Secondary unit e.g. trailer tail lamp, controlling device for use in motor vehicle, has opto-coupler producing control signals for controlling controller to switch operating condition of secondary unit e.g. trailer tail lamp

摘要

The device has an opto-coupler (Opt) receiving an operating signal of a primary unit e.g. tail lamp (L1), and producing control signals for controlling a controller (St1) to switch an operating condition of a secondary unit e.g. trailer tail lamp (L2). A data bus is provided for controlling the primary unit. The secondary unit is only temporally connected with a motor vehicle. The control signals produced by the optocoupler are completely independent of a data bus signal. An independent claim is also included for a control unit for switching of an operating condition of a secondary unit.