cut a lead of speaker wire (about a foot or two) and strip both ends. put one end in you sub box and touch the other end to a battery, like from a cordless drill or something. i always use my 9.6v makita batteries to pop speakers. that will tell you if your sub is hooked up or not. also you can test the ohms across the speaker. if you get nothing then it's not connected, if you do get a reading then it's hooked up. sometimes the leads come off of the terminals inside the box. good luck son