PRIZM GSI

Ignition system consists of a distributor which uses a signal rotor and pick-up coil/crank angle sensor to produce reference signals to the ECM. External ignitor is mounted on right side of firewall in engine compartment.

Power for ignition coil is provided through the ignition switch. As rotating signal rotor passes pole piece of pick-up coil/crank angle sensor, a reference signal is sent to the ECM and ignitor. The ignitor sends a RPM reference signal to the ECM. The ECM uses reference signals to determine when to signal the ignitor to open ground circuit for primary ignition.

When ignitor opens ground circuit for primary ignition, magnetic field around ignition coil windings collapses, producing an induced high voltage surge used to operate the spark plugs. Ignitor sends a signal back to ECM to confirm primary ignition circuit operation was completed.