Circuit Description

The engine control module (ECM) provides ignition voltage to the coil side of the fuel pump relay whenever the engine is cranking or running. The control module enables the fuel pump relay as long as the engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, the control module de-energizes the fuel pump.

The fuel pump relay control circuit is pulled up to 2.5 volts within the ECM using a bypass resistor that is connected internally to ignition voltage. This resistor allows the ECM to detect a high voltage condition if the fuel pump control circuit is open when the pump relay is not commanded ON. The control module monitors the voltage on the fuel pump relay control circuit. If the ECM detects a low voltage condition on the control circuit with the engine cranking or running, this DTC sets.