1st. Disconnect the battery and get a test light between the battery cable and the battery post.
If the light lights up you have a draw on the battery.
Make sure the doors are closed and the key is out. Then start pulling fuses one at a time till you find the one the draw is on. The light will not light up unless there is something drawing current through the the bulb.
This will narrow it down to that circut and help you figure it out.
A wiring diagram would be helpfull to see what is on the circut effected.
I would also unplug the alt and disconnect the battery cable to it. There is a chance you have a bad diode causing a drain. If you disconnect the alt and the light goes out you need to replace the alt.
