Join Date: Jun 2017
Location: Denver CO
Model: GL1500 Aspencade 1980 GL1100 STD Vetter
Low Fuel light depends on the current flow thru a negative-coefficient Thermistor (temperature-sensitive resistor) in the fuel tank. Resistance is high while the thermistor is immersed in fuel and is cool, resistance drops once the thermistor is dry and allowed to heat up, heating aided by the current draw of the incandescent bulb (which increases resistance when lit), thus lighting the bulb. One side of this bulb has +12v, the other side goes thru the fuel thermistor to ground.
So an LED light will be "Always On" due to the reduced current loading, and due to the dynamics of an incandescent bulb vs an LED I don't think the LED will give the desired results even with a load resistor. It could be made to work but you'd have to design some switching circuitry.
The short answer is to put the regular bulb back in the dash.
1972 CL-350 (1980-1988) sold
1978 Suzuki GS-550 (1985-2005) sold
1977 GL1000 (2002-2006) sold
1980 GL1100 STD Vetter (2005-)
1993 GL1500 Aspencade (2017-)
1983 Trav-Lite Camper (2010-)