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Current textSource: eCFR

§ 393.24 Requirements for head lamps, auxiliary driving lamps and front fog lamps.

Current wording, in the annual edition revised as of Oct. 1, 2005.

eCFR (current) ↗
What changedOct. 1, 1996 wording → Oct. 1, 2005 wording (current)+187 added−322 removedHide

(a) MountingHeadlamps. Head lamps and auxiliary road lighting lamps shall be mounted so that the beams are readily adjustable, both vertically and horizontally, and the mounting shall be such that the aim is not readily disturbed by ordinary conditions of service.
(b) Head lamps required. Every bus, truck, and truck tractor shall be equipped with aheadlamps headlightingas systemrequired composedby of§ at least two head lamps, not including fog or other auxiliary lamps, with an equal number on each side of the vehicle393.11(a). The headlightingheadlamps system shall provide an upper and lower beam distribution of light, selectable at the driver's will.
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(c) otherMounting. thanHeadlamps lightingshall devicesbe mounted and reflectors:
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(d) Aiming. andHeadlamps, intensity.auxiliary Headdriving lamps shall be constructed and installedfront sofog aslamps to provide adequate and reliable illumination and shall conformbe aimed to meet the appropriateaiming specificationspecifications set forth in theFMVSS SAENo. Standards108 1(49 forCFR “Electric Head Lamps for Motor Vehicles” or “Sealed-Beam Head Lamp Units for Motor Vehicles571.”
[33 FR 19735108), Dec.SAE 25J581, 1968,and asSAE amended at 41 FR 53031J583, Decrespectively.
[70 3, 1976; 53 FR 4939748046, DecAug. 715, 19882005]

49 CFR § 393.24 — Requirements for head lamps, auxiliary driving lamps and front fog lamps.. Text current through October 22, 2026. This wording effective October 1, 2005 to present. Source: eCFR (current), https://www.ecfr.gov/current/title-49/section-393.24. Retrieved from FMCSR.com, https://fmcsr.com/reg/393.24, on October 26, 2026. Unofficial compilation; verify against the official source.

(a) Headlamps. Every bus, truck and truck tractor shall be equipped with headlamps as required by § 393.11(a). The headlamps shall provide an upper and lower beam distribution of light, selectable at the driver's will and be steady-burning. The headlamps shall be marked in accordance with FMVSS No. 108. Auxiliary driving lamps and/or front fog lamps may not be used to satisfy the requirements of this paragraph.

(b) Auxiliary driving lamps and front fog lamps. Commercial motor vehicles may be equipped with auxiliary driving lamps and/or front fog lamps for use in conjunction with, but not in lieu of the required headlamps. Auxiliary driving lamps shall meet SAE Standard J581 Auxiliary Upper Beam Lamps, July 2004, and front fog lamps shall meet SAE Standard J583 Front Fog Lamp, August 2004. (See § 393.7 for information on the incorporation by reference and availability of these documents.)

(c) Mounting. Headlamps shall be mounted and aimable in accordance with FMVSS No. 108. Auxiliary driving lamps and front fog lamps shall be mounted so that the beams are aimable and the mounting shall prevent the aim of the lighting device from being disturbed while the vehicle is operating on public roads.

(d) Aiming. Headlamps, auxiliary driving lamps and front fog lamps shall be aimed to meet the aiming specifications in FMVSS No. 108 (49 CFR 571.108), SAE J581, and SAE J583, respectively.

[70 FR 48046, Aug. 15, 2005]

Amendment history

2 distinct wordings on file since Oct. 1, 1996
  1. Oct. 1, 2005 → presentannual editions 2005–2016diff vs. previousviewing
    [70 FR 48046, Aug. 15, 2005]
  2. Oct. 1, 1996 → Oct. 1, 2005annual editions 1996–2004
    [33 FR 19735, Dec. 25, 1968, as amended at 41 FR 53031, Dec. 3, 1976; 53 FR 49397, Dec. 7, 1988]

A new entry appears whenever the regulatory words change between government snapshots. Day-precise from the eCFR (2017 onward); before that, one snapshot per annual CFR edition (revised as of October 1). Bracketed citations are the Federal Register history printed with the section. Set a case date in the header to read any earlier wording.