I have no harness for my stereo and need to find which wires do what? Any

I have tried to find using a multimeter, and thought I had it at one point. I need to know what the original wires do.
X reg Ford Focus thanks

You will have 2 X 8 wire block connectors
1 will have 8 thin wires (Speakers) just plug together
The other will have 3 Thick wires
Red = Switched Positive
Yellow = Permanent Positive
Black = Negative
and 2 or 3 thin wires
Blue = Electric Aerial Trigger
Brown = Radio lights On/Off with car lights
Others can be for Mute if Dedicated Mobile phone mount installed
Andy CI have no harness for my stereo and need to find which wires do what Any help