Battery Drain
 

I have 1999 Mustang GT and have had a battery drain for several months, ussually overnight. Today we did a complete check, first by checking the Optima battery was took a load of 800 Amps. Then we staring pulling fuses and found with all the fuses out and only the #39 fuse in, (which is for the Gem), we had 200 MA. We just about came to the conclusion that the Gem is bad.
Has anybody had this problem and can you suggest something that we might have overlooked ? Also if the Gem is replaced , does it have to be reprogram in the 1999 ?

Lee