Theory of Operation
WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) provides the Fuel Rail Pressure Sensor with a 5-Volt supply and sensor ground, and receives a signal voltage back from the Fuel Rail Pressure Sensor. This sensor signal voltage changes based on the pressure in the fuel rail. The PCM will light the MIL lamp immediately after the diagnostic runs and fails. During this time the customer may experience a power and or speed derate. The PCM will turn off the MIL light after the diagnostic runs and passes in four consecutive drive cycles.