Automotive LED bulbs blowing fuses

3157 Type dual use (running and brake light) keeps blowing fuses...??? I am at a loss why they would do this. I've made sure the connection is correct and there are no shorts, anyone? /ubbthreads/images/graemlins/help.gif

Check the voltage at the taillight and then reproduct that voltage on the bence and see what current the module takes, with all combinations -- running, beake, and running+brake (depending on manufacturer/model, the last case may or may not be used).

Then do the same thing with the incandescent bulb you replaced -- the incandescent running light will probably take about 0.5A and the brake light will take about 2 or 2.25A, and together I guess they might take close to 2.75A. It's hard to imagine that the replacement LED bulb could take that current and be happy.
What's the vehicle?

check the base of the bulb with another good bulb to see if the pins line up properly. Also check it on a car battery with a ammeter, make sure to connect one pin at a time then both to see if what the current is. Be prepared to pull the meter leads quickly if it pegs out your ammeter. Use the 10amp scale or higher if your meter has it.