stored in memory devices 18 and 20 for carrying out system functions for example a liquid level processing routine is provided to read an analog to digital converter on sender card 14 the liquid level processing routine provides a ratio rad of the liquid level to battery voltage periodically in an embodiment of the present invention liquid level processing routine is completed at least every 120 milliseconds in order to capture an accurate profile of the liquid level there are two basic types of liquid level senders 14 forward and reverse the present invention contemplates using either a forward or a reverse liquid level sender a forward sender is one in which the sender card resistance increases with increasing liquid level volume in contrast a reverse sender is one in which the sender card resistance decreases with increasing liquid level volume preferably a forward sender is used in system 10 to provide a more accurate liquid level reading since the liquid level sender reading error is smaller at lower resistance values providing better accuracy at a near empty tank condition in a preferred embodiment the liquid level reading is ratioed to its supply voltage sbatt to compensate for any errors due to battery voltage fluctuations and differing regulator voltages in yet another embodiment of the present invention a voltage divider circuit instead of a precision reference voltage and.