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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.”

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NHTSA's Interpretation Files Search



Displaying 7311 - 7320 of 16501
Interpretations Date
 

ID: nht91-4.20

Open

DATE: June 12, 1991

FROM: Quang Van Nguyen -- Inventor, Houston Express Reprographics, Inc.

TO: Samuel K. Skinner -- Secretary of Transportation, U.S. Department of Transportation

COPYEE: Phil Gramm

TITLE: Re: New Invention for Auto Safety

ATTACHMT: Attached to letter dated 8-7-91 from Paul Jackson Rice to Quang Van Nguyen (A38; Std. 108)

TEXT:

According to the World News Report, in 1988 alone, there were 25,614 automobile passengers killed in an automobile accidents in the U.S.. Among these, the majority of the accidents did not occur because of the somewhat negligence of the drivers, but rather, and more importantly, they occurred because of the miscommunication between the drivers themselves.

A while ago, I, myself, was a witness of a accident of this nature on the highway. What occurred was that a car from behind hit a car in the front in the back and killed one woman and two children. This incident occurred because the car in front was in the center lane and had an engine failure. The driver naturally put on the emergency light and tried to move to the right lane quickly to avoid being hit; but unfortunately, as the car was changing lanes, another car, coming from the back of the right lane, hit the right rear end of the car with the engine problem. The impact was so bad that three of the passengers died instantly. However, the real reason that this accident occurred is that WHEN THE EMERGENCY LIGHTS ARE BLINKING, THE TURN SIGNAL LIGHTS DO NOT WORK AT ALL!! I understand that we cannot avoid an engine failure, a dead battery, or running out of gas on the road or highway; this will happen to all of us at least on time during our lives; but, how can the car behind know that the car in front has an emergency and wants or needs to change lanes??

Therefore, I would like to present to you my new invention, the EMERGENCY AND SAFETY LIGHTS (see copies attached). With my new invention, accidents like this can be avoided and thousands of lives can be saved. This is because my patent pending emergency lights is a very simple device which ALLOWS THE DRIVER OF AN AUTOMOBILE TO SET THE EMERGENCY LIGHTS ON WHEN NEEDED FOR AN EMERGENCY; BUT, RATHER THAN NOT BEING ABLE TO USE THE SIGNAL LIGHTS, THAT DRIVER WILL BE ABLE TO USE THEM AT THE SAME TIME WITH THE EMERGENCY LIGHTS, acknowledging to other drivers that he intends to turn or make a lane change.

I truly wish that your department will support my invention and approve it to be used for all types of automobiles in the U.S.A. because it costs less than $25.00 and it will help avoid unnecessary accidents and save our society thousands of lives.

I thank you very much in advance for you time and I am looking forward to hearing from you.

Figure 1 -- Drawing of Upper Installation (graphics omitted)

Figure 2 -- Drawing of Lower Installation (graphics omitted)

Figure 3 -- Wiring Diagram for Blinking Portion of the E.L.S.

(graphics omitted)

Figure 4 -- Wiring Diagram for Braking Portion of the E.L.S.

(graphics omitted)

ID: nht91-4.21

Open

DATE: June 17, 1991

FROM: Ivan Lee -- Deputy General Manager, Regulation Affairs, Hyundai America Technical Center, Inc.

TO: Paul Jackson Rice -- Chief Counsel, NHTSA

TITLE: Re: FMVSS 214, Side Impact

ATTACHMT: Attached to letter dated 7-23-91 from Paul Jackson Rice to Ivan Lee (A38; Std. 214)

TEXT:

We would like to request your assistance with an interpretation regarding Federal Motor Vehicle Safety Standard.

As you know, pursuant to the newly adopted side impact rule of FMVSS 214, all the light duty vehicle manufacturers are required to meet the yearly phase-in schedule, beginning with model year 1994.

To fulfill this requirement, Hyundai is making every effort to work out with the regulation as much as possible. But because Hyundai is limited carline manufacturer, we think Hyundai needs an alternative approach to comply with the requirement.

