Lesson 1.3 — Lighting

Why this matters

Inoperable lamps are the #1 violation issued during roadside inspections in North America. FMCSA wrote 344,225 "inoperative required-lamp" citations in one recent year — 11.75% of all truck inspection violations nationwide.

A dark lamp is also what officers call a gateway violation. A burned-out tail lamp gives the officer probable cause to pull you over, and once you are stopped, a full Level I inspection follows. The one bulb you didn't check becomes brakes, tires, paperwork, logs — everything.

The walk-around for lights takes 60 seconds. This module shows you what to check and what colors must be where.

WHITE Headlamps, license plate lamp. Nothing else on the front should be white.

AMBER Front turn signals, front side markers, front clearance lamps, front-half side markers on trailers. Amber means "front half of the vehicle."

RED Tail lamps, stop lamps, rear turn signals (can be red OR amber), rear side markers, rear clearance, rear ID cluster, rear reflectors. Red means "back half of the vehicle."

Federal rule: an amber stop lamp or amber tail lamp is prohibited. A red side marker on the front of the trailer is a violation. Get the color right.

1 Headlamps and front lamps

1. Turn on low beam. Walk to the front. Both headlamps lit, white, equal brightness.
2. Switch to high beam. Both lamps brighter. Check the high-beam indicator on the dash.
3. Turn on left turn signal. Front-left turn signal flashes amber. Front-left side marker stays solid amber.
4. Repeat right side.
5. Turn on hazards (4-way flashers). All four turn signals flash at once.

If a lamp is dark, dim, cracked, or fogged with water — write it on the DVIR.

2 Stop lamps, tail lamps, ID cluster

1. Have a helper stand behind the trailer. Or back up to a wall and use the reflection.
2. Press the foot brake. Both rear stop lamps light up red, bright.
3. Release the brake. Stop lamps go off. Tail lamps stay on (dimmer red).
4. Look at the three-lamp ID cluster at the top center of the trailer rear. All three lit, red.
5. Turn signals — left, then right. Each side flashes at the rear.

Out of service: no working tail lamp on either side. No working stop lamp on either side.

3 Side markers, clearance, conspicuity tape

1. Walk both sides of the tractor and the trailer with the marker lights ON.
2. Front side marker (closest to the cab on the trailer): amber.
3. Rear side marker (closest to the rear of the trailer): red.
4. Clearance lamps at the upper corners of the trailer: amber on the front, red on the rear.
5. Conspicuity tape (red-and-white striped tape on trailer sides and rear): clean, present, not peeling. Required on trailers 80 inches or wider, built after Dec 1993.

If a side marker is dark or the wrong color — write it on the DVIR.

4 Reflectors and license plate lamp

1. Reflectors do not light up — they reflect. Check that they are present and clean.
2. Rear reflectors: red, one on each side near the rear.
3. Side reflectors: amber near the front, red near the rear.
4. License plate lamp: white, lit when the headlamps are on, plate readable from 50 feet at night.

A missing or damaged reflector is a 393.11 violation even if every lamp on the truck works.

Dim or yellow headlamp — the bulb is dying, or moisture is in the lens. Won't pass at night. Replace it.

Water trapped inside a lens — the seal is broken. Bulb will short out soon. Write it on the DVIR.

Cracked or missing lens cover — automatic violation under 393.11.

Conspicuity tape peeling, dirty, or missing sections — required to be clean and continuous. Replace peeling sections.

One stop lamp brighter than the other — the dimmer one is failing. Replace the bulb.

Wrong color anywhere — an aftermarket clearance lamp in white instead of amber, a tinted cover that makes a red lamp look orange. Automatic violation.

Loose lamp housing — road vibration loosens mounts. If you can wiggle a lamp, the mount needs tightening.

License plate not readable at night — your plate lamp is out or aimed wrong.

1. 60-second walk-around with the lights on. Every trip. Front, both sides, rear. One full lap.
2. Keep spare bulbs in the cab. A 5-minute bulb change at the yard prevents a 90-minute roadside stop.
3. Clean the lenses. Mud, road salt, and bug spatter cut visibility by half. A wet rag fixes it.
4. If you can't tell whether a lamp is bright enough, replace it. A dim lamp is a dark lamp to an inspector.
5. Write it on the DVIR. A bulb out that the shop knows about is a maintenance ticket. A bulb out that the inspector finds is a citation.

• ○ Tire tread depth
• ○ Brake adjustment
• ✓ Inoperable required lamp
• ○ Hours of service

• ○ Red
• ✓ Amber
• ○ White
• ○ Blue

• ○ A red tail lamp
• ○ An amber front turn signal
• ✓ An amber stop lamp
• ○ A white headlamp

• ○ One burned-out clearance lamp on the trailer
• ○ A dirty rear reflector
• ✓ No working tail lamp on either side
• ○ A missing valve cap on a tire (not a lighting item but distractor)

• ○ 1
• ○ 2
• ✓ 3
• ○ 5