SAAB WIS ONLINE

Relays

Relays




Main relay

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 shut-off 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-off of the spark plugs.

Fuel pump relay

The fuel pump relay is located in the relay holder under the dashboard adjacent to the steering wheel. The relay supplies the fuel pump and oxygen sensor preheaters.

The fuel pump relay is controlled via the anti-theft alarm's control module from pin 56 of the Trionic engine control module. Grounding pin 56 causes the relay to operate.



If the ignition has been switched off for longer than 15 minutes, the fuel pump relay will operate for 2 seconds when the ignition switch is turned to the ON position. The purpose of this is to build up the fuel pressure prior to pre-injection, which takes place when the crankshaft starts to rotate.

The fuel pump relay then operates as soon as the ECM receives pulses from the crankshaft position sensor.