With the finalized schedule and Hyundai's alternative schedule listed in the table below, we would like to request your comments if Hyundai's alternative plan is acceptable or not.

94MY 95MY 96MY 97MY

Requirement 10 % 25 % 40 % 100 % Alternative Plan 20 % 20 % 50 % 100 % +/- % + 10 % - 5 % + 10 % 0

As you see in the table, compliance percentage of 1st year (1994) and 3rd year (1996) will exceed 10% more than requirement and 2nd year (1995) will be 5% short. However, as a whole, total compliance rate of alternative schedule is 15% more than requirement. We would appreciate if you would review Hyundai's plan and kindly provide us your opinion. Should you have any question, please feel free to contact Mr. Y.K. Moon of my staff at (313) 747-6600.

ID: nht91-4.22

Open

DATE: June 18, 1991

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Andreas Geis -- Robert Bosch GMBH, Automotive Division

TITLE: None

ATTACHMT: Attached to letter dated 10-2-90 from Paul Jackson Rice to S. Kadoya; Also attached to letter dated 4-19-91 from Andreas Geis to U.S. Department of Transportation, NHTSA

TEXT:

This responds to your letter asking how a vehicle should be loaded when determining compliance with Standard No. 104, Windshield Wiping and Washing Systems. You suggested that the vehicle's loading state could influence the position and size of the vision areas. As explained below, a vehicle must comply with the vision area requirements in Standard No. 104 under each and every loading condition between and including unloaded and loaded to the maximum recommended weight.

Standard No. 104 does not specify a loading condition for the development of vision areas, nor does SAE Recommended Practice J903a (May 1966), presently incorporated by reference into the Standard. Furthermore, there is no mention of the vehicle loading condition in the compliance test procedures for Standard No. 104. Since no loading condition is specified in the standard, the question arises whether the absence of loading conditions means that a vehicle complies with Standard No. 104 if it complies with the vision area requirements at any single loading condition between unloaded and fully loaded or whether the vehicle must comply with the vision area requirements at every loading condition between unloaded and fully loaded.

NHTSA has recently discussed this issue at length in an October 2, 1990 letter to Mr. S. Kadoya of Mazda Research and Development of North America, Inc. (copy enclosed). As a general matter, when a standard does not specify a particular test condition, there is a presumption that the requirements of the standard must be met at all such test conditions. This presumption that the standard must be met at all positions of unspecified test conditions can only be overcome if the language of the standard as a whole or its purposes indicate an intention to limit unspecified test conditions to a particular condition or conditions.

Applying this test to the vision area requirements in Standard No. 104, we begin with the presumption that the vision area requirements must be met under all loading conditions. We must then examine the standard as a whole and its purposes to see if there are any indications of an intention to limit Standard No. 104 to a particular loading condition or conditions. Nothing in the language of Standard No. 104 suggests an intention to limit the standard to a particular vehicle loading condition. In fact, there is some indication in the language of the standard that it's requirements are intended to be met irrespective of loading condition (see sections S4.1.1.2 and S4.1.1.3). Moreover, the purpose of the standard, to ensure driver visibility by requiring wiper systems to clear a specific portion of the windshield, is only serve if the wiper system functions adequately at all loading conditions. Therefore, since the language and purpose of

Standard No. 104 indicate no intention to limit the standard's requirements to a particular vehicle loading condition, the presumption that a wiper system must comply at all loading conditions stands.

I hope this information is helpful. Please contact us if you have any further questions.

ID: nht91-4.23

Open

DATE: June 18, 1991

FROM: Mickey Hale -- General Sales Manager, Jackie Cooper Olds-GMC

TO: Steve Kratzke

TITLE: None

ATTACHMT: Attached to letter dated 8-14-91 from Paul Jackson Rice to Mickey Hale (A38; Std. 208; VSA 108(a)(2))

TEXT:

I am writing in regard to our conversation on June 18, 1991, concerning the installation of seat belts on a used motor vehicle. This is a used 1990 Chevrolet full size van that is having a conversion package built.

