Leds can sometimes cause funky issues because there is less current draw than the original incandescents. This can make the computer think something is wrong and not function properly (this is why you get a fast flash in the blinkers when leds are installed or one incandescent bulb is out). Adding resistors inline on each wire going to the bulb can solve this because it 'masks' the drop in current draw.
Not saying this is for sure your problem, it could be something as simple as a bad connection or a bent pin in the pig tail plug.
This is the fabrication section by the way, maybe posting in the electrical section will get some better responses..