Check the clear plastic cover on the back of the light, the tabs break off, and you'll get moisture. A friend had that problem, and I put it back in place wedged with a piece of foam. Dried up in 2 days. One car I bought had water not moisture. I took the light out, and tipped it up and water ran out of it as fast as a garden hose. When the tabs are broken, just glue it on with some RTV silicone.