A truck light check belongs before sundown
Lights are the easiest defect on a truck to find and among the cheapest to fix, yet they still park trucks at roadside. The answer is a check done in daylight, while you can still repair what fails.
Written by Rigo Diaz
Truck lights in numbers
A truck light check before sundown means testing every lamp and reflector that 49 CFR 393.11 requires: headlamps on both beams, turn signals and flashers, tail and stop lamps, clearance, identification, and side marker lamps, plus reflectors and tape. Do it in daylight, because state laws require lights on from about sunset.
A dead lamp is the easiest vehicle defect to find. It is also one of the most common reasons a truck is parked at roadside: in CVSA's 2026 International Roadcheck, lights were the fourth most common vehicle out-of-service violation in the U.S.
I spent more than six years in risk management before I founded Simplex, and I have led it for more than 25 years since. This checklist covers which lamps your tractor and trailer must carry, a walk-around that tests every one before dark, and what a missed lamp costs on your safety record. For how to drive once it is dark, see our guide to truck driving at night.
The full briefing, read aloud
8 chapters. Select one to jump to it.
Generated with AI text-to-speech from this article's key insights, in order, rather than reading it word for word. Chapter times come from a transcript of the audio. The article itself was written and reviewed by Rigo Diaz.
Key takeaways
State law sets the clock
Texas requires lighted lamps from half an hour after sunset; Florida from sunset, including twilight. Check before either starts.
Required lamps must always work
Under 49 CFR 393.9, every required lamp must be capable of operating at all times, so a dead one is a violation at noon too.
Know your tractor and trailer list
49 CFR 393.11 sets the lamps and reflectors each unit carries: amber at the front and sides, red at the rear.
Two laps catch every lamp
One lap with low beams, flashers, and running lamps on, and one for the stop lamps and the other turn signal.
Lighting violations weigh 6
In FMCSA's Safety Measurement System, a dead headlamp, tail, stop, or turn lamp carries a severity weight of 6 out of 10, plus 2 if it puts the truck out of service.
In this articleContents
When do truck lights have to be on?
State law sets the time, and it starts at or shortly after sunset. Federal rules require a commercial motor vehicle to be operated under the laws of the state it is in (49 CFR 392.2), and states draw the line differently:
- Texas requires lighted lamps at nighttime, which it defines as half an hour after sunset to half an hour before sunrise, and whenever a person or vehicle 1,000 feet ahead can't be clearly seen (Transportation Code 547.302, with the definition in 541.401).
- Florida requires them from sunset to sunrise, including the twilight hours, and during any rain, smoke, or fog (Florida Statutes 316.217).
That is why the check belongs before sundown, not at it. In daylight, in the yard, a dead lamp is a quick repair. Found after dark on the road, it is a defect you are already driving with.
Daylight doesn't excuse a dead lamp either. Under 49 CFR 393.9, every required lamp must be capable of operating at all times, and you rely on stop lamps and turn signals all day.
Which lights must you always check on a truck?
Every lamp and reflector that 49 CFR 393.11 requires for your type of vehicle. Its Table 1 sets the list for a truck tractor and for a trailer 80 inches or wider:
| Lamp or reflector | Truck tractor | Trailer 80 in. or wider |
|---|---|---|
| Headlamps, high and low beam | 2, white | None |
| Front turn signals | 2, amber | None |
| Front identification lamps | 3, amber, top center | None |
| Front clearance lamps | 2, amber | 2, amber |
| Side marker lamps and side reflectors | Amber, at the front | Amber at the front, amber midway if over 30 ft, red at the rear |
| Tail and stop lamps | 2 each, red | 2 each, red |
| Rear turn signals and hazard flashers | 2, amber or red, plus 2 amber flashers at the front | 2, amber or red |
| Rear identification and clearance lamps | None | 3 identification and 2 clearance, red |
| Rear reflex reflectors | 2, red | 2, red |
| License plate lamp | 1, white, not required while towing a trailer | 1, white |
| Backup lamp | 1 or 2, white | None |
| Conspicuity tape or reflectors | If built after July 1997: back of cab and mud flaps | Sides and rear |
Three color rules catch drivers out: front and side lamps are amber except the red rear side markers, rear lamps are red (rear turn signals may be amber), and no truck may carry an amber stop or tail lamp (393.11(c)). Every exterior lamp must burn steadily except turn signals, hazard flashers, and authorized warning lamps, and the stop lamps must come on with the service brakes (49 CFR 393.25).
