Violation code

393.28-WS-6

Wiring Systems - Bare, loose, dangling, chafing or poorly connected wires.

Vehicle Maintenance3Non-OOS· SMS Appendix A v3.20

393.28-WS-6 is a Other Vehicle Defect violation under 49 CFR §393.28-WS-6. It falls in the Vehicle Maintenance BASIC with a severity weight of 3/10. Nationally it was cited 3,597 times in the last five years, with an OOS rate of 0.3%.

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National roadside inspection stats

as of 6/20/2026

Inspections

3,528

that found this code

Violations

3,597

total written

OOS rate

0.3%

11 OOS

Source: FMCSA roadside inspection data (last 5 years). The OOS rate is the share of these violations that led the officer to mark the driver or vehicle out of service.

Violation group: Other Vehicle Defect
Regulation §: 393.28-WS-6
Severity weight: 3
Used in SMS: Yes
Status: Active
Updated: 6/20/2026

Last updated June 2026

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Notes

DSMS: Y | Comment: Added in 3.15 | Footnote: As of February 1, 2023, the violations in this table are included in SMS. Only violations cited on or after February 1 are included in SMS calculations. This update aligns SMS with how violations are being cited in a new software used for roadside inspections.

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Challenging 393.28-WS-6 through FMCSA DataQs

If this violation was written incorrectly, here are the angles trucking-safety managers use to contest it. Playbook: Vehicle Maintenance (general).

Common ways to challenge this code

Pre-trip inspection showed compliant brakes
The driver's pre-trip DVIR documented compliant brake adjustment and operation. The cited defect arose en route or was misclassified at roadside.
Evidence that wins
- ✓Driver Vehicle Inspection Report (DVIR) from that date
- ✓Repair invoice or shop record
- ✓Post-citation re-inspection certificate (clean)
Momentary failure exception (§393.9)
The required lamp was inoperative only momentarily due to vibration, temperature, or similar transient cause — explicitly exempted under §393.9.
Evidence that wins
- ✓Photograph showing the lamp operable before / after the stop
- ✓Repair invoice if a fuse or bulb was replaced
Tread measurement disputed
The tread depth measurement was taken at a worn point that is not representative, contrary to NHTSA/FMCSA measurement standards.
Evidence that wins
- ✓Independent tread gauge reading from same tire (multiple positions)
- ✓Photograph of the tire with a reference scale
Documented maintenance schedule disproves the defect
Carrier's periodic-inspection records show the cited defect could not reasonably have existed at the time of inspection.
Evidence that wins
- ✓Periodic inspection certificate (§396.17)
- ✓Maintenance work order proximate to inspection date

Common pitfalls — avoid these

⚠DataQs cannot remove a violation simply because the defect was repaired after the stop

⚡ Draft a challenge for 393.28-WS-6 →Read the DataQs guide first

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Frequently asked questions about 393.28-WS-6

What does violation 393.28-WS-6 mean?

393.28-WS-6 is the FMCSA roadside-inspection violation code for "Wiring Systems - Bare, loose, dangling, chafing or poorly connected wires.", part of the Other Vehicle Defect group, cited under 49 CFR §393.28-WS-6.

What BASIC does 393.28-WS-6 affect?

393.28-WS-6 falls under the Vehicle Maintenance BASIC in the FMCSA Safety Measurement System (SMS).

What is the CSA severity weight of 393.28-WS-6?

393.28-WS-6 carries a severity weight of 3 out of 10. Higher weights indicate violations more closely tied to crash risk, and they count more toward a carrier's Vehicle Maintenance score.

Is 393.28-WS-6 an out-of-service (OOS) violation?

No. 393.28-WS-6 is not an out-of-service violation, so on its own it does not trigger an out-of-service order at the roadside.

How many CSA points does 393.28-WS-6 add to a carrier's score?

The point contribution of 393.28-WS-6 depends on its severity weight (3/10) multiplied by a time weight of 3, 2, or 1 based on how recent the inspection is. You can calculate the exact contribution with the CSA points calculator.

Can 393.28-WS-6 be challenged through DataQs?

Yes. If you believe 393.28-WS-6 was recorded in error, you can file a Request for Data Review (RDR) through the FMCSA DataQs system with supporting evidence. A successful challenge can remove or correct the violation on your record.

Keep going

CSA points calculator How to challenge a violation Draft a DataQs letter for 393.28-WS-6 Vehicle Maintenance BASIC Carrier CSA lookup CSA glossary

393.28-WS-6

National roadside inspection stats

Challenging 393.28-WS-6 through FMCSA DataQs

Pre-trip inspection showed compliant brakes

Momentary failure exception (§393.9)

Tread measurement disputed

Documented maintenance schedule disproves the defect