. Stanley Electric Co. Ltd. 2-9-13 Nakameguro Meguro-ku Tokyo 153 Japan; Dear Mr. Chikada: This is in reply to your letter with respect to tw types of decorative lighting devices intended for installation 'on the rear face, and at the top of optional motorcycle rear trunks respectively.' I regret the delay in responding. Type A and Type B would be installed on the same motorcycle. Type A would be installed at the top of the trunk. It consists of an elongated device, illuminated by LEDs when the taillamp is on. Type B is installed on the motorcycle itself. It is a rectangular device, illuminated by an incandescent bulb, which is mounted on the vertical centerline and is flanked by the tail and stop lamps. The distance between the center of the light sources on the two devices is 290mm. (approximately ll 1/2 inches). Both devices emit red light, and their maximum intensity is less than the minimum intensity of the taillamp. You have asked whether it is permitted to equip a motorcycle with the Type A and Type B accessory lamps. If the answer is affirmative, you have asked whether an LED could be used as the light source for Type B. You have also asked whether the maximum intensity of each device separately should be less than the minimum intensity of the tail lamp, or whether the combined maximum intensity of both devices should be less than the minimum intensity of the tail lamp. Paragraph S5.1.3 of Federal Motor Vehicle Safety Standard No. 108 (formerly S4.1.3) permits the installation of these lamps if they do not impair the effectiveness of the lighting equipment required by the standard. In this instance, the question to be asked is whether the devices, activated with the taillamps, impair the effectiveness of the taillamps, or the stop lamps. The devices are, in effect, supplemental taillamps, and as such, arguably do not appear to impair the effectiveness of the taillamps required by the standard no matter what their intensity is. The diagram of Type B indicates that the stop lamps and taillamps are in the same compartment, presumably incorporating a dual filament bulb. Although the stop lamps when activated are brighter than the taillamps, their proximity to the supplemental devices Type A and Type B, each of which are emitting a red light, leads to the possibility that the stop signal would not be as effective as it would be were there no other red lights in the vicinity, and hence impaired within the meaning of S5.1.3. A stop signal must be instantly perceived so that a following driver may determine appropriate action to take. However, we note that this configuration is similar to other stop/taillamp configurations on many vehicles in use on the highways. This would indicate that such configurations do not result in impairment. Thus, the answer to your first question is that both Types of devices are permitted under the standard. Your second question is whether LEDs are acceptable light sources for Type B. Since there is no restriction on light sources for a lighting device not required by Standard No. 108, you may use the LEDs as light sources. Your third question is whether the maximum intensity of Type A and Type B, separately, should be less than the minimum intensity of the taillamp. Even though Type A and Type B are optional devices, in the configuration depicted where Type B is immediately flanked on both sides by a taillamp, the appearance of the three lamps would be that of a multicompartment lamp, even though they may actually be separate. To help assure that impairment of either the taillamp or stop lamp does not occur, the intensity of Type B should be identical with that of the taillamps. Otherwise, observers may assume that Type B (which you intend to have an intensity less than a taillamp) is actually the taillamp, and the actual taillamps (which you intend to have an intensity greater than Type B) might appear to be stop lamps that are continually on. This would be deemed impairment since there would be three intensity levels, increasing the possibility of confusion of the intent of the lamps. As for Type A, its vertical separation decreases the possibility for confusion. If the light sources are LEDs, the color would be a different shade of red that the stop and taillamps. Thus, the intensity is less important. However, it functions as an auxiliary taillamp and should be within the same intensity range as the original equipment taillamps. Finally, you asked whether the combined maximum intensity of both devices would be less than the minimum intensity of the taillamps. Again, this would create three levels of intensity, and could cause confusion in understanding the intent of the lamps. As noted above, the individual intensities should be similar to the intensity of the taillamps. I hope that this answers your questions. Sincerely, Stephen P. Wood Acting Chief Counsel; |
Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov 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.