Have you checked all the fuses under the hood and inside the cabin?
Unfortunately I and my known KJ sites do not have the wiring diagrams for any KJ newer than the 2006 KJs. The wiring is probably pretty much the same as the 2006 KJs....unlikely Jeep would have made major changes to the 2007 KJ model when the KK was on the near horizon!
So download the 2006 KJ Service Manual here if you do not already have it....includes wiring diagrams.
It is very weird because the Flasher unit has nothing to do with the brake lights and vice versa and the grounds for the front lights are separate from the brake lights...the multifunction switch like wise only selects left or right indicators inside the Flasher Unit....flasher unit should work when pressed. None of these units are on the common CAN/PCI bus so I doubt there is a problem there.
I would use the 2006 KJ Service Manual and a cheap Digital Multi meter to try trace the problem ie. look for +12 voltage on all the points where they should be....with reference to the ground wires at the bulbs and also with reference to chassis...in case a ground has gone missing.
The wiring harness on the KJs goes around the whole engine bay in a circle with some connectors in the line...possibly a connector common to all these failing components has come loose?
KJ Manuals:
Index of /manuals/Jeep/KJ
