Wayne & Others. 3 way's to check low fuel light working and how critical it is. #1.Take the cover off to expose the top of the fuel sending unit. Jumper clip the red & Black wire and you will see the light is working. #2.If you really want to see how critical it is on low or empty. Take the unit out and hook up digital multimeter with a buzzer. Connect the red and black wire to the meter and slowly turn the unit upright as the inside is droping and the see where the buzz comes in. Mine comes in at the very bottom. Ain't much gas left. Switch the meter to ohm's x10 and the ohm's reading at the bottom of the sending unit should be less than 1 ohm. #3. Run out of gas. John vin 11004