Monitor Description

To monitor the fuel pump (for low pressure side) circuit, the ECM checks the fuel pump control signal (FPC) and diagnostic signal (DI). The FPC voltage varies between approximately 0 V to approximately 12 V (duty signal). Based on the condition of the fuel pump control ECU malfunction, the DI voltage varies between approximately 0 V and approximately 12 V. The ECM then compares the variance of the FPC voltage and DI voltage, and determines if the fuel pump circuit is malfunctioning. When the ECM determines that the fuel pump circuit is malfunctioning, a DTC is set immediately.