Ignition Circuit Sense

Purpose

Signal indicates to the Control Module that the ignition circuit is energized, and the engine is being rotated, (by combustion or the starter motor).

Based on this information the PCM decides whether or not to energize the fuel pump, fuel injectors, ignition coil(s) and oxygen sensor heater element.

Operation

When the key is in the on position, the PCM constantly monitors the ignition circuit.

- A pulsed signal at this input indicates that the ignition system has been activated by the ignition switch, and the engine is rotating.

- When a signal is being received by the PCM, the PCM energizes the Auto Shutdown (ASD) and fuel pump relays. These two relays supply battery voltage to; the fuel injector(s), fuel pump, ignition coil(s) and oxygen sensor heater.