Auto Shutdown (ASD) Relay
Power to the fuel pump is supplied through the Auto Shutdown (ASD) relay and the SMEC. The ASD interrupts power to the fuel pump when the ignition switch is in "RUN" position and no distributor signal is present. When the SMEC receives a signal from the distributor during engine cranking, it grounds ASD relay, closing the contacts. When contacts are closed, power is applied to fuel pump. When distributor signal is lost, the SMEC opens the ASD relay, which cuts power supply to fuel pump, fuel injectors and ignition coil. This prevents fuel flow should the vehicle be involved in an accident or if engine stalls. See Fig 1 .