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Frequently asked questions about cars and motorcycles
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Schematic diagram of the fuel level indicator in a car.

Model: (Various brands) Various
Part: Dashboard

The path of electricity, as shown in our diagram, is as follows: from the 12-volt battery, we go to the indicator, which has two terminals: power input (with the key inserted) and output/signal. From here, a wire goes to the sensor in the tank. From the indicator, we go to the sensor in the tank, which is the "signal wire" that reaches the terminal of the potentiometer connected to the movable brush of the float. From the sensor, the current goes to ground, so the current does not physically return to the battery through a dedicated wire, but instead uses the metal structures of the car (the body) as a "return wire." When the tank is full, the float is up, and the potentiometer provides low resistance, causing the needle to move towards "F" (full); when the tank is empty, the float is down, and the potentiometer provides high resistance, causing the needle to move towards "E" (empty).

Posted on 3 December 2025 by ScegliAuto

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