Theory Of Operation
The Direct Injection system sprays fuel at a very high pressure directly into the combustion chamber. There are two sides to the fuel system, the low pressure (supply) side and high pressure (control) side. The high pressure side is monitored using feedback from the Fuel Rail Pressure Sensor (FRPS). The Powertrain Control Module (PCM) provides a shared 5-Volt supply and sensor ground to the FRP Sensor. There are two internal pressure sensor signals that provided to the PCM. The PCM performs typical circuit diagnostics on signal 1.
The PCM does not monitor or set faults against FRP Sensor Signal 2.
The fuel system is under a constant pressure (even with engine off). Before servicing any fuel system hose, fitting or line, fuel system pressure must be released. Refer to FUEL SYSTEM PRESSURE RELEASE .