7-PIN type N connector 12V

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

The 7-PIN connector is an outdated plug standard used in the past for the basic lighting of semi-trailers and other towed vehicles. This connection was part of an older system in which functions were not yet combined in one connector.

In current practice, this connector is no longer used in new construction or modern conversions. The additional functions that were missing at the time were later integrated into the 13-PIN connector, which has now become the standard.

The N connector was standardised under the ISO 1724 standard, with the designation "N" standing for Normal. This connection was mainly found on light semi-trailers and on vehicles not yet equipped with a 13-PIN connection.

Pin assignment

PIN	Function	Colour
1	Direction indicator left	Yellow
2	Rear fog light	Blue / brown
3	Mass (for PIN 1 to 7)	White
4	Direction indicator right	Green
5	Rear/ licence plate light right	Brown
6	Brake lights	Red
7	Rear/ licence plate light left	Black

Colour differences in practice

According to the ISO standard, blue was the prescribed wire colour for PIN 2 (rear fog light). In practice , however, brown was also used, depending on manufacturer or cable set. If in doubt, the connection was checked with a multimeter or according to the semi-trailer's scheme.

In what situations was the N connector used?

The 7-PIN connector was used for semi-trailers without additional electrical functions such as constant power supply or reversing lights. Typical applications were:

small semi-trailers
boat semi-trailers
luggage trolleys
horse semi-trailers without reversing lights

For applications with more functions , this connector was not suitable, which eventually led to the introduction of the 13-PIN connector.

Adapter adapters between 7- and 13-PIN connections

When the towing vehicle and semi-trailer have different connections, an adapter offers a solution. For example:

13-PIN connection to the vehicle → 7-PIN semi-trailer
7-PIN connection to the vehicle → 13-PIN semi-trailer

Please note: With an adapter from 13 to 7, only basic functions are transmitted. Functions such as constant current or reversing lights will then not work.

LED lighting and CAN-bus interference

When a vehicle with CAN-bus system drives a semi-trailer with LED lighting via a 7-PIN connector, interference may occur. Causes:

LEDs draw less current, which is not recognised as "load"
The system gives error messages or switches off the lighting

Common symptoms:

Flashing or failing lighting
Dashboard errors
Lighting that stays on after uncoupling

Read more in our blog:
Fix CAN-bus interference with LED lighting
Or check out our CAN-bus solutions

Frequently asked question

What is the difference between a 7-Pin N and S connector?

The N connector was used for the basic lighting. The S connector (ISO 3732) used to be additionally used for functions such as battery supply and reversing lights, especially in caravans. In practice, these systems were later replaced by the 13-PIN connector, which combines all functions.

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Author

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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