Circuit Description

WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.

The CNG fuel gauge system consists of the Fuel Tank Pressure (FTP) sensor, Fuel Tank Temperature (FTT) sensor, Pulse Width Modulated (PWM) output circuit, dash mounted fuel gauge and dash mounted fuel gauge select switch (Bi-fuel/KL6 only). Alternative Fuels Engine Control Module (AF ECM) monitors fuel pressure and fuel temperature in CNG fuel tank. Volume of CNG varies with pressure and temperature. In order to display an accurate fuel gauge reading, AF ECM will perform a calculation based upon fuel pressure and temperature and determine correct amount of fuel remaining in fuel tank. AF ECM converts calculated fuel level into a PWM signal that is monitored by PCM. PCM sends fuel level information to instrument panel fuel gauge via Class 2 serial data circuit. Vehicles that are equipped with Bi-fuel (KL6) option also utilize a fuel gauge select switch. Fuel gauge select switch is monitored by PCM. When switch is pressed, PCM will display fuel level for non-operating fuel system, for about 10 seconds.