Interpretation ID: aiam3954
Branch Manager
Mazda (North America)
Inc.
24402 Sinacola Court
Farmington Hills
MI 48018;
Dear Mr. Nakaya: Please forgive our delay in responding to your letter of May 30, 1984 asking for interpretations of Standard No. 108 as it applies to center high-mounted stoplamps.; In your letter you stated that the preamble to the final rule discusse the definition of 'window opening' and concluded that the rear window opening shall be the perimeter of the rear glazing that is unobstructed and free of opaqueness. You have presented two rear window designs in which (1) ceramic opaque dots descend in increasing size to the bottom of the glazing and in which (2) shaded material becomes progressively darker as it descends, though the material is translucent, not opaque. You also show a design with an interior-mounted windshield wiper, including motor and cover, placed on the rear vertical centerline above the bottom of the glazing. In each instance you have asked at what point would the National Highway Traffic Safety Administration (NHTSA) consider an 'obstruction' exists for purposes of defining the bottom of the window.; The phrase 'window opening' does not appear in Standard No. 108. Th preamble discussion appears to be irrelevant with respect to the final rule, and was intended as a clarification of proposed location requirements which, in fact, were not adopted. The notice of proposed rulemaking of January 8, 1981, proposed a definition of 'daylight opening' as 'the maximum unobstructed opening through the glazing surface...,' relating to three alternative locations proposed for the lamp in which the term 'daylight opening' was used as a locational reference. For instance, in Alternative 1, proposed paragraph S4.3.1.9(a) would have placed 'the center of the lamp within 3 inches of the outside bottom edge of the rear window daylight opening.' When the final rule was adopted in October 1983, none of the three alternatives was judged acceptable and a requirement allowing more design freedom was adopted omitting all reference to 'daylight opening.' Paragraph S4.3.1.8 simply specified that 'no portion of the lens shall be higher than the top of the back window or lower than three inches below the bottom of the back window. The requirement was even further relaxed in the May 1984 response to petitions for reconsideration in which paragraph S4.3.1.8 was amended to allow mounting 'at any position on the centerline' (note, no limitation on upper mounting height relative to the rear window) and if 'mounted below the rear window, no portion of the lens shall be lower than 6 inches on convertibles, or 3 inches on other passenger cars.' The preamble also clarified that, if the lamp were mounted on the interior, photometric compliance would be judged with the glazing in place.; Thus, whether glazing is opaque or obstructed is not the question manufacturer must ask in determining the location of the lamp with respect to the lower edge of the window. If the lamp is mounted on the interior, it must meet photometric and visibility requirements with the glazing in place, taking into account any graduated dots on or opaqueness of that glazing, and any wiper motor. If the lamp is mounted on the outside, its upper permissible height is determined by the height of the car and not by the window. The question of opaqueness or obstruction is irrelevant to the lower permissible height of 3 inches below the window. The window is the perimeter of its glazing, and 3 inches is measured from the lower edge.; Sincerely, Jeffrey R. Miller, Chief Counsel