most aftermarket stereos have the following wire colors.

Let me know if your sony has the same colors...

Yellow - +12V Constant power
Black - Ground
Red - +12V Accessory power
Orange - Illumination (Sometimes orange/white)
Blue or blue/white antenna trigger / remote turn on lead for amplifiers (now depending on the radio, if it has both, some radios will turn off the antenna when on cd mode)
Yellow with black stripe - Typically cellular mute - when this wire is grounded radio will say mute ( not available on all radios)

Speaker connections:

White + Left Front
White/Black - Left Front
Grey + Right front
Grey/Black - Right front
Green + Left Rear
Green/Black - Left Rear
Purple + Right Rear
Purple/Black - Right rear

Those are your typical aftermarket stereo wire colors. it is pretty much a standard now a days, but some older units had different colors. but I am pretty sure most any radio made in the last 5 years at least should have those color combinations.

If you need the wire colors for your car to hook things up, post your model and year and I will see what I can find out...

__________________
'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon