my 1990 xj did that . i changed the flashers yes both . i changed the flasher for the turn signals & for the 4 ways. then i found it to be a bad socket in the front right. change your flasher first then check your sockets.

93 xj stroked 4.2 w/4.0 head avenger supercharged 6.5" long arm 35" buckshots rubicon 44's front & rear