The turn signal switch may be bad even though that the blinkers work because Mother Chrysler used to wire the brake lights through the emergency flashers years ago.
I'm not sure if that was still the norm in the 90s.
Just for the record, I've replaced two turn signal switches in the past when I had brake light problems and that is what solved my problems.
RED JEEP CLUB MEMBER #92
'92 WRANGLER, 2.5 Litre, 5 Speed, Rag Top, Superwinch LP8500, Cepek 130W Driving Lights, 31x10.50/AT with no lift, Of course! It rubs!
Had the same issue a couple of weeks ago during reassembly of my 92 yj after bedliner install. Basically the brake switch can and will give you a false reading. While installed no brake lights. When removed from jeep switch was working. I did find in my trouble shooting a fuse that was loose because some where in this jeeps past somebody thought out was a good idea to jam something into the fuse block. Fixed that issue and reinstalled brake switch. Brake lights work however, now sometimes they will not cut off. Brake light switch is sticking. Just my 2
Do you have power going to the switch and back out? Check using a test light. I've seen switches test good with a meter, but the contacts can't pass enough power to light the lights. The meter doesn't put any load on the switch. Next, just follow the circuit to the turn signal swtich, checking connections and wiring.
2014 Rubicon, 6 speed, Mopar 2" with Fox, 285's on Level 8 Punch Wheels
2015 Renegade Trailhawk
Did you pull the housings off of the tub and check the mounting screws for rust?
When I had issues with my brake lights, they were doing all kinds of strange things, it ended up being a bad ground connection (stock lights use the mounting screws to ground to the tub).
maroon 1987 Grand Wagoneer. stock for now...