I have a 2003 f150 xlt flareside. I am having major charging system problems. Last night the charging system warning light came on. Today I replaced the alternator and had the battery checked. Both are good to go, but my battery is still draining and the light is still on. Fuses appear good. No idea what is going on, someone please help!!

 

You need to make a test to see if the system is chargeing.
Place a voltmeter accross the battery and observe the voltage just after cranking and startup.
It should show 15 plus volts and taper back in just a few minutes as an indication the system is chargeing under regulator control.
There is a charge lead fuse on the firewall called a megafuse with 175 amp rateing.
There should be a second fuse in an inline holder near the alternator. It is a 20 amp.
Be sure the plugup at the alternator is set in tight and no blades are bent over.
A little about the charge lamp circuit.
It is powered through the ignition switch and a fuse.
If it lights it shows that circuit is complete and good.
It lights when it gets a ground from the alternator regulator.
When the alternator is outputting at a high enough level, the regulator take the ground away and the charge light goes out as an indication the alternator is outputting.
If it stays on, there is a system issue with the alternator.
Maybe you got a bad replacement.
Check it out first so you know what you have.
.
Replacing parts without final testing leaves you in confusion.
Good luck.

 

I've already done all this. Mine is a 2003, it does not have the inline fuse, nor the mega fuses on the firewall. My problem still exists. I'm not getting any voltage from the orange/blue wire coming out of the alternator harness.

 

Well ok for not having the fuses.
If you see an issue, change the alternator again.
You don't have many choices.