Funny, I asked the Service Manager if they did a check of the battery cables/alternator wires with an Ohm Meter previously in conjunction with installing the last alternator to ensure they are good, and he could not confirm. It seems they do the bare minimum that GM pays for when they are honoring the 12 mo./12k mi. replacement. I didn't actually pay for diagnostics but they claim they diagnosed the alternator failed previously.

We'll see what they say about the true root cause soon...

 

Ok, so the dealer shop says the alternator failed, and they replaced it and are running additional diagnostics in the morning, per GM. The GM alternators are remanufactured, NOT brand-new, which could explain things if there is a quality problem in the rebuilds.

Hopefully this new reman one will last a lot longer...