One requirement changed in 2026. Since March 23, a truck tractor towing a trailer no longer needs a rear license plate lamp, under an FMCSA final rule. Running bobtail with a rear plate, it still does.
How do you do a truck light check, step by step?
Make two laps around the truck: one with the running lights on, and one for the stop lamps and the other turn signal. This sequence follows the seven-step inspection method in the CDL manual (Texas DPS edition, section 2.1.5).
Step 1: Start at the trailer cord
Plug the electrical cord into the trailer and fasten the safety catch. The cord should not be cut, chafed, spliced, or taped, and it should not drag or get pinched. A loose plug can darken every trailer lamp at once, and an unplugged cord has its own code on FMCSA's violation list.
Step 2: Low beams, flashers, then high beams
Set the parking brake, turn off the engine, and take the key with you. Turn on the low beams and the four-way flashers, then walk to the front: both low beams and both flashers should be on. Back in the cab, push the dimmer switch and confirm the high beams work.
Step 3: Running lamps and the right turn signal
Turn on the parking, clearance, side marker, and identification lamps and the right turn signal, then walk all the way around. Clean every lamp, reflector, and lens as you go, and check that each one is intact and the right color.
Step 4: Stop lamps and the left turn signal
Turn off all lights. Turn on the stop lamps by setting the trailer hand brake or having a helper press the pedal, and switch on the left turn signal. Check the left front and left rear signals and both stop lamps.
Step 5: Reflectors, tape, and the load
Check that reflectors and conspicuity tape are clean, intact, and uncovered. 49 CFR 392.33 bars driving with any required lamp or reflective material hidden by the tailboard, the load or its covering, dirt, or added equipment; only tape on a trailer's front-end protection device may be covered by the load.
A load that sticks out more than 4 inches past the sides, or more than 4 feet past the rear, needs its own marker lamps whenever headlamps are required, and those lamps may run on batteries. Wide or long loads may also need an oversize permit.
Step 6: Fix it before you leave, and look again at stops
Don't drive until you are satisfied the lighting devices and reflectors work (49 CFR 392.7). Look at the lamps and reflectors again whenever you stop, as the CDL manual advises. The same two laps belong inside your full pre-trip inspection; this is its lighting portion, done early enough to fix what you find.
What does a dead lamp cost on your safety record?
A roadside violation in the Vehicle Maintenance BASIC, weighted by how strongly it relates to crash risk. In FMCSA's Safety Measurement System violation list, light defects fall into three groups:
| Group | Typical citations | Severity weight |
|---|---|---|
| Lighting | Headlamp, tail, stop, or turn lamp out or missing; hazard flashers or backup lamp out; any required lamp or reflector obscured | 6 |
| Reflective sheeting | Conspicuity tape missing or inadequate; reflex reflectors missing | 3 |
| Clearance, identification, other | Clearance, identification, side marker, or license plate lamp out; trailer cord unplugged | 2 |
Weights run from 1 to 10. A lighting violation weighs 6, the same as a steering violation and more than most brake violations, which weigh 4. An out-of-service violation adds 2, recent inspections count more, and nothing older than 24 months is used, according to FMCSA's SMS methodology. Our guide to the seven BASICs explains how these scores add up.
