Circuit Description

The CNG fuel gage system consists of the following components:

• The fuel tank pressure (FTP) sensor
• The fuel tank temperature (FTT) sensor
• The dash mounted fuel gage select switch
• The dash mounted fuel gage

The powertrain control module (PCM) monitors the CNG FTP and FTT sensors. The volume of CNG stored in the tank varies with pressure and temperature. In order to display an accurate fuel gage reading, the PCM performs a calculation of based upon the CNG tank fuel pressure and temperature. Refer to Compressed Natural Gas (CNG) Temperature vs Percent Full .

The fuel gage select switch allows the vehicle operator to observe the fuel level for the non-operating system. When the switch is applied, the PCM will display the fuel level of the non-operating fuel system for about 10 seconds.

The PCM sends the fuel level information to the instrument panel fuel gage on the Class 2 serial data circuit.