That's what I thought at first, but I checked out the connector views for PDC connectors C7 and C5 which those wires go into. On C7, they feed into Pin 27, 29, and 33 which are labeled as "Trailer Tow Backup Lamp Relay Ctrl.", "Trailer Tow Tail Lamp Relay Ctrl.", and "Right Rear Turn Signal Ctrl." respectively. On C5 they go to Pin 12 which is shown as "Left Rear Turn Signal Ctrl." This matches the above diagram showing them going from the Module Body Ctrl. to the fuse box.
Looking at the diagram for the C5/C6 on the body control module, all the pins that harness feeds into are marked for the aforementioned lights. I checked every pin on the connectors for that module and only one is labeled as a brake signal. It's pin 18 on C4 which is a DG/WH which feeds to the brake control connector under the driver side dash.
Interestingly, the DG wire which is supposed to go the the brake controller, isn't shown on the instructions for the 82216007AB kit. On the instructions you posted earlier for my kit, it at least referenced it, saying that it needed to be tied back. I attached the instructions for the 82216007AB kit below. It only shows the 5 wires on harness A feeding into C7/C5.
If the wiring diagrams are to be believed, that DG wire from the brake controller should go to a connector labeled Inline Body/Underbody 2. Which is located here:
I've got some digging to do it seems. If the controller wiring is connected properly, when I find that connector, one side should have a DG wire with no corresponding wire on the other connector. If so, that's where the DG wire from the 7 way connector should have gone