How do these things read? Is the light just a warning, or does it mean I am really low.... 
Full Version: Whats the deal with the gas tank "reserve" light?
Im driving around and my fuel gauge says I have 1/4 of a tank left, but the light is on. How do these things read? Is the light just a warning, or does it mean I am really low....
How do these things read? Is the light just a warning, or does it mean I am really low....
The needle on the gauge works through resistance. Dirty connections, etc., can all change the reading.
The light works from a strip of metal on the bottom of the float inside the fuel tank. When the float gets low enough in the tank, the metal strip shorts across two contacts, providing a ground path for the light. About the only thing that'll change when it comes on is if the wires break or if the float gets messed up.
IOW, the light is more reliable than the gauge. You have "about" a gallon left when it comes on for real. (It will come on in the corners for a while before it stays on when level.)
--DD
The light works from a strip of metal on the bottom of the float inside the fuel tank. When the float gets low enough in the tank, the metal strip shorts across two contacts, providing a ground path for the light. About the only thing that'll change when it comes on is if the wires break or if the float gets messed up.
IOW, the light is more reliable than the gauge. You have "about" a gallon left when it comes on for real. (It will come on in the corners for a while before it stays on when level.)
--DD
Could be a defective sending unit. Get a stick and dip your tank to see how much gas it really has. If it's a 1/4 way up, sending unit, wiring...ect
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