i had an issue with mine not illuminating when i got one the brakes not that long ago. first off if it was illuminating all the time it almost sounds like u had either the bulb or the plug upside down. but if it quit doing that on its own im not sure. make sure the contact plates are getting contact good to the metal pieces on the back of the bulb. and not possibly contacting both. those things can bend and cause issues. check this and let me know. if the problem continues ill try to replicate ur issue on mine