GF54.30-P-3018RT Display Fuel Quantity, Function

GF54.30-P-3018RT Display Fuel Quantity, Function

Component Identification:

Function requirements:
^ Circuit 15 ON

Function
The fuel level and reserve indicator is designed as an analog display. The display values are shown immediately after circuit 15 ON. In the process the pointer runs up in a damped manner. The fuel pump supplies the fill level (M3/3), two fuel level sensors located in the right or left tank half supplying the signals for the fill level. The left tank half fuel level sensor and the right tank half fuel level sensor change their resistance corresponding to the tank fill level. The fuller the tank the lower the resistance. The sensor measured values are read in by the SAM control unit and made available to the instrument cluster on CAN-B (in percent values). The instrument cluster evaluates this information with the aid of the tank characteristic and actuates the display accordingly.

Refueling
The "refueling" status is established by comparing the instantaneous display value with the measured tank contents from the instrument cluster. When the difference between the two values is greater than the defined value (3 liters with ignition OFF, 7 liters with ignition ON), then refueling is detected. When the ignition is switched off and after the expiry of the settling down condition (fuel sloshing around in the tank) another measurement takes place which is then stored. The display is updated once circuit 15 ON is switched on again, the stored value being compared with the new measurement. The pointer is run up to the corresponding value in a damped manner.

Reserve range
The reserve range extends from "0" to "Reserve". This corresponds to a quantity of 0 to approx l.
If the reserve range is reached, the fuel reserve indicator lamp lights up yellow when the engine is running. The lamp is triggered with a delay period to prevent the lamp flickering.

In the event of a fault the pointer of the fuel level and reserve indicator is moved onto "0" in a damped manner. The fuel reserve indicator lamp is not actuated.

Detection of seized fuel tank sensor (USA only)
Detection of a seized fuel tank sensor is active as of a mileage of approx. s > 160 kilometers or 100 miles. Detection of a seized fuel tank sensor is recognized if the fuel sensor resistance value does not change at least by a defined value within a certain mileage. If this condition occurs, a corresponding seized error bit is set for sensor 1 and/or sensor 2. The bit is erased again when the requested change of a sensor has occurred.
The sensor seizure is entered in the fault memory of the instrument cluster.

If the rear SAM control unit issues the signal "tank cap not closed", the fuel reserve indicator lamp flashes at 2.5 Hz (200 ms on/200 ms off) in the instrument cluster as long as the signal is set.