The front two seats will have shoulder belts installed. The middle and rear seats will have lap belts installed. It is Jackie Cooper Enterprise's understanding that this meets the NHTSA safety standards.

I would like to have a written document as per our conversation that confirms this does meet those safety standards.

ID: nht91-4.24

Open

DATE: June 19, 1991

FROM: Gerald Farr -- P. Eng., Senior Compliance Engineer, Compliance Engineering and Vehicle Testing, Road Safety and Motor Vehicle Regulation Directorate, Transport Canada

TO: Paul Jackson Rice -- Chief Counsel, NHTSA

TITLE: Re: FMVSS 210 - S4.3.1.1

ATTACHMT: Attached to letter dated 7-16-91 from Paul Jackson Rice (signature by Kenneth Weinstein) to Gerald Farr (A38; Std. 210)

TEXT:

I am writing at this time to determine whether or not there have been any "official" interpretations of the method used to calculate the angle specified in FMVSS 210, section 4.3.1.1. This section requires that a LINE FROM the seating reference point (or adjusted seating reference point) TO the nearest contact point of the belt with the hardware attaching it to the anchorage, must extend FORWARD from the anchorage at an angle with the horizontal of not less than 20 and not more than 75 degrees.

There are two particular areas of interest.

1. When the angle of the line which joins the two points (SRP and belt anchorage) is calculated with respect to the horizontal, is the calculation made using a three dimensional protocol or a two dimensional protocol. (The two dimensional protocol would not take into account the transverse ("y") coordinate of the two points.)

2. Have any interpretations been made concerning what constitutes "the nearest contact point of the belt with the hardware connecting it to the anchorage"?

I would appreciate receiving any information you can provide concerning this matter. I can be reached at (613)998-1999 if you wish to discuss this further.

ID: nht91-4.25

Open

DATE: June 19, 1991

FROM: Rosemary Dunlap -- President, Motor Voters

TO: Paul Jackson Rice -- Chief Counsel, NHTSA

TITLE: None

ATTACHMT: Attached to letter dated 9-10-91 from Paul Jackson Rice to Rosemary Dunlap (A38; VSA 103(a))

TEXT:

Thank you very much for your letter of June 10 regarding the question of possible federal preemption of state disclosure laws. The information is helpful. I also appreciate your sending a copy of the relevant portion of the transcript from Barry Felrice's Public/Industry meeting.

According to the transcript, Barry stated that NHTSA believes states would have authority to require information disclosure, as long as it was accurate, and IS NOT REQUIRED TO BE AFFIXED TO THE VEHICLE.

Auto industry lobbyists raised the issue of disclosure placement in Virginia, which proposed to require disclosure on a window sticker. However, they did not identify the legal cite for their argument. California's pending disclosure bills have a similar provision. Therefore, this is a pressing issue.

For the legal cite for that aspect--whether the sticker could be required to be affixed to the vehicle--Barry invited people to feel free to ask you.

So--to take Barry up on his invitation--would you please refer me to the legal cite concerning requiring disclosure information affixed to the vehicle?

Again, many thanks for your assistance.

Attachment A

FROM TRANSCRIPT OF NHTSA/INDUSTRY MEETING ON JULY 18, 1990

This is a different case. Here we -- there is nothing in federal law that preempts or otherwise prohibits a state from establishing information disclosure requirements as long as the information is accurate and is NOT REQUIRED TO BE AFFIXED TO THE VEHICLE. And we think there is federal preemption there but if a state wants to provide dealerships provide point of sale information to consumers or that there be information in an owner's manual we believe that they have authority to do that.

And the second part of this question asks, what are our views on such state laws? We would have to give any kind of opinion as to whether a particular state law was good or bad or if we agreed with it based on the specifics of that particular law and I really don't want to give a general statement that we disapprove of the states being in this area.

MR. DANA: AIAM. About petitions -- did you just say as long as that information labeling requirement whatever, IS NOT ATTACHED TO THE VEHICLE?

MR. FELRICE: Yes.

AS LONG AS IT IS NOT REQUIRED TO BE AFFIXED TO THE VEHICLE.

