Why are there 2 greys? How do I tell which is radio illumination and which is LF speaker -? Why do I have a thin left over black wire? What is this for? What is the purple wire and why is it not referred to in the wiring diagram...they only mention a pink.

the wiring diagram says purple is gain control for amp and pink is amp turn on. you can tell which wire is illum by putting a meter on the car side and turn on the lights one will have voltage the other is the speaker