Code 16 - OPTI-Spark Ignition System - Low Resolution Pulse: Notes

Ignition system supplies 2 timing inputs to ECM, a high resolution signal (360 pulses per camshaft revolution) and a low resolution signal (8 pulses per camshaft revolution). ECM can determine if either timing input is not being received by comparing inputs. If ECM detects high resolution pulse without detecting low pulse, Code 16 will set. Reference signal on resolution line toggles between zero and 5 volts as camshaft turns.

1. Code 16 will set if 720 high resolution timing pulses occur before any low resolution pulses are detected.
2. This step determines if ECM is sending out a signal to distributor for processing. If this signal is not available or is shorted to ground or voltage, distributor cannot ground it to produce reference pulses.