The fuel pump is activated by a relay that controls the Powertrain Control Module (PCM). The relay function makes it possible for high amperage current to reach the fuel pump without going through the Powertrain Control Module (PCM).
This relay has two sides: a control side and a switch side, which correspond to a coil and a set of electrical contacts respectively. The side with the coil corresponds to the low amperage side. It has a 12-volt power supply when the power switch is passed plus ground. The ground circuit is activated by the PCM controller whenever necessary.
If the fuel pump controller initiates the fuel pump, the PCM initiates the relay coil in the same way, and thus, the coil pulls the electrical contacts closed and thus completes the fuel pump circuit. The fuel pump controller is there to ensure that the voltage flows in the fuel pump activation circuit. Each time the ignition switch is passed, the Powertrain Control Module (PCM) activates the fuel pump circuit for a few seconds, thus activating the fuel pump and safeguarding the system. Again, an RPM signal must be present for the PCM to activate the fuel pump.
The fuel pump controller is always being monitored for faults. When it is turned on, both the controller voltage and the ground circuit voltage must be low, and when the controller is turned off, its voltage and the ground circuit must be high or close to the battery voltage. If the Powertrain Control Module (PCM) does not observe the expected voltage, the DTC code P0230 OBD2 is set.