Circuit Description

In a direct fuel injection system, fuel is taken from the fuel tank by the low-pressure fuel pump and delivered to the high-pressure fuel pump installed to the cylinder head. The high -pressure pump increases fuel pressure to 5-10 MPa and injects the fuel directly into the cylinders through the fuel injectors. Fuel volume in the low-pressure fuel line is maintained by the fuel pump controller in response to PWM sensor signals from the ECM. The ECM sends these signals in response to pressure sensor feedback. Under moderate temperature conditions, line pressure is maintained at a constant 380 kPa. In torrid areas, line pressure is maintained at a constant 550 kPa.

The low pressure fuel pump relay is controlled by the ECM. The relay becomes active 3 seconds after the ignition switch is turned to the ON position. If the engine is started, the relay remains active (current flow continues through the relay). If the engine is not started, the relay becomes inactive.

The injector power device (IPD) is built-into the ECM. The IPD has a diagnostic function that monitors output circuit condition. The ECM interprets the data from the IPD to determine whether or not there are abnormalities in the output circuit.

If an open area is detected in the low-pressure fuel delivery system circuit or its related circuitry, the code data is stored in memory.