LED outline marker lights on HGVs and trailers
Outline marker lights — sometimes called end outline marker lamps — are required on commercial vehicles and trailers that exceed 2.1 metres in width. They are positioned at the outermost edges of the front and rear of the vehicle to indicate the vehicle's full width in low-visibility conditions or darkness. The colour requirements are amber at the front and red at the rear, with the lamp mounted as close as practicable to the outermost edge of the vehicle.
LED marker lights have largely replaced traditional bulb-and-reflector units in this category. The advantages are a significantly longer service life, lower power draw on the vehicle's electrical system, and faster switching speed which is relevant for the incremental indicator function on some rear lamp assemblies. On trailer applications where the electrical connection is made and broken regularly, the robustness of an LED unit over a conventional bulb in a vibrating environment is a significant practical benefit.
ECE R91 is the relevant type-approval regulation for side marker lamps. End outline marker lamps must carry the appropriate ECE approval marking confirming they meet the photometric requirements for the position they are used in. Check the approval marking on any replacement lamp before fitting.
Connector compatibility matters on trailer applications. Outline marker lights on trailers connect via the trailer wiring harness. Confirm the connector type when ordering — Hella DIN or AMP/Superseal connectors are common on European trailers, and the correct connector for your trailer's harness must be specified.
Frequently Asked Questions
What vehicles are required to have outline marker lights?
Under the Road Vehicles (Lighting) Regulations 1989, vehicles and trailers exceeding 2.1 metres in width must be fitted with front and rear outline marker lamps. Most HGV tractors and standard semi-trailers exceed this width. The lamps must be positioned as close as practicable to the outer edge of the vehicle.
What is the difference between an outline marker light and a side marker light?
An end outline marker lamp is fitted at the front and rear extremities of the vehicle to indicate its full width. A side marker lamp is fitted along the side of the vehicle at intervals to indicate the vehicle's length. Both are required on vehicles and trailers over certain dimensions under the Lighting Regulations. Both must carry the appropriate ECE approval marking for their position.
What ECE approval do outline marker lights need?
Side and outline marker lamps for road use require ECE Regulation 91 (ECE R91) approval. The approval marking should be visible on the lamp body. Lamps without ECE approval markings are not compliant for road use on UK vehicles. Check the approval before fitting.
Are LED marker lights a direct replacement for traditional bulb units?
On most applications, LED marker lights fit the same mounting positions as the original bulb units and use the same electrical connectors. The wiring polarity must be correct — unlike conventional bulbs, LED units will not illuminate if the supply polarity is reversed. Check polarity before fitting if the lamp fails to illuminate on first test.
