Lighting device and reflector requirements apply to most commercial vehicles on the road today, but motor vehicles manufactured on or before December 25, 1968, must, at a minimum, meet requirements that were in effect on the date of the vehicle’s manufacture.
Stop lamps must activate when brakes are applied. Lamps and reflectors must be visible, with exceptions. Certain trailers manufactured on or after December 1, 1993, must also have retroreflective sheeting or additional reflex reflectors to make them more visible. Trailers manufactured before December 1, 1993, must be retrofitted with retroreflective sheeting or additional reflectors as stated in 49 CFR 393.13.
Other than head lamps and certain temporary lamps, all lamps must be securely mounted on a permanent part of the vehicle. Temporary lamps on motor vehicles being transported in driveaway–towaway operations, and temporary electric lamps on loads that are outside the footprint of the vehicle—called projecting loads—must be securely attached.
See 49 CFR 393 Subpart B for complete requirements and exceptions for lighting devices and reflectors.