Marker lights with indicator function are the upgrade that combines safety and appearance, and trailer manufacturers in all categories are increasingly opting for them. This smart lighting offers a premium look that immediately catches the eye. Not only on long and heavy vehicles, but certainly also on compact trailers.

In this blog you will learn:

• The possibilities for flashing marker lights with indicator function on smaller trailers (O1 and O2 category).
• Tips and wiring diagrams to put into practice
• Plug-and-play solutions for trailer manufacturers

Why sequential side lighting is becoming increasingly popular

A trailer with marker lights with indicator function contributes to road safety. It greatly improves visibility. It significantly reduces the risk of accidents involving vulnerable road users such as cyclists and pedestrians.

In addition, it gives your vehicle a professional and modern look that exudes confidence.

As of 1 January 2025, progressive side lighting is mandatory for newly registered O3 and O4 trailers. The side indicator function may be completed with approved side marker lights that flash synchronously. If you would like to know more about obligations, please refer to our article on trailer lighting rules

Professional look for smaller trailers (O1 and O2 category)

Although it is (still) not mandatory on all vehicles, flashing side marker lights are increasingly used on trailers. This can help prevent damage and accidents. We are seeing this more and more on rental trailers, agricultural vehicles, and transport trailers. With little effort, you add a powerful visual upgrade that sets your trailers apart in a competitive market.

If you want to go one step further, the article reverse work lights on trailers may also be of interest to you. Here we explain how to connect these.

Connecting flashing side marker lights

There are two common ways of flashing the side marking.

Option 1: Via an extension cable + control unit

This wiring diagram shows an example of how the side markings can be connected using a control unit. We see a 7-PIN connector with 1.5 extension cable + 3-pole Superseal input + 2-pole SuperSeal output. This taps the indicator and position light signal without risk of interference.

Option 2: directly via multifunctional rear lights

Option 2: Directly via a multifunctional taillight

Do you want to connect marker lights with indicator functions in a simple and clear way? Then using a multifunctional rear light with multiple SuperSeal connections is a smart and efficient solution. These rear lights allow you to connect multiple functions via one central unit. Think of:

• Marker lights with indicator function (via direction indicator)
• Reverse lighting
• Fog lights
• Third brake lamp or work light (for a rear light with several SuperSeals connections).

This solution not only makes the installation clear, but also saves you valuable time on the production floor. No separate branching or additional cabling is required. You work directly from the rear light, completely plug & play.

For example via the VC 2000 or VC 6000 series, with built-in control unit and multiple SuperSeal connections. Ideal for OEM and trailer manufacturers looking for speed and simplicity.

Plug & play solutions with complete wiring harnesses

TRALERT® is all about smart simplicity, which is why we offer complete lighting solutions. These plug-&-play solutions allow you to save time and costs when installing lighting. This means minimal installation time and less susceptibility to error. Whether you work with a standard wiring harness or a customised solution for your vehicles, installation is always quick and straightforward.

Fully canbus compatible

The marker lights with indicator function should work seamlessly with the other lighting. To ensure that the side lighting is both continuous and synchronous with the direction indicator without interference. This is also known as canbus / interference-free lighting.

Solutions from TRALERT® specialists for vehicle builders

Are you a vehicle builder and want to learn more about suitable lighting solutions? Request a non-binding consultation with one of our product specialists.

Regulations for blinking marker lights with indicator function

Marker lights with indicator function are no longer just an attractive addition - they are the new standard. Since 2024, it is mandatory for all new O3 and O4 trailers within the EU to use side lighting that flashes synchronously with the direction indicators. But even on smaller trailers (where it is not mandatory), this dynamic side lighting offers direct added value. It increases visibility, improves safety and gives the trailer a modern, professional look.

More on this in our complete overview of trailer lighting regulations.

Frequently asked questions

What are marker lights with indicator function?

Marker lights with indicator function are side lights that flash synchronously with the trailer's direction indicator. They increase visibility and safety.

Are marker lights with indicator function mandatory for all trailers?

No, only for new vehicles in the O3 and O4 categories within the EU.

How do I connect marker lights with indicator function to 12V or 24V?

This can be done via a Canbus control box or via the rear light with SuperSeal connector. View our schemes or request support if you are a wagon builder.

Is a Canbus control box always necessary?

In modern vehicles, a Canbus control box prevents error messages and ensures correct signal processing. Definitely recommended.

Do flashing side lights comply with ECE R48?

Yes, our systems comply with the placement requirements and specifications of ECE R48 regulation for side markings on 12V trailers.