Current textIn force on Oct. 1, 2011Source: annual CFR editions 2006–2016
§ 393.81 Horn.
Current wording, in the annual edition revised as of Oct. 1, 2006.
Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 2011 edition's wording. An amendment that took effect between Oct. 1, 2011 and Oct. 1, 2011 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, 2011. This wording effective October 1, 2006 to present. Source: govinfo, 2011 edition, https://www.govinfo.gov/app/details/CFR-2011-title49-vol5/CFR-2011-title49-vol5-sec393-81. Retrieved from FMCSR.com, https://fmcsr.com/reg/393.81?asof=2011-10-01, on October 26, 2026. Unofficial compilation; verify against the official source.
Every bus, truck, truck-tractor, and every driven motor vehicle in driveaway-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, 1996- Oct. 1, 1996 → Oct. 1, 2006annual editions 1996–2005
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.