CAN-Bus Illuminator modules combine the running light, brake light and turn signal functions all onto one single output wire per left and right rear turn signal. So if you want to add a custom single wire LED, Halogen or plain bulb rear turn signal, these modules will allow the signal lights to operate as running lights, brake lights and turn signals. Even if the turn signals you purchase are double wire, (dual filament or dual intensity) you can simply twist both of the hot wires together and the module will do the rest!