ISO 1185

Updated: 09/12/2025
By: Kevin van Mierlo

ISO 1185 - The standard for the 7-Pin N (24 V) connector for trucks and semi-trailers

ISO 1185 is the international standard for the 7-PIN connector (24 V), the standard connection for lighting and signalling between truck/semi-trailer and semi-trailer, semi-trailer or heavy-duty towed equipment. This standard guarantees uniform PIN assignment, compatibility and reliability for lighting and braking systems on 24 V systems.

Wiring diagram 7-PIN N (24 V) connector according to ISO 1185

PIN	Function	Note
1	Mass (chassis / earth)	White
2	Rear/contour lights left	Black
3	Left-hand direction indicator	Yellow
4	Brake lights (stop light)	Red
5	Right direction indicator	Green
6	Rear/contour lights right	Brown
7	Semi-Trailer brake signal / spare	Blue (or according to manufacturer)

The ISO 1185 connector is designed for basic lighting and brake signals. Reversing lights, constant power supply or additional functions are outside the scope of this standard for which an additional 7-Pin "S" connector (ISO 3731) or modern 15-PIN plug (ISO 12098) is required.

Where do we see ISO 1185 connectors?

The 24 V 7-PIN connector according to ISO 1185 is applied to:

Truck + semi-trailer combinations
Industrial semi-trailers, flatbed semi-trailers and heavy equipment
Agricultural tractors and towed implements on 24 V
(Sometimes) construction and work semi-trailers within the heavy transport segment

These connectors are widely used in the truckand semi-trailer industry as they meet the technical requirements for heavier transport.

Limitations of ISO 1185

Because ISO 1185 offers only 7 poles and focuses on basic lighting and brake signals:

Reversing lights, constant power supply or additional functions are not possible with just an ISO 1185 connector.
Heavier or more modern semi-trailers often require an additional 7-PIN "S" connector (ISO 3731) or a combined 15-PIN connection (ISO 12098).
In the case of LED lighting or modern CAN-bus systems, additional modules or adaptations may be required to ensure correct loading and reliability.

ISO 1185 and the evolution of semi-trailers

Due to increasing complexity of semi-trailers - such as lighting, braking systems, data communication - ISO 1185 is increasingly inadequate for modern applications. Many fleet operators, builders and suppliers are stepping up to modern standards such as ISO 12098 or even specialised connectors for EBS/ABS systems.

Nevertheless, ISO 1185 remains relevant in applications where basic lighting and simple semi-trailers are sufficient. For new installations or upgrades, TRALERT® recommends considering future expansion and applying a modern standard immediately if possible.

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Kevin van Mierlo

Lighting expert at TRALERT® - Kevin tests lighting and finds out everything about legislation. He can tell you all about it.

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