I have had the same problem since my jeep was a month old, I cannot find the problem, changed out all the bulbs, still blows fuse immediately. Believe its fuse 18(15A) brakes work, Front and rear turn signals work, back up light works too. My signal light on front flares were removed when i installed after market flares.
I have been pulled over a handful of times(warnings only thank god). Dealer wants the Jeep for a day to try and fix it, its my daily driver. Post if you find a solution.
Also must be a common problem, i look for it now in other JK's and have seen more than a few with same problem, almost always on passenger side.