1996 GMC Suburban

Electrical problem
1996 GMC Suburban V8 Four Wheel Drive Automatic 125000 miles

While listening to the radio at normal levels, for no apparent reasons, the radio volume raises to a deafening level. I am able to turn the volume down when this happens. I turned the speed control volume control off. I have replaced the radio with another stock radio and I still have the same problem. Any assistance would be appreciated. This problem almost caused my wife to crash, because the high volume startled her.
October 31, 2010.

Could be caused by the built-in amplifier-

Oct 31, 2010.