Interpretation ID: 2285y
70 Lenox Road
Wayne, NJ 07470
Dear Mr. Crisci:
This is in response to the telephone call you made to me after receiving the interpretation of Motor Vehicle Safety Standard No. l08 furnished you on August 7, l989.
To summarize, you wished to know whether a "safety light flasher" to be installed on your motorcycle would conflict with DOT regulations. This device flashes a motorcycle headlamp between upper and lower beam for 2 to 4 seconds, then returns the light to the beam it was in when the flasher was activated. If the headlamp is off, the flasher will turn it on and initiate an identical flash cycle. We advised you that Standard No. l08 allowed flashing headlamps only on vehicles equipped with turn signals (S5.5.10(c)), and that the provision applicable to motorcycle headlamps (S5.5.l0(d)) permitted only headlamp modulators, which must provide varying intensities within a single beam, and not between beams.
You have questioned this interpretation because motorcycles are required to be equipped with turn signals. We have reviewed Standard No. l08, and have concluded that your device is prohibited, albeit for reasons other than section S5.5.10(c). Section S5.5.1 requires that the means for switching between upper and lower beams conform to one of two SAE Recommended Practices, either J564a, or J565b. The first requires that the switch be operated by a simple movement of the driver's hand or foot. We do not interpret this as allowing automatic switching between upper and lower beams. Although the second provides for automatic switching, it is in the context of changing the upper beam to the lower one when oncoming traffic is approaching. Your device does not contain this feature.
We must also bring your attention to section S5.1.3. This section prohibits the installation of supplementary lighting devices if they impair the effectiveness of lighting equipment that is required by Standard No. l08. In our opinion, a device that switches between upper and lower beam at times when the headlamp is illuminated would impair the roadway illumination that the headlamp is intended to supply. In addition, if the flasher caused lamps other than the headlamp to flash (such as the taillamp, which must be activated when the headlamp is steady-burning), that are required to be steady-burning in use, a noncompliance with section S5.5.11(e) would result.
Sincerely,
Stephen P. Wood Acting Chief Counsel
/ref:l08 d: 2/l4/90