jmlcolorado

Started having dead batteries last Monday morning.
Truck sat all weekend and wasn't started.
So all week I've been charging up each night as it would totally drain the batteries overnight.

Hooked up the meter and pulled each and every fuse and found fuse #13 to be the culprit. FSM Power feed.
Crap!
I was hoping another fuse would better locate the problem.
Mind you, absolutely no other fuse or relay causes the amperage to drop to a normal level.
Truck off, both negatives unhooked, and drivers side negetive terminal hooked in series with the meter, I get 2.07 amp draw. With the #13 fuse unhooked I get 700 Ma which is about where it should be.


Any ideas on where to start!?
Is the ICM and FCM the same thing?
I suppose if it were, I'll be replacing it since my cooling fan doesn't work as it should, (manually switched for the last couple years) and the parking lights on the drivers side all don't work (per design) due to a poorly wires trailer.
If all of these things stem from the ICM/FCM, battery drain is motivation to replace


Edit: Noticed the ONLY thing not working with the FCM fuse removed is headlights. I do have retrofit HID's so going with the oath of least resistance, I unplugged the HID's to see if they are the cause of the loss. They aren't.
So if the FCM only disables the headlights, and every other power option works fine, what's the purpose of the FCM?