check the settings in the head unit and on the amp. if there is some bass coming from the sub obviously the signal is getting to the amp and the amp and sub are working. check voltage at the terminals of the amp, car not running should be somewhere between 11-13 volts. 12.5ish if nothing is on. with the car running should be around 13.8-14.4v, maybe less due to UD pulley... get someone to hold the revs around 2500-3000 and it should be sitting at around 13.8 at least.
if all that shows ok... take it to someone who knows what they are doing... they will test the head unit to make sure its ok
