Check the nut at the end of the PDC under the cover.
Just a wild guess, but pull the fuel pump relay and look at the pins, are any discolored blue or black? The PCM and the fuel pump share a power source, if the fuel pump is sucking down the power it seems possible the PDC would try to compensate.
That 19 volts sure sounds familiar, but I'm old and the old brain just doesn't work like it used to.
If you have low voltage going to the dark green and black wire at the PCM, for whatever reason, it is likely you will get high charging.
If you have a short in the alternator near the end of the windings, it is likely you will get high charging. You may be able to pick this up checking the ground at the case with the battery negative ground, using your low scale volt setting. You'll typically get a little voltage like 0.2-0.3 volts anything higher and something is wrong.
It may be the voltage regulator built into the PCM is taking a dump and there isn't much you can do about it. They say if you arch the B+ (dark green and black) wire at the PDC multiple times or even the battery terminals multiple times (with the key in the run position), it can scramble the brains in the PCM and mess with the program. I really don't know if it is fact or fiction, but I'm pretty careful about arching the battery terminals multiple times when I put them back on and make sure the key is off.
You should have stored codes that may put you on the right track. At least three different alternator failure codes (if I remember correctly) that may help narrow down the exact problem.