Originally Posted by docvette
An LED can possibly Run for weeks from the drain of an electrolytic Capacitor, provided the Cap was large enough..Like one of those OLD computer power supply caps, 1 MFD @ 100000 WVDC..(The ones that are so popular with Car Stereo Installers now..to keep high current drain stable on "Thump")
A Single LED would last for months on a fully charged cap of that type..a screwdriver to discharge a cap like that will burn/melt the blade like a battery would.
So If you don't have a High power Low Capacitance Cap elsewhere in the car, check at the array circuit boards (If they are accessible) look for an Electrolytic cap on the board, It will say something like : 150 MFD @ 25 WVDC, and have a + and - on it..See if the voltage is there.
Also, do you have a "Ballast" of sorts..on that system to cause enough Draw on the flasher to flash with a mix of incandescent and LED lamps? If so , It may be installed wrong or defective. Check for that.
Good Points Doc
Something else to try is with the ignition off flip on the turn signals to one side and see if the other side goes out. If there is a capacitor on teh board that the leds are attached to if you disconnect the plug to the board, theoriginal light plug, the bulb should stay lit with no connection. Also unplug both lights and test with your meter for voltage at the wiring, if it is a real low current leak you may see the voltage go back up to 12 volts when you remove the load. You may also want to take the front bulbs out to test. The problem could be up front also. It takes a lot more current to light an 1157 than an led. Thats for sure.
Also if you disconnect the battery and the light go out you know its not a capacitor in the line. This should be a real simple test. Just remove the negative battery cable.
This will eliminate a lot of possibilities