If the roadster brake light is only partially lit then the lighting control module is not the source of the problem. The problem is internal to the brake light unit itself. Probably a poor/loose solder. When my wife and I bought our roadster in January the center brake light was out on the right side. My wife insisted on replacing it so we did. I sold the defective unit to another forum member who was fully aware that only half of it worked. He bench tested it a few weeks after receiving it. THE WHOLE THING LIT UP. That means that what ever was loose got jarred back together during shipping and handling. Pretty likely that it will fail again after being installed on a car and the trunk lid closed a few times.

IMHO there is no better expert on this forum for electrical issues and testing than ALA_XFIRE.