I've had blinker problems with my 98 tj. I opened the hood to check the oil (with causes the courtesy light, not the underhood light to go on because someone messed up) and when I closed it and got in the blinkers didn't work at all. Then, after a few minutes of messing with it, i turned on the hazards, which worked, and then magically, the blinkers worked. I agree with neale_rs: gremlins.