Fuel Gauge

The magnetic fields of the two coils moves the fuel gauge pointer. The two coils are at right angles to each other. The battery voltage is applied to the E coil and the circuit divides at the opposite end of the E coil. One voltage path continues to ground through the F coil, as the other goes to ground through the variable resistor of the fuel level sender.

The resistance of the fuel level sender is low when the fuel tank is low. A large flow of current passes through the E coil and the fuel level sender resistor. The current pulls the pointer towards the E on the scale.

The fuel level resistance is high when the fuel tank is full. The increased current flowing though the F coil moves the pointer to the F on the scale. With the two coils operating the pointer, the fuel gauge is not affected by the any changes in the voltage of the system.