I noticed something today when converting my sidemarker bulbs to LEDs from www.superbrightleds.com. I think when the lights are off, and the turn signal is on, the current flows in one direction through the sidemarkers when the flash on, and when the lights are on, it flows in the other direction. anyone ever put a meter on them? since normal filament bulbs work just fine with current in either direction, so they work fine whether the lights are on or off, but with LEDs, they are diodes, and only illuminate when current flows in a certain direction. hense the reason that they only work properly when the lights are on, and not when off. I don't really care since I never drive my car without the running lights on, no matter what time of day it is. but just an FYI for anyone wanting to do this, you'll have to change them back for your inspections!