Good reply.
I recently had a very similar experience with one of my C4s, but the wiring is very similar (perhaps identical?) and the brake lights wouldn't work - but turn and hazards did! Again, if you look at the wiring charts for the car everything for those lights goes through the steering column and through the turn signal and hazard switch.
So, i started looking at all the wiring, traced the problem back to the steering column (no big surprise) and was quite pleased to find it was simply the big, long connector for the wiring harness to the steering column. Somehow it had worked loose just a tiny bit, but enough to stop the brake lights from working. Pushed it all back together and with a couple of wire-ties I locked it all into place.
Just posting that in case someone else has a similar strange problem.
Happy Motoring - lovely day here so I am going to take out one of the Vettes to go shopping.
______________
C3: 1979 Corvette Coupe, Auto, L-48, Red/Doeskin (my wife's fave);
C4s: 1986 C4 coupe (SCCA road race car), satin black, 4+3, Z51 package, L-98; & 1993 C4 coupe, white, 6-speed, LT-1.