Fuel Pump Relay: Description and Operation

Relay Identification:

Purpose

Relay supplies battery voltage to the fuel pump and oxygen sensor heater element, when grounded by the Powertrain Control Module (PCM).

Operation

The PCM grounds the relay when the ignition switch is in the START or RUN position and the PCM is receiving reference signals from the distributor pick-up.

If the PCM does not receive a signal from the distributor pick-up, (engine not running), the PCM interrupts the relay ground and no voltage is supplied to the fuel pump and oxygen sensor heater element.

Note: The PCM controls the Auto Shutdown (ASD) and fuel pump relays simultaneously, through the same ground circuit.