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

The main relay is located in the relay holder under the dashboard by the steering wheel.

The relay supplies the injectors, ignition discharge module, idle air control valve, EVAP canister purge valve and the evaporative emission canister's shutoff valve. The main relay is controlled from engine control module pin 31. The relay operates when this pin is grounded.

If the ignition has been switched off for more than 15 minutes, the main relay will operate for 6 seconds when the ignition switch is turned to the ON position.

The main relay then operates as soon as the ECM receives pulses from the crankshaft position sensor. When the engine has been stopped, the main relay continues to operate for approx. 6 seconds in order to supply the ignition discharge module and allow burn-of of the spark plugs.