Stock light? Sounds like a filament out. One wire usually ground, one wire, running light-dim filament, one wire brake-brighter filament. All based on a 1157 bulb. Good luck. OMThx for the reply. Sorry for the lack of clarity in my post. I've gotten it figured out but having problems with the brake light. It lights up but doesn't brighten up when I press either two of my brake levers. The OEM light had only three wires and my aftermarket light only has three. Not sure what to do...