I need a wiring diagram

to what car is it being fitted?

standard stereo wireing is as follows:

SPEAKERS
+White -White/black Front left
+Grey -Grey/black Front right
+Green -Green/black Rear left
+Purple -Purple/black Rear right

POWER
+12v Con Yellow
+12v Ign Red
+12v Antenna Blue
-12v Return Black
Tele mute brown
Illumination Orange

Hope this helps somewhat.

If you could post a picture of the plug at the back of the radio or a drawing of same then I think I might be able to help you.