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 Fuel Rail Sensor is a combination pressure and temperature sensor. The pressure sensor operates as a typical three wire sensor with a 5-volt reference circuit; a signal circuit and a sensor return circuit. The temperature sensor operates as a typical two wire sensor. It has a signal circuit and shares the sensor return circuit with the pressure sensor.
The Powertrain Control Module (PCM) uses the CNG Fuel Rail Sensor inputs to monitor the low side pressure and temperature to calculate the CNG Fuel Injector pulse width (on time). During normal operation the low side pressure is approximately 10.3 bar (150 psi).