Borrowing a truck to tow a trailer for moving.
I noticed that when going up a hill and the engine kicks down (RPMs go up above 2800) the voltage will drop and the battery light goes on. It is otherwise is fine. Cruising around town it stays at 14 volts.
2001 GMC Sierra 1500 5.3
Searching the googles, people say its the alternator, the PCM, the voltage regulator and any other thing. Some say replacing the alternator doesn’t work cause the voltage regulation is outside the alternator.
Then I read this article on RVC https://www.motor.com/magazinepdfs/042010_09.pdf. Which makes it more complicated.
Any ideas?