Spec sheets for LED truck tail lamps are full of shorthand: sequential, dynamic, ULA, SEA, ESS, hyperflash. This is the plain-language version — what each term means, why it exists, and where it applies in the OIRAN JAPAN range.

Sequential (dynamic) turn signals

A standard turn signal blinks: all LEDs on, all LEDs off. A sequential turn signal — also called a dynamic turn signal — lights its LEDs in a sweep that flows outward in the direction of the turn, then repeats. Beyond the look, the motion itself communicates: a moving sweep reads as direction, not just as a flash. On OIRAN spec sheets, look for "Dynamic Turn Signal" in the features row.

Switchable sequential

Some lamps let you choose the behavior. The OIRAN ZERO lists "Dynamic Turn Signal (On/Off)" — the sweep can be enabled or disabled. The COMBO MINI goes further and is sold in SEQUENTIAL and STANDARD variants. Reasons to choose standard operation exist: fleet policy, personal taste, or local vehicle rules. Switchable-sequential lamps keep the decision in your hands.

ULA and SEA

Two mode codes appear across the OIRAN catalog, and both describe animations rather than required lighting functions:

  • SEA is the side-marker animation function. On the SAMURAI series (L, M and S), the built-in light bar can serve as an animated side marker in addition to its role in the rear signature — one lamp, two duties.
  • ULA is the animation profile applied to the lamp's main functions on supported models — the sweep pattern behind the sequential behavior described above.

Model-by-model support is listed on each product page; if a spec row names ULA or SEA, the lamp supports that mode.

ESS: the Emergency Stop Signal

Under hard braking, an ESS-equipped vehicle rapidly flashes its stop lamps to warn traffic behind — a regulated behavior in ECE markets. When an OIRAN lamp is listed as "compatible with Emergency Stop/Signal (ESS) systems," it means the lamp responds correctly on trucks that trigger this function. Nearly the entire tail lamp lineup is ESS-compatible; some compact models, such as the JUNIOR, use a dedicated harness for ESS operation.

Hyperflash, and the canceler that fixes it

The most common LED retrofit surprise: the turn signals suddenly blink at double speed, and a bulb-failure warning may appear on the dash. Nothing is broken. The truck's flasher relay measures current to detect burned-out bulbs, and an LED lamp draws a fraction of what a filament bulb draws — so the relay assumes a failure and speeds up. That is hyperflash.

The fixes, in order of common use:

  • A load resistor (hyperflash canceler) restores the electrical load the relay expects. Our resistors come in ratings for brake, small and turn-signal lamps, and the compatibility sheets map the correct resistor per truck model. Resistors dissipate their energy as heat — mount them to bare metal, away from wiring looms.
  • Built in or in the box. The ZERO has hyperflash canceling built into the lamp. The KAKU (indicator type) includes an anti-hyperflash resistor in the package. The JUNIOR offers optional resistor kits OERO-04N (24V) and OERO-04CT (12V).
  • Flasher-side control. A blinker controller replaces the load-sensing behavior at the relay itself.

Plug-in harnesses

Every OIRAN lamp is designed to install with a plug-in harness: the harness connects to the truck's factory connector, and the factory wiring is never cut. That makes the install reversible, keeps the loom intact, and is the main reason a full tail lamp swap fits inside an hour per side. The compatibility sheets list the correct harness code for supported truck models.

Show-mode controllers

For event and display use, the side marker controller drives marker lamps through 16 animation patterns with adjustable speed. One clear caution: on public roads, only the original lighting mode complies with safety standards — animation modes are for show grounds and private property.

Compliance, briefly

ECE-certified OIRAN models carry engraved E-marks with certification numbers published on each product page. EU / EEA: verify local regulations before road use — rules on sequential signals and animations vary by country and vehicle category.

Where to start

If you are choosing a lamp rather than decoding one, the practical companion to this glossary is How to choose LED taillights for Japanese trucks — or go straight to the tail lamp lineup.