I would look at the blinker switch plug or something along that line. But if you have all LED lights there are many flashers that say they work with LEDs but I have found they don't The only one I have found that works is made by Peterson. I'm using the 500 series. But you can try the small one with the wire you ground, but I have not had any luck with it.
http://www.pmlights.com/products.cfm?cId=5&fId=23