I'm replacing the rear speakers on my 2011 nissan sentra. The stock speakers were a 6" and a tweeter with a wiring harness of 4 wires. I have 6x9s that have a positive and negative. I am cutting the harness out to direct wire. Now how do I direct wire those 4 wires to my new 6x9s pos. And neg. ? I can provide pictures. Thanks!