Interesting, mine was the same way but I found another flasher wired up under the dash that contolled the turn signal. i got two flasher from walmart, model 552 last summer. they both seem to go out a couple weeks ago so i put in another yesterday. it worked. they must be cheap or i have a voltage problem. i assumed when the flasher wouldnt stay in my fuse box the previous owner wired it in somewhere, but i havent followed the wires to find out.

not sure if i helped, goodluck

86 CJ7, 258, MC2100 Carb, 4" Rough Country lift, 34" Swampers, Jeeperman bumper/tire carrier