Fuel Level Gauge
Description
Fuel Level Gauge
The fuel level gauge pointer indicates the current fuel level in the fuel tank and returns to the empty position when the ignition is switched off. The gauge is operated by an output from the fuel gauge to the fuel tank sender which is integral with the fuel pump.
Fuel Level Gauge - Up to 2002.5 Model Year
The sender is a float operated rotary potentiometer which provides a variable resistance to earth for the output from the gauge. Movement of the sender unit float arm varies the electrical resistance across the sender unit, so the voltage of the control signal and the resultant deflection of the gauge pointer are directly related to the level of fuel in the tank. When the sender float is at its lowest point, indicating an empty fuel tank, the resistance to earth is at its greatest.
The measured resistance is processed by the instrument pack to implement an anti-slosh function. This monitors the signal and updates the fuel gauge pointer position at regular intervals. This prevents constant needle movement caused by fuel movement in the tank due to cornering or braking.
A warning lamp is located in the face of the fuel gauge and illuminates when the fuel level is at or below 2.2 gallons (10 litres).
The fuel level sender signal is converted into a CAN message by the instrument pack as a direct interpretation of the fuel tank contents in litres. The ECM uses the CAN message to suspend OBD misfire detection when the fuel level is below 15% capacity.
Fuel Gauge Resistance Read out Table - Up to 2002.5 Model Year
Sender Unit Resistance, Nominal Gauge Reading
Ohms
503 Empty
413 Low fuel level illumination
302 Half full
135 Full
Fuel Level Gauge - From 2002.5 Model Year
A new design fuel level sensor is introduced from 2002.5 model year and is fitted to all petrol and diesel models. Unlike the previous sensor, this sensor is sealed from the fuel preventing contamination of the contacts.
The new sensor requires modifications to the instrument pack fuel gauge calibration, therefore, the new sensor cannot be fitted to a pre 2002.5 model year vehicle.
The sensor is a MAgnetic Passive Position Sensor (MAPPS) which provides a variable resistance to earth for the output from the fuel gauge. The gauge comprises a series of 51 film resistors mounted in an arc on a ceramic surface. The resistors are wired in series with individual contacts. A soft magnetic foil with 51 flexible contacts is mounted a small distance above the film resistors. A magnet, located below the ceramic surface, is attached to the sender unit float arm. As the float arm moves the magnet follows the same arc as the film resistors. The magnet pulls the flexible contacts onto the opposite film resistor contacts forming an electrical circuit.
The film resistors are arranged in a linear arc with resistance ranging from 50 to 1000 Ohms. The electrical output signal is proportional to the amount of fuel in the tank and the position of the float arm. The measured resistance is processed by the instrument pack to implement an anti-slosh function. This monitors the signal and updates the fuel gauge pointer position at regular intervals, preventing constant pointer movement caused by fuel movement in the tank due to cornering or braking.
A warning lamp is incorporated into the face of the fuel gauge and illuminates when the fuel level is at or below 1.5 gallons (7 litres) for petrol engines and 0.88 gallons (4 litres) for diesel engines.
The fuel level sender signal is converted into a CAN message by the instrument pack as a direct interpretation of the fuel tank contents in litres. The ECM uses the CAN message to suspend OBD misfire detection when the fuel level is below 15% capacity.
Fuel Gauge Resistance Read out Table - From 2002.5 Model Year
