Pcm Code E23, Est CKT Problem: Description

PCM Code E23 will set under either of following conditions:

• Reference pulses are being received by PCM and by-pass line is low, but PCM detects pulses on EST line. This could be caused by by-pass line shorted to voltage at distributor.
• Reference pulses are being received by PCM and by-pass line is high, but PCM does not detect a signal from EST line. This could be caused by an open or shorted ground circuit on EST line or by-pass line.