I give up. What Model year Mustang are we talking about?
Assuming this is a 2002 Mustang, then the connector in the picture is GEM connector C201B. The WH/YE wire is powered from fuse F2.39. Since you have stated that removing fuse F2.39 stops the parasitic draw, then disconnecting the connector that actually brings power into the GEM makes sense.
Just wondering. Have you verified that the door ajar switches actual work as intended? What about the key lock/unlock switch in the drivers door lock? If not, this could be keeping the GEM activated and thus preventing the GEM from going into "sleep" mode.
Assuming this is a 2002 Mustang, then the connector in the picture is GEM connector C201B. The WH/YE wire is powered from fuse F2.39. Since you have stated that removing fuse F2.39 stops the parasitic draw, then disconnecting the connector that actually brings power into the GEM makes sense.
Just wondering. Have you verified that the door ajar switches actual work as intended? What about the key lock/unlock switch in the drivers door lock? If not, this could be keeping the GEM activated and thus preventing the GEM from going into "sleep" mode.