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Reading the regulations as they stood on March 10, 2026. Current text may differ.Switch to current
Current textIn force on March 10, 2026Source: eCFR

§ 393.78 Windshield wiping and washing systems.

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

eCFR as of March 10, 2026 ↗
49 CFR § 393.78 — Windshield wiping and washing systems.. Text in force on March 10, 2026. This wording effective October 1, 2005 to present. Source: eCFR as of March 10, 2026, https://www.ecfr.gov/on/2026-03-10/title-49/section-393.78. Retrieved from FMCSR.com, https://fmcsr.com/reg/393.78?asof=2026-03-10, on October 26, 2026. Unofficial compilation; verify against the official source.

(a) Vehicles manufactured on or after December 25, 1968. Each bus, truck, and truck-tractor manufactured on or after December 25, 1968, must have a windshield wiping system that meets the requirements of FMVSS No. 104 (S4.1) in effect on the date of manufacture. Each of these vehicles must have a windshield washing system that meets the requirements of FMVSS No. 104 (S4.2.2) in effect on the date of manufacture.

(b) Vehicles manufactured between June 30, 1953, and December 24, 1968. Each truck, truck-tractor, and bus manufactured between June 30, 1953, and December 24, 1968, shall be equipped with a power-driven windshield wiping system with at least two wiper blades, one on each side of the centerline of the windshield. Motor vehicles which depend upon vacuum to operate the windshield wipers, shall have the wiper system constructed and maintained such that the performance of the wipers will not be adversely affected by a change in the intake manifold pressure.

(c) Driveaway-towaway operations. Windshield wiping and washing systems need not be in working condition while a commercial motor vehicle is being towed in a driveaway-towaway operation.

[70 FR 48054, 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 48054, Aug. 15, 2005]
  2. Oct. 1, 1996 → Oct. 1, 2005annual editions 1996–2004

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.