12 volts comes from the Automatic Shutdown (ASD) relay. The relay turns on for two seconds when the ignition switch is first turned on, then it turns off. It is turned on again by the engine computer when the computer sees engine rotation, (cranking or running). Rotation is indicated by pulses from the pickup assembly in the distributor. The relay sends 12 volts to the ignition coil, alternator field, injector, and fuel pump or pump relay.
You should only have 12 volts to the fuel pump for the first two seconds after turning on the ignition switch, and when the engine is rotating.
Caradiodoc
Monday, March 30th, 2009 AT 4:34 AM
