Theory Of Operation

WARNING: This page is about a different car, the 2013 RAM 2500 HD and 2012 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.

The CNG Tank Pressure Sensor is mounted on the inlet side of the CNG Fuel Pressure Regulator. The CNG Tank Pressure Sensor operates as a typical three wire sensor with a 5-volt reference circuit, a signal circuit and a sensor return circuit.

The CNG Tank Pressure Sensor is used for two different purposes. The Powertrain Control Module (PCM) receives an input to determine if the pressure in the system is high enough to allow for proper CNG operation. The high pressure side of the system must be approximately 16.55 bar (240 psi) or above for the PCM to switch to CNG mode.

The PCM also sends the pressure signal to the Cabin Compartment Node (CCN). The CCN uses the pressure signal to calculate the percentage of CNG fuel left in the system which is displayed as the CNG Fuel level on the dash. When the system is fully pressurized, the pressure will be approximately 248.2 bar (3600 psi).

If one of the manual valves are closed, or if one of the CNG Tank Solenoids does not open properly, the CNG range will be reduced by half and the CNG Fuel Gauge will show the fuel consumption at twice the normal rate.