I would contact BD for specific troubleshooting instructions first. Electrical components are never returnable, so make sure you have the correct diagnosis first. as an aside, Given the tiny capacity of the NiCad battery and the fact that it is only there to pass the "taillight on for 20 min without the engine running " requirement, I don't understand why D.S. kit manufacturers like B.D. haven't switched to L.E.D. tail/brake and turn signals. I drive truck, and these are standard on new equipment. They never burn out, are totally sealed, and best of all, require a tiny fraction of the juice that incandescant or halogen or any other type of lights do. They cost a lot more, but when a single burned out bulb costs you $50 or more at the chicken coop, its cheap insurance.