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

Power Distribution Center:

The ASD relay supplies voltage to the ignition coil, and fuel injectors. It is not located inside the SBEC, but it is turned OFF and ON by the SBEC (controls the ground). The Crankshaft Position Sensor (CPS) signal goes directly to the SBEC II, and in the event that the SBEC II sees no signal, the ground is removed from the ASD circuit. If the ignition switch is ON and the engine is OFF, the SBEC II will allow the ground to be applied to the ASD for approximately 3 seconds, then if no Crankshaft Position Sensor (CPS) signal is sensed the SBEC II removes the ground from the circuit. If the ground is removed from the ASD relay circuit, then the ASD relay acts as an OPEN switch in the power circuits to the fuel injectors, and ignition coil causing a no start condition.