I had the toad Brake Buddy activate (I think the break away switch shorted) while towing up a long up grade.I did not get the wireless light indication until I began to feel the MH was sluggish.

After pulling over, I noticed some blue smoke from under the MH. On inspection there was a small amount of fluid dripping from the back of the tranny.

The fluid level was full and the drip went away after a period of time.

Is there a breather/over pressure vent that would leak some fluid when the tranny is stressed in this scenario? It continued to shift and perform normal after the brake buddy was disconnected.

Primetic, I really can not help you directly with determining what might be leaking or why. I would probably call Allison to discuss: 800-524-2303.

Also, I found a pdf file at an Allison website that discusses "Fluid Leak Diagnosis" in paragraph 2-9, page 37. I tried to copy and paste but it seems to be protected from copying. This file is for 3000 and 4000 trasmission products. But it seems to be generic enough to generally help. The pdf file can be found
Here

Paragragh 2-10 provides a small comment regarding the breather.

Hopefully someone with experience will respond with some more specific information. SteveG