DTC P023: Ignition Control Circuit Problem: Description

For complete description of how ignition spark is controlled by the PCM and Ignition Control Module, refer to THEORY & OPERATION -- ALLANTE article. Code P023 will set under either of the two following conditions:

1. 4X reference pulses are being received by the PCM and the bypass line is low, and the PCM detects pulses on the ignition control line. This could be caused by the bypass line shorted to voltage, or a faulty ignition control module.
2. 4X reference pulses are being received by the PCM and the bypass line is high, and the PCM does NOT detect a signal on the ignition control line. This could be caused by an open or a shorted to ground ignition control line or bypass line open or shorted to ground.