MR. DANA: All right.

MR. FELRICE: AND WHAT THE LEGAL CITE FOR THAT PARTICULAR ASPECT IS I DON'T KNOW AND YOU CAN FEEL FREE TO ASK JACK RICE, OUR CHIEF COUNSEL, who said you can say this, Barry.

Now the last questions asks, To what extent we plan to continue soliciting the opinions of consumer groups or others in round table meetings?

For instance, in a recent one, we had an issue about lap/shoulder belts. These will be done periodically. Jerry Curry wants to reach out a lot. We've had meetings with insurers, with manufacturers, consumer groups -- the rear seat lap shoulder belt meeting was an interesting one because we sort of had everybody there together: dealers, manufacturers, consumer groups and insurers. We don't have a particular time table that we'll do these. And probably -- I think everyone wants to do them once every six months, once every year, and I think we will continue to do that and as specific subjects come up, like rear seat lap shoulder belt retrofit kits that merit a specific meeting. ...we'll just call it then. So they will be continued but there is no specific schedule for doing that.

And I will answer any other questions.

MR. BENNETT: Milford Bennett, General Motors.

Barry, a follow up on Item 22. Side Impact. BIOSID AND SID...

Attachment B

California Legislature 1991-92 Regular Session Assembly Bill No. 71 (Text omitted)

ID: nht91-4.26

Open

DATE: June 20, 1991

FROM: Brett Reed -- Design Engineer, Morse Controls, Inc.

TO: Office of the Chief Counsel, NHTSA

COPYEE: R. Breitenstein; A. Paynter; F. Witt

TITLE: None

ATTACHMT: Attached to letter dated 9-16-91 from Paul Jackson Rice to Brett Reed (A38; Std. 102)

TEXT:

Morse Controls requests that your office issue an interpretation of Motor Motor Vehicle Safety Standard No. 102 and its application to electronic transmission shift controls. Specifically, as it relates to controls that operate automatic transmissions used in heavy duty trucks and RV's and on solenoid operated powershift transmissions used in various on and off highway vehicles.

Section S3.1.3 of this standard reads as follows:

S3.1.3 Starter Interlock - The engine starter shall be inoperative when the transmission shift lever is in a forward or reverse drive position.

Is the intent of this standard to render the engine starter inoperative when the transmission is in a forward or reverse drive gear or when the shift lever, the driver's interface to the transmission, is in such a gear? It would seem that the real thrust of this standard would be to inhibit the operation of the engine starter when the transmission is in a drive gear, thus avoiding the obvious safety hazards. The position of the shift lever, the driver's interface to the transmission, may well be dismissed in certain operational scenarios, provided this prime safety consideration has been met.

At the time this specification was written, transmissions were generally controlled by mechanical linkages or cables that were directly connected to the shift lever. Thus, the shift lever (the human interface) always matched the gear that the transmission was in. With the introduction of electronic shift systems and fully electronic transmissions, the connection between the shift lever and the transmission is rarely performed by direct mechanical means. This raises the possibility that the shift lever position may not match the gear currently engaged by the transmission in situations where the transmission control circuitry overrides the shift lever selection in the interest of safety, transmission protection or other criteria related to specific applications.

Such systems do require that the transmission be in neutral before enabling the operation of the engine starter, in accordance with the perceived intent of MVSS No. 102.

Any attempt to artificially match the electronic shift lever's position to the gear currently engaged by the transmission in such override situations not only burdens the shift lever with considerable cost and complexity, but also raises safety and reliability concerns. Similarly, requiring the

shift lever to be moved to neutral when the transmission itself is already in neutral due to some override condition imposes unnecessary safety hazards in some applications. The interests of public safety will be best served by requiring that the engine starter be inoperative when the transmission itself, not the transmission shift lever, is in a forward or reverse drive gear.

We, therefore, respectfully request that you review this matter and render an interpretation of the intent of this standard. Feel free to contact us for clarification of any points we have raised. Thank you in advance for your consideration of this matter.

