When used with the replacement circuit board and matching flasher works perfectly with the running lights and turn signal function. Unfortunately, the 4-way flashers DO NOT WORK with LEDs in front and back. I had to remove the front Yellow LEDs and replace them with the stock 1157 bulbs for the 4-way flasher to work. Still works well with the running lights and turn signals using the stock front bulbs. So - really couldn't use the Yellow LEDs. I'll investigate other flashers - electronic flasher from NAPA did not solve the problem.