System Description: Description

Fuel level sensor unit and fuel pump records the fill level in the fuel tank. The BCM reads in the signals from the fuel level sensor unit and fuel pump directly and sends them to the combination meter via CAN communication. The combination meter receives the signals from the fuel level sensor unit and fuel pump, evaluates them and actuates the fuel level indicator accordingly by means of a stepper motor. If the reserve range has been reached (approx. 12.5 % of maximum tank capacity), the combination meter actuates the low fuel lamp. A corresponding message is shown in the information display.
The reserve range is defined by comparing the measured fill level against a stored tank characteristic.
If the reserve range drops to approx. 50 %, a gas station symbol in the form of a gasoline pump is shown in the Range menu instead of the distance reading.

DISPLAY CHARACTERISTICS OF FUEL GAUGE

After ignition switch ON, the current fill level is displayed. In the process the pointer runs up in a buffered manner.
After an engine start the display value for t = 4 s is updated every t = 0.8 s, to maintain a value below the full on-board electrical system voltage. After this time, or as soon as the vehicle starts off, the display is updated with a delay.
When ignition switch is switched off, the fuel level indicator pointer moves gradually back to zero.

NOTE:

By comparing the change in the fill level with the calculated composite mileage, it is possible to detect whether the fill level sensors are firmly attached. If the fill level over a certain distance drops more quickly than technically feasible based on composite mileage, the fill level sensor is recognized as being malfunction and the corresponding message is shown in the information display.