Interpretation ID: 18322.ztv

Mr. Yaichi Oishi
General Manager
Government Affairs Department
Toyota Technical Center, USA, Inc.
1850 M Street, NW
Washington, DC 20036

Dear Mr. Oishi:

This is in reply to your letter of July 7, 1998, requesting an interpretation of Federal Motor Vehicle Safety Standard No. 108.

You cite S7.5(d)(2):

The lower and upper beams of a headlamp system consisting of two lamps, each containing either one or two replaceable light sources, shall be provided as follows:

(i) The lower beam shall be provided . . .

(A) By the outboard light source (or the upper one if arranged vertically) . . .

(ii) The upper beam shall be provided. . .

(A) By the inboard light source (or the lower one if arranged vertically) . . .

Toyota believes that the outboard light source must always provide the lower beam, except when neither light source is outboard of the other, i.e. when the light sources "are arranged perfectly vertically," the upper light source must provide the lower beam. You comment that "since it is nearly impossible to have light sources arranged 'perfectly vertically,' we believe that the agency's intent was that the light source may be considered outboard rather than vertically arranged for light source offsets beyond a certain nominal distance." You have determined that the nominal distance between optical axes should be 5 mm because "this is the distance at which we believe the two light sources can be optically recognized as being arranged offset from one another."

By way of background, this specification was originally adopted in the 1970s to apply to four-lamp sealed beam headlighting systems in which each lamp was identical in size and contained only a single light source. When the lamps were mounted horizontally, side by side with identical horizontal centerlines, the outboard lamps were required to be the ones providing the lower beam, which also served to mark the width of the vehicle. When the lamps were mounted vertically, one atop the other with identical vertical centerlines, the lower beam continued to mark the width of the vehicle, but it was required to be the uppermost headlamp in order to provide a greater seeing distance. This established the location priority for the lower beam, that it be the outermost beam, and uppermost beam if the vertical axes of the lamps coincided.

Paragraph S7.5(d)(2) extends this specification to headlighting systems consisting of two replaceable bulb headlamps with one or two light sources. The 1990s have seen the advent of headlighting systems and locations that were not contemplated when the location priority was established. We must therefore interpret S7.5(d)(2) and similar location requirements in a manner that best implements the agency's original safety intent, that the lower beam must be no further inboard than, and no lower than, the upper beam. Accordingly, where the vertical or horizontal axes of headlamps or light sources do not coincide, what is "upper" and "lower" will be determined by the relationship of the horizontal axes of a system's headlamps or light sources. The Toyota design depicts a system in which the lower beam headlamps are the outermost, in accordance with Standard No. 108. But the upper beam is provided by a headlamp whose horizontal axis is higher on the vehicle than the horizontal axis of the lower beam headlamp. This arrangement does not meet the intent that the lower beam be provided by "the upper one if arranged vertically."

In the forthcoming notice of proposed rulemaking to rewrite the headlamp specifications of Standard No. 108, the agency intends to propose modifying the current language to make the outboard position the only location requirement for the lower beam unless the upper and lower beams are arranged exactly vertically. This will ensure that the most frequently used headlamp beam can also serve to indicate the overall width of the vehicle from the front.

On March 25, 1998, we responded to a request by Stanley Electric Co. for an interpretation of S7.5(e)(2)(i)(A), the similar location specification for a two-lamp headlamp system each containing two replaceable light sources. I enclose a copy for your information. In the Stanley design, the lower beam was provided by the uppermost light source but its vertical centerline was inboard of that of the upper beam light source. We informed Stanley the design of this headlamp system did not comport with the original intent of Standard No. 108 that the lower beam be provided by either the outermost lamp or by one with an identical vertical centerline to the upper beam lamp. We concluded by saying that "the lower beam light source must not only be the uppermost of the two light sources but, also, its vertical centerline must not be inboard of the vertical centerline of the upper beam light source."

If you have any questions, you may call Taylor Vinson of this Office (202-366-5263).

Sincerely,
Frank Seales, Jr.
Chief Counsel
Enclosure
d.10/29/98
ref:108