Circuit Description

The PCM provides ignition voltage to control fuel pump relay. PCM has the ability to detect electrical malfunction on relay control circuit. When ignition switch is first turned on, PCM energizes fuel pump relay which then applies power to fuel pump. Relay will remain on as long as engine is running or cranking and the PCM is receiving reference pulses.

If no reference pulses are present, PCM de-energizes fuel pump relay within 2 seconds after ignition is turned on or engine is stopped. Fuel pump can be activated by using scan tool's output controls function, even with engine off.

DTC will set when PCM detects an electrical malfunction on fuel pump relay control circuit and condition is present for 0.5 second.