What was done incorrectly when the starter was installed? The idea that the alternator was affected could have been due to a fusible link that goes from the starter to the alternator. But I think that would have caused a problem from the start.
Do me a favor. I need you to test the alternator output.
Here is a link that explains how it's done:
Here is the thing. I'm not sure what all has happened or changed, but the voltage regulator is integral to the powertrain control module. If there was a power surge to the PCM, it may have caused damage.
I attached the charging system wiring schematic below and circled the PCM/Generator field control. That is the portion in the PCM that controls the voltage.
Try the test above and let me know what you find.
See pic below.
Sunday, November 27th, 2022 AT 11:31 PM