My '16 Ram ED w/ 71k has low voltage issues. Sometimes it charges, sometimes it will not. Thought it was battery, it is not. Put in a new Alternator ( from O'reillys , 230 Amp), worked for about 4 days now,, it is in battery saver mode and the volts are 11. It was suggested the PCM may need replacing. Any tips for a mild weekend mechanic?