The three following photos are from our 2004 Journey 36G so the locations may differ with other models. The general location is in what I call the power compartment.
First photo shows the power compartment. The Tow Controller is located behind the sheet metal wall to the right of the photo, adjacent to the transfer switch box which in this photo has the top removed. The wall can be dismounted by removing screws; they are obvious.
The second photo shows the Tow Controller with cap removed mounted above the Allison ECU which is the silver color.
The third photo shows a closer look of the Tow Controller. The TC has the cap off and you can see the six 20 amp and one 10 amp mini fuses mounted in a row across the bottom. There is one slot for a spare fuse which I found empty. The eight gray boxes are control relays. The cable plugged into the top left goes to the toad plug mounted at the fender. The FreightLiner help desk can provide wiring diagrams. Before I put this back together I removed the strain from the two wiring cables feeding into the top of the Tow Controller.
Although this photo does not show the third box clearly, it is mounted below the Allison ECU and is called, per FreightLiner, a Vehicle Interface Module (VIM). This contains no fuses just relays. The relays: neutral start relay, exhaust brake relay, neutral sense relay, reverse lamps and two spares.