Thank you.
They are for the wiring to an optional trailer brake controller. The white is ground and the violet-white is a brake pedal switch signal. The Ford official brake controller doesn't use the violet-white wire for the brake pedal signal, it instead uses the high mount stop light wiring for the trailer brake controller brake signal. The white ground wire wasn't used either, as the official Ford brake controller uses a dash mounted ground screw for a ground point. So, neither are used.
The wire's work just fine for a standard 4 wire brake controller. I have a Tekonsha controller that I hooked up almost 3 years ago, still working perfectly. I'm kind of old school and like the under dash units.
Yes, the under dash wires are used for the Ford accessory TBC. The Ford controller connects just like any TBC with the addition of a second module that interfaces with the center brake light. The center brake light is used for the brake signal on the Ford unit. That signal is PWM and needs the secondary controller to convert the signal to a steady input for the TBC (which is a Redac unit).
If that is correct than how come those wires are open in my truck (check the photos in my OP) ?! I have the FORD TBC as the dealer option. I later even downloaded the wiring instructions from FORD to check if the dealership cut any corner or sloppy workmanship (I’ve OCD with trust issues). Everything seemed to be wired as the instructions. Either those two wires aren’t used per FORD instructions or I overlooked and missed something ?! It’s was setup by the dealership exactly how @RangerBill described.
The brake signal under the dash is not used for the Ford TBC, but I think that is the only one. IIRC, I had three bare wires and used two of them, but it was a few years ago.
As I said above, the official Ford trailer brake controller does not use the white and violet-white wire, only the yellow and blue wires and a connection to the high mount stop light. Please re-read my reply above.
