i am hooking up a stereo in my 04 cav i know to run the switched power source from my wiper fuse here's my ? the sub i have has a light that lights up when the bass hits but i need a 12v switched power source for it to work. can i use the wiper fuse too on top of it being used for the stereo or will my car explode i dont want to cut any wires under my steering column unless its absolutely necessary

You should be fine, but if you installed an aftermarket head unit then it "should" have an output for the amp remote turn on. Either way your car isn't going to explode.