that sounds like the problem I had a few weeks back. It was the flasher unit.
they talk about it here
basically you need to pop off the trim behind the steering wheel in front of the guage cluster and there are 2 screws to remove beneath that, 1 more screw on side of dash on drivers side, and then 2 bolts under dash, and then remove lower dash. You need to reach up with some tiny hands (LOL) and pull out the old flasher unit and replace with new. People say they are cheap and you can find them at any parts store, good luck with that. I found 1 locally it was 40something, and dealer had it was well for over 50. I bought a used one from someone parting out a WJ. Mine has been fine since I replaced it. There is also talk on that link I posted about opening the unit and soldering 2 pieces that get cracks in them, I have heard a lot of people do that successfully also. Good Luck.