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ISO 3732:2003
Road vehicles - Connectors for the electrical connection of towing and towed vehicles - 7-pole connector type 12 S (supplementary) for vehicles with 12 V nominal supply voltage
ISO 3732:2003 specifies the dimensions of, and requirements for, 7-pole connectors of type 12 S and their contact allocation for the electrical connection of towing (passenger cars or light commercial vehicles) and towed vehicles with 12 V nominal supply voltage, thus ensuring interchangeability. A 12 S connector is intended to be used in addition to a 12 N connector according to ISO 1724 where more than 7 poles are required.
International Organization for Standardization [iso]