Battery Drain Problem - I've done my homework

[jim97gst]

I've got a battery drain problem that seems very strange. I'm getting a 12 V drain when I disconnect the battery and check the voltage across the neg battery post and ground. I get it down to 0.5 V when I disconnect ALL of the following:

60 amp underhood main fuse
20 amp sunroof fuse in cabin
15 amp unmarked fuse in cabin
alternator plug
alternator ground

If I connect EITHER on of the following with rest of the above still disconnected, I get about a 10 V drain.

alternator plug
alternator ground

If I connect ANY ONE of the following with the rest of the above still disconnected, I get about a 12 V drain.

60 amp underhood main fuse
20 amp sunroof fuse in cabin
15 amp unmarked fuse in cabin

I recently tapped the ECU to hook up an AVC-R, but it works fine and hasn't seemed to cause any problems. My best guess is an alternator diode just because everytime I've had an alternator problem I've had strange stuff happen. I don't know what that 15 amp fuse is in the cabin, and I doubt it's the sunroof as I haven't had any problems with it. I suppose it could be multiple things that happened to happen at once. Any ideas? HELP!!!!!!

TIA

 

[240sxpooter]

A battery drain test is done measuring AMPS not volts. .050amps is around normal