I was stopped for no brake light, but the bulb was good and a new one failed to fix the problem. Trouble shooting procedures included switching sockets with no luck. Brake switch didn’t seem probable, but I don’t have diagrams to tell me how the lights are wired.
I finally found the problem when I switched the lens ass’y and found that the problem followed the lens. Further checking with an ohmmeter showed that there was an open in the bad lens.
Any idea what would have caused this problem? Everything would be sealed. I’ve seen fuses fail because they overheated because of internal resistance.