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: aiam1610OpenMr. C. E. Bryant, Bendix Home Systems, Inc., 2695 Peachtree Square, Peachtree Industrial Blvd., Doraville, GA 30340; Mr. C. E. Bryant Bendix Home Systems Inc. 2695 Peachtree Square Peachtree Industrial Blvd. Doraville GA 30340; Dear Mr. Bryant: This is in reply to your letter of August 21, 1974, asking whether th terms 'loaded vehicle weight' or 'rated cargo load' include the liquid for both water potable tanks and waste holding tanks in the case of motor homes and multi-purpose passenger vehicles. You indicated in a phone conversation with Mike Peskoe of this office on September 4, 1974, that the purpose of your question is to determine whether the weight of this liquid would be included in a manufacturer's computation of gross vehicle weight rating. You also ask for definitions of 'loaded vehicle weight' and 'rated cargo load.'; It is not required that a determination of gross vehicle weight ratin include the weight of a full amount of liquid in both the potable and the waste holding tanks on the assumption, stated in your letter, that in actual use the holding tank is empty when the potable tank is filled, and the liquid is drawn gradually from one tank to the other. It should be placed in the potable tank for determining GVWR, for this more closely reflects a new vehicle configuration.; The term 'loaded vehicle weight' is not defined in the Federal moto vehicle safety standards or regulations nor are we aware of its use therein. A related term, 'maximum loaded vehicle weight,' is defined in Motor Vehicle Safety Standard No. 110 (49 CFR 571.110), but this definition is not applicable to your question. 'Rated cargo load' is also not specifically defined, but is used in the requirements for gross vehicle weight rating in 49 CFR 567 and as a test condition in Motor Vehicle Safety Standard No. 208. It is intended to mean the manufacturer's good faith rating of the weight of a vehicle's full cargo.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam2895OpenMr. W. G. Milby, Manager, Engineering Service, Blue Bird Body Company, P.O. Box 937, Fort Valley, GA 31030; Mr. W. G. Milby Manager Engineering Service Blue Bird Body Company P.O. Box 937 Fort Valley GA 31030; Dear Mr. Milby: This responds to your August 3, 1978, letter asking how to compute th area of a sample of a body panel when testing for compliance with Standard No. 221, *School Bus Body Joint Strength*.; In your letter, you suggest that the net cross- sectional area of th sample is determined by multiplying the width of the sample by its thickness and then subtracting the area of each discreet fastener hole. The National Highway Traffic Safety Administration agrees that this procedure yields the correct area of the sample, and it is the method used by the agency in its compliance testing.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam4042OpenMr. Wayne D. Buhler, Director of Engineering, Onspot, Inc., 1424 E. 800 N., Orem, UT 84057; Mr. Wayne D. Buhler Director of Engineering Onspot Inc. 1424 E. 800 N. Orem UT 84057; Dear Mr. Buhler: This responds to your letter requesting a review of your 'Onspot Safet Chain,' an automatic snowchain, for compliance with existing regulations. According to your letter, the current units are being installed both as original equipment and in the aftermarket on 1/2 ton and larger vehicles, although prototypes are being developed for passenger cars. The device is activated by pulling a dash mounted electrical switch which activates an electric solenoid valve, allowing air to pass from an air tank on the Onspot air chambers. For the future, you are considering using a push pull air switch mounted at the dash which would get air supply from the tank or manifold, thus eliminating the solenoid valve. On vehicles with air-mechanical brakes, air is generally used from the secondary air reservoir, or the primary reservoir if that is all that is available. On vehicles with hydraulic brakes, an auxiliary air system is provided. I regret the delay in responding to your letter.; By way of background information, the National Highway Traffic Safet Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles or equipment comply with applicable safety standards. The following represents our opinion based on the facts provided in your letter.; NHTSA does not have any regulations covering automatic snowchains However, it is possible that installation of the Onspot Safety Chain could affect a vehicle's compliance with other safety standards. We note in particular that since the device may be tied into a vehicle's air brake system, it could affect a vehicle's compliance with Federal Motor Vehicle Safety Standard No. 121, *Air Brake Systems*.; If your device is installed as original equipment on a new vehicle, th vehicle manufacturer is required to certify that, with the device installed, the vehicle satisfies the requirements of all applicable safety standards. If the device is added to a previously certified new motor vehicle prior to its first sale, the person who modifies the vehicle would be an alterer of a previously certified motor vehicle and would be required to certify that, as altered, the vehicle continues to comply with all of the safety standards affected by the alteration.; If the device is installed on a used vehicle by a business such as garage, the installer would not be required to attach a certification label. However, it would have to make sure that it did not knowingly render inoperative the compliance of the vehicle with any safety standard. This is required by section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act.; Enclosed is an information sheet which identifies relevant Federa statutes and NHTSA standards and regulations affecting motor vehicle and motor vehicle equipment manufacturers. I note that the Vehicle Safety Act's provisions requiring manufacturers to notify purchasers of safety-related defects and to remedy such defects without charge apply regardless of whether an item of motor vehicle equipment is covered by a safety standard.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam3787OpenMr. Pekka Suuronen, Hella, Inc., P.O. Box 1064, Cranford, NJ 07016; Mr. Pekka Suuronen Hella Inc. P.O. Box 1064 Cranford NJ 07016; 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 |
