SInce my revious post I have found the 9355093 EPROM , the only one on my board on the 2004 chevy silverado. I checked voltage and found 4 to 4.9 volts on 4 terminals on one side of the chip. 0 on all 4 terminals on the other side. I unsoldered the four with 0 volts as they were the easiest to get to. Radio worked with my previouse method but went out again. I unsoldered the other four terminals and removed the chip. Radio did not work and in a few seconds I heard popping sounds and then nothing worked including the clock. I was using some old 4 ohm speakers and had the heat sink off the side of the case so I am not sure what blowed. I guess the theftlock system beat me on this one. Dale