My battery drai
So my truck a 2000 GMC Sierra, battery light was
on n voltage was @14 had daughter take it too
auto zone they said it was fine. Next day drove to
my truck battery light still on. Omw home radio
shutdown lights dimmed fast n so did battery
voltage could it be my alternator
Possibly, but it could also be the computer or a broken circuit in the charging system. This rig the charging system is computer controlled so you need the right equipment to check everything involved with the charging system not just the alternator. Now DO NOT disconnect a battery cable with the engine running, you could fry a bunch of electronics due to a feedback that can be generated. Recharge the battery with a slow charger, preferably overnight, then take it to your favorite shop for further testing.