Interpretation ID: GF003174

Mr. Jack W. DeYoung
Tumbleweed Trucks, Inc.
318 Kwanzan Drive
Lynden, WA 98264

Dear Mr. DeYoung:

This responds to your facsimile dated April 9, 2004, seeking further clarification of our interpretation letter sent to you on April 2, 2004. You believe we mistakenly assumed that your hazard warning signal flasher is a closed type instead of an open type flasher.

In the April 2, 2004, letter, we indicated that the newly reprogrammed flash rate of your hazard warning signal flasher would comply with the current requirements of Federal Motor Vehicle Safety Standard No. 108 (FMVSS No. 108). However, we also stated that the flash pattern in your device is very different from what the agency contemplated in incorporating SAE Recommended Practice J945 by reference in the standard, and noted that existing hazard warning signal flashers operate at an essentially constant rate. Because we believe that motor vehicle safety is best promoted by standardization of lighting signals and because very different flash patterns have the potential to cause confusion, we indicated that we plan in the near future to modify Standard No. 108 in a way that would preclude your design.

In your latest facsimile, you state that your hazard warning signal flasher is a closed type flasher, as opposed to an open type flasher. You also ask that we explain how your flasher can comply with the requirements set forth in J945, and fail to comply with the requirements of Figure 1.

First, J945 and its accompanying Figure 1 specify requirements for "Flash Rate and Percent Current On Time." The flash rate must be 60 to 120 flashes per minute for "normally open" (i.e., variable load) flashers, and 90 to 120 flashes per minute for "normally closed" (i.e., fixed load) flashers. In the present case, the distinction between "normally open" or "normally closed" flashers is irrelevant because your hazard warning signal flasher would satisfy either requirement of flashes per minute.

Second, our previous letter did not indicate that your hazard warning signal flasher failed to comply with the requirements of Figure 1. Instead, we indicated our concern with the fact that while your flasher met the flashes-per-minute average identified in Figure 1, each individual flash cycle in your flash pattern is outside the parameters established in Figure 1.

If you need further assistance, please contact George Feygin of my staff at this address or at (202) 366-2992.

Sincerely,

Jacqueline Glassman
Chief Counsel

ref:108
d.6/14/04