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ID: aiam1240OpenMr. Pundalik K. Kamath, Senior Safety Engineer, Oshkosh Truck Corporation, P.O. Box 560, Oshkosh, WI 54901; Mr. Pundalik K. Kamath Senior Safety Engineer Oshkosh Truck Corporation P.O. Box 560 Oshkosh WI 54901; Dear Mr. Kamath:This is in reply to your letter of August 6, 1973, i which you inquire whether incomplete vehicles manufactured before the effective date of Motor Vehicle Safety Standard No. 121, 'Air Brake Systems,' (September 1, 1974) must conform to the standard. You ask further whether complete vehicles manufactured from these incomplete vehicles must conform if they are completed after the effective date of the standard.; Incomplete vehicles manufactured before the effective date of Moto Vehicle Safety Standard No. 121 need not conform to that standard, and complete vehicles manufactured from those incomplete vehicles also need not conform to the standard.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0847OpenMr. Arthur N. Maupin, C. and M. Company, P. O. Box 1285, Zanesville, OH, 43701; Mr. Arthur N. Maupin C. and M. Company P. O. Box 1285 Zanesville OH 43701; Dear Mr. Maupin: This is in reply to your letter of August 12, 1972, in which you aske which manufacturers are subject to the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 302. You also asked us for permission to include copies of FMVSS No. 302 in your promotional literature, and requested copies of any modification or supplements to the flame test.; Any manufacturer of passenger cars, multipurpose passenger vehicles trucks, or buses manufactured on or after September 1, 1972, is subject to the requirements of the standard. FMVSS No. 302 is a published Federal regulation, and you may reproduce it and distribute it in your promotional literature. I have enclosed a copy of a Notice of Proposed Rule Making, 36 F.R. 9565, which would amend the standard.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam3768OpenMr. Paul Scully, Vice President, Peterson Manufacturing Co., 4200 East 135th Street, Grandview, MO 64030; Mr. Paul Scully Vice President Peterson Manufacturing Co. 4200 East 135th Street Grandview MO 64030; Dear Mr. Scully: This is in reply to your letter of October 25, 1983, to Mr. Cavey o this agency asking for a copy 'of an NHTSA ruling issued sometime ago which supposedly permits the triple identification lights normally mounted on the top rear center line of semi-trailers to be mounted at the lower sill location.'; I enclose a copy of an interpretation furnished the State of Wisconsi on June 18, 1981, concerning this practice by Fruehauf Corporation. In summary, Fruehauf demonstrated to us the impracticability of mounting the lights at the top of a body with high-opening doors and a narrow header (chiefly because of vulnerability of the wiring).; The agency's interpretation was limited to vehicles of that specifi configuration, and was not intended to apply to semi-trailers in general.; If you have any further questions, we shall be glad to answer them. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1755OpenMr. Al Zajic, Engineering Department, American Trailers, Incorporated, 1500 Exchange Avenue, Box 26568, Oklahoma City, OK 73126; Mr. Al Zajic Engineering Department American Trailers Incorporated 1500 Exchange Avenue Box 26568 Oklahoma City OK 73126; Dear Mr. Zajic: This is in acknowledgment of your Defect Information Report i accordance with the defect reporting regulations, Part 573.; The Defect Information Report involves: 25 Aluminum Grain Hoppe Doubles trailers. Possibility that the lower side rail in the area of the upper coupler assembly may develop fatigue cracks. This information was furnished in your letter of January 10, 1975.; The following National Highway Traffic Safety Administratio identification number has been assigned to the campaign *75-0009*. The first quarterly status report for this campaign is required to be submitted by May 5, 1975. Please refer to the above number in all future correspondence concerning this campaign.; On December 26, 1974, an amendment to the National Traffic and Moto Vehicle Safety Act of 1966 (the Act) became effective. This amendment, among other provisions, modifies the content of the required owner notification and also changes some of the associated procedures. Since your owner notification letter was mailed after this date, section 153 of the amended Act should have been followed. Your letter should have referred to a specific date as the earliest date on which the defect will be remedied without charge (section 153(a)(5). Because remedy without charge is contingent upon actual dates, we believe the inclusion of a specific date is preferable to the statement in your letter. The date stated should be the earliest date on which parts and facilities can reasonably be expected to be available, and may be the same, an earlier, or a later date than the date of your letter. You must also include information that is responsive to section 153(a)(6) of the Act. As the procedures referred to in that section have not been published, it is sufficient if you advise owners that they may write to the Administrator, National Highway Traffic Safety Administration, Washington, D. C. 20590, if they find American Trailers to have failed or to have been unable to perform the repair satisfactorily.; It is therefore necessary that you send a revised notification lette by first class mail to the registered owners of those trailers which have not yet been corrected. A copy of your revised notification letter should be sent to this office (unless a 100 percent completion rate makes this unnecessary).; A copy of the Act including the 1974 amendment is enclosed. If yo desire further information, please contact Messrs. W. Reinhart or James Murray of this office at (202) 426- 2840.; Sincerely, Andrew G. Detrick, Director, Office of Defect Investigation, Motor Vehicle Programs; |
