What are the requirements for amber lighting on 24V trailers?

In this blog you will read:

• Where the term amber comes from and what its function is.
• What are the laws and regulations regarding amber lighting on trailers?

What exactly do we mean by amber lighting’?

By amber lighting’, we mean orange-yellow vehicle lighting designed to improve the visibility and signalling of a trailer or vehicle. In the industry, this is often referred to as ‘orange lighting’ or ‘yellow lighting’. However, official bodies and regulations use the term amber’. Examples include functions such as side marker lights, indicators and other warning lights. Amber light stands out clearly in traffic and prevents confusion with white or red light, thereby making an important contribution to road safety.

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Which lighting on a truck trailer should be amber ?

Amber lighting is used on trailers for side marker lights, indicators and safety signals. Amber-coloured lights may not be used everywhere on a trailer . For side marker lights and indicators, amber is the prescribed colour. For front lighting, white is the standard, whilst rear lights must be red. The assessment therefore always starts with the light function: is it a side marker, indicator, rear light, position light or a combined function? This table explains when amber is and is not permitted.

Type of lighting	Colour	Is amber permitted?	Focal point
Type of lighting: Side marker light	Colour: Amber	Is amber permitted?Yes, this is the standard	Point to note: Onlythe rear side marker light may be red, subject to certain conditions, when it is combined or integrated with a red rear light function.
Type of lighting: Indicator	Colour: Amber	Is amber permitted?Yes, this is the standard	Point to note: Flashes at a fixed frequency and with appropriate switching
Type of lighting: Flashingside marker lights	Colour: Amber	Is amber lighting permitted?Yes, provided it is synchronised and functionally linked	Point to note: Relevant for new O3 and O4 semi-trailers; an alternative is a separate side indicator
Type of lighting: Rear light or position light	Colour: Red	Is amber permitted?No	Please note: Amber is not a permitted colour here
Type of lighting: Front position or contour lights	Colour: White	Is amber permitted?No	Point to note: White at the front, red at the rear
Type of lighting: Signal lighting (flashing light, warning light, warning bar)	Colour: Amber; blue is reserved for emergency services	Is amber permitted?Only where permitted by law	Please note: R65 approval and national authorisation for the vehicle and its use are required; blue lighting is not permitted on standard commercial vehicles or trailers
Type of lighting: Styling lights	Colour: No recognised function	Are amber lights permitted?In principle, no	Important note: Only permitted if it fulfils an approved function

For the broader regulations concerning amber lighting and other light functions on trailers , please refer to our overview of regulations for truck and semi-trailer lighting. You can find the mounting requirements in ECE R48 for amber side marker lights, so that you can assess colour and position separately.

Are amber marker lights permitted to flash in unison on a trailer?

A marker light is not automatically a flashing light: by default, a side marker light remains on continuously. However, ECE R48 does permit, under certain conditions, amber side markers to flash in phase with the indicator on the same side. The light, circuitry and mounting must be suitable for this. Connecting a standard steady-beam light to the flasher circuit without appropriate control is therefore not a suitable solution.

For newer vehicles, these requirements have been further tightened. For new O3 and O4 semi-trailers, this has been a key focus within ECE R48 since 1 January 2025: side visibility must then be ensured by means of side markings that flash in sync with the indicator, or by a separate side indicator. This improves the visibility of the vehicle’s flank when turning and changing lanes. In practice, there is no automatic obligation to retrofit existing vehicles, but if in doubt, always check the vehicle category, registration date and national inspection practices. We are also seeing this increasingly on small trailers for safety reasons (though this is not automatically permitted in every country). You can read how to achieve this in the article on marker lights with indicator function on small trailers.

Which ECE approval is relevant for amber semi-trailer lighting?

Three ECE regulations are particularly important for amber trailer lighting. ECE R48 specifies how the lighting must be fitted to the vehicle: its position, visibility, spacing and circuit configuration. ECE R148, on the other hand, governs the type-approval of light signalling functions, such as side marker lights and indicators. This regulation has consolidated several older lighting regulations, including the former R91. In addition, ECE R10 is relevant to the electromagnetic compatibility of electronic lighting, which is particularly important in the case of LED lighting.

Amber is used in vehicle lighting for signalling purposes, as the colour clearly distinguishes the white front from the red rear of the vehicle.

Frequently asked questions about amber lighting on trailers

Is orange lighting the same as amber lighting?

Yes. In type approval, amber is the official designation for orange-yellow light; in practice, fitters and buyers use both terms interchangeably. You should therefore not choose a light based on the product name, but on its function and the corresponding colour requirement.

Are amber side marker lights compulsory on a semi-trailer?

Side marker lights are compulsory on semi-trailers longer than 6 metres, which almost always fall into categories O3 and O4. The prescribed colour is amber, with the sole exception of the rear light, which may be red when combined with a red rear light function. Please check this for each vehicle configuration.

Are amber lighting systems permitted at the rear of a trailer?

Not as a rear light: that must be red. The rear indicators are amber, and only the rearmost side marker light may be red under certain conditions. So always determine the function of the light first before looking at the colour.

Is it permissible for an amber marker light to be an indicator?

There’s a reason for this. A side marker light is, by design, intended as a steady-burning marker light on the side of the trailer. Under certain conditions, an amber side marker light may flash in synchronisation with the indicator on the same side, provided that the light, mounting position and wiring are suitable for this purpose.

This means that the marker light must not be used arbitrarily as an additional flashing indicator. The function must be configured correctly: the left indicator must flash in sync with the left indicator, the right indicator with the right indicator, and the operation must comply with the requirements of ECE R48.

This is particularly relevant for new O3 and O4 semi-trailers, as lateral visibility when indicating must be correctly addressed. This can be achieved with amber side marker lights that flash in sync, or with a separate side indicator. A red rear side marker light must not flash in sync with these.

In short: an amber marker light with indicator function may only flash in unison with the main lights if it has been correctly approved as a side marker light, correctly connected and used within the correct vehicle configuration.

TRALERT® dark-look marker lights

Approved semi-trailer lighting from TRALERT®

Choosing the right amber lighting is all about the combination of function, approval and mounting. TRALERT® supplies 24V trailer lighting, marker lights and plug-&-play lighting systems that allow side markers, indicators and cabling to be technically coordinated. Would you like more information? Our advisers are here to help.