The standard ISO 1724 for trailer connectors was developed in the late 70s to create a standard for the electrical connection between towing vehicle and trailer. The first version of the standard dates back to 1980. The latest revision is from 2003. Its purpose is to transfer the lighting functions so that the trailer's lighting corresponds to the car's lighting.

Two types of 7-pin 12V connectors

The standard has the addition "Type N" for "normal". There is also a "Type S" for 7-pin 12V trailer connectors which is defined in the standard ISO 3732. The "S" stands for "supplemental" as Type S connectors transfer additional functionalities - for example the steady plus for a caravan. For a better recognizability, the "normal" system features a black housing while the housing of the supplementary system is white. Due to a different contact arrangement whithin the connectors, users can not accidentally plug a normal plug into a supplementary socket and vice versa.

Application of ISO 1724 Type N

Connectors according to ISO 1724 can only be used for simple trailers because the 7 pins can only transfer the most basic lighting functions. This does not cover the reversing light so if a reversing light is mandatory, the driver has to use either a second 7-pin connector (ISO 3732) or a 13-pin connector (ISO 11446). The same applies for towing a caravan as ISO 1724 cannot provide steady plus.

Scope of ISO 1724 Type N

The standard ISO 1724 specifies the dimensions of, and contact allocation tests and requirements for, 7-pole connectors of type 12 N for the electrical connection of towing and towed vehicles with 12 V nominal supply voltage, thus ensuring interchangeability.