Operation CHARM: Car repair manuals for everyone.

Fuel Gauge

The magnetic fields of the 2 coils move the fuel gauge pointer. The coils are at right angles to each other. The 2 coils are connected to each other. The fuel level Pulse-Width Modulated (PWM) circuit from the PCM connects at a middle point. Battery voltage is applied to the end of the coil at the E end. Ground is applied at the other coil's F end.

The fuel level sender resistance is proportional to the fuel level. The voltage across the sender is the fuel level input signal that is applied to the PCM on CKT 30 and CKT 452. The PCM provides a Pulse-Width Modulated (PWM) fuel level output signal on CKT 455 (PPL/WHT) to the instrument cluster fuel gauge.

When the tank is low, the fuel level sender resistance is low. A larger current passes through the E coil in order to move the pointer toward E on the scale. When the tank is full, the sender resistance is high. More current flows through the F coil. This moves the pointer toward F on the scale.

With 2 coils operating the pointer, the gauge is not affected by changes in the vehicle's electrical system.