NHTSA proposed cyan marker lamps and narrower manual-control rules for FMVSS 108

The National Highway Traffic Safety Administration proposed amending Federal Motor Vehicle Safety Standard No. 108, which covers lamps, reflective devices and associated equipment, to allow an optional cyan marker lamp on vehicles equipped with an automated driving system. The notice was filed for public inspection on October 23 and published in the Federal Register on October 26 under docket NHTSA-2026-1519. Comments are due by November 25.

The proposed specification sets the color as the cyan defined in SAE J578 and requires the lamp to be steady burning when activated, with at least one visible from the front, each side and the rear. One or two are allowed on each face, giving a minimum of four and a maximum of eight, mounted not less than 15 inches from the ground.

NHTSA proposed it as an if-equipped standard. The agency said it had tentatively determined that it lacked sufficient information to conclude there was a safety need to require the lamps on all vehicles equipped with an automated driving system, so it is not proposing to mandate them. Because the amendment would explicitly permit optional installation and activation under the proposed criteria, NHTSA said it would also prohibit installing the lamps on vehicles without automated driving functionality.

Two further changes would limit requirements for manually operated turn signal, hazard warning and beam-switching controls to vehicles that have manually operated driving controls, and would carry the term telltale through the standard to match FMVSS No. 101. Two unrelated changes address headlamp test voltage and vertical headlamp arrangements. NHTSA said the proposal is separate from the vehicle-lighting negotiated rulemaking it announced earlier in October.