Okay for a while now my Subwoofer (Alpine 12" Type R) has been on the frits from time to time it seemed to come on and off whenever it pleased and now it doesnt work at all. All the connections are good, no fuses are blown and ive tested my wires for continuity and they all seem to be in working order. The amp seems to be fine also, the light is on. My head unit is a Pioneer DEH-P4000UB.

 

If you do not have a meter, disconnect the sub and take a small battery like 9V for this case. Touch the terminals of the battery to the terminals of the sub (use a small length of wire for this and tape the wire to the battery. If the sub goes "pop" and moves, then the subs coils are still intact. This would indicate that there may be a problem with the amp. To test it, plug the sub back into it. Take a IPOD or other cd player and plug it directly into the amp. If all of a sudden the sub comes alive, you may have a problem with the rca cable in the car shorting out or a bad cd player. Test the rca cable by plugging in the IPOD or other cd player into the front of the rca that is buried in the car. If it works, problem is in the cd player in the dash.

 

Since the amp light is on your remote output must be working. Try switching the rca cables on the P4000 to another output (front or rear). If the sub starts working you know the sub output is bad.