I have a 91 Jeep Cherokee Laredo, with the straight six, that had the brake & hazard lights go out. The running lights, back-ups, and turn signals all work.
What I found was that there is a fuse in the box (passenger side) under the hood that is labeled Hazards (15 amp) that had no power to it.
We jumped the fuse to another 15 amp across from it, and the brake & hazard lights work great.
Once I trace the wire that is supposed to provide power to that fuse, I will post the results.