Circuit Description

PCM provides ignition voltage to control fuel pump. PCM has ability to detect an electrical malfunction on relay control circuit. When ignition is first turned on, PCM energizes fuel pump relay which applies power to fuel pump. Fuel pump relay will remain on as long engine is running or cranking and 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. With engine off/stopped, fuel pump can be turned on by using scan tool output controls function. If electrical malfunction is detected, DTC will set.

Conditions for setting DTC:

• Ignition is on.
• PCM detects an electrical malfunction on fuel pump relay control circuit.
• Conditions met for .5 second.