Fuel Gauge

The magnetic fields of two coils, which are at right angles to each other, move the fuel gage pointer. The two coils are connected to each other and the fuel level sender at a middle point. Battery voltage is applied to the end of the coil at the E end, and to ground at the other coil's F end.

When the tank is low, the fuel level sender resistance is low. A larger current passes through the E coil and the fuel gage sender resistor to move the pointer towards E on the scale. When the tank is full, the sender resistance is high. More current now flows through the F coil, which moves the pointer towards F on the scale.

With two coils operating the pointer, the gage is not affected by changes in the vehicle's electrical system.

The Oldsmobile Eighty-Eight also contains a Fuel Level Module which buffers a second fuel level signal output to the Powertrain Control Module (PCM). The Oldsmobile Ninety-Eight has no Fuel Level Module or signal to the PCM.