Modulating Headlights

There have been questions concerning if Modulating Headlights are legal in Tennessee. Yes, they are legal in all states per the Executive Order in the Federal Motor Vehicle Standards shown below. If you get a ticket for a modulating headlight you MUST fight it in court in order to educate the law enforcement official that this equipment is legal.

Department of Transportation

National Highway Traffic Safety Administration

Federal Motor Vehicle Safety Standards

49 CFR Parts 571

[Docket No. 97-57; Notice 1]

Executive Order 12866

Motorcycle Headlamp Modulation System

s7.9.1 A headlamp on a motorcycle may be wired to either the upper or the lower beam from its maximum intensity to a lesser intensity provided that:

(a) The rate of modulation shall be 240 +/- 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% of the maximum intensity measured at the same point.

(d) The modulator switch shall be wired in the power feed 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 the 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 the horizontal plane. Headlamp modulation shall cease whenever the level of light . . . . less then 270 lux.

Partial reprint of:

Federal Register: Feb. 21 1996 (Volume 61 No. 35)

The Exact Text and Location

The exact text from the FEDERAL MOTOR VEHICLE SAFETY STANDARDS

[Code of Federal Regulations]
[Title 49, Volume 5, Parts 400 to 999]
[Revised as of October 1, 1999]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR571.108]

[Page 226-299]

TITLE 49--TRANSPORTATION

CHAPTER V--NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS--Table of Contents

Subpart B--Federal Motor Vehicle Safety Standards

Sec. 571.108 Standard No. 108; Lamps, reflective devices, and associated equipment.

S5.5.10 The wiring requirements for lighting equipment in use are:

(c) A motorcycle headlamp may be wired to allow either its upper
beam or its lower beam, but not both, to modulate from a higher
intensity to a lower intensity in accordance with section S5.6;

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Last modified: August 10, 2006