My car recently started acting up

What was the exact fault code number? The symptoms all suggest low system voltage and the common cause is worn brushes inside the alternator.

You're right, it does say high voltage. We don't run into that very often. To add to the misery, Chrysler used the same circuit configuration from 1970 through at least 2000, and a simple grounded wire could cause that, but they changed the design by 2002 or 2003 so that can't happen. The only thing that can cause high voltage is the voltage regulator inside the Engine Computer. It's either defective or it's responding to incorrect information. I haven't worked on one of this design yet so I don't know what "normal" is, but I would start by measuring the voltages on the two smaller terminals on the back of the alternator while the engine is running. I think you're going to find 0 volts on one of them and typically something between 4 - 11 volts on the other one. The greater the difference between them, the higher the output voltage will be on the fat bolted-on wire.

Measure the battery voltage while the engine is running. If it is lower than the voltage on the alternator's output terminal, look for a blown or loose bolted-in fuse in the under-hood fuse box. The battery voltage must remain between 13.75 and 14.75 volts. If it is high, either there's a problem with the wire the Engine Computer senses system voltage on, (so it thinks system voltage is too low and it's trying to bump it up), or the voltage regulator in the computer is defective. It's rare to have a regulator circuit failure, but if the sensing wire has a problem, the system voltage might be too high but that code wouldn't set because the computer would be thinking the voltage is low or normal.