Interpretation ID: 19873.ztv

Mr. Daniel R. Todd
Muth Mirror Systems
4221 High Tech Lane
Sheboygan, WI 53082-0418

Dear Mr. Todd:

This is in reply to your e-mails of April 15 and April 19, 1999, requesting confirmation that an interpretation that this Office provided John K. Roberts of Muth Mirror Systems on January 15, 1991, with respect to a "Stop Turn Mirror" ("STM") is valid also for a revised version of that device.

The original STM was designed to appear as a mirror to the vehicle operator, but as a stop and turn signal indication system to the operator of a vehicle following. Your current "Signal Mirror" provides a "high intensity chevron shaped signal which is mounted behind and projects through the mirror," and is operated by the turn and hazard warning signal system. That is to say, the chevron signal in the exterior rearview mirror on the driver's side of the vehicle will indicate a left turn, and the chevron signal in the exterior rearview mirror on the passenger side of the mirror will indicate a right turn. Both chevron signals will activate simultaneously when the hazard warning signal is activated.

You are also developing a "high extended mount stop lamp" (HEMSL) which is operated when the brakes are applied; this feature consists of "a straight line of high intensity lamps" centered near the top edge of the mirror, which also "are mounted behind and project through the mirror surface." As you explained to Taylor Vinson of this office on May 24, the stop signal will appear simultaneously in both exterior mirrors. You have asked us four questions about how our 1991 letter applies to these two new mirrors.

The first question relates to Federal Motor Vehicle Safety Standard No. 108's prohibition of combining a center high mounted stop lamp (CHMSL) with any other lamp or reflective device. We advised in 1991 that a mirror was not a reflective device for purposes of Standard No. 108, and that the question would be whether the turn signal functions of the STM were clearly separated from the stop function so that the question does not arise as to whether they are combined. You have asked "Based on the updated device description provided above and current code interpretation, does the Chief Counsel's remarks still stand."

The original STM provided a stop signal through the interior rearview mirror, whereas the new mirror system provides a stop signal through the two exterior mirrors. The stop signals are supplementary to the stop lamps that are mounted on the rear of the vehicle. Paragraph S5.4 Equipment combinations of Standard No. 108 does not prohibit combining stop lamps, other than CHMSLs with other lighting devices. The question that must be answered with respect to supplementary lighting equipment is whether they impair the effectiveness of lighting equipment required by Standard No. 108. With respect to the Muth mirror, we do not conclude that such an impairment exists. This also answers your final question: whether the stop and turn signal function may be combined in the Signal Mirror alone which does not incorporate a CHMSL. The answer is yes; Standard No. 108 does not prohibit the combining of supplementary stop and turn signal/hazard warning signal lamps.

Our 1991 letter also discussed the possibility of the STM replacing the original equipment CHMSL. We advised that the STM could not do so if it were intended to be located in the exterior rear view mirrors rather than the center interior mirror. This is the configuration of your HEMSL. Thus, the supplementary stop lamp HEMSL may not replace the original equipment CHMSL.

You next ask "If the HEMSL, mounted in the exterior rear-view mirrors, provided a certain geometric visibility and photometric output such that it contributed to the required CHMSL visibility and photometric standard, in this theoretic system of three lamps, could the lamp mounted on the centerline have its geometric and photometric requirements tailored such that when combined with the HEMSLs and provided the overall CHMSL requirements indicated in Standard No. 108?" The answer is no; Standard No. 108 requires that there be a single, not multiple, lamp comprising the CHMSL, and that that single CHMSL meet all specified photometric and visibility requirements, and not share them with an array of three lamps.

If you have further questions, you may phone Taylor Vinson (202-366-5263).

Sincerely,
Frank Seales, Jr.
Chief Counsel
ref:108
d.6/14/99