What are headlight modulators and are they legal in Texas?
There’s nothing specific in the Texas Transportation Code (TRC) regarding the use of headlight modulators as defined by NHTSA. Check local ordinances pertaining to modulator use. The National Highway Transportation Safety Administration (NHTSA) defines a headlight modulator as the wiring of either the upper or lower beam to vary from its maximum intensity to a lesser intensity. For more information please read the Code of Federal Regulations 571.108(9.4).