Hi, I’ve got an 07 Ram 1500 (4.7L SLT), and I came home from work the other day and everything worked fine, the next morning I went to work and I had lost all 3 of my brake lights and rear signal lights (but the tail lights work). The headlights and front signal lights work fine…and the 4-way’s work in the front but not in the back.

Also, when I hook up my trailer, the brake lights, 4-ways and rear signal lights work on the trailer.

It’s not the bulbs, because the reverse lights work…I’ve changed out all the fuses, and replaced the brake switch. My brain is boggled!

 

Reverse lights have their own switch, so maybe problem is with the circuit boards.
You could try removing a tail light then disconnecting the plug that goes into board. Use a probe to test the plug pins for ground and power.