You're looking at a fair amount of work to wire in the Prodigy. The DP's don't have a brake switch like a gasser, which makes it difficult to do. Lately, many have been buying the wireless units and skipping the hassle.
If you don't want to go wireless, here are some suggestions: Go to your "run bay" (large bay under driver's window and start there. Pick up a power lead out of the big black box, (plenty to choose from). Connect up a wire for 12 volts and add a fuse. Pick a suitable ground connection and wire in a ground. Next, (from that bay) run a wire the length of the coach to the rear trailer plug. Lastly, there is a wire in the loom at the bottom of the box that says brake lights. I tapped into this on a neighbor's coach and found it did not provide a full 12 volts, but was active when the brake pedal was depressed. I tapped into this line and then connected it to an automotive relay. I added 12 volts to the relay (again fused) that would give a full 12 volts when the relay was activated by the brake light wiring.
Once you have this all done, you can feed the four wires up through the top of the run bay and into the armrest/control panel inside the coach. Once in there, you can fish it out the front of that box and under the dash.
Don & Mary
2014 Newmar Dutch Star - All Electric - 450 ISL
2016 GMC Canyon 4WD Crew Cab