November 15, 2021 Tim Koenders

LED trailer lighting flashes. How do I solve this?

When connecting LED lights to your trailer, it can happen that the lights do not work or that the LED lights blink. This is annoying, but fortunately there are several solutions. So you do not have to worry if the LED lighting on your trailer flashes. In most cases, this is due to the CANBUS system of the towing vehicle. This is a safety system for data transfer between electronic components in a car, without the intervention of the central computer. In general, LED lighting has many advantages. However, in terms of connection to (older) vehicles, such problems can sometimes arise. One of these problems can therefore be a blinking LED lamp. We would like to explain to you how it is possible that the LED lighting on your trailer does not work. But more importantly, we'll explain how you can solve the problems.

led trailer lighting flickering bulb not working

Is your trailer ready for LED lighting?

More and more 'old' lighting is being replaced by LED lighting. This is because LED lighting has many advantages over conventional lighting such as halogen. Halogen lighting, for example, loses a lot of energy to heat. This is not the case with LED. Partly because of this, LED lighting lasts longer. Furthermore, LED lighting is more resistant to peak voltages and is more easily available in many shapes and colours. Would you like more information about the differences between halogen and LED? Read our blog: Halogen vs LED, the differences.

Because LED lighting loses less energy to heat, it also needs less energy to shine. Due to the lower energy demand, it happens that the LED lighting is sometimes seen by the on-board computer and sometimes not. There is simply too little resistance given off to the towing vehicle to measure whether the light is working or not. This results in an error message on the dashboard or a varying resistance note. The varying resistance note causes the LED lights to flash. More information on how to solve this will follow later.

Different lighting for trailers

Lighting malfunctions are, of course, very annoying and you don't want them. Especially since you sometimes cannot find out where the fault comes from with the amount of lighting you have on a trailer. There is a lot of lighting available and some of it is mandatory. Typical mandatory lights are license plate lights, tail lights, retroreflectors and side markings. You must have these lights on at all times when driving on public roads. Except for the compulsory fog light and flashing light, of course. It also depends on the width of your trailer whether or not front lights are also compulsory. Which rules exactly apply to the different types of lighting can be read in our blog on "What rules apply to lighting on a trailer?

What causes LED lights not to work?

Newer cars are equipped with the previously mentioned 'CANBUS system'. This system ensures that any error messages are made clear to the driver. You can see it as a tool that simply detects defective parts in a car. The system knows that, in the original situation, a certain amount of energy has to go to the trailer lighting. As mentioned before, LED lighting uses a lot less energy. The CANBUS system detects that much less energy goes to the lighting and therefore thinks that the lighting does not have enough energy to burn. Because of this, the on-board computer wrongly thinks there is a defect.

led trailer lighting flickering bulb not workingHow should I solve the problems with my LED lighting?

The problem is common and therefore - fortunately - various solutions have already been devised. Each solution has its own advantages and disadvantages. Not every solution is suitable for every situation. So pay close attention to your situation and what is best for it. If you do not find the solution, you can always contact us. Some solutions that you can find in the TRALERT® assortment are the ILS microprocessor, the LED control box, resistors and the ZS-Canbus wiring unit. Also, you can find plug and play Canbus Proof lamps that have been extensively tested on various tow vehicles.

ILS microprocessor

An ILS microprocessor is a very simple solution to the problem of LED lighting for your trailer. The microprocessor makes a branch of the existing signal. This signal is then sent by the processor without an error message. This ensures that the LED lighting on your trailer will work again. Remember that every light needs an ILS microprocessor. If you do not, you will be stuck with a blinking LED light.

TRALERT® has various microprocessors in its product range. The difference lies in the number of pins and the voltage. The ILS microprocessors from TRALERT® are available with 3 pin and with 4 pin. Both options are equipped with 12v and 24v connections. So have a good look at which microprocessor is applicable to you.

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ILS-3P12 microprocessor

The ILS-3P12 is one of the microprocessors from TRALERT®. The processor prevents error messages on the on-board computer. This CANBUS solution is 3 pin 12v equipped. An ILS microprocessor is required for each lamp.

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ils led

LED control box

Another option is the LED control box. This also ensures that the lighting is working properly again. The control box has several advantages compared to the ILS microprocessor. A major advantage is that you only need one control box. Even if the on-board computer gives several error messages, one control box will solve your problem. The control box is very easy to install by means of plug & play assembly. This saves a lot of costs in comparison with other options. The control box is often used for problems with a trailer. An ideal solution for the problems with the LED lighting of your trailer.

TRALERT® offers two different control boxes. Both have a 12 V connection. This is because the control box is often used with a trailer. 12 V connections are used in most cars. Therefore, this is a good match. One control box has a 7-pin connection and the other has a 12-pin connection. That is the only difference between the two control boxes.

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V10AC-CTRL7 Control box

This LED control box ensures that the LED lighting on your trailer simply works. Prevent flashing LED lights. The control box is often used for trailers. One control box is enough to make all the lighting work. Besides this 7-pole control box, there is also a 13-pole control box available.

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led control box


A common way to solve malfunctions is the use of resistors. Resistors also ensure that the CANBUS system does not give error messages. Just like with microprocessors, a resistor is needed for each error message. This makes a resistor a bit more difficult to use compared to the control box. The advantage of resistors is that it is easier to work with certain vehicles. The control box is ideal for the trailer but is less likely to be used in other vehicles. Resistors are easy to use for different vehicles.

TRALERT® has two different resistors in its product range. The difference is in the voltage. One resistor is suited for a 12 V connection. The other resistor is suitable for a 24 V connection. The different resistors are therefore also designed for different vehicles.

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LR12 resistor

The power resistor is an ideal solution for non-working LED lights. The resistor ensures that the LED lighting simply works again on your vehicle. No more error messages or blinking LED lights. This resistor is for 12v, there is also a resistor for 24v available.

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led resistor


The ZS Canbus cabling unit is slightly more difficult compared to the other solutions. The cabling unit has to be built into the vehicle. Once you have built the unit in, you will never have to count on an error message again. For the longer term, this is a very good solution.

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ZSCANBUS cabling unit

The ZS Canbus cabling unit is a good option to solve problems with the LED lighting. When the cabling unit is installed, you will never have to count on an error message again.

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canbus cabling unit

Canbus Proof lamps

Another possibility is the Canbus Proof LED lights. When the lights used on a trailer are Canbus Proof, you can be sure that you will not receive an error message. Prevention is better than cure. A Canbus Proof bulb is the solution when it comes to LED lighting that does not work. There is no need to build in or place anything. The Canbus Proof bulb gives you the certainty of good working LED lights.

If you already have the non-optimal light bulbs, the Canbus Proof bulb is probably not the option for you. In that case, it is best to choose one of the other three solutions. If you still have to purchase the lights, you should definitely look at the Canbus Proof lamps.

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VC-2712B5CAN Canbus proof rear light

This handy CANBUS proof tail light prevents error messages on the board computer. The bulb is 99.9% CANBUS proof. Furthermore, the lamp is equipped with a convenient 5-PIN connector and 12v.

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canbus proof rear light flashing led lamp

 Why TRALERT® solutions?

As previously mentioned, TRALERT® has many different solutions for trailer LED flashing lights. There is a good solution for every situation. In addition to its wide range of solutions, TRALERT® also has its own technical service department. If you have any questions, you can always contact us. We will help you with personal solutions for the flashing LED lamp. In addition, personal advice will enable you to quickly solve any LED lamp failures. TRALERT® has 90% of its products in stock. If you place an order before 15:00 hours, we will ship it the same day. You can expect the product the next day and have the blinking LED lamp working again.