§FMCSR.com
Historical textIn force on Sept. 30, 2000Source: annual CFR editions 1996–2004

§ 393.24 Requirements for head lamps and auxiliary road lighting lamps.

Wording first on file in the 1996 annual edition, superseded by the 2005 annual edition.

govinfo, 1999 edition ↗
Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 1999 edition's wording. An amendment that took effect between Oct. 1, 1999 and Sept. 30, 2000 would not appear until the next edition, so check the citations below and the Federal Register for exact effective dates.
49 CFR § 393.24 — Requirements for head lamps and auxiliary road lighting lamps.. Text in force on September 30, 2000. This wording effective October 1, 1996 to October 1, 2005. Source: govinfo, 1999 edition, https://www.govinfo.gov/app/details/CFR-1999-title49-vol4/CFR-1999-title49-vol4-sec393-24. Retrieved from FMCSR.com, https://fmcsr.com/reg/393.24?asof=2000-09-30, on October 26, 2026. Unofficial compilation; verify against the official source.

(a) Mounting. 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 a headlighting system composed of at least two head lamps, not including fog or other auxiliary lamps, with an equal number on each side of the vehicle. The headlighting system shall provide an upper and lower distribution of light, selectable at the driver's will.

(c) Fog, adverse-weather, and auxiliary road-lighting lamps. For the purposes of this section, fog, adverse-weather, and auxiliary road lighting lamps, when installed, are considered to be a part of the headlighting system. Such lamps may be used in lieu of head lamps under conditions making their use advisable if there be at least one such lamp conforming to the appropriate SAE Standard 1 for such lamps on each side of the vehicle.

1 Wherever reference is made in these regulations to SAE Standards or SAE Recommended Practices, they shall be: (a) As found in the 1985 edition of the SAE Handbook with respect to parts and accessories other than lighting devices and reflectors. (b) When reference is made in these regulations to SAE Standards or SAE Recommended Practices, they shall be as found in the 1985 edition of the SAE Handbook: (1) With respect to parts and accessories other than lighting devices and reflectors: (2) Lighting devices and reflectors on motor vehicles manufactured on and after March 7, 1990, shall conform to FMVSS 571.108 (49 CFR 571.108) in effect at the time of manufacture of the vehicle. Should a conflict arise between FMVSS 571.108 and a SAE Standard, FMVSS 571.108 will prevail.

(d) Aiming and intensity. Head lamps shall be constructed and installed so as to provide adequate and reliable illumination and shall conform to the appropriate specification set forth in the SAE Standards 1 for “Electric Head Lamps for Motor Vehicles” or “Sealed-Beam Head Lamp Units for Motor Vehicles.”

[33 FR 19735, Dec. 25, 1968, as amended at 41 FR 53031, Dec. 3, 1976; 53 FR 49397, Dec. 7, 1988]

Amendment history

2 distinct wordings on file since Oct. 1, 1996
  1. Oct. 1, 2005 → presentannual editions 2005–2016diff vs. previous
    [70 FR 48046, Aug. 15, 2005]
  2. Oct. 1, 1996 → Oct. 1, 2005annual editions 1996–2004viewing
    [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.