ID: nht91-4.27

Open

DATE: June 24, 1991

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Elizabeth Anania

TITLE: None

ATTACHMT: Attached to letter dated 5-31-91 from Elizabeth Anania to Steve Kratzke; (OCC 6100)

TEXT:

This responds to your letter to Mr. Steve Kratzke of my staff, requesting that the National Highway Traffic Safety Administration (NHTSA) grant permission to a repair business to modify your motor vehicle.

You explained that your husband, Vincent Anania, has some paralysis of his right arm and hand as a result of a stroke a year ago. You explained that your husband wishes to begin driving again and was recently evaluated by Bryant Driving School in Raleigh who determined that he was qualified to drive. However, the seat in your automobile does not move far enough back to allow your husband to enter the vehicle. You asked for permission to have your vehicle modified so that the seat can move further back. I hope the following discussion explaining our regulations will be of assistance to you.

I would like to begin by clarifying that there is no procedure by which persons petition for and are granted permission from NHTSA to arrange to have a motor vehicle repair business modify their motor vehicle. Repair businesses are permitted to modify vehicles without obtaining permission from NHTSA to do so, but are subject to certain regulatory limits on the type of modifications they may make. In certain limited situations, we have exercised our discretion in enforcing our regulations to provide some allowances to a repair business which cannot conform to our regulations when making modifications to accommodate the special needs of persons with disabilities. Since your situation is among those given special consideration by NHTSA, this letter should provide you with the relief you seek.

Our agency is authorized to issue Federal Motor Vehicle Safety Standards (FMVSS) that set performance requirements for new motor vehicles and items of motor vehicle equipment. Manufacturers are required by the National Traffic and Motor Vehicle Safety Act (Safety Act) to certify that their products conform to our safety standards before they can be offered for sale. Manufacturers, distributors, dealers and repair businesses modifying certified vehicles are affected by S108(a)(2)(A) of the Safety Act. It prohibits those businesses from knowingly rendering inoperative any elements of design installed on a vehicle in compliance with a FMVSS. In general, S108(a)(2)(A) would require repair businesses which modify motor vehicles to ensure that they do not remove, disconnect or degrade the performance of safety equipment installed in compliance with an applicable safety standard. Violations of S108(a)(2)(A) are punishable by civil fines up to $1,000 per violation.

In situations such as yours where a vehicle must be modified to accommodate the needs of a particular disability, we have been willing to consider any

violation of S108(a)(2)(A) a purely technical one justified by public need. I can assure you that NHTSA would not institute enforcement proceedings against a repair business that modifies the seat on your vehicle to accommodate your husband's condition. We caution, however, that only modifications necessary to accommodate your husband's condition should be made to the seat.

If you have further questions or need some additional information in this area, please contact Mary Versailles of my staff at this address or by telephone at (202) 366-2992.

ID: nht91-4.28

Open

DATE: June 25, 1991

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Takashi Odaira -- Chief Representative, Emission & Safety, Isuzu Technical Center of America, Inc.

TITLE: None

ATTACHMT: Attached to letter dated 4-29-91 from Takashi Odaira to P.J. Rice (OCC 5987)

TEXT:

This responds to your letter requesting an interpretation on whether the Isuzu 2-door Coupe is subject to the rear seat requirements set forth in the final rule on Standard No. 214, Side Door Strength, published on October 30, 1990 (55 FR 45722). As noted by your letter, the rear seat requirements do not apply to passenger cars which have rear seating areas that are so small that the SID dummy cannot be accommodated according to the specified positioning procedures. The issues raised by your letter are addressed below.

By way of background information, the National Highway Traffic Safety Administration 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 meet applicable standards. The following provides our opinion based on the facts provided in your letter.

Your letter describes the positioning of the SID as follows:

In this vehicle, when the SID dummy is seated at the rear outboard passenger position according to the specified positioning procedures, the dummy's head comes into contact with the roof and backlight glass which have steep slopes. To avoid the interference, in our test, the head was tilted forward as much as possible and, in addition, the upper torso was also tilted forward, away from the seat back. Only in this way, could we accommodate the dummy in the seating area without changing the orientation of the thorax midsagittal plane, or affecting the H-point.

