Main Relay (Computer/Fuel System): Description and Operation

PGM-FI Main Relay Schematic View:

PURPOSE
Supplies power to the fuel injectors, Engine Control Module (ECM), and fuel pump.

OPERATION
One relay is energized whenever the ignition is on which supplies the battery voltage to the ECM, power to the fuel injectors, and power for the second relay. The second relay is energized for 2 seconds when the ignition is switched on, and when the engine is running, to supply power to the fuel pump.

CONSTRUCTION
The Programmed Fuel Injection (PGM-FI) Main Relay actually contains two individual relays.