Lights also park trucks. In CVSA's 2026 International Roadcheck, inspectors in the U.S. recorded 1,514 out-of-service violations for lights, 12.7% of the total, behind only brake systems, tires, and 20% defective brakes.
From the risk side, a light violation is the hardest kind to explain afterward, because a two-lap walk-around finds it. Our CSA program tracks roadside results, so a repeat lamp citation points to the truck, driver, or yard routine that needs attention.
Who is responsible for a lamp that's out: the driver or the carrier?
Both. The driver may not drive until satisfied the lights work, and the carrier may not operate a truck, or let one be operated, unless it is equipped as Part 393 requires (49 CFR 393.1(c)).
- The end-of-day report covers lights. Under 49 CFR 396.11, the driver vehicle inspection report must cover lighting devices and reflectors and list any defect found.
- The carrier closes the loop. It repairs any listed defect likely to affect safety, certifies the repair or that none was needed before the truck runs again, and keeps the report for three months.
- One-truck carriers are exempt from the report rule, not from the lighting rules or the driver's duty to check.
For a fleet, that adds up to a short written policy: lights checked before dispatch on any run that ends after sunset, spare bulbs on board, and lamp repairs logged like any other repair. Our guide to FMCSA maintenance records covers what that log must show.
How Simplex helps you keep light violations off your record
The driver's two laps are the first step. The reports, repairs, and roadside results behind them need an owner too.
Roadside results, tracked
Through our CSA program, our team monitors your CSA data and helps fix the training and policies behind repeat violations.
Records an auditor checks
Our DOT safety compliance team sets up and maintains the programs FMCSA samples, including documented vehicle maintenance.
A routine that keeps checking
Our compliance programs include CSA monitoring, annual inspection tracking, preventive maintenance records, and a DOT mock audit.
Frequently asked questions
When inspecting your lights, which lights must you always check?+
Do truck lights have to work during the day?+
When do truck headlights have to be on?+
Does a semi truck need a license plate light?+
Can a truck have amber brake lights?+
Where this information comes from
The requirements below come from federal regulation, Texas and Florida statutes, the CDL manual, FMCSA's Safety Measurement System, and CVSA's published results, checked on October 20, 2026.
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1
eCFR — 49 CFR 393.11
Table 1 of required lamps and reflectors by vehicle type, conspicuity systems, the amber stop lamp ban, and the license plate lamp exception.
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2
eCFR — 49 CFR 393.9
Required lamps must be operable at all times and not obscured.
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3
eCFR — 49 CFR 392.7
The driver must be satisfied lighting devices and reflectors work before driving.
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4
Texas Transportation Code, Chapter 547
Section 547.302: lighted lamps at nighttime and when visibility is under 1,000 feet.
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5
Florida Statutes 316.217
Lighted lamps from sunset to sunrise, including twilight, and in rain, smoke, or fog.
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6
Texas DPS — Commercial Motor Vehicle Drivers Handbook (DL-7C)
The seven-step inspection method's light checks (2.1.5) and trailer electrical line inspection (11.6.1).
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7
FMCSA — SMS Appendix A Violation List
Violation groups and severity weights for lighting, reflective sheeting, and clearance lamp citations.
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8
CVSA — 2026 International Roadcheck Results
Lights as the fourth most common U.S. vehicle out-of-service violation, released August 25, 2026.
Written by
Rigo Diaz
Founder & CEO, Simplex Group
Founder and CEO of Simplex Group, with more than 25 years leading the company and helping trucking entrepreneurs navigate compliance, insurance, and the day-to-day demands of running a carrier. Before founding Simplex, he spent more than six years in risk management, experience that continues to shape how he approaches insurance, compliance, and carrier risk today.
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Two laps around the truck, before the sun goes down
Check the cord, run the lamps, test the signals, clean what you can reach, and fix what fails while it is still light. That routine keeps the most visible defect on a truck off your record.
If you want help building light checks, inspection reports, and CSA monitoring into one routine, talk to our team.