My question is relative to getting a LED to function correctly in a resistance sensitive circuit. Here is the situation. 1. The Battery Warning Light in an automobile I am restoring currently uses an incandescent bulb. 2. Functionally, the light is on when the ignition is turned on, but goes off when the engine starts. 3. This works fine with the incandescent bulb, but not with a LED, even if I put the same incandescent bulb in the circuit (parallel). 4.With just the LED in the circuit, it never goes off. This is because the circuit has about .5V leakage voltage through the device (which is a Lucas 3AW Warning Light Unit) when the engine is running (and correctly, 12V when just the ignition is on). 5. With both the LED and the incandescent in the circuit, the incandescent does not come on and the LED does not go off, both with ignition on and engine running. 6. I have also put a potentiometer in the circuit with just the LED and cranked it from 1 Ohm to 100K Ohms, with no effect. 7. Of course, an easy answer is to just use the incandescent, except that the dash is wired and complete and installed, and I prefer to get the LED to work. Any thoughts or suggestions would be very much appreciated.