what i like to do to make sure is use a test light and test every fuse, in every location. i have seen fuses look good but are not. make sure to have ign on to test fuses easier.
from that point if they all look good i would go to switch and test wires there. (break switch & parking light switch), now if it's turn signals then check relays for that.
cant say i have seen that issue from replacing a seat..though i have had to change my break switch several times on my 95.
95 YJ, 4" suspension lift, 32's, 2.5l 4 cyl (350 built and waiting to be installed in spring, along with ford 8.8 rear end)