OK Led bulbs run at a different resistance... Your Typical Bulb runs a higher resistance and the resistance causes it to pull more amps.. When the bulb pulls a certain amount of amps thru the flasher unit.. The Flasher unit is like a automatic circuit breaker and it opens and closes with the heat thats created from the amps being pulled thru it.. When you Run an LED Bulb your not pulling the amps to trip the flasher to flash the bulb Thus having a problem like one bulb is brunt out in your car either no flash or super fast flash.. So when you Install an LED Bulb in a Standard Filament type bulb space your not drawing what that system is designed to draw so it WILL Not work.. If you go the VLED Website I believe its V-LEDs.com you can Buy a Resistor package from them they offer a 6ohm and a 3ohm and you run the resistor from your Turn Signal + wire to the Ground wire and Boom you got working lights... I would Email them or look on their site to determine what OHM you need and I think they were about 10$ for a Pair.. I have purchased hundreds of dollars worth of stuff from them and they are a great company to work with and The product is far Superior to any other LED bulb out there..