What would make my right side tail lights go out on a 2004 Mercedes Benz CL500

Hello, The SAM (signal acquisition module) sends power to the lighting systems on the vehicle. Given the nature of the recent weather, however, I would say that testing at the SAM may or may not turn the issue up. There may be water damage anywhere between the lighting switches and lights, and the flash of lights tells me that the potential to function is there, and you are likely looking for a bad integrated module.