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ID: aiam3292OpenMr. William G. Milby, Manager, Engineering Services Department, Blue Bird Body Company, P.O. Box 937, Fort Valley, GA 31030; Mr. William G. Milby Manager Engineering Services Department Blue Bird Body Company P.O. Box 937 Fort Valley GA 31030; Dear Mr. Milby:#This responds to your letter of January 16, 1980, i which you asked a number of questions pertaining to Federal Motor Vehicle Safety Standard No. 101-80, *Controls and Displays*. The answers to your questions are presented below and are numbered to correspond with the numbering of the questions in your letter.#1. Section 5.2.1 provides that where Table 1 of Standard 101-80 shows both a symbol and identifying words or abbreviations for a particular control, use of the symbol is mandatory and use of the words or abbreviations is optional.#2. When a manufacturer identifies a control with both the symbol shown in Table 1, Column 3, and the identifying words or abbreviations shown in Table 1, Column 2, only the symbol is subject to the illumination requirements of Section S5.3. That section states that with certain exceptions (i.e., foot operated controls or hand operated controls mounted upon the floor, floor console or steering column or in the windshield header area) 'the identification required by S5.2.1 or S5.2.2 of any control listed in column 1 of Table 1 and accompanied by the word 'yes' in the corresponding space in column 4 shall be capable of being illuminated whenever the headlights are actuated.' Since this section refers only to the identification required by Safety Standard 101-80, it does not apply to identification which is optional under the standard.#3., 4., 5., 6., 7., 8. In questions designated by these numbers, you asked whether the following controls are subject to the identification and illumination requirements of Standard 101-80:#>>>(a) a driver comfort fan which is not a part of the windshield or rear window defrosting and defogging system or the heating and air conditioning system,#(b) hot water flow valves for heaters which are opened in winter and then closed again in summer,#(c) heater fresh air control valves used to control the ratio of fresh to recirculated air entering the heater,#(d) driver's side window defroster control,#(e) driver's fresh air vent control,#(f) fan control for an optional driver's heater which directs air at the driver's feet.<<<#Section 5 of Standard 101-80 states that each vehicle that is subject to the standard and is manufactured with any control listed in Section 5.1 or in column 1 of Table 1 must comply with the requirements of Standard 101-80 regarding the location, identification and illumination of such control. Of the controls listed above, those lettered (a), (d) and (e) are not listed in either of these locations and thus are not subject to these requirements. Items (b), (c) and (f) are part of a heating or air conditioning system indicated in column 1 of Table 1 and is therefore subject to the location and identification requirements of Standard 101-80. However, the fan control, which directs air at the driver's feet, is not subject to the illumination requirements, since section 5.3.1 states, 'control identification for a heating and air conditioning system need not be illuminated if the system does not direct air directly upon windshield.' Likewise, if the hot water flow valves and fresh air control valves are 'mounted upon the floor, floor console or steering column, or in the windshield header area,' then section 5.3.1 does not require them to be illuminated.#9. In your question 9, you asked whether the penultimate line in Table 2 concerning malfunctions in antilocks applies only to vehicles equipped with air brakes and whether the last line concerning brake system malfunctions applies only to vehicles equipped with hydraulic brakes.#The penultimate line of Table 2 applies to all vehicles less than 10,000 pounds GVWR which are equipped with an antilock system, regardless of whether they are air or hydraulic brake equipped vehicles. The agency included the reference to Standard 105, *Hydraulic Brake Systems*, to indicate that section 5.3 of that standard permits a manufacturer to use either a yellow or red warning light depending on whether there is a separate indicator that only warns of antilock failure or there is an indicator which warns of antilock and other brake system failures.#The last line of Table 2 concerning the telltale for brake system malfunction applies to all vehicles equipped with this type of telltale regardless of the type of brake system. The agency included the reference to Standard 105 since section 5.3 of that standard specifies other requirements that brake system malfunction indicators used in hydraulic brake systems must meet.