Hi there. I've had this problem myself. its quite easy to fix, but it is time consumng. what you need to do is get a multi-meter and put it on the Ohms setting.
using this, measure the green and red wires (speaker wires) when you get a resistance that is a pair for one speaker, do that for te rest of the speaker wires.
then set your multi meter for voltage. get a good ground on the negative probe.
Start probing the rest of the remaining wires, there should be one with constant 12v, one with switched 12v when the ignition is on. one Ground wire and the illumination wire.
ive attached where each of these wires will go.
