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

Relay Locations:

PURPOSE

Relay supplies battery voltage to fuel injectors and ignition coil when energized by engine controller.

OPERATION

Engine controller energizes ASD relay by supplying relay ground, when ignition switch is in START or RUN position and engine controller is receiving a reference signal from distributor.

When the ground is applied, the relay is energized, and voltage is allowed to flow to fuel injectors and ignition coil.

When engine controller does not receive reference signal from ignition system, (indicating engine is not running), then the engine controller interrupts relay ground circuit and no voltage is supplied to fuel injectors and ignition coil.

Engine controller controls fuel pump relay and Auto Shutdown (ASD) relay simultaneously, through same ground circuit.