Retrieving Audio Diagnostic Codes In 02 Sc 430

[G02]

I tried to perform a audio diagnostic check on my factory system in my 02 SC430. I have the 03 service manual which told me to press and hold the 1&6 buttons,then press the disc button 3 times,wait 40 seconds and the system will go into diagnostic mode,then by pressing the tune button you can check system componets.This did not work on my 02.Does anyone know the procedure /sequence for checking the 02 audio system?

THANKS,