#10. This agency has never established specific size requirements for the identification symbols specified in Tables 1 and 2 of Standard 101-80. Sections 5.2.1 and 6 only require that such symbols be visible to a driver restrained by crash protection equipment.#11. None of the display requirements of Table II of Standard 101-80 apply to vehicles with a GVWR exceeding 10,000 pounds. Displays included in such vehicles in accordance with other standards are subject only to the provisions of those standards.#12. Section 5.3.1 provides that the illumination requirements of Standard 101-80 do not apply to hand operated controls mounted on the steering column. Accordingly, they are not applicable to a hazard control mounted on the steering column.#13. If the clearance lamps are controlled with the headlamp switch, Table 1, footnote 2, of the standard provides that the only identification required is the headlamp switch symbol.#14. Standard 101-80, section 5.2.1, states that controls must be identified with the symbol indicated in Table 1 and that such identification shall be placed on or adjacent to the control. The agency has previously indicated that manufacturers could use a symbol that is a minor deviation from the required symbol, as long as the symbol used substantially resembles that specified in the standard (43 FR 27541, June 26, 1978). Thus, if the wiper symbol you want to use is only a minor deviation and substantially resembles the required wiper symbol, you may use it.#15. You enclosed in your letter a blueprint showing a bank of switches which control multispeed fans and asked whether the identification shown in the print would comply with the requirements of Standard 101-80. Since the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1391) requires manufacturers to certify their compliance with all applicable Federal motor vehicle safety standards, this agency does not approve products. However, from our understanding of the information you have provided, it appears that the identification you propose to use for fan controls would comply with Standard 101-80. This opinion is based on the fact that your blueprint shows use of the fan symbol in accord with section 5.2.1 and identification of each function of the fan switch in accord with section 5.2.2.#16. With respect to air conditioning systems:#>>>(1) Section 5.3.1 does not require illumination of the control identification if the system does not direct air directly upon the windshield.#(2) Table 1 and section 5.2.1 require the fan symbol to be used to identify the fan for an air conditioning system,#(3) If the air conditioning system control regulates temperature over a quantitative range, the extreme positions must be identified in accord with 5.2.2.<<<#17. With respect to vehicles over 10,000 pounds GVWR, the requirements of Standard 101-80 concerning telltales used to indicate high engine coolant temperature or low engine oil pressure are inapplicable. With respect to vehicles less than 10,000 pounds GVWR, these requirements are applicable. In a letter to Ford Motor Company (copy enclosed), this agency stated that use of the engine symbol which Ford proposed for identification of such telltales would comply with the requirements of Standard 101-80.#Sincerely, Frank Berndt, Chief Counsel; |
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ID: aiam4557OpenMr. William Shapiro Volvo Cars of North America Rockleigh, NJ 07647; Mr. William Shapiro Volvo Cars of North America Rockleigh NJ 07647; "Dear Mr. Shapiro: This responds to your letter concerning the testin of hydraulic brake hose assemblies to the whip resistance requirement (S5.3.3) of Standard No. 106, Brake Hoses. I regret the delay in responding. Your question relates to Table II of Standard No. 106, which specifies the amount of slack that should be introduced when mounting brake hose assemblies on the whip test apparatus. (The amount of the hose indicated as 'slack' in Table II is the difference between the projected length of the hose assembly (when mounted in the whip test machine) and the free length of the hose while maintained in a straight position.) Slack must be present in the hose when mounted on the whip test machine to enable the proper 'whipping' movement of a brake hose assembly. Without slack, an assembly would probably be incapable of withstanding any rotation of the movable header of the whip test apparatus described in Standard No. 106 without rupturing. Table II specifies the amount of slack for some sizes of assemblies, and not for others. You ask whether a hydraulic brake hose assembly of a size falling in the latter category--viz., an assembly comprised of a brake hose that is 19 to 24 inches in free length, and which is more than one-eighth inch or three millimeters (mm.) in diameter--'need not be tested to meet or exceed the whip resistance requirement' of the standard. With regard to NHTSA's Standard No. 106 compliance testing, your understanding is correct that Table II does not specify the amount of slack for testing assemblies of the size you describe. Due to the absence of the slack specification, NHTSA does not require testing of such assemblies to the whip resistance requirements of the standard. With regard to your certification that the brake hose assemblies you manufacture comply with all applicable requirements of Standard No. 106, you are correct that hydraulic brake hose assemblies of the size you describe are not subject to the whip resistance requirements. However, the agency urges manufacturers to ensure that these assemblies perform in a safe manner while subject to environmental conditions of vehicle operations which may result in flexing of the brake hose or brake hose assembly. Please contact my office if you have further questions. Sincerely, Erika Z. Jones 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.