A light tester would not do anything but prove you is getting power to the fuse. Unless you want to remove a wire and test between the live wire and the naked terminal a light won't do it. When you turn on your new fangled digital meter and you do not have your leads touching whatever that reads on the meter is a open circuit. If you test the fuse and get no change on the meter then you have an open circuit. You must remove the wires on what ever you are testing so you wont get a false read. Does that meter of yours have an audible ohms selection? When you get a good part the meter beeps telling you that component is good. That is what I use.