Have a tricky problem with radio, all fuses fine, removed and manually put 12v to power and grounded, Radio asking for code intermittenly while using this test to see if radio can be salvaged. put back in car and no code request. Take out again and test with external 12v and again sometimes I get a code request and sometimes just nothing. maybe there is another common problem I am missing that is internal to the radio itself. Probably time to invest in something after market and we have never spilt anything on it so might just be flakey after all these years of tunes.