Djzs147

I have a 99 sc300 I'm having trouble geting radio turned on..I found gro.und wire and constant power wire which hooks up to yellow wire on aftefrmarket radio..now where do I hook up the power to switch radio on/off? What color wire..I can't find any harness diagram same as my stock pioneer system..please help just need the radio to power on that's all..this is so frustrating