Itzamna wrote:Also read into your local laws. Just because it's legal in a nation or state, does not neccessarily make it legal in your local area. I don't think they're legal around here because I have never seen one here. When I went to Michigan, it seemed 2 out of 3 had a headlight modulator. I just ride with my brights on everywhere.

They always seem to notice me then, since they're always flashing their lights at me.

If your modulator complies with FMVSS 108, then the state has to accept it. This doesn't mean you won't get stopped or get a ticket. Some LEO's are not keen to every nuance of the law. However, you would easily beat the ticket in court. The modu;ators are legal in all 50 states.
Here's some of the law:
This Federal law supersedes all state laws and makes motorcycle headlight modulators
legal in all 50 states. FMVSS 108 (Federal Motor Vehicle Safety Standards) (49 CFR Part
571.108 S7.9.4) allows motorcycle headlight modulation systems all 50 states provided they
comply with the standards set forth in this section. Title 49 USC 30103 (b1) (US Codes)
prohibits any state from forbidding a system that conforms to FMVSS 108. Click here to
see the regulation.
Code of Federal Regulation - Title 49, Volume 5, Parts 400 to 999 - Revised as of October 1, 2000
From the U.S. Government Printing Office via GPO Access [CITE: 49CFR571.108] [Page 236-307]
TITLE 49: TRANSPORTATION - CHAPTER V, NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION,
DEPARTMENT OF TRANSPORTATION PART 571, FEDERAL MOTOR VEHICLE SAFETY STANDARDS -
Subpart B--Federal Motor Vehicle Safety Standards - Sec. 571.108 Standard No. 108;
Lamps, reflective devices, and associated equipment - S7.9.4 Motorcycle headlamp modulation system.
S7.9.4.1 A headlamp on a motorcycle may be wired to modulate either the upper beam or the lower beam from its
maximum intensity to a lesser intensity, provided that:
(a) The rate of modulation shall be 240 <plus-minus> 40 cycles per minute.
(b) The headlamp shall be operated at maximum power for 50 to 70 percent of each cycle.
(c) The lowest intensity at any test point shall be not less than 17 percent of the maximum intensity measured at
the same point.
(d) The modulator switch shall be wired in the power lead of the beam filament being modulated and not in the
ground side of the circuit.
(e) Means shall be provided so that both the lower beam and upper beam remain operable in the event of a
modulator failure.
(f) The system shall include a sensor mounted with the axis of its sensing element perpendicular to a horizontal
plane. Headlamp modulation shall cease whenever the level of light emitted by a tungsten filament light operating
at 3000 deg. Kelvin is either less than 270 lux (25 foot-candles) of direct light for upward pointing sensors or less
than 60 lux (5.6 foot-candles) of reflected light for downward pointing sensors. The light is measured by a silicon
cell type light meter that is located at the sensor and pointing in the same direction as the sensor. A Kodak Gray
Card (Kodak R-27) is placed at ground level to simulate the road surface in testing downward pointing sensors.
(g) When tested in accordance with the test profile shown in Figure 9, the voltage drop across the modulator when
the lamp is on at all test conditions for 12 volt systems and 6 volt systems shall not be greater than .45 volt. The
modulator shall meet all the provisions of the standard after completion of the test profile shown in Figure 9.
(h) Means shall be provided so that both the lower and upper beam function at design voltage when the headlamp
control switch is in either the lower or upper beam position when the modulator is off.
S7.9.4.2(a) Each motorcycle headlamp modulator not intended as original equipment, or its container, shall be
labeled with the maximum wattage, and the minimum wattage appropriate for its use. Additionally, each such
modulator shall comply with S7.9.4.1 (a) through (g) when connected to a headlamp of the maximum rated power
and a headlamp of the minimum rated power, and shall provide means so that the modulated beam functions at
design voltage when the modulator is off.
(b) Instructions, with a diagram, shall be provided for mounting the light sensor including location on the
motorcycle, distance above the road surface, and orientation with respect to the light.