Car Stereos: alternator noise, loud buzz, toyota camry

Question
1998 toyota camry alternator noise.loud buzz through speakers when lights are on using the dimmer control.DOES NOT HAPPEN ALL THE TIME.where do i start?aftermarket installed.

Answer
Karl, first I would make my own ground point in behind the radio.  Connect the radio to a short ground wire that is securely fastened in behind the dash.  That should solve the problem.  Your problem is usually caused an open or weak circuit.  The culprit is usually a weak ground.  The ground should be large, short, and securely fastened.  Hope this helps, Scott