Abstract: An electrical interface device (210) is provided for disengageable or removable coupling with an existing master connector substantially non-removably mounted on a towing vehicle in order to allow for the connection of the electrical systems of differently configured towed vehicles without any modification of the device (210). The device (210) comprises a first end (218a) presenting a first master connector (222) and a second master connector (224), and a second end (218b) presenting a third interface connector (225). An alignment mechanism (229) ensures proper alignment, and a locking mechanism (231) avoids inadvertent uncoupling of the device (210) from the existing master connector. In use, the second end (218b) of the device (210) is coupled with the existing master connector, and an electrical connector of the towed vehicle is coupled with the first or second master connectors (222,224), thereby slaving the electrical system of the towed vehicle to that of the towing vehicle.