Fuel Gauge: Description and Operation

When the ignition switch is in ON (II) or START (III), battery voltage is supplied through fuse 25 to the gauges in the gauge assembly.

Fuel Gauge
The fuel gauge has two intersecting coils wound around a permanent magnet rotor. Voltage applied to the coils, through fuse 25, generates a magnetic field. The magnetic field, controlled by the fuel gauge sending unit, causes the rotor to rotate and the gauge needle to move. As the resistance in the sending unit varies, current through the gauge coils changes. The gauge needle moves toward the coil with the strongest magnetic field.
The fuel gauge sending unit's resistance varies from about 2 - 5 ohms at full, to about 110 ohms at empty. When you turn the ignition switch off, the gauge remains at the last reading until you turn the ignition switch to ON (II) or START (III) again.