Ever figure it out? My 2000 xj did the same thing...blink once, 2 times, depending on the mood it was in....anyways I went to my local auto parts store and bought a new flasher relay for $20...they let me try it out too...idk if it's the same for grands (assuming grand cherokee from your name) but mine was by the left driver's knee under the steering column. Unscrew the plastic, then the metal, and reach in and the flasher relay should be to the left...Good Luck!!
2000 Cherokee Classic
3" Zone lift, THULE roof rack, Hella 500 Black Magics