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Home >> Saab >> 2007 >> 9-3 2.0T, 2D Convertible, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 52 (Main Instrument Unit) >> Descriptions and operation >> Fuel gauge >> Notes

Fuel gauge: Notes

WARNING: This page is about a different car, the 2006 Saab 9-5. However, it is still accessible from the selected car via links, so may be relevant.

The fuel gauge gives the driver information on how much fuel is left in the tank. It consists of a fuel gauge in the main instrument unit and a level sensor in the tank.

Fig 1: Fuel Gauge Communication Diagram
G05038747Courtesy of SAAB-SCANIA OF AMERICA, INC.
Fig 2: Fuel Gauge - Circuit Diagram
G05036819Courtesy of SAAB-SCANIA OF AMERICA, INC.

The level sensor has variable resistance where the value corresponds to the level of the float sensor in the tank, and the resistance increases with a higher fuel level.

The sensor is connected to the main instrument unit control module, pin 31, where it is supplied with B+ and grounded via pin 15.

The control module measures the sensor resistance value every 50ms and then calculates an average value after 6.4 seconds. Using this value the fuel gauge needle is moved to a position representing the fuel level in the tank.

To enable a more accurate display with small amounts of fuel in the tank, the main instrument display control module switches to measuring fuel consumption once the amount of fuel drops below 10 litres.

The main instrument unit control module sends information on the fuel level to the buses.