Woa Woa Woa. First plug something else into it, use a different cord, try your device on a wall plug, and then check the fuses for any black marks. Replace the fuse that runs to the lighter. These are the FIRST THINGS to check before you go buying testers and risking blowing lines when a fuse is a simple replacement with a few cents and a few moments. Geeze. Talk about going at this upsidedown.

Thanks your advice makes sense because it sure doesnt make sense to try to carefully check the fuse and accidentally blow out more fuses