Why is my LED lighting flickering? Causes and solutions for CAN-bus errors

Are you experiencing flickering LED lighting, lighting failure, or a dashboard error message related to lighting? This may have occurred after modifications or additions were made to the lighting system. This phenomenon is known as a CAN-bus problem/error.

In this article, we explain:

• Which CAN-bus interference occurs?

• How to solve and prevent these interferences

What is a CAN-bus system?

A CAN-bus system (Controller Area Network) is the nervous system of modern vehicles. It ensures that all electronic components communicate with each other. Think of lighting, sensors and control units.

Instead of separate cables for each function, the system uses one data line. This makes vehicles more efficient and lighter. At the same time, it constantly checks that all components are working properly.

The difference between 12V and 24V systems is mainly in the voltage and usage. Light vehicles such as cars often work with 12V. Heavier vehicles such as trucks usually use 24V. Both systems have their own margins for voltages and power consumption.

LED lighting uses much less power than traditional bulbs. As a result, the CAN-bus system sometimes thinks a light is faulty. This leads to error messages, flashing lighting or even failure.

An interference such as flashing lighting or failure of a light

When an interference occurs in the CAN-bus system, the vehicle displays a message on the dashboard. This message usually appears as a symbol with an orange or yellow light and an exclamation mark in it. This usually indicates one of the following problems:

• Flashing or flickering lighting
• Rapid flashing indicator (hyper-flashing)
• Error messages on the dashboard such as "light defective"
• Total lighting failure
• Weakly burning or pulsating lights

Flashing lighting often indicates a mismatch between LEDs and CAN-bus detection requirements.

Causes of CAN-bus problems with LED lighting

But what causes these interferences? This can be due to, among other things:

• Too low current draw of LEDs compared to traditional lighting
• Control pulses from the communication system visible to LEDs
• Missing or incorrect resistance, causing the system to detect an error

Solutions for CAN-bus problems

Fortunately, there are several effective solutions to fix CAN-bus problems in LED lighting:

• Using CAN-bus compatible LED lighting
• Mounting load resistors to increase power consumption
• Application of a control box that both corrects resistance and filters control pulses. Which maintains the control function.
• Accurate programming of the control box on vehicles with limited margins
• Check all cabling and plug connections for optimal operation
• This will ensure that the system continues to function correctly without error messages or flashing problems.

Preventing CAN-bus problems

Prevention is better than cure. By taking into account the requirements of the communication system in advance, you will prevent interference in practice. In doing so, pay attention to:

• The right choice for lighting with CAN-bus support
• Compliance with ECE standards and EMC compatibility ECE R10
• Working with reliable partners who think along in the design process, such as TRALERT®
• Correct mounting and connections, carried out by experienced professionals

By cooperating with specialists as early as the design phase, you save time, money and interference afterwards.

Situation: Error message "light on semi-trailer defective".

A common situation: a semi-trailer where the left indicator only works 1-2 times and then gives an error message on the dashboard. This often occurs when LED lighting has been applied without additional modifications.

Solution:

• Install a suitable resistance or CAN-bus control box to adjust the wattage
• Check the plug connections and clean the contacts
• Inspect wiring for breaks or loose connections
• Possible activation of the semi-trailer mode in the vehicle or mounting of a suitable module

Frequently asked questions (FAQ)

Why does my LED lighting not work on my semi-trailer?

This is often due to the lower power consumption of LED lights, causing the CAN-bus system to generate an error message or not switch on the lights.

Do I always need resistors with LED lighting?

Not always. Do you use CAN-bus compatible LEDs or a control box? Then additional resistance is often not necessary. What does a lighting error message mean? This usually means that the vehicle detects that a light is consuming insufficient power or is not working correctly.

Can I adapt my vehicle for LED lighting?

Yes, via a vehicle control box or software modifications, your vehicle can be made suitable for LED lighting.

How can I stop an error message in the CAN-bus system?
By adding the right resistance to the system or by installing a control box for the network protocol that corrects the pulses and current draw.

Also check out our article with general tips for vehicles with 24 Volt lighting systems.

TRALERT® as a partner for fault-free vehicle lighting

TRALERT® thinks with you and offers CAN-bus compatible systems for every application. From plug packages to complete customisation: we provide an efficient approach that prevents problems and optimises your work process.

Would you also like to equip your semi-trailers, semi-trailers or other towed equipment with a reliable, fault-free LED lighting solution?

Get information from our specialists or book an appointment at the TRALERT® Experience centre.