Circuit Description

Fuel pump relay coil is supplied power via main relay (switched battery feed). ECM controls relay by grounding control circuit via an internal driver.

Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by ECM. When ECM is commanding a component on, voltage of control circuit should be low (near zero). When ECM is commanding control circuit to component off, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, this DTC will set.

When ECM detects reference pulses from Crankshaft Position (CKP) sensor, ECM will enable fuel pump. Relay is used to control high current flow to fuel pump. This allows ECM driver to only have to handle relatively low current used by relay.

Conditions for setting DTC:

• A short to ground, open, or short to battery voltage detected on control circuit.