I am upgrading to the Pioneer DEH-P7800MP receiver in my Mustang, but I CANNOT use the existing wiring harness that came with the DEH-P4700MP receiver. The wiring pin layouts are completely different. So I need to reintegrate the new wiring harness and the receiver into my 2004 Mustang. How do I go about doing this? Can I just match wire colors and solder wires together? I couldn't find a wire diagram for my car. Thanks.