hello my factory radio on my 91 ls 400 has not been working for about 3 months, so i removed it to see if i had current coming through the wires, so when i removed the radio, there were three plastic plug-in wire connections two white and one blue, so i test them with a 12v tester and only one of the white ones showed current, should all of them have juice if so how could this be fixed, or is it the radio itself..i have check both fues also. any suggestions thank you