2000 Chevy Silverado with a 4.8 liter v8. I noticed my volts dropping especially when braking or turning. I took my truck to Wal-mart and their diagnosis was I need to replace the battery which I did. This has not fixed the problem. I had autozone do a test and they said my battery, alternator and starter were ok. I was told it still could possibly be the alternator has a diode going bad. Any suggestions of what may be going on?