393.78

393.78 Violation: Inoperative or Damaged Windshield Wipers

A required windshield wiping system was recorded as missing, damaged, or unable to keep the windshield clear.

Check my DOT safety record Have our team review it Read 49 CFR 393.78
Plain-English answer

What does violation code 393.78 mean?

A required windshield wiping system was recorded as missing, damaged, or unable to keep the windshield clear.

Why carriers pay attention

How 393.78 can affect a trucking safety record

Wiper violations depend on whether the installed system operated effectively and whether the cited equipment was required for the vehicle and conditions.

FMCSA inspection data can flow into the Safety Measurement System used to organize carrier performance into Behavior Analysis and Safety Improvement Categories, commonly called FMCSA SMS BASICs. The carrier should verify the inspection, the assigned BASIC, and whether the violation is included in the official calculation.

How it gets cited

Common 393.78 inspection situations

  • A wiper motor, arm, linkage, control, or blade does not function.

  • A worn blade leaves streaking that the inspector records as ineffective operation.

DataQ review

When a 393.78 violation may deserve a closer look

A DataQ challenge should identify a specific factual or legal error in the inspection data. These are review questions—not assumptions that the violation should be removed.

Potential review angles

  • The wiper system operated across the required windshield area at inspection.
  • The report confuses a washer-system issue with a wiper-system violation.
  • The cited side, component, or vehicle is incorrect.

Evidence to collect

  • Video of the wiper system operating near the inspection time
  • Technician diagnosis distinguishing wiper and washer components
  • Photographs of the windshield, arms, and blades
Compliance expert review

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DataQs changes in 2026

A stronger review process still requires a stronger record.

FMCSA’s 2026 DataQs overhaul adds independent review stages, decision deadlines, and more detailed explanations. Carriers still carry the burden of identifying the error and supporting the requested correction.

See the 2026 DataQs changes
Frequently asked questions

393.78 violation FAQ

What does a 393.78 violation mean?

A required windshield wiping system was recorded as missing, damaged, or unable to keep the windshield clear.

Which FMCSA SMS BASIC is associated with 393.78?

Code 393.78 is commonly associated with the Vehicle Maintenance BASIC in the FMCSA Safety Measurement System. Inclusion and weighting should be confirmed on the carrier’s official record.

Can a trucking company challenge a 393.78 violation?

A carrier may submit an FMCSA DataQs Request for Data Review when the underlying inspection data is incomplete or incorrect. A repair made after the inspection does not by itself prove the original 393.78 finding was wrong.

What evidence helps review a 393.78 violation?

Useful evidence may include video of the wiper system operating near the inspection time, technician diagnosis distinguishing wiper and washer components, photographs of the windshield, arms, and blades. The best evidence is tied to the cited vehicle, driver, location, and inspection time.

Keep reviewing

Related DOT violation codes

View all violation guides
393.60CDamaged or Discolored WindshieldVisibility393.9Inoperable Required LampLighting396.17CNo Proof of Periodic InspectionInspection and maintenance393.75A3Flat Tire or Audible Air LeakTires and wheels

Source references: 49 CFR 393.78 and FMCSA roadside inspection data. This guide is general information and does not guarantee a DataQs outcome or replace legal advice.