FMCSA released supplemental details on Grote's radar-controlled auxiliary warning lamps and reopened public comment through November 19; the requested five-year exemption has not been granted.
FMCSA published supplemental information October 20
The Federal Motor Carrier Safety Administration published notice 2026-21390 on October 20, 2026 concerning Grote Industries' application for an exemption from the steady-burning exterior-lamp requirement. The agency reopened public comment because Grote supplied operational details that differed from or clarified the original application.
Comments are due November 19
FMCSA will accept comments on the supplemental information through November 19, 2026 under docket FMCSA-2026-0100. The notice asks commenters to address relevant information summarized in the new notice and docket memorandum rather than unrelated lighting issues.
The exemption has not been granted
This publication is a notice of supplemental information and request for comments, not a final approval. Motor carriers do not receive authority to install or operate non-steady auxiliary lamps merely because Grote filed an application or FMCSA reopened the docket.
Grote requested a five-year exemption
Grote's December 10, 2025 application seeks a five-year exemption from 49 CFR 393.25(e), which generally requires exterior lamps on commercial motor vehicles to be steady-burning. The request would cover motor carriers operating CMVs equipped with auxiliary lamps controlled by Grote's Rear-End Collision Warning system.
The system uses rear-facing radar
According to Grote's supplemental explanation, the self-contained radar can detect an approaching vehicle at approximately 200 meters, evaluate relative motion and calculate time to collision. When the programmed threshold is reached, the system automatically activates auxiliary amber warning lamps without driver input.
The application described a short collision threshold
The original filing described activation at a time-to-collision threshold associated with a substantial impending-collision risk, typically between 2.1 and 4.0 seconds. The value is part of the applicant's proposed design, not a new federal following-distance rule for drivers.
The RCW lamps pulse amber for up to four seconds
Grote now says the auxiliary lamps pulse amber for up to four seconds each time the rear-end warning circuit activates and do not transition to steady-burning red for an RCW event. This differs from the original description, which contemplated a transition to steady red while the collision risk remained.
Steady red is tied to brake activation
The supplemental information says any transition to steady-burning red belongs to Grote's separate brake-activated auxiliary warning function. When a rear-end warning and braking occur at the same time, the brake-activated function takes priority and controls the shared auxiliary lamps.
The same auxiliary lamps can serve both functions
Grote proposes using the same lamps for the radar-based rear-end warning and its brake-activated pulsating-lamp function. FMCSA sought more detail because the original application did not fully explain the priority between these functions or the meaning shown to a following motorist.
Public comments previously raised signal-meaning concerns
During the earlier comment period, parties questioned how motorists would interpret the warning and its relationship to other collision technology. CVSA expressed concern that a steady red signal unrelated to braking could be mistaken for a brake indication, one reason the new color and sequence clarification is material.
The requested scope covers all CMVs
Grote clarified that it wants the exemption to apply to all commercial motor vehicles. For combinations with more than one trailing unit, including doubles and triples, it says the system would be installed and operated on the rearmost unit.
The applicant says the system is automatic
Grote told FMCSA that the driver would not need to activate or interact with the RCW system and that its radar would not interfere with other radar-based vehicle detection systems. These are applicant representations for agency review, not an FMCSA finding that the system already satisfies the equivalent-safety standard.
FMCSA must apply an equivalent-safety test
Federal law permits FMCSA to grant an exemption only when it determines the exemption would likely achieve a safety level equivalent to or greater than compliance with the existing rule. The agency must consider the application, safety analysis and public comments and publish a separate decision.
A final grant would include conditions
If FMCSA ultimately grants the request, a later Federal Register notice must identify the regulation covered, effective period and terms and conditions. If the request is denied, the agency must explain the denial. Until that decision, fleets should continue following the existing lamp rule and applicable equipment instructions.
Primary-source note
This report is based on Federal Register document 2026-21390, published October 20, 2026, and its description of Grote's supplemental information. CDL Truck Pro has not treated the application as approval, converted the proposed time-to-collision range into a driver rule or represented the applicant's technical claims as final agency findings.
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Official sources
FMCSA notice 2026-21390: Grote supplemental informationRegulations.gov docket FMCSA-2026-010049 CFR 393.25: Requirements for lamps other than head lamps49 CFR 381.315: FMCSA exemption processCDL Truck Pro provides educational information. Confirm licensing, safety, tax, and regulatory requirements through current official sources and qualified professionals.