I don't know the freightliner at all but there is a general idea that we find fuses in separate locations, some for the RV / coach portion and others for the chassis portion. The chassis builder puts in what he needs and then the RV builder adds what he needs.
So if you know where the fuses are for things like headlights, turn signals, I would start there as the tranny is part of that group.
Hope that's a bit of help and perhaps somebody with more specific info n the freightliner comes along later!