Battery light is on after alternator change

Probe it from the alternator all the way to the battery. Find the voltage drop or open circuit.

If light is on alternator is not charging recheck your steps for connections

you have a circuit using electricity while vehicle is not in use. Defective alarm? Defective Stereo system? interior light not turning off when doors are closed?

REPLACE YOUR PMC POWER RELAY IN YOUR FUSE BOX.

Hi Ron.
I would take it to a mechanic that you trust. Its very possible that you have a bad BCM, ( Body Control Module). Hope this helps.

Its probably the alternator. It will need to be tested on the vehicle with the engine running and the light illuminated. Measure the battery voltage with the engine running. It should be at least 13.5 volts. If it is lower have the alternator tested at a shop with a charging system tester.

starter is drawing to many amps for the battery. defective starter.

A bad battery, bad connections, or the alternator is not charging, Have them checked.

you should remove your alternator and take it into an auto parts store and they can test it for you.
this alt had an internal regulator which can be replaced easy.
your auto parts store will be able to full feld your alt to bypass the regulator. this is how you test it to see if the regulator is bad.

you didnt say how many miles are on this truck .
most of these ford alt will last 120,000 or more
on the back side of the alt you will see the replaceable regulator.

If he replaced the battery that would have cleared the code. There is another issue. Was the alternator aftermarket? Just becuase it is new does not mean good. Those are easy to install I would return it to where you got it and try another.