What 393.11TT means in plain language
FMCSR 393.11TT addresses inadequate or missing lighting devices and reflectors on commercial motor vehicles. This covers everything from headlights and taillights to side markers, clearance lights, and reflective materials required by federal safety standards.
When an inspector cites you for 393.11TT, they've observed that your truck is missing one or more required lights or reflectors, or that the ones present aren't functioning properly. This isn't a judgment call—the regulation has specific requirements for what must be on your vehicle and how it must work. A broken lens, a burned-out bulb you haven't replaced, a missing reflector tape, or a light assembly that's come loose or damaged all fall under this violation.
The key distinction: 393.11TT is about the physical presence and condition of lights and reflectors themselves. If a light doesn't illuminate at all, that's typically cited as 393.9 (Inoperable Required Lamp). This code focuses on whether the device exists and is in acceptable condition before we even test whether it works.
What our enforcement data actually shows
Across 13 million inspections, we've recorded 1,822 citations for 393.11TT all-time, with 1,095 citations in the last 12 months and 239 in the last 90 days. This ranks the violation at #556 out of 3,036 FMCSR codes by citation volume—a moderate-frequency citation, but one that shows consistent enforcement.
The out-of-service rate for 393.11TT is 0.0%. Not a single citation in our database has resulted in an out-of-service order. This is significantly lower than the all-FMCSR average OOS rate of 31.4%. In practical terms: getting cited for 393.11TT will not immediately sideline your truck. You'll receive a citation and have time to correct the violation, but you can typically continue operating once the inspector documents the defect.
Monthly trends show citation activity remaining relatively steady throughout 2025 and into early 2026, with peaks of 124 citations in September 2025 and troughs around 35 citations in April 2025. The consistency suggests this is not a seasonal enforcement surge but rather a baseline hazard that inspectors catch year-round.
Who gets cited most
Our inspection records show Texas leads by far with 491 citations for 393.11TT in the last 180 days, followed distantly by Iowa with 5 citations and Illinois with 2. The OOS rate remains 0.0% across all top states—no geographic variation in severity.
Texas's dominant share reflects the state's sheer volume of commercial traffic and border crossing activity. If you operate heavily in Texas, this violation should rank higher on your pre-trip inspection checklist simply because the enforcement frequency is orders of magnitude higher than elsewhere.
Among carriers, our data shows fleets such as Transportes Aguila de Ciudad Juarez SA de CV with 36 citations, Transportes de Carga Saul Salinas SA de CV with 26 citations, and Edna Lizeth Garza Alegria with 15 citations. These numbers reflect exposure (fleet size and miles driven) rather than negligence—larger fleets will naturally accumulate more citations over time. The pattern does suggest that international and cross-border carriers see higher citation frequency for lighting defects, possibly because aging trucks or higher utilization rates lead to more wear and tear on lighting assemblies.
How severe is this compared to similar codes
In the vehicle maintenance category, 393.11TT sits in the middle range by citation frequency. The code 393.9 (Inoperable Required Lamp) is far more heavily cited—180,097 citations all-time with a 6.9% OOS rate—suggesting inspectors encounter inoperable lamps more often than missing or inadequate lighting devices. Our data shows 79 shared inspections between 393.11TT and 393.9 in the last 90 days, meaning some trucks fail both: the device is present but broken, or multiple light failures occur on the same vehicle.
Compared to 393.78 (Windshield condition defective) with 157,894 citations and 0.3% OOS rate, or 393.47E (Slack adjuster defective) with 180,363 citations and 0.0% OOS rate, 393.11TT is less frequently cited but equally unlikely to result in an out-of-service order. The broader category code 393.11 (Lighting devices/reflectors) has 179,734 citations and 1.8% OOS rate, indicating that while the specific defects vary, they rarely lead to immediate removal from service.
How to avoid it
Before every trip, do a complete lighting walk-around:
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Check all four corners. Walk to the front of your truck and verify both headlights are present, clean, and aimed correctly. Move to each side and check clearance lights (the amber or red lights along the trailer sides). Go to the rear and confirm taillights, stop lights, and reflectors are all present and clean. Don't just look—touch the lens to ensure it's not cracked or missing.
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Inspect reflective tape and retroreflectors. These don't burn out; they wear off. Run your hand along the sides and rear of your trailer. If tape is peeling, missing, or severely faded, replace it before you roll. Our data shows 393.11TT citations correlate with inspections involving brake and coupling defects, suggesting comprehensive pre-trip attention matters—if one system shows neglect, inspectors will look harder at others.
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Clean light lenses. Road grime, mud, and salt accumulate. A dirty lens reads as "inadequate" light output during an inspection. Spend 30 seconds wiping down all light covers and reflective surfaces before you leave the lot.
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Replace damaged light assemblies immediately. If you hit something or notice a lens cracked, a mounting bracket loose, or a housing hanging, don't defer the repair. Our data shows Freightliner trucks (617 citations for this code all-time) and Kenworth trucks (293 citations) are cited most frequently—if you're in an older or heavily-used unit, lighting assembly wear is common. Carry spare bulbs and have a plan to repair or source replacement housings quickly.
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Document your inspections. Keep records of when you last replaced bulbs or tape, and note any repairs made. If cited, this history supports your case that the violation was transient or already being corrected.
The 79 shared inspections with 393.9 (Inoperable Required Lamp) and 42 shared inspections with 393.78 (Windshield condition defective) tell us that lighting defects often cluster with other visibility issues. Treating pre-trip lighting and glass inspection as a single critical routine—not an afterthought—will reduce your risk across multiple violation categories.