Ok I have a 1998 ford contour and the wiring diagram doesn't match. I just bought a new radio and i'm trying install it. The problem is the wiring diagram for the car is saying I have two brown and yellow wires and also two white and purple wires. These wires are supposed to be the negatives to the speakers. In the car i have one brown and yellow and one white and purple wire. I have a solid white, solid brown, and a brown nd red wire but i dont know what speaker they go to?