Interpretation ID: aiam5186
Suite 303 Glendale
CA 91202;
Dear Mr. Shieh: This replies to your undated letter to the Office o Enforcement, NHTSA, asking questions about an emergency communication product intended to be permanently mounted in the back window of an automobile. The product uses light emitting diodes to form messages for the drivers of following cars to read. I enclose a copy of a letter dated August 17, 1989, that the agency sent to Alan S. Eldahr who asked for our comments on a similar device. The same advice applies to your product. As you will see, our opinion is that the product is of doubtful legality under Federal law when used on passenger cars manufactured on or after September 1, 1985, which are equipped with center highmounted stoplamps. In addition, the product must not create a noncompliance with the Federal field of view requirements for interior rear view mirrors. Thus, we cannot answer your question about the maximum size of a permanent structure to be installed in an automobile because that will vary from car to car. With respect to your other questions, there are no Federal specifications for the material of the base support. The 'restriction' on the product's wiring is that it must not interfere with the functioning of any Federally required lamp on the vehicle. This agency is the only government agency you have to consult on the product. Sincerely, John Womack Acting Chief Counsel Enclosure;