Historical textIn force on Oct. 1, 1999Source: annual CFR editions 1996–2005
§ 393.81 Horn.
Wording first on file in the 1996 annual edition, superseded by the 2006 annual edition.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 Oct. 1, 1999 would not appear until the next edition, so check the citations below and the Federal Register for exact effective dates.
49 CFR § 393.81 — Horn.. Text in force on October 1, 1999. This wording effective October 1, 1996 to October 1, 2006. Source: govinfo, 1999 edition, https://www.govinfo.gov/app/details/CFR-1999-title49-vol4/CFR-1999-title49-vol4-sec393-81. Retrieved from FMCSR.com, https://fmcsr.com/reg/393.81?asof=1999-10-01, on October 26, 2026. Unofficial compilation; verify against the official source.
Every bus, truck, truck-tractor, and every driven motor vehicle in drive-away-towaway operations shall be equipped with a horn and actuating elements which shall be in such condition as to give an adequate and reliable warning signal.
Amendment history
2 distinct wordings on file since Oct. 1, 1996A 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.