Interpretation ID: 21067.ztv

John F. Letchford, Esq.
Dilworth Paxson LLP
3200 Mellon Bank Center
1735 Market Street
Philadelphia, PA 19103-7595

Dear Mr. Letchford:

This is in reply to your letter of November 30, 1999, with respect to whether "a device that causes the backup lamps to steadily burn for a few seconds upon actuation of the horn would violate" 49 CFR 571.108 ( Federal Motor Vehicle Safety Standard No. 108).

Specifically, the device would cause the upper beam of a vehicle's headlamps to flash and "backup lights to illuminate and burn steadily" for three seconds or less, when the vehicle's horn is sounded. The purpose of the device is to provide a visual warning to others in front of or behind a vehicle of a potential danger or threat requiring an audible warning, i.e, use of the horn. You have cited S5.5.10(b) of Standard No. 108 which permits headlamps to be wired to flash for signaling purposes, but you are concerned with S5.5.10(d) that requires all other lamps to be wired to be steady burning.

S4 of Standard No. 108 defines "flash" as a "cycle of activation and deactivation of a lamp by automatic means . . . ." We would not regard a backup lamp that illuminated steadily for three seconds or less to be a lamp that is not steady burning within the meaning of S5.5.10(d), or flashing, within the definition of S4. However, the determinative question is whether a backup lamp can be used for purposes other than to indicate a reverse movement of the vehicle. The answer is no. See SAE Standard J593c, Backup Lamps, February 1968, which Tables I and III of Standard No. 108 incorporate by reference (copy enclosed). Paragraph 2 of Installation Requirements states that "Backup lamps shall not be lighted when the vehicle is in forward motion." It is clear that the device you discuss is intended to be used under normal operating conditions of the vehicle on the public roads, and that its installation would create a noncompliance with Standard No. 108.

We appreciate your client's interest in motor vehicle safety and regret that we cannot provide the letter you requested.

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

Sincerely,
Frank Seales, Jr.
Chief Counsel
Enclosure
ref:108
d.3/30/2000