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Fuel gauge

Fuel gauge

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.



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.

Fuel reserve indicator lamp

With about 10 litres of fuel remaining in the tank, the lamp lights up to indicate low fuel level. The lamp is supplied with current from the main instrument unit and grounded by the main instrument unit's control module when it is to be lit.

The main instrument unit lights this lamp for three seconds when the ignition is switched on.

Fuel consumption

The engine control module sends information on the fuel quantity consumed to the bus.

The main instrument unit control module uses the information to control the fuel gauge (under 10 litres).

Diagnosis

An open circuit/short circuit sets diagnostic trouble code B1720. The gauge needle indicates 0 litres and the fuel reserve indicator lamp lights up.