Abstract: A photo-coupled control apparatus for vehicle auxiliary lighting system comprises a combination of a photo coupling set. The set includes a control light emitter assembly and a control light sensor assembly. The control light emitter assembly is attached to the interior surface of the windshield of the vehicle, and has a light emitting device for emitting light signals. The control light sensor assembly is attached to the exterior surface of the windshield at a location opposite the location of the control light emitter assembly across the windshield, and has a light sensing device for receiving the light signals emitted by the light emitting device of the control light emitter assembly. A switch is connected to an electrical power source for providing electric power to the light emitting device of the control light emitter assembly when the switch is turned on for emitting the light signals.