I was wiring up my sub woofers today and I accidentally crossed the 12v switched with the 12v constant. There was a spark and my head unit stopped working immediately. I went and bought a new one thinking I fried the pioneer I was using. I plug in the brand new pioneer head unit to the wiring harness and still nothing. I checked all the fuses and nothing was blown. I have no idea at this point why my head units will not work.