How to wire brake controller on Thor Vegas 2018:
The Thor Vegas 2018 does not come with a brake controller wiring harness behind the dash, unlike most other RVs. The 7 way RV style trailer plug harness is pre-wired next to the tow hitch, except that the trailer brake wire (blue 10 AWG) is not run all the way to the driver area. This wire is #2 in the image below.
I purchased a Tekonsha 90195 P3 Electronic Brake Control.
In general this is the wiring instructions:
+12V Connect the black 12 AWG wire from the brake controller harness to the thin (~14 AWG) brown/red wire in the wire harness that is located to the right and above of the gas pedal with a blue 18-14 AWG Quick Splice Wire Tap Connector:
Ground Connect the white wire from the brake controller harness to the ring and self-tapping screw to ground to firewall located to the right and above the gas pedal.
Brake signal Connect the red wire from the brake controller harness into violet/white wire coming out of brake pedal switch with a red 22-18 AWG Quick Splice Wire Tap Connector:
Trailer brake Connect to 12 gauge blue wire that deadends in the angled Ford chassis harness connector located under the driver side wheel. This is the hardest step and took the most time to perform. The wire from the trailer connector is a 10 AWG blue wire.
This wire connects into the ford harness and turns into a 12 AWG light blue wire near the gas tank.
The ford harness travels along the frame rail and dead ends into another angled ford harness that is located near the driver side wheel. The two harnesses can be seperated by unbolting them.
This harness has to be carefully spliced open with a razor to expose the 12 AWG ligth blue wire. Its located at the corner of the wire harness. You can see that the other ford wiring harness has no female end and no wire on the other side, which is what is meant by dead ending. I then used a red 22-18 AWG Quick Splice Wire Tap Connector to tap a new black 18 AWG wire to the blue ford wire.
I then ran this new wire into the engine bay by going into the RV and fishing a bike shifter cable (stiff metal wire) through the wire loom located to the left side of the driver seat.
Here is where the wire comes into the firewall from the engine bay:
I then attached the new black wire from the engine bay to the shifter cable wire with tape and then pulled the wire from inside the RV into the RV. I then connected this wire to the blue wire on the brake controller harness.
Let me know if this is need more clarification. This was a fairly challenging project and took me a while to trace the brake controller wire.