I have 2007 Mazda 6i. My headlights (low beam) and signal lights stopped working. I had that issue before. My lights worked whenever they wanted to. Sunny days no lights but when it was raining outside they worked fine. Now they stopped working completely. High beams are working fine. To use a signal light, I have to put on high beams. Do you think it's ground wire's fault? Loose wire? Do you know where to look for it? Any help appreciated.

 

Pull the air filter out, box and all. Underneath the air box you'll find a plastic connector with 4 or more wires going to it that is bolted to the body. This is a common ground that Mazda uses. It is also a typical fail point for the 6i. You may find the ground itself is poor where the bolt meets the body, or one of the wires has gone bad in the connector. Usually its corrosion between the body and the common ground. Hope that helps