You noted, however, that "(t)his condition . . . obviously does not meet the positioning procedure of paragraphs S7.1.3(a) and (b), which provides, 'The upper torso of the test dummy rests against the seat back.'" You stated that it is therefore your interpretation that the vehicle cannot accommodate the SID dummy and that the rear seat requirements are not applicable to it. You requested our views regarding your understanding.

In the preamble to the October 1990 final rule, NHTSA noted that, for some vehicles where the roof has a steep rear slope, the SID head can be tilted so as to accommodate the test dummy without changing the specified orientation of the thorax midsagittal plane or affecting the H-point (two of the specifications in the S7 positioning procedure). The agency also noted that there are some cars with rear seating areas that are so small that the SID dummy cannot be accommodated according to the specified

positioning procedures, even if the head is adjusted fore-aft.

Section S3 of Standard No. 214 provides that the rear seat requirements do not apply to "passenger cars which have rear seating areas that are so small that the (SID) dummies cannot be accommodated according to the positioning procedure specified in S7." Thus, if any aspect of the positioning procedure, including the specification that the upper torso rests against the seat back, cannot be met, the vehicle is not required to meet the rear seat requirements of Standard No. 214.

With regard to whether the Isuzu 2-door Coupe is subject to Standard No. 214's rear seat requirements, NHTSA cannot make a determination that the rear seat requirements do not apply to a vehicle based solely on a description and photographs of that test procedure. If the agency should conduct a compliance test for the vehicle, it would attempt to position the SID dummies in the rear seat according to the specified seating procedure. If NHTSA were unable to position SID dummies in the rear of the vehicle according to the specified procedure, it would conclude that the rear seat requirements do not apply to that particular vehicle.

I hope you find this information helpful. If you have further questions, please contact Mary Versailles of my staff at this address or by telephone at (202) 366-2992.

ID: nht91-4.29

Open

DATE: June 25, 1991

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Debby Funk

TITLE: None

ATTACHMT: Attached to letter dated 6-4-91 from Debby Funk to The United States Department of Transportation (OCC 6130)

TEXT:

This responds to your letter of June 4, 1991, to the Department requesting information regarding regulations on the display of lighted signs in vehicles. If they are not prohibited, you are interested in regulations governing size, placement, color, luminosity, and power source "(i.e. batteries, wire connections to either brake lights or cigarette lighter)."

There are no Federal regulations or restrictions that directly prohibit the use of lighted signs in vehicles. However, there may be State and local laws that do. We are not in a position to advise you as to these laws, but you may write the American Association of Motor Vehicle Administrators for an opinion. The address is 4600 Wilson Boulevard, Arlington, Va. 22203.

If you are contemplating a commercial venture in supplying lighted signs for use in motor vehicles, there are somewhat different considerations. Under the National Traffic and Motor Vehicle Safety Act, once a vehicle has been sold and in use, a manufacturer, distributor, dealer, or motor vehicle repair business may not modify it in any way that would create a noncompliance with any Federal motor vehicle safety standard with which the vehicle originally complied. Thus, installation of a lighted sign by any of the foregoing persons could affect compliance with Standard No. 111, Rearview Mirrors and Standard No. 108, Lamps, Reflective Devices, and Associated Equipment. If the size of the sign interferes with the field of view in the interior mirror, a mirror must be provided on the exterior of the passenger side (most new cars today come equipped with these mirrors). If the sign is wired to the stop lamps, it must not result in a diminution of power that reduces the light from the lamp below the minimum levels specified in the standard. However, if the device is intended for owner installation, the foregoing discussion does not apply, as the Vehicle Safety Act does not prohibit owners from modifying their vehicles in any manner they choose, even if the modification creates a noncompliance.

Our regulations do prohibit combining the center highmounted stop lamp with any other lamp or device such as a lighted display sign. However, there is no Federal prohibition governing manufacture and sale of these devices. If you have further questions, we shall be pleased to respond.

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.