Overview. RGB Fog Warning Canceller Module Some vehicle manufacturers such as BMW and Audi are using alternating current on new cars to extend the lifetime of halogen bulbs. This is also often the case on DRLs, to achieve a lower brightness during the day. Specifically, this is called Pulse Width Modulation. Some Multicolor Fog Light kits require continuous current to operate correctly. If installed on a circuit with alternating current, the lights will flicker very quickly when the vehicle is turned on. The solution for this is the RGB Fog Warning Canceller Module. To regulate the signal, you will need one module.