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 a PWM driver circuit and ground circuit to the Fuel Control Actuator (FCA). The PCM varies the current to this valve to provide the correct fuel flow to the High Pressure Pump based on operating conditions. The FCA is a normally open valve. High circuit resistance may cause fuel pressure to be higher than commanded at light loads. Excessive current draw or a short circuit will cause the PCM to turn the driver off during the remainder of that ignition cycle. The PCM will not turn the driver back on until the ignition is cycled off, and back on, and the current draw or short circuit is gone. The PCM illuminates the MIL lamp and the ETC lamp immediately after the diagnostic runs and fails. During this time the customer may experience low power. The PCM turns off the MIL lamp after the diagnostic runs and passes in four consecutive drive cycles.