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

Power Supply Circuit:

PURPOSE/OPERATION
The control relay supplies positive current to purge solenoid, air flow sensor, engine control module, and injectors. When the ignition switch is turned on, battery voltage is applied from the ignition switch to the engine control module. This is turns ON the ignition power transistor and energizes the multipoint fuel injection control relay coil. This turns ON the multipoint fuel injection control relay switch and power is supplied from the battery to the engine control module through the multipoint fuel injection control relay switch.