§393.93 requires that the driver's seat in every CMV manufactured on or after January 1, 1965, be equipped with a Type 1 (lap) or Type 2 (lap and shoulder) seat belt assembly meeting FMVSS 209. Other designated seating positions are addressed in §393.93(c). The seat itself must be secured to the floor or chassis with anchorages meeting §393.93(d) strength requirements.
Severity weight + OOS
Severity weight 4 in the Vehicle Maintenance BASIC. A driver's seat belt that is missing, cut, frayed through, anchored incorrectly, or non-functional is an out-of-service condition — the driver cannot legally operate without it. Compare to §392.16 (driver failing to wear the belt that is present), which is a separate Unsafe Driving cite.
How it gets cited
The patterns are physical condition (cut webbing, sun-damaged webbing that has lost tensile strength), missing retractor function (belt does not retract or lock), and anchorage damage (a bolt has pulled through the floor pan, the buckle frame is fatigued). The §393.93 cite is the equipment finding; the §392.16 cite is the behavioral one.
How to prevent it
- Inspect seat belt condition on every pre-trip — webbing, retractor lock, buckle latch.
- Replace seat belts on a maintenance schedule for older vehicles — UV degrades webbing on a clock that runs even when the belt sits unused.
- Verify seat anchorages at every §396.17 annual inspection; pulled anchorages from collision damage are easy to miss.
How Roadworthy HQ helps
§393.93 findings link to the vehicle record and route through the §396.9(d)(3) repair certification before return to service — the missing belt is replaced and the replacement is documented in the audit binder.