We need to do two things first and foremost before we can figure this out. Let's get the battery tested and if it is drained again, we need to charge it or replace it so that it is okay.
https://www.2carpros.com/articles/car-battery-load-test
Then we need to test the alternator and not run the vehicle for long periods of time as it will just drain the battery again.
https://www.2carpros.com/articles/how-to-check-a-car-alternator
Once we know if the alternator itself is ok, we can test the actual charging system when the engine is running by putting a meter on the battery and it should be 13-15 volts.
There could be an issue in the PCM but the voltage regulator is internal to the alternator so it would be the PCM not telling the regulator to turn the field control.
Let me know what you find. Thanks
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Monday, March 1st, 2021 AT 4:38 PM