i have a bose sub with built in amp that uses a plug and wire harness that connects to the plug for power, ground, audio in and stuff. i dont have the wire harness that connects to the plug so i cut the plug and cant figure out witch wires are what. there are 4 wires going into it, yellow, orange, black and purple. inside going to the sub are red+, green-. what should have continuity to what to know what wire is what. all i have is a circuit testing set and i think a continuity tester should tell what is what. thank you